With data-client added as library module (#3656)

* With data-client added as library module

* Fix build

data-client/.gitignore

@@ -0,0 +1,59 @@
+# Built application files
+*.apk
+*.ap_
+
+# Files for the ART/Dalvik VM
+*.dex
+
+# Java class files
+*.class
+
+# Generated files
+bin/
+gen/
+out/
+
+# Gradle files
+.gradle/
+build/
+
+# Local configuration file (sdk path, etc)
+local.properties
+
+# Proguard folder generated by Eclipse
+proguard/
+
+# Log Files
+*.log
+
+# Android Studio Navigation editor temp files
+.navigation/
+
+# Android Studio captures folder
+captures/
+
+# IntelliJ
+*.iml
+.idea/
+
+# Keystore files
+# Uncomment the following line if you do not want to check your keystore files in.
+#*.jks
+
+# External native build folder generated in Android Studio 2.2 and later
+.externalNativeBuild
+
+# Google Services (e.g. APIs or Firebase)
+google-services.json
+
+# Freeline
+freeline.py
+freeline/
+freeline_project_description.json
+
+# fastlane
+fastlane/report.xml
+fastlane/Preview.html
+fastlane/screenshots
+fastlane/test_output
+fastlane/readme.md

data-client/.travis.yml

@@ -0,0 +1,23 @@
+language: android
+jdk: oraclejdk8
+android:
+  components:
+    - platform-tools
+    - tools
+
+    # The BuildTools version used by your project
+    - build-tools-28.0.3
+
+    # The SDK version used to compile your project
+    - android-28
+
+    # Additional components
+    - extra-android-m2repository
+
+licenses:
+    - android-sdk-preview-license-.+
+    - android-sdk-license-.+
+before_script:
+    - chmod +x gradlew
+
+script: "./gradlew test"

data-client/LICENSE

@@ -0,0 +1,201 @@
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+
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data-client/README.md

@@ -0,0 +1,101 @@
+# Wikimedia Android data client
+An Android library for communicating with Wikimedia projects, with Rx bindings and other utilities.
+
+## Motivation and philosophy
+
+Here are the purposes for creating this library:
+
+* Encapsulate the various model structures that are returned by MediaWiki APIs,
+as well as by REST APIs provided by Wikimedia services.
+
+* Provide high-level bindings for Retrofit and RxJava for executing calls to MediaWiki APIs to
+further simplify client integration, while also allowing customization and extension.
+
+* Provide numerous common utility methods, so that they don't need to be duplicated.
+
+## Integration with your app
+
+Add the dependency to your Gradle file as usual:
+
+```
+implementation "com.dmitrybrant:wikimedia-android-data-client:0.0.18"
+```
+
+The only nontrivial point of integration with the library is the `AppAdapter` class:  You
+need to create a class that inherits from `AppAdapter` and implement its methods.  The
+methods are mostly self-explanatory, and deal with user account management, cookie storage,
+and a few other customizations.
+
+Once you create this class (suppose it's called `MyAppAdapter`), you should pass it into
+the `AppAdapter` singleton when your app starts:
+
+```
+@Override
+public void onCreate() {
+    ...
+    AppAdapter.set(new MyAppAdapter());
+    ...
+}
+```
+
+## Making calls to APIs
+
+Notice that there is an interface called `Service` that contains a number of API definitions
+for talking with a MediaWiki server. To use any of the functions in the interface, you should
+use the `ServiceFactory` class. For example:
+
+```
+WikiSite wiki = new WikiSite("en.wikipedia.org");
+
+Observable observable = ServiceFactory.get(wiki).fullTextSearch("foo");
+```
+
+That's it! Notice that most of the API calls return an `Observable` response which you can
+feed into an Rx subscription.
+
+Note: the `ServiceFactory` class contains automatic caching logic, so that multiple calls to
+`get()` the service for the same `WikiSite` will be very efficient.
+
+## Custom API calls
+
+The `ServiceFactory` class also allows you to provide a service interface with custom
+API functions. Suppose you create your own service interface that looks like this:
+
+```
+public interface MyInterface {
+
+    @GET("action=myawesomeaction")
+    Observable<MyAwesomeResponse> myAwesomeApiCall(@Query("parameter1") parameter);
+
+}
+```
+
+You can then use it with `ServiceFactory` this way:
+
+```
+WikiSite wiki = new WikiSite("my.awesome.wiki");
+
+Observable observable = ServiceFactory.get(wiki, "https://my.awesome.wiki/", MyInterface.class)
+        .myAwesomeApiCall("foo");
+```
+
+## Utility methods
+
+The library contains a potpourri of utility methods found under the `util` package. Feel free
+to browse through them and use them as necessary.
+
+## License
+
+Copyright 2019 Wikimedia Foundation
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

data-client/build.gradle

@@ -0,0 +1,147 @@
+buildscript {
+    ext.kotlin_version = '1.3.31'
+    repositories {
+        jcenter()
+        google()
+    }
+    dependencies {
+        classpath "com.android.tools.build:gradle:3.4.1"
+        classpath "com.github.dcendents:android-maven-gradle-plugin:2.1"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+plugins {
+    id "com.jfrog.bintray" version "1.7.3"
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+    apply plugin: 'com.android.library'
+    apply plugin: 'kotlin-android'
+    apply plugin: 'kotlin-android-extensions'
+
+    apply plugin: 'com.github.dcendents.android-maven'
+    apply plugin: 'com.jfrog.bintray'
+}
+
+version = "${VERSION_NAME}"
+group = "${GROUP_ID}"
+
+android {
+    compileSdkVersion 28
+
+    defaultConfig {
+        minSdkVersion 19
+        targetSdkVersion 28
+        versionCode 1
+        versionName "${VERSION_NAME}"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+    lintOptions {
+        abortOnError false
+    }
+    compileOptions {
+        sourceCompatibility = '1.8'
+        targetCompatibility = '1.8'
+    }
+}
+
+dependencies {
+
+    String retrofitVersion = '2.4.0'
+
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+
+    implementation "androidx.core:core:1.0.2"
+    implementation "com.squareup.retrofit2:retrofit:$retrofitVersion"
+    implementation "com.squareup.retrofit2:converter-gson:$retrofitVersion"
+    implementation "com.squareup.retrofit2:adapter-rxjava2:$retrofitVersion"
+    implementation "io.reactivex.rxjava2:rxjava:2.2.3"
+    implementation "io.reactivex.rxjava2:rxandroid:2.1.0"
+    implementation 'org.apache.commons:commons-lang3:3.8.1'
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
+
+    testImplementation 'junit:junit:4.12'
+    testImplementation 'org.mockito:mockito-core:2.8.9'
+    testImplementation 'org.robolectric:robolectric:3.8'
+    testImplementation "com.squareup.okhttp3:mockwebserver:3.12.1"
+    testImplementation "commons-io:commons-io:2.6"
+}
+
+task sourcesJar(type: Jar) {
+    from android.sourceSets.main.java.srcDirs
+    classifier = 'sources'
+}
+artifacts {
+    archives sourcesJar
+}
+
+Properties properties = new Properties()
+if ( project.rootProject.file('local.properties').isFile() ) {
+    properties.load(project.rootProject.file('local.properties').newDataInputStream())
+}
+
+bintray {
+    user = properties.getProperty("bintray.user")
+    key = properties.getProperty("bintray.apikey")
+	println 'Bintray user: ' + user
+    configurations = ['archives']
+    pkg {
+        repo = 'maven'
+        name = "${ARTIFACT_ID}"
+        vcsUrl = 'https://github.com/wikimedia/wikimedia-android-data-client.git'
+        licenses = ['Apache-2.0']
+        version {
+            name = "${VERSION_NAME}"
+        }
+        publish = true
+    }
+}
+
+install {
+    repositories.mavenInstaller {
+        // This generates POM.xml with proper parameters
+        pom {
+            project {
+                packaging 'aar'
+
+                name "${ARTIFACT_ID}"
+                artifactId "${ARTIFACT_ID}"
+                description 'Android library for accessing the Wikimedia APIs.'
+                url 'https://github.com/wikimedia/wikimedia-android-data-client'
+                inceptionYear '2019'
+
+                licenses {
+                    license {
+                        name 'The Apache Software License, Version 2.0'
+                        url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
+                    }
+                }
+                developers {
+                    developer {
+                        id 'dmitrybrant'
+                        name 'Dmitry Brant'
+                        email 'me@dmitrybrant.com'
+                    }
+                }
+            }
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+}

data-client/gradle.properties

@@ -0,0 +1,25 @@
+# Project-wide Gradle settings.
+
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+# Default value: -Xmx10248m -XX:MaxPermSize=256m
+# org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
+
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+
+VERSION_NAME=0.0.27
+GROUP_ID=com.dmitrybrant
+ARTIFACT_ID=wikimedia-android-data-client
+GRADLE_BINTRAY_PLUGIN_VERSION=1.7.3
+android.useAndroidX=true
+android.enableJetifier=true

data-client/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Fri Jun 07 09:14:55 EDT 2019
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-all.zip

data-client/gradlew

@@ -0,0 +1,160 @@
+#!/usr/bin/env bash
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn ( ) {
+    echo "$*"
+}
+
+die ( ) {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+esac
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
+function splitJvmOpts() {
+    JVM_OPTS=("$@")
+}
+eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
+JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+
+exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"

data-client/gradlew.bat

@@ -0,0 +1,90 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windowz variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+if "%@eval[2+2]" == "4" goto 4NT_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+goto execute
+
+:4NT_args
+@rem Get arguments from the 4NT Shell from JP Software
+set CMD_LINE_ARGS=%$
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

data-client/proguard-rules.pro

@@ -0,0 +1,25 @@
+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in F:\android-sdk-windows/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

data-client/scripts/generate_wiki_languages.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python
+# coding=utf-8
+
+from datetime import datetime, timedelta
+import lxml
+import lxml.builder as lb
+import json
+import requests
+
+
+QUERY_SITEMATRIX = 'https://www.mediawiki.org/w/api.php?action=sitematrix' \
+    '&format=json&formatversion=2&smtype=language&smstate=all'
+
+QUERY_ALLUSERS = '/w/api.php?action=query&format=json&formatversion=2&list=allusers' \
+    '&aulimit=50&auactiveusers=1&auwitheditsonly=1'
+
+lang_keys = []
+lang_local_names = []
+lang_eng_names = []
+lang_rank = []
+
+
+def add_lang(key, local_name, eng_name, rank):
+    rank_pos = 0
+    # Automatically keep the arrays sorted by rank
+    for index, item in enumerate(lang_rank):
+        rank_pos = index
+        if (rank > item):
+            break
+    lang_keys.insert(rank_pos, key)
+    lang_local_names.insert(rank_pos, local_name)
+    lang_eng_names.insert(rank_pos, eng_name)
+    lang_rank.insert(rank_pos, rank)
+
+
+data = json.loads(requests.get(QUERY_SITEMATRIX).text)
+
+for key, value in data[u"sitematrix"].items():
+    if type(value) is not dict:
+        continue
+    language_code = value[u"code"]
+    if language_code == 'got':
+        # 'got' is Gothic Runes, which lie outside the Basic Multilingual Plane
+        # Android segfaults on these. So let's ignore those.
+        continue
+    site_list = value[u"site"]
+    if type(site_list) is not list:
+        continue
+    wikipedia_url = ""
+    for site in site_list:
+        if "wikipedia.org" in site[u"url"] and u"closed" not in site:
+            wikipedia_url = site[u"url"]
+    if len(wikipedia_url) == 0:
+        continue
+    # TODO: If we want to remove languages with too few active users:
+    # allusers = json.loads(requests.get(wikipedia_url + QUERY_ALLUSERS).text)
+    # if len(allusers[u"query"][u"allusers"]) < 10:
+    #    print ("Excluding " + language_code + " (too few active users).")
+    #    continue
+    # Use the AQS API to get total pageviews for this language wiki in the last month:
+    date = datetime.today() - timedelta(days=31)
+    unique_device_response = json.loads(requests.get('https://wikimedia.org/api/rest_v1/metrics/unique-devices/' +
+                                                     wikipedia_url.replace('https://', '') + '/all-sites/monthly/' +
+                                                     date.strftime('%Y%m01') + '/' + date.strftime('%Y%m01')).text)
+    rank = 0
+    if u"items" in unique_device_response:
+        if len(unique_device_response[u"items"]) > 0:
+            rank = unique_device_response[u"items"][0][u"devices"]
+    print ("Rank for " + language_code + ": " + str(rank))
+    if language_code == 'zh':
+        add_lang(key='zh-hans', local_name=u'简体中文',
+                 eng_name='Simplified Chinese', rank=rank)
+        add_lang(key='zh-hant', local_name=u'繁體中文',
+                 eng_name='Traditional Chinese', rank=rank)
+        continue
+    if language_code == 'no':  # T114042
+        language_code = 'nb'
+    add_lang(language_code, value[u"name"].replace("'", "\\'"), value[u"localname"].replace("'", "\\'"), rank)
+
+
+add_lang(key='test', local_name='Test', eng_name='Test', rank=0)
+add_lang(key='en-x-piglatin', local_name='Igpay Atinlay', eng_name='Pig Latin', rank=0)
+
+# Generate the XML, for Android
+NAMESPACE = 'http://schemas.android.com/tools'
+TOOLS = '{%s}' % NAMESPACE
+x = lb.ElementMaker(nsmap={'tools': NAMESPACE})
+
+keys = [x.item(k) for k in lang_keys]
+local_names = [x.item(k) for k in lang_local_names]
+eng_names = [x.item(k) for k in lang_eng_names]
+
+resources = x.resources(
+    getattr(x, 'string-array')(*keys, name='preference_language_keys'),
+    getattr(x, 'string-array')(*local_names, name='preference_language_local_names'),
+    getattr(x, 'string-array')(*eng_names, name='preference_language_canonical_names'))
+resources.set(TOOLS + 'ignore', 'MissingTranslation')
+
+with open('../src/main/res/values/languages_list.xml', 'wb') as f:
+    f.write(lxml.etree.tostring(resources, pretty_print=True,
+                                xml_declaration=True, encoding='utf-8'))

data-client/scripts/make-templates.py

@@ -0,0 +1,183 @@
+#!/usr/bin/env python
+# coding=utf-8
+
+import copy
+import os
+import json
+import codecs
+import requests
+from jinja2 import Environment, FileSystemLoader
+
+
+CHINESE_WIKI_LANG = "zh"
+SIMPLIFIED_CHINESE_LANG = "zh-hans"
+TRADITIONAL_CHINESE_LANG = "zh-hant"
+
+# T114042
+NORWEGIAN_BOKMAL_WIKI_LANG = "no"
+NORWEGIAN_BOKMAL_LANG = "nb"
+
+
+# Wikis that cause problems and hence we pretend
+# do not exist.
+# - "got" -> Gothic runes wiki. The name of got in got
+#   contains characters outside the Unicode BMP. Android
+#   hard crashes on these. Let's ignore these fellas
+#   for now.
+# - "mo" -> Moldovan, which automatically redirects to Romanian (ro),
+#   which already exists in our list.
+OSTRICH_WIKIS = [u"got", "mo"]
+
+
+# Represents a single wiki, along with arbitrary properties of that wiki
+# Simple data container object
+class Wiki(object):
+    def __init__(self, lang):
+        self.lang = lang
+        self.props = {}
+
+
+# Represents a list of wikis plus their properties.
+# Encapsulates rendering code as well
+class WikiList(object):
+    def __init__(self, wikis):
+        self.wikis = wikis
+        self.template_env = Environment(loader=FileSystemLoader(
+            os.path.join(os.path.dirname(os.path.realpath(__file__)), u"templates")
+            ))
+
+    def render(self, template, class_name, **kwargs):
+        data = {
+            u"class_name": class_name,
+            u"wikis": self.wikis
+        }
+        data.update(kwargs)
+        rendered = self.template_env.get_template(template).render(**data)
+        out = codecs.open(u"../src/main/java/org/wikipedia/staticdata/" + class_name + u".java", u"w", u"utf-8")
+        out.write(rendered)
+        out.close()
+
+
+def build_wiki(lang, english_name, local_name):
+    wiki = Wiki(lang)
+    wiki.props["english_name"] = english_name
+    wiki.props["local_name"] = local_name
+    return wiki
+
+
+def list_from_sitematrix():
+    QUERY_SITEMATRIX = 'https://www.mediawiki.org/w/api.php?action=sitematrix' \
+        '&format=json&formatversion=2&smtype=language&smstate=all'
+
+    print(u"Fetching languages...")
+    data = json.loads(requests.get(QUERY_SITEMATRIX).text)
+    wikis = []
+
+    for key, value in data[u"sitematrix"].items():
+        if type(value) is not dict:
+            continue
+        site_list = value[u"site"]
+        if type(site_list) is not list:
+            continue
+        wikipedia_url = ""
+        for site in site_list:
+            if "wikipedia.org" in site[u"url"] and u"closed" not in site:
+                wikipedia_url = site[u"url"]
+        if len(wikipedia_url) == 0:
+            continue
+        wikis.append(build_wiki(value[u"code"], value[u"localname"], value[u"name"]))
+
+    return wikis
+
+
+# Remove unsupported wikis.
+def filter_supported_wikis(wikis):
+    return [wiki for wiki in wikis if wiki.lang not in OSTRICH_WIKIS]
+
+
+# Apply manual tweaks to the list of wikis before they're populated.
+def preprocess_wikis(wikis):
+    # Add TestWiki.
+    wikis.append(build_wiki(lang="test", english_name="Test", local_name="Test"))
+
+    return wikis
+
+
+# Apply manual tweaks to the list of wikis after they're populated.
+def postprocess_wikis(wiki_list):
+    # Add Simplified and Traditional Chinese dialects.
+    chineseWiki = next((wiki for wiki in wiki_list.wikis if wiki.lang == CHINESE_WIKI_LANG), None)
+    chineseWikiIndex = wiki_list.wikis.index(chineseWiki)
+
+    simplifiedWiki = copy.deepcopy(chineseWiki)
+    simplifiedWiki.lang = SIMPLIFIED_CHINESE_LANG
+    simplifiedWiki.props["english_name"] = "Simplified Chinese"
+    simplifiedWiki.props["local_name"] = "简体中文"
+    wiki_list.wikis.insert(chineseWikiIndex + 1, simplifiedWiki)
+
+    traditionalWiki = copy.deepcopy(chineseWiki)
+    traditionalWiki.lang = TRADITIONAL_CHINESE_LANG
+    traditionalWiki.props["english_name"] = "Traditional Chinese"
+    traditionalWiki.props["local_name"] = "繁體中文"
+    wiki_list.wikis.insert(chineseWikiIndex + 2, traditionalWiki)
+
+    bokmalWiki = next((wiki for wiki in wiki_list.wikis if wiki.lang == NORWEGIAN_BOKMAL_WIKI_LANG), None)
+    bokmalWiki.lang = NORWEGIAN_BOKMAL_LANG
+
+    return wiki_list
+
+
+# Populate the aliases for "Special:" and "File:" in all wikis
+def populate_aliases(wikis):
+    for wiki in wikis.wikis:
+        print(u"Fetching Special Page and File alias for %s" % wiki.lang)
+        url = u"https://%s.wikipedia.org/w/api.php" % wiki.lang + \
+              u"?action=query&meta=siteinfo&format=json&siprop=namespaces"
+        data = json.loads(requests.get(url).text)
+        # according to https://www.mediawiki.org/wiki/Manual:Namespace
+        # -1 seems to be the ID for Special Pages
+        wiki.props[u"special_alias"] = data[u"query"][u"namespaces"][u"-1"][u"*"]
+        # 6 is the ID for File pages
+        wiki.props[u"file_alias"] = data[u"query"][u"namespaces"][u"6"][u"*"]
+    return wikis
+
+
+# Populates data on names of main page in each wiki
+def populate_main_pages(wikis):
+    for wiki in wikis.wikis:
+        print(u"Fetching Main Page for %s" % wiki.lang)
+        url = u"https://%s.wikipedia.org/w/api.php" % wiki.lang + \
+              u"?action=query&meta=siteinfo&format=json&siprop=general"
+        data = json.loads(requests.get(url).text)
+        wiki.props[u"main_page_name"] = data[u"query"][u"general"][u"mainpage"]
+    return wikis
+
+
+# Returns a function that renders a particular template when passed
+# a WikiList object
+def render_template(template, filename, **kwargs):
+    def _actual_render(wikis):
+        wikis.render(template, filename, **kwargs)
+        return wikis
+    return _actual_render
+
+
+# Kinda like reduce(), but special cases first function
+def chain(*funcs):
+    res = funcs[0]()
+    for func in funcs[1:]:
+        res = func(res)
+
+
+chain(
+    list_from_sitematrix,
+    filter_supported_wikis,
+    preprocess_wikis,
+    WikiList,
+    populate_aliases,
+    populate_main_pages,
+    postprocess_wikis,
+    render_template(u"basichash.java.jinja", u"SpecialAliasData", key=u"special_alias"),
+    render_template(u"basichash.java.jinja", u"FileAliasData", key=u"file_alias"),
+    render_template(u"basichash.java.jinja", u"MainPageNameData", key=u"main_page_name"),
+)

data-client/scripts/templates/basichash.java.jinja

@@ -0,0 +1,36 @@
+/*
+This file is auto-generated from a template (/scripts/templates).
+If you need to modify it, make sure to modify the template, not this file.
+*/
+package org.wikipedia.staticdata;
+
+import android.support.annotation.NonNull;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+public final class {{class_name}} {
+    @NonNull private static final Map<String, String> DATA_MAP = Collections.unmodifiableMap(newMap());
+
+    @NonNull public static String valueFor(String key) {
+        if (DATA_MAP.containsKey(key)) {
+            return DATA_MAP.get(key);
+        }
+        return DATA_MAP.get("en");
+    }
+
+    @SuppressWarnings({"checkstyle:methodlength", "SpellCheckingInspection"})
+    private static Map<String, String> newMap() {
+        final int size = {{wikis|length}};
+        Map<String, String> map = new HashMap<>(size);
+
+        {%- for wiki in wikis %}
+        map.put("{{wiki.lang}}", "{{wiki.props[key]}}");
+        {%- endfor %}
+        return map;
+    }
+
+    private {{class_name}}() { }
+}
+

data-client/src/main/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="org.wikipedia.dataclient">
+    <application android:allowBackup="true" android:label="@string/app_name" android:supportsRtl="true">
+    </application>
+</manifest>

data-client/src/main/java/org/wikipedia/AppAdapter.java

@@ -0,0 +1,38 @@
+package org.wikipedia;
+
+import androidx.annotation.NonNull;
+
+import org.wikipedia.dataclient.SharedPreferenceCookieManager;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.login.LoginResult;
+
+import okhttp3.OkHttpClient;
+
+public abstract class AppAdapter {
+
+    public abstract String getMediaWikiBaseUrl();
+    public abstract String getRestbaseUriFormat();
+    public abstract OkHttpClient getOkHttpClient(@NonNull WikiSite wikiSite);
+    public abstract int getDesiredLeadImageDp();
+
+    public abstract boolean isLoggedIn();
+    public abstract String getUserName();
+    public abstract String getPassword();
+    public abstract void updateAccount(@NonNull LoginResult result);
+
+    public abstract SharedPreferenceCookieManager getCookies();
+    public abstract void setCookies(@NonNull SharedPreferenceCookieManager cookies);
+
+    public abstract boolean logErrorsInsteadOfCrashing();
+
+    private static AppAdapter INSTANCE;
+    public static void set(AppAdapter instance) {
+        INSTANCE = instance;
+    }
+    public static AppAdapter get() {
+        if (INSTANCE == null) {
+            throw new RuntimeException("Please provide an instance of AppAdapter when using this library.");
+        }
+        return INSTANCE;
+    }
+}

data-client/src/main/java/org/wikipedia/captcha/Captcha.java

@@ -0,0 +1,19 @@
+package org.wikipedia.captcha;
+
+import androidx.annotation.NonNull;
+
+import org.wikipedia.dataclient.mwapi.MwResponse;
+
+public class Captcha extends MwResponse {
+    @SuppressWarnings("unused,NullableProblems") @NonNull private FancyCaptchaReload fancycaptchareload;
+    @NonNull String captchaId() {
+        return fancycaptchareload.index();
+    }
+
+    private static class FancyCaptchaReload {
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String index;
+        @NonNull String index() {
+            return index;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/captcha/CaptchaResult.java

@@ -0,0 +1,49 @@
+package org.wikipedia.captcha;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.edit.EditResult;
+
+// Handles only Image Captchas
+public class CaptchaResult extends EditResult {
+    private final String captchaId;
+
+    public CaptchaResult(String captchaId) {
+        super("Failure");
+        this.captchaId = captchaId;
+    }
+
+    protected CaptchaResult(Parcel in) {
+        super(in);
+        captchaId = in.readString();
+    }
+
+    public String getCaptchaId() {
+        return captchaId;
+    }
+
+    public String getCaptchaUrl(WikiSite wiki) {
+        return wiki.url("index.php") + "?title=Special:Captcha/image&wpCaptchaId=" + captchaId;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        super.writeToParcel(dest, flags);
+        dest.writeString(captchaId);
+    }
+
+    public static final Parcelable.Creator<CaptchaResult> CREATOR
+            = new Parcelable.Creator<CaptchaResult>() {
+        @Override
+        public CaptchaResult createFromParcel(Parcel in) {
+            return new CaptchaResult(in);
+        }
+
+        @Override
+        public CaptchaResult[] newArray(int size) {
+            return new CaptchaResult[size];
+        }
+    };
+}

data-client/src/main/java/org/wikipedia/concurrency/RxBus.java

@@ -0,0 +1,26 @@
+package org.wikipedia.concurrency;
+
+import androidx.annotation.NonNull;
+
+import io.reactivex.Observable;
+import io.reactivex.android.schedulers.AndroidSchedulers;
+import io.reactivex.annotations.CheckReturnValue;
+import io.reactivex.disposables.Disposable;
+import io.reactivex.functions.Consumer;
+import io.reactivex.subjects.PublishSubject;
+import io.reactivex.subjects.Subject;
+
+public class RxBus {
+
+    private final Subject<Object> bus = PublishSubject.create().toSerialized();
+    private final Observable<Object> observable = bus.observeOn(AndroidSchedulers.mainThread());
+
+    public void post(Object o) {
+        bus.onNext(o);
+    }
+
+    @CheckReturnValue
+    public Disposable subscribe(@NonNull Consumer<Object> consumer) {
+        return observable.subscribe(consumer);
+    }
+}

data-client/src/main/java/org/wikipedia/createaccount/CreateAccountException.java

@@ -0,0 +1,12 @@
+package org.wikipedia.createaccount;
+
+import androidx.annotation.NonNull;
+
+/**
+ * Exception thrown when an account creation request FAILs
+ */
+public class CreateAccountException extends RuntimeException {
+    CreateAccountException(@NonNull String message) {
+        super(message);
+    }
+}

data-client/src/main/java/org/wikipedia/createaccount/CreateAccountResult.java

@@ -0,0 +1,57 @@
+package org.wikipedia.createaccount;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import androidx.annotation.NonNull;
+
+public class CreateAccountResult implements Parcelable {
+    @NonNull private final String status;
+    @NonNull private final String message;
+
+    public CreateAccountResult(@NonNull String status, @NonNull String message) {
+        this.status = status;
+        this.message = message;
+    }
+
+    @NonNull
+    public String getStatus() {
+        return status;
+    }
+
+    @NonNull
+    public String getMessage() {
+        return message;
+    }
+
+    @Override
+    public void writeToParcel(Parcel parcel, int flags) {
+        parcel.writeString(status);
+        parcel.writeString(message);
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    protected CreateAccountResult(Parcel in) {
+        status = in.readString();
+        message = in.readString();
+    }
+
+    @NonNull
+    public static final Parcelable.Creator<CreateAccountResult> CREATOR
+            = new Parcelable.Creator<CreateAccountResult>() {
+        @Override
+        public CreateAccountResult createFromParcel(Parcel in) {
+            return new CreateAccountResult(in);
+        }
+
+        @Override
+        public CreateAccountResult[] newArray(int size) {
+            return new CreateAccountResult[size];
+        }
+    };
+
+}

data-client/src/main/java/org/wikipedia/createaccount/CreateAccountSuccessResult.java

@@ -0,0 +1,43 @@
+package org.wikipedia.createaccount;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import androidx.annotation.NonNull;
+
+class CreateAccountSuccessResult extends CreateAccountResult implements Parcelable {
+    private String username;
+
+    CreateAccountSuccessResult(@NonNull String username) {
+        super("PASS", "Account created");
+        this.username = username;
+    }
+
+    String getUsername() {
+        return username;
+    }
+
+    @Override
+    public void writeToParcel(Parcel parcel, int flags) {
+        super.writeToParcel(parcel, flags);
+        parcel.writeString(username);
+    }
+
+    private CreateAccountSuccessResult(Parcel in) {
+        super(in);
+        username = in.readString();
+    }
+
+    public static final Creator<CreateAccountSuccessResult> CREATOR
+            = new Creator<CreateAccountSuccessResult>() {
+        @Override
+        public CreateAccountSuccessResult createFromParcel(Parcel in) {
+            return new CreateAccountSuccessResult(in);
+        }
+
+        @Override
+        public CreateAccountSuccessResult[] newArray(int size) {
+            return new CreateAccountSuccessResult[size];
+        }
+    };
+}

data-client/src/main/java/org/wikipedia/csrf/CsrfTokenClient.java

@@ -0,0 +1,213 @@
+package org.wikipedia.csrf;
+
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+import org.wikipedia.AppAdapter;
+import org.wikipedia.dataclient.Service;
+import org.wikipedia.dataclient.ServiceFactory;
+import org.wikipedia.dataclient.SharedPreferenceCookieManager;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.dataclient.mwapi.MwQueryResponse;
+import org.wikipedia.login.LoginClient;
+import org.wikipedia.login.LoginResult;
+import org.wikipedia.util.log.L;
+
+import java.io.IOException;
+
+import retrofit2.Call;
+import retrofit2.Response;
+
+public class CsrfTokenClient {
+    private static final String ANON_TOKEN = "+\\";
+    private static final int MAX_RETRIES = 1;
+    private static final int MAX_RETRIES_OF_LOGIN_BLOCKING = 2;
+    @NonNull private final WikiSite csrfWikiSite;
+    @NonNull private final WikiSite loginWikiSite;
+    private int retries = 0;
+
+    @Nullable private Call<MwQueryResponse> csrfTokenCall;
+    @NonNull private LoginClient loginClient = new LoginClient();
+
+    public CsrfTokenClient(@NonNull WikiSite csrfWikiSite, @NonNull WikiSite loginWikiSite) {
+        this.csrfWikiSite = csrfWikiSite;
+        this.loginWikiSite = loginWikiSite;
+    }
+
+    public void request(@NonNull final Callback callback) {
+        request(false, callback);
+    }
+
+    public void request(boolean forceLogin, @NonNull final Callback callback) {
+        cancel();
+        if (forceLogin) {
+            retryWithLogin(new RuntimeException("Forcing login..."), callback);
+            return;
+        }
+        csrfTokenCall = request(ServiceFactory.get(csrfWikiSite), callback);
+    }
+
+    public void cancel() {
+        loginClient.cancel();
+        if (csrfTokenCall != null) {
+            csrfTokenCall.cancel();
+            csrfTokenCall = null;
+        }
+    }
+
+    @VisibleForTesting
+    @NonNull
+    Call<MwQueryResponse> request(@NonNull Service service, @NonNull final Callback cb) {
+        return requestToken(service, new CsrfTokenClient.Callback() {
+            @Override public void success(@NonNull String token) {
+                if (AppAdapter.get().isLoggedIn() && token.equals(ANON_TOKEN)) {
+                    retryWithLogin(new RuntimeException("App believes we're logged in, but got anonymous token."), cb);
+                } else {
+                    cb.success(token);
+                }
+            }
+
+            @Override public void failure(@NonNull Throwable caught) {
+                retryWithLogin(caught, cb);
+            }
+
+            @Override
+            public void twoFactorPrompt() {
+                cb.twoFactorPrompt();
+            }
+        });
+    }
+
+    private void retryWithLogin(@NonNull Throwable caught, @NonNull final Callback callback) {
+        if (retries < MAX_RETRIES
+                && !TextUtils.isEmpty(AppAdapter.get().getUserName())
+                && !TextUtils.isEmpty(AppAdapter.get().getPassword())) {
+            retries++;
+
+            SharedPreferenceCookieManager.getInstance().clearAllCookies();
+
+            login(AppAdapter.get().getUserName(), AppAdapter.get().getPassword(), () -> {
+                L.i("retrying...");
+                request(callback);
+            }, callback);
+        } else {
+            callback.failure(caught);
+        }
+    }
+
+    private void login(@NonNull final String username, @NonNull final String password,
+                       @NonNull final RetryCallback retryCallback,
+                       @NonNull final Callback callback) {
+        new LoginClient().request(loginWikiSite, username, password,
+                new LoginClient.LoginCallback() {
+                    @Override
+                    public void success(@NonNull LoginResult loginResult) {
+                        if (loginResult.pass()) {
+                            AppAdapter.get().updateAccount(loginResult);
+                            retryCallback.retry();
+                        } else {
+                            callback.failure(new LoginClient.LoginFailedException(loginResult.getMessage()));
+                        }
+                    }
+
+                    @Override
+                    public void twoFactorPrompt(@NonNull Throwable caught, @Nullable String token) {
+                        callback.twoFactorPrompt();
+                    }
+
+                    @Override public void passwordResetPrompt(@Nullable String token) {
+                        // Should not happen here, but call the callback just in case.
+                        callback.failure(new LoginClient.LoginFailedException("Logged in with temporary password."));
+                    }
+
+                    @Override
+                    public void error(@NonNull Throwable caught) {
+                        callback.failure(caught);
+                    }
+                });
+    }
+
+    @NonNull public String getTokenBlocking() throws Throwable {
+        String token = "";
+        Service service = ServiceFactory.get(csrfWikiSite);
+
+        for (int retry = 0; retry < MAX_RETRIES_OF_LOGIN_BLOCKING; retry++) {
+            try {
+                if (retry > 0) {
+                    // Log in explicitly
+                    new LoginClient().loginBlocking(loginWikiSite, AppAdapter.get().getUserName(),
+                            AppAdapter.get().getPassword(), "");
+                }
+
+                Response<MwQueryResponse> response = service.getCsrfTokenCall().execute();
+                if (response.body() == null || response.body().query() == null
+                        || TextUtils.isEmpty(response.body().query().csrfToken())) {
+                    continue;
+                }
+                token = response.body().query().csrfToken();
+                if (AppAdapter.get().isLoggedIn() && token.equals(ANON_TOKEN)) {
+                    throw new RuntimeException("App believes we're logged in, but got anonymous token.");
+                }
+                break;
+            } catch (Throwable t) {
+                L.w(t);
+            }
+        }
+        if (TextUtils.isEmpty(token) || token.equals(ANON_TOKEN)) {
+            throw new IOException("Invalid token, or login failure.");
+        }
+        return token;
+    }
+
+    @VisibleForTesting @NonNull Call<MwQueryResponse> requestToken(@NonNull Service service,
+                                                                   @NonNull final Callback cb) {
+        Call<MwQueryResponse> call = service.getCsrfTokenCall();
+        call.enqueue(new retrofit2.Callback<MwQueryResponse>() {
+            @Override
+            public void onResponse(@NonNull Call<MwQueryResponse> call, @NonNull Response<MwQueryResponse> response) {
+                if (call.isCanceled()) {
+                    return;
+                }
+                cb.success(response.body().query().csrfToken());
+            }
+
+            @Override
+            public void onFailure(@NonNull Call<MwQueryResponse> call, @NonNull Throwable t) {
+                if (call.isCanceled()) {
+                    return;
+                }
+                cb.failure(t);
+            }
+        });
+        return call;
+    }
+
+    public interface Callback {
+        void success(@NonNull String token);
+        void failure(@NonNull Throwable caught);
+        void twoFactorPrompt();
+    }
+
+    public static class DefaultCallback implements Callback {
+        @Override
+        public void success(@NonNull String token) {
+        }
+
+        @Override
+        public void failure(@NonNull Throwable caught) {
+            L.e(caught);
+        }
+
+        @Override
+        public void twoFactorPrompt() {
+            // TODO:
+        }
+    }
+
+    private interface RetryCallback {
+        void retry();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/RestService.java

@@ -0,0 +1,194 @@
+package org.wikipedia.dataclient;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.restbase.RbDefinition;
+import org.wikipedia.dataclient.restbase.RbRelatedPages;
+import org.wikipedia.dataclient.restbase.page.RbPageLead;
+import org.wikipedia.dataclient.restbase.page.RbPageRemaining;
+import org.wikipedia.dataclient.restbase.page.RbPageSummary;
+import org.wikipedia.feed.aggregated.AggregatedFeedContent;
+import org.wikipedia.feed.announcement.AnnouncementList;
+import org.wikipedia.feed.configure.FeedAvailability;
+import org.wikipedia.feed.onthisday.OnThisDay;
+import org.wikipedia.gallery.Gallery;
+import org.wikipedia.readinglist.sync.SyncedReadingLists;
+
+import java.util.Map;
+
+import io.reactivex.Observable;
+import retrofit2.Call;
+import retrofit2.Response;
+import retrofit2.http.Body;
+import retrofit2.http.DELETE;
+import retrofit2.http.GET;
+import retrofit2.http.Header;
+import retrofit2.http.Headers;
+import retrofit2.http.POST;
+import retrofit2.http.PUT;
+import retrofit2.http.Path;
+import retrofit2.http.Query;
+
+public interface RestService {
+    String REST_API_PREFIX = "api/rest_v1/";
+
+    String ACCEPT_HEADER_PREFIX = "accept: application/json; charset=utf-8; profile=\"https://www.mediawiki.org/wiki/Specs/";
+    String ACCEPT_HEADER_SUMMARY = ACCEPT_HEADER_PREFIX + "Summary/1.2.0\"";
+    String ACCEPT_HEADER_MOBILE_SECTIONS = ACCEPT_HEADER_PREFIX + "mobile-sections/0.12.4\"";
+    String ACCEPT_HEADER_DEFINITION = ACCEPT_HEADER_PREFIX + "definition/0.7.2\"";
+
+    String REST_PAGE_SECTIONS_URL = "page/mobile-sections-remaining/{title}";
+
+    /**
+     * Gets a page summary for a given title -- for link previews
+     *
+     * @param title the page title to be used including prefix
+     */
+    @Headers({
+            "x-analytics: preview=1",
+            ACCEPT_HEADER_SUMMARY
+    })
+    @GET("page/summary/{title}")
+    @NonNull
+    Observable<RbPageSummary> getSummary(@Nullable @Header("Referer") String referrerUrl,
+                                         @NonNull @Path("title") String title);
+
+    /**
+     * Gets the lead section and initial metadata of a given title.
+     *
+     * @param title the page title with prefix if necessary
+     */
+    @Headers({
+            "x-analytics: pageview=1",
+            ACCEPT_HEADER_MOBILE_SECTIONS
+    })
+    @GET("page/mobile-sections-lead/{title}")
+    @NonNull
+    Observable<Response<RbPageLead>> getLeadSection(@Nullable @Header("Cache-Control") String cacheControl,
+                                                    @Nullable @Header(Service.OFFLINE_SAVE_HEADER) String saveHeader,
+                                                    @Nullable @Header("Referer") String referrerUrl,
+                                                    @NonNull @Path("title") String title);
+
+    /**
+     * Gets the remaining sections of a given title.
+     *
+     * @param title the page title to be used including prefix
+     */
+    @Headers(ACCEPT_HEADER_MOBILE_SECTIONS)
+    @GET(REST_PAGE_SECTIONS_URL)
+    @NonNull Observable<Response<RbPageRemaining>> getRemainingSections(@Nullable @Header("Cache-Control") String cacheControl,
+                                                                        @Nullable @Header(Service.OFFLINE_SAVE_HEADER) String saveHeader,
+                                                                        @NonNull @Path("title") String title);
+    /**
+     * TODO: remove this if we find a way to get the request url before the observable object being executed
+     * Gets the remaining sections request url of a given title.
+     *
+     * @param title the page title to be used including prefix
+     */
+    @Headers(ACCEPT_HEADER_MOBILE_SECTIONS)
+    @GET(REST_PAGE_SECTIONS_URL)
+    @NonNull Call<RbPageRemaining> getRemainingSectionsUrl(@Nullable @Header("Cache-Control") String cacheControl,
+                                                           @Nullable @Header(Service.OFFLINE_SAVE_HEADER) String saveHeader,
+                                                           @NonNull @Path("title") String title);
+
+    // todo: this Content Service-only endpoint is under page/ but that implementation detail should
+    //       probably not be reflected here. Move to WordDefinitionClient
+    /**
+     * Gets selected Wiktionary content for a given title derived from user-selected text
+     *
+     * @param title the Wiktionary page title derived from user-selected Wikipedia article text
+     */
+    @Headers(ACCEPT_HEADER_DEFINITION)
+    @GET("page/definition/{title}")
+    @NonNull Observable<Map<String, RbDefinition.Usage[]>> getDefinition(@NonNull @Path("title") String title);
+
+    @Headers(ACCEPT_HEADER_SUMMARY)
+    @GET("page/random/summary")
+    @NonNull Observable<RbPageSummary> getRandomSummary();
+
+    @Headers(ACCEPT_HEADER_SUMMARY)
+    @GET("page/related/{title}")
+    @NonNull Observable<RbRelatedPages> getRelatedPages(@Path("title") String title);
+
+    @GET("page/media/{title}")
+    @NonNull Observable<Gallery> getMedia(@Path("title") String title);
+
+    @GET("feed/onthisday/events/{mm}/{dd}")
+    @NonNull Observable<OnThisDay> getOnThisDay(@Path("mm") int month, @Path("dd") int day);
+
+    @Headers(ACCEPT_HEADER_PREFIX + "announcements/0.1.0\"")
+    @GET("feed/announcements")
+    @NonNull Call<AnnouncementList> getAnnouncements();
+
+    @Headers(ACCEPT_HEADER_PREFIX + "aggregated-feed/0.5.0\"")
+    @GET("feed/featured/{year}/{month}/{day}")
+    @NonNull Observable<AggregatedFeedContent> getAggregatedFeed(@Path("year") String year,
+                                                                 @Path("month") String month,
+                                                                 @Path("day") String day);
+
+    @GET("feed/availability")
+    @NonNull Observable<FeedAvailability> getFeedAvailability();
+
+
+    // ------- Reading lists -------
+
+    @Headers("Cache-Control: no-cache")
+    @POST("data/lists/setup")
+    @NonNull Call<Void> setupReadingLists(@Query("csrf_token") String token);
+
+    @Headers("Cache-Control: no-cache")
+    @POST("data/lists/teardown")
+    @NonNull Call<Void> tearDownReadingLists(@Query("csrf_token") String token);
+
+    @Headers("Cache-Control: no-cache")
+    @GET("data/lists/")
+    @NonNull Call<SyncedReadingLists> getReadingLists(@Query("next") String next);
+
+    @Headers("Cache-Control: no-cache")
+    @POST("data/lists/")
+    @NonNull Call<SyncedReadingLists.RemoteIdResponse> createReadingList(@Query("csrf_token") String token,
+                                                                         @Body SyncedReadingLists.RemoteReadingList list);
+
+    @Headers("Cache-Control: no-cache")
+    @PUT("data/lists/{id}")
+    @NonNull Call<Void> updateReadingList(@Path("id") long listId, @Query("csrf_token") String token,
+                                          @Body SyncedReadingLists.RemoteReadingList list);
+
+    @Headers("Cache-Control: no-cache")
+    @DELETE("data/lists/{id}")
+    @NonNull Call<Void> deleteReadingList(@Path("id") long listId, @Query("csrf_token") String token);
+
+    @Headers("Cache-Control: no-cache")
+    @GET("data/lists/changes/since/{date}")
+    @NonNull Call<SyncedReadingLists> getReadingListChangesSince(@Path("date") String iso8601Date,
+                                                                 @Query("next") String next);
+
+    @Headers("Cache-Control: no-cache")
+    @GET("data/lists/pages/{project}/{title}")
+    @NonNull Call<SyncedReadingLists> getReadingListsContaining(@Path("project") String project,
+                                                                @Path("title") String title,
+                                                                @Query("next") String next);
+
+    @Headers("Cache-Control: no-cache")
+    @GET("data/lists/{id}/entries/")
+    @NonNull Call<SyncedReadingLists> getReadingListEntries(@Path("id") long listId, @Query("next") String next);
+
+    @Headers("Cache-Control: no-cache")
+    @POST("data/lists/{id}/entries/")
+    @NonNull Call<SyncedReadingLists.RemoteIdResponse> addEntryToReadingList(@Path("id") long listId,
+                                                                             @Query("csrf_token") String token,
+                                                                             @Body SyncedReadingLists.RemoteReadingListEntry entry);
+
+    @Headers("Cache-Control: no-cache")
+    @POST("data/lists/{id}/entries/batch")
+    @NonNull Call<SyncedReadingLists.RemoteIdResponseBatch> addEntriesToReadingList(@Path("id") long listId,
+                                                                                    @Query("csrf_token") String token,
+                                                                                    @Body SyncedReadingLists.RemoteReadingListEntryBatch batch);
+
+    @Headers("Cache-Control: no-cache")
+    @DELETE("data/lists/{id}/entries/{entry_id}")
+    @NonNull Call<Void> deleteEntryFromReadingList(@Path("id") long listId, @Path("entry_id") long entryId,
+                                                   @Query("csrf_token") String token);
+
+}

data-client/src/main/java/org/wikipedia/dataclient/Service.java

@@ -0,0 +1,401 @@
+package org.wikipedia.dataclient;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.captcha.Captcha;
+import org.wikipedia.dataclient.mwapi.CreateAccountResponse;
+import org.wikipedia.dataclient.mwapi.MwPostResponse;
+import org.wikipedia.dataclient.mwapi.MwQueryResponse;
+import org.wikipedia.dataclient.mwapi.SiteMatrix;
+import org.wikipedia.dataclient.mwapi.page.MwMobileViewPageLead;
+import org.wikipedia.dataclient.mwapi.page.MwMobileViewPageRemaining;
+import org.wikipedia.dataclient.mwapi.page.MwQueryPageSummary;
+import org.wikipedia.edit.Edit;
+import org.wikipedia.edit.preview.EditPreview;
+import org.wikipedia.login.LoginClient;
+import org.wikipedia.search.PrefixSearchResponse;
+import org.wikipedia.wikidata.Entities;
+
+import io.reactivex.Observable;
+import retrofit2.Call;
+import retrofit2.Response;
+import retrofit2.http.Field;
+import retrofit2.http.FormUrlEncoded;
+import retrofit2.http.GET;
+import retrofit2.http.Header;
+import retrofit2.http.Headers;
+import retrofit2.http.POST;
+import retrofit2.http.Query;
+
+/**
+ * Retrofit service layer for all API interactions, including regular MediaWiki and RESTBase.
+ */
+public interface Service {
+    String WIKIPEDIA_URL = "https://wikipedia.org/";
+    String WIKIDATA_URL = "https://www.wikidata.org/";
+    String COMMONS_URL = "https://commons.wikimedia.org/";
+    String META_URL = "https://meta.wikimedia.org/";
+
+    String MW_API_PREFIX = "w/api.php?format=json&formatversion=2&errorformat=plaintext&";
+
+    String MW_PAGE_SECTIONS_URL = MW_API_PREFIX + "action=mobileview&prop="
+                                                + "text|sections&onlyrequestedsections=1&sections=1-"
+                                                + "&sectionprop=toclevel|line|anchor&noheadings=";
+
+    int PREFERRED_THUMB_SIZE = 320;
+
+    String OFFLINE_SAVE_HEADER = "X-Offline-Save";
+    String OFFLINE_SAVE_HEADER_SAVE = "save";
+    String OFFLINE_SAVE_HEADER_DELETE = "delete";
+    String OFFLINE_SAVE_HEADER_NONE = "none";
+
+    // ------- MobileView page content -------
+
+    /**
+     * Gets the lead section and initial metadata of a given title.
+     *
+     * @param title the page title with prefix if necessary
+     * @return a Retrofit Call which provides the populated MwMobileViewPageLead object in #success
+     */
+     /*
+      Here's the rationale for this API call:
+      We request 10 sentences from the lead section, and then re-parse the text using our own
+      sentence parsing logic to end up with 2 sentences for the link preview. We trust our
+      parsing logic more than TextExtracts because it's better-tailored to the user's
+      Locale on the client side. For example, the TextExtracts extension incorrectly treats
+      abbreviations like "i.e.", "B.C.", "Jr.", etc. as separate sentences, whereas our parser
+      will leave those alone.
+
+      Also, we no longer request "excharacters" from TextExtracts, since it has an issue where
+      it's liable to return content that lies beyond the lead section, which might include
+      unparsed wikitext, which we certainly don't want.
+    */
+    @Headers("x-analytics: preview=1")
+    @GET(MW_API_PREFIX + "action=query&redirects=&converttitles="
+            + "&prop=extracts|pageimages|pageprops&exsentences=5&piprop=thumbnail|name"
+            + "&pilicense=any&explaintext=&pithumbsize=" + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<MwQueryPageSummary> getSummary(@Nullable @Header("Referer") String referrerUrl,
+                                                 @NonNull @Query("titles") String title,
+                                                 @Nullable @Query("uselang") String useLang);
+
+    /**
+     * Gets the lead section and initial metadata of a given title.
+     *
+     * @param title the page title with prefix if necessary
+     * @param leadImageWidth one of the bucket widths for the lead image
+     */
+    @Headers("x-analytics: pageview=1")
+    @GET(MW_API_PREFIX + "action=mobileview&prop="
+            + "text|sections|languagecount|thumb|image|id|namespace|revision"
+            + "|description|lastmodified|normalizedtitle|displaytitle|protection"
+            + "|editable|pageprops&pageprops=wikibase_item"
+            + "&sections=0&sectionprop=toclevel|line|anchor&noheadings=")
+    @NonNull Observable<Response<MwMobileViewPageLead>> getLeadSection(@Nullable @Header("Cache-Control") String cacheControl,
+                                                                       @Nullable @Header(OFFLINE_SAVE_HEADER) String saveHeader,
+                                                                       @Nullable @Header("Referer") String referrerUrl,
+                                                                       @NonNull @Query("page") String title,
+                                                                       @Query("thumbwidth") int leadImageWidth,
+                                                                       @Nullable @Query("uselang") String useLang);
+
+    /**
+     * Gets the remaining sections of a given title.
+     *
+     * @param title the page title to be used including prefix
+     */
+    @GET(MW_PAGE_SECTIONS_URL)
+    @NonNull Observable<Response<MwMobileViewPageRemaining>> getRemainingSections(@Nullable @Header("Cache-Control") String cacheControl,
+                                                                                  @Nullable @Header(OFFLINE_SAVE_HEADER) String saveHeader,
+                                                                                  @NonNull @Query("page") String title,
+                                                                                  @Nullable @Query("uselang") String useLang);
+    /**
+     * TODO: remove this if we find a way to get the request url before the observable object being executed
+     * Gets the remaining sections request url of a given title.
+     *
+     * @param title the page title to be used including prefix
+     */
+    @GET(MW_PAGE_SECTIONS_URL)
+    @NonNull Call<MwMobileViewPageRemaining> getRemainingSectionsUrl(@Nullable @Header("Cache-Control") String cacheControl,
+                                                                      @Nullable @Header(OFFLINE_SAVE_HEADER) String saveHeader,
+                                                                      @NonNull @Query("page") String title,
+                                                                      @Nullable @Query("uselang") String useLang);
+
+    // ------- Search -------
+
+    @GET(MW_API_PREFIX + "action=query&prop=pageimages&piprop=thumbnail"
+            + "&converttitles=&pilicense=any&pithumbsize=" + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<MwQueryResponse> getPageImages(@NonNull @Query("titles") String titles);
+
+    @GET(MW_API_PREFIX + "action=query&redirects="
+            + "&converttitles=&prop=description|pageimages&piprop=thumbnail"
+            + "&pilicense=any&generator=prefixsearch&gpsnamespace=0&list=search&srnamespace=0"
+            + "&srwhat=text&srinfo=suggestion&srprop=&sroffset=0&srlimit=1&pithumbsize=" + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<PrefixSearchResponse> prefixSearch(@Query("gpssearch") String title,
+                                                     @Query("gpslimit") int maxResults,
+                                                     @Query("srsearch") String repeat);
+
+    @GET(MW_API_PREFIX + "action=query&converttitles="
+            + "&prop=description|pageimages|pageprops&ppprop=mainpage|disambiguation"
+            + "&generator=search&gsrnamespace=0&gsrwhat=text"
+            + "&gsrinfo=&gsrprop=redirecttitle&piprop=thumbnail&pilicense=any&pithumbsize="
+            + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<MwQueryResponse> fullTextSearch(@Query("gsrsearch") String searchTerm,
+                                                  @Query("gsrlimit") int gsrLimit,
+                                                  @Query("continue") String cont,
+                                                  @Query("gsroffset") String gsrOffset);
+
+    @GET(MW_API_PREFIX + "action=query&prop=coordinates|description|pageimages"
+            + "&colimit=50&piprop=thumbnail&pilicense=any"
+            + "&generator=geosearch&ggslimit=50&pithumbsize=" + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<MwQueryResponse> nearbySearch(@NonNull @Query("ggscoord") String coord,
+                                                @Query("ggsradius") double radius);
+
+
+    // ------- Miscellaneous -------
+
+    @GET(MW_API_PREFIX + "action=fancycaptchareload")
+    @NonNull Observable<Captcha> getNewCaptcha();
+
+    @GET(MW_API_PREFIX + "action=query&prop=langlinks&lllimit=500&redirects=&converttitles=")
+    @NonNull Observable<MwQueryResponse> getLangLinks(@NonNull @Query("titles") String title);
+
+    @GET(MW_API_PREFIX + "action=query&prop=description|pageprops&redirects")
+    @NonNull Observable<MwQueryResponse> getPagePropsAndDescription(@NonNull @Query("titles") String titles);
+
+    @GET(MW_API_PREFIX + "action=query&prop=description")
+    @NonNull Observable<MwQueryResponse> getDescription(@NonNull @Query("titles") String titles);
+
+    @GET(MW_API_PREFIX + "action=query&prop=imageinfo&iiprop=timestamp|user|url|extmetadata&iiurlwidth=" + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<MwQueryResponse> getImageExtMetadata(@NonNull @Query("titles") String titles);
+
+    @GET(MW_API_PREFIX + "action=sitematrix&smtype=language&smlangprop=code|name|localname")
+    @NonNull Observable<SiteMatrix> getSiteMatrix();
+
+    @GET(MW_API_PREFIX + "action=query&meta=siteinfo")
+    @NonNull Observable<MwQueryResponse> getSiteInfo();
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&generator=random&redirects=1&grnnamespace=0&grnlimit=50&prop=pageprops|description")
+    @NonNull Observable<MwQueryResponse> getRandomWithPageProps();
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&generator=random&redirects=1&grnnamespace=6&grnlimit=50"
+            + "&prop=description|imageinfo&iiprop=timestamp|user|url|mime&iiurlwidth=" + PREFERRED_THUMB_SIZE)
+    @NonNull Observable<MwQueryResponse> getRandomWithImageInfo();
+
+    @GET(MW_API_PREFIX + "action=query&prop=categories&clprop=hidden&cllimit=500")
+    @NonNull Observable<MwQueryResponse> getCategories(@NonNull @Query("titles") String titles);
+
+    @GET(MW_API_PREFIX + "action=query&list=categorymembers&cmlimit=500")
+    @NonNull Observable<MwQueryResponse> getCategoryMembers(@NonNull @Query("cmtitle") String title,
+                                                            @Nullable @Query("cmcontinue") String continueStr);
+
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=thank")
+    @NonNull Observable<MwPostResponse> thank(@Nullable @Field("rev") String rev,
+                                              @Nullable @Field("log") String log,
+                                              @NonNull @Field("token") String token,
+                                              @Nullable @Field("source") String source);
+
+
+    // ------- CSRF, Login, and Create Account -------
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=tokens&type=csrf")
+    @NonNull Call<MwQueryResponse> getCsrfTokenCall();
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=tokens&type=csrf")
+    @NonNull Observable<MwQueryResponse> getCsrfToken();
+
+    @SuppressWarnings("checkstyle:parameternumber")
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=createaccount&createmessageformat=html")
+    @NonNull Observable<CreateAccountResponse> postCreateAccount(@NonNull @Field("username") String user,
+                                                           @NonNull @Field("password") String pass,
+                                                           @NonNull @Field("retype") String retype,
+                                                           @NonNull @Field("createtoken") String token,
+                                                           @NonNull @Field("createreturnurl") String returnurl,
+                                                           @Nullable @Field("email") String email,
+                                                           @Nullable @Field("captchaId") String captchaId,
+                                                           @Nullable @Field("captchaWord") String captchaWord);
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=tokens&type=login")
+    @NonNull Call<MwQueryResponse> getLoginToken();
+
+    @Headers("Cache-Control: no-cache")
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=clientlogin&rememberMe=")
+    @NonNull Call<LoginClient.LoginResponse> postLogIn(@Field("username") String user, @Field("password") String pass,
+                                                       @Field("logintoken") String token, @Field("loginreturnurl") String url);
+
+    @Headers("Cache-Control: no-cache")
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=clientlogin&rememberMe=")
+    @NonNull Call<LoginClient.LoginResponse> postLogIn(@Field("username") String user, @Field("password") String pass,
+                                                       @Field("retype") String retypedPass, @Field("OATHToken") String twoFactorCode,
+                                                       @Field("logintoken") String token,
+                                                       @Field("logincontinue") boolean loginContinue);
+
+    @Headers("Cache-Control: no-cache")
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=logout")
+    @NonNull Observable<MwPostResponse> postLogout(@NonNull @Field("token") String token);
+
+    @GET(MW_API_PREFIX + "action=query&meta=authmanagerinfo|tokens&amirequestsfor=create&type=createaccount")
+    @NonNull Observable<MwQueryResponse> getAuthManagerInfo();
+
+    @GET(MW_API_PREFIX + "action=query&meta=userinfo&list=users&usprop=groups|cancreate")
+    @NonNull Observable<MwQueryResponse> getUserInfo(@Query("ususers") @NonNull String userName);
+
+
+    // ------- Notifications -------
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=notifications&notformat=model&notlimit=max")
+    @NonNull Observable<MwQueryResponse> getAllNotifications(@Query("notwikis") @Nullable String wikiList,
+                                              @Query("notfilter") @Nullable String filter,
+                                              @Query("notcontinue") @Nullable String continueStr);
+
+    @FormUrlEncoded
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=echomarkread")
+    @NonNull Observable<MwQueryResponse> markRead(@Field("token") @NonNull String token, @Field("list") @Nullable String readList, @Field("unreadlist") @Nullable String unreadList);
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=notifications&notprop=list&notfilter=!read&notlimit=1")
+    @NonNull Observable<MwQueryResponse> getLastUnreadNotification();
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=unreadnotificationpages&unplimit=max&unpwikis=*")
+    @NonNull Observable<MwQueryResponse> getUnreadNotificationWikis();
+
+
+    // ------- User Options -------
+
+    @GET(MW_API_PREFIX + "action=query&meta=userinfo&uiprop=options")
+    @NonNull Observable<MwQueryResponse> getUserOptions();
+
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=options")
+    @NonNull Observable<MwPostResponse> postUserOption(@Field("token") @NonNull String token,
+                                                 @Query("optionname") @NonNull String key,
+                                                 @Query("optionvalue") @Nullable String value);
+
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=options")
+    @NonNull Observable<MwPostResponse> deleteUserOption(@Field("token") @NonNull String token,
+                                                   @Query("change") @NonNull String key);
+
+
+    // ------- Editing -------
+
+    @GET(MW_API_PREFIX + "action=query&prop=revisions&rvprop=content|timestamp&rvlimit=1&converttitles=")
+    @NonNull Observable<MwQueryResponse> getWikiTextForSection(@NonNull @Query("titles") String title, @Query("rvsection") int section);
+
+    @FormUrlEncoded
+    @POST(MW_API_PREFIX + "action=parse&prop=text&sectionpreview=&pst=&mobileformat=")
+    @NonNull Observable<EditPreview> postEditPreview(@NonNull @Field("title") String title,
+                                               @NonNull @Field("text") String text);
+
+    @FormUrlEncoded
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=edit&nocreate=")
+    @SuppressWarnings("checkstyle:parameternumber")
+    @NonNull Call<Edit> postEditSubmit(@NonNull @Field("title") String title,
+                                       @Nullable @Field("section") Integer section,
+                                       @NonNull @Field("summary") String summary,
+                                       @Nullable @Field("assert") String user,
+                                       @NonNull @Field("text") String text,
+                                       @Nullable @Field("basetimestamp") String baseTimeStamp,
+                                       @NonNull @Field("token") String token,
+                                       @Nullable @Field("captchaid") String captchaId,
+                                       @Nullable @Field("captchaword") String captchaWord);
+
+    @FormUrlEncoded
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=edit&nocreate=")
+    @NonNull Observable<Edit> postAppendEdit(@NonNull @Field("title") String title,
+                                       @NonNull @Field("summary") String summary,
+                                       @NonNull @Field("appendtext") String text,
+                                       @NonNull @Field("token") String token);
+
+    @FormUrlEncoded
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=edit&nocreate=")
+    @NonNull Observable<Edit> postPrependEdit(@NonNull @Field("title") String title,
+                                        @NonNull @Field("summary") String summary,
+                                        @NonNull @Field("prependtext") String text,
+                                        @NonNull @Field("token") String token);
+
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=tag")
+    @FormUrlEncoded
+    Observable<MwPostResponse> addEditTag(@NonNull @Field("revid") String revId,
+                                          @NonNull @Field("add") String tagName,
+                                          @NonNull @Field("reason") String reason,
+                                          @NonNull @Field("token") String token);
+
+    @Headers("Cache-Control: no-cache")
+    @GET(MW_API_PREFIX + "action=query&meta=wikimediaeditortaskscounts")
+    @NonNull Observable<MwQueryResponse> getEditorTaskCounts();
+
+    @GET(MW_API_PREFIX + "action=query&generator=wikimediaeditortaskssuggestions&prop=pageprops&gwetstask=missingdescriptions&gwetslimit=3")
+    @NonNull Observable<MwQueryResponse> getEditorTaskMissingDescriptions(@NonNull @Query("gwetstarget") String targetLanguage);
+
+    @GET(MW_API_PREFIX + "action=query&generator=wikimediaeditortaskssuggestions&prop=pageprops&gwetstask=descriptiontranslations&gwetslimit=3")
+    @NonNull Observable<MwQueryResponse> getEditorTaskTranslatableDescriptions(@NonNull @Query("gwetssource") String sourceLanguage,
+                                                                               @NonNull @Query("gwetstarget") String targetLanguage);
+
+
+    // ------- Wikidata -------
+
+    @GET(MW_API_PREFIX + "action=wbgetentities")
+    @NonNull Observable<Entities> getEntitiesByTitle(@Query("titles") @NonNull String titles,
+                                                     @Query("sites") @NonNull String sites);
+
+    @GET(MW_API_PREFIX + "action=wbgetentities&props=labels&languagefallback=1")
+    @NonNull Call<Entities> getWikidataLabels(@Query("ids") @NonNull String idList,
+                                              @Query("languages") @NonNull String langList);
+
+    @GET(MW_API_PREFIX + "action=wbgetentities&props=descriptions|labels|sitelinks")
+    @NonNull Observable<Entities> getWikidataLabelsAndDescriptions(@Query("ids") @NonNull String idList);
+
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=wbsetdescription&errorlang=uselang")
+    @FormUrlEncoded
+    @SuppressWarnings("checkstyle:parameternumber")
+    Observable<MwPostResponse> postDescriptionEdit(@NonNull @Field("language") String language,
+                                                   @NonNull @Field("uselang") String useLang,
+                                                   @NonNull @Field("site") String site,
+                                                   @NonNull @Field("title") String title,
+                                                   @NonNull @Field("value") String newDescription,
+                                                   @Nullable @Field("summary") String summary,
+                                                   @NonNull @Field("token") String token,
+                                                   @Nullable @Field("assert") String user);
+
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=wbsetlabel&errorlang=uselang")
+    @FormUrlEncoded
+    @SuppressWarnings("checkstyle:parameternumber")
+    Observable<MwPostResponse> postLabelEdit(@NonNull @Field("language") String language,
+                                             @NonNull @Field("uselang") String useLang,
+                                             @NonNull @Field("site") String site,
+                                             @NonNull @Field("title") String title,
+                                             @NonNull @Field("value") String newDescription,
+                                             @Nullable @Field("summary") String summary,
+                                             @NonNull @Field("token") String token,
+                                             @Nullable @Field("assert") String user);
+
+    @Headers("Cache-Control: no-cache")
+    @POST(MW_API_PREFIX + "action=wbcreateclaim&errorlang=uselang")
+    @FormUrlEncoded
+    Observable<MwPostResponse> postCreateClaim(@NonNull @Field("entity") String entity,
+                                               @NonNull @Field("snaktype") String snakType,
+                                               @NonNull @Field("property") String property,
+                                               @NonNull @Field("value") String value,
+                                               @NonNull @Field("uselang") String useLang,
+                                               @NonNull @Field("token") String token);
+
+}

data-client/src/main/java/org/wikipedia/dataclient/ServiceError.java

@@ -0,0 +1,12 @@
+package org.wikipedia.dataclient;
+
+import androidx.annotation.NonNull;
+
+/**
+ * The API reported an error in the payload.
+ */
+public interface ServiceError {
+    @NonNull String getTitle();
+
+    @NonNull String getDetails();
+}

data-client/src/main/java/org/wikipedia/dataclient/ServiceFactory.java

@@ -0,0 +1,68 @@
+package org.wikipedia.dataclient;
+
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.collection.LruCache;
+
+import org.wikipedia.AppAdapter;
+import org.wikipedia.json.GsonUtil;
+
+import retrofit2.Retrofit;
+import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;
+import retrofit2.converter.gson.GsonConverterFactory;
+
+public final class ServiceFactory {
+    private static final int SERVICE_CACHE_SIZE = 8;
+    private static LruCache<Long, Service> SERVICE_CACHE = new LruCache<>(SERVICE_CACHE_SIZE);
+    private static LruCache<Long, RestService> REST_SERVICE_CACHE = new LruCache<>(SERVICE_CACHE_SIZE);
+
+    public static Service get(@NonNull WikiSite wiki) {
+        long hashCode = wiki.hashCode();
+        if (SERVICE_CACHE.get(hashCode) != null) {
+            return SERVICE_CACHE.get(hashCode);
+        }
+
+        Retrofit r = createRetrofit(wiki, wiki.url() + "/");
+
+        Service s = r.create(Service.class);
+        SERVICE_CACHE.put(hashCode, s);
+        return s;
+    }
+
+    public static <T> T get(@NonNull WikiSite wiki, Class<T> service) {
+        return get(wiki, wiki.url() + "/", service);
+    }
+
+    public static <T> T get(@NonNull WikiSite wiki, @Nullable String baseUrl, Class<T> service) {
+        Retrofit r = createRetrofit(wiki, TextUtils.isEmpty(baseUrl) ? wiki.url() + "/" : baseUrl);
+        return r.create(service);
+    }
+
+    public static RestService getRest(@NonNull WikiSite wiki) {
+        long hashCode = wiki.hashCode();
+        if (REST_SERVICE_CACHE.get(hashCode) != null) {
+            return REST_SERVICE_CACHE.get(hashCode);
+        }
+
+        Retrofit r = createRetrofit(wiki, TextUtils.isEmpty(AppAdapter.get().getRestbaseUriFormat())
+                        ? wiki.url() + "/" + RestService.REST_API_PREFIX
+                        : String.format(AppAdapter.get().getRestbaseUriFormat(), "https", wiki.authority()));
+
+        RestService s = r.create(RestService.class);
+        REST_SERVICE_CACHE.put(hashCode, s);
+        return s;
+    }
+
+    private static Retrofit createRetrofit(@NonNull WikiSite wiki, @NonNull String baseUrl) {
+        return new Retrofit.Builder()
+                .client(AppAdapter.get().getOkHttpClient(wiki))
+                .baseUrl(baseUrl)
+                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
+                .addConverterFactory(GsonConverterFactory.create(GsonUtil.getDefaultGson()))
+                .build();
+    }
+
+    private ServiceFactory() { }
+}

data-client/src/main/java/org/wikipedia/dataclient/SharedPreferenceCookieManager.java

@@ -0,0 +1,166 @@
+package org.wikipedia.dataclient;
+
+import android.text.TextUtils;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.AppAdapter;
+import org.wikipedia.util.log.L;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import okhttp3.Cookie;
+import okhttp3.CookieJar;
+import okhttp3.HttpUrl;
+
+public final class SharedPreferenceCookieManager implements CookieJar {
+    private static final String CENTRALAUTH_PREFIX = "centralauth_";
+    private static SharedPreferenceCookieManager INSTANCE;
+
+    // Map: domain -> list of cookies
+    private final Map<String, List<Cookie>> cookieJar;
+
+    @NonNull
+    public static SharedPreferenceCookieManager getInstance() {
+        if (INSTANCE == null) {
+            try {
+                INSTANCE = AppAdapter.get().getCookies();
+            } catch (Exception e) {
+                L.logRemoteErrorIfProd(e);
+            }
+        }
+        if (INSTANCE == null) {
+            INSTANCE = new SharedPreferenceCookieManager();
+        }
+        return INSTANCE;
+    }
+
+    public SharedPreferenceCookieManager(Map<String, List<Cookie>> cookieJar) {
+        this.cookieJar = cookieJar;
+    }
+
+    private SharedPreferenceCookieManager() {
+        cookieJar = new HashMap<>();
+    }
+
+    public Map<String, List<Cookie>> getCookieJar() {
+        return cookieJar;
+    }
+
+    private void persistCookies() {
+        AppAdapter.get().setCookies(this);
+    }
+
+    public synchronized void clearAllCookies() {
+        cookieJar.clear();
+        persistCookies();
+    }
+
+    @Nullable public synchronized String getCookieByName(@NonNull String name) {
+        for (String domainSpec: cookieJar.keySet()) {
+            for (Cookie cookie : cookieJar.get(domainSpec)) {
+                if (cookie.name().equals(name)) {
+                    return cookie.value();
+                }
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public synchronized void saveFromResponse(@NonNull HttpUrl url, @NonNull List<Cookie> cookies) {
+        if (cookies.isEmpty()) {
+            return;
+        }
+        boolean cookieJarModified = false;
+        for (Cookie cookie : cookies) {
+            // Default to the URI's domain if cookie's domain is not explicitly set
+            String domainSpec = TextUtils.isEmpty(cookie.domain()) ? url.uri().getAuthority() : cookie.domain();
+            if (!cookieJar.containsKey(domainSpec)) {
+                cookieJar.put(domainSpec, new ArrayList<>());
+            }
+
+            List<Cookie> cookieList = cookieJar.get(domainSpec);
+            if (cookie.expiresAt() < System.currentTimeMillis() || "deleted".equals(cookie.value())) {
+                Iterator<Cookie> i = cookieList.iterator();
+                while (i.hasNext()) {
+                    if (i.next().name().equals(cookie.name())) {
+                        i.remove();
+                        cookieJarModified = true;
+                    }
+                }
+            } else {
+                Iterator<Cookie> i = cookieList.iterator();
+                boolean exists = false;
+                while (i.hasNext()) {
+                    Cookie c = i.next();
+                    if (c.equals(cookie)) {
+                        // an identical cookie already exists, so we don't need to update it.
+                        exists = true;
+                        break;
+                    } else if (c.name().equals(cookie.name())) {
+                        // it's a cookie with the same name, but different contents, so remove the
+                        // current cookie, so that the new one will be added.
+                        i.remove();
+                    }
+                }
+                if (!exists) {
+                    cookieList.add(cookie);
+                    cookieJarModified = true;
+                }
+            }
+        }
+        if (cookieJarModified) {
+            persistCookies();
+        }
+    }
+
+    @Override
+    public synchronized List<Cookie> loadForRequest(@NonNull HttpUrl url) {
+        List<Cookie> cookieList = new ArrayList<>();
+        String domain = url.uri().getAuthority();
+
+        Log.d("CookieManager", "Domain:" + domain);
+
+        for (String domainSpec : cookieJar.keySet()) {
+            List<Cookie> cookiesForDomainSpec = cookieJar.get(domainSpec);
+
+            if (domain.endsWith(domainSpec)) {
+                buildCookieList(cookieList, cookiesForDomainSpec, null);
+            } else if (domainSpec.endsWith("commons.wikimedia.org")) {
+                Log.d("CookieManager", "Adding centralauth cookies");
+                // For sites outside the wikipedia.org domain, transfer the centralauth cookies
+                // from commons.wikimedia.org unconditionally.
+                buildCookieList(cookieList, cookiesForDomainSpec, CENTRALAUTH_PREFIX);
+            }
+        }
+        return cookieList;
+    }
+
+    private void buildCookieList(@NonNull List<Cookie> outList, @NonNull List<Cookie> inList, @Nullable String prefix) {
+        Iterator<Cookie> i = inList.iterator();
+        boolean cookieJarModified = false;
+        while (i.hasNext()) {
+            Cookie cookie = i.next();
+            if (prefix != null && !cookie.name().startsWith(prefix)) {
+                continue;
+            }
+            // But wait, is the cookie expired?
+            if (cookie.expiresAt() < System.currentTimeMillis()) {
+                i.remove();
+                cookieJarModified = true;
+            } else {
+                outList.add(cookie);
+            }
+        }
+        if (cookieJarModified) {
+            persistCookies();
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/WikiSite.java

@@ -0,0 +1,320 @@
+package org.wikipedia.dataclient;
+
+import android.net.Uri;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.language.AppLanguageLookUpTable;
+import org.wikipedia.page.PageTitle;
+import org.wikipedia.util.UriUtil;
+
+/**
+ * The base URL and Wikipedia language code for a MediaWiki site. Examples:
+ *
+ * <ul>
+ *     <lh>Name: scheme / authority / language code</lh>
+ *     <li>English Wikipedia: HTTPS / en.wikipedia.org / en</li>
+ *     <li>Chinese Wikipedia: HTTPS / zh.wikipedia.org / zh-hans or zh-hant</li>
+ *     <li>Meta-Wiki: HTTPS / meta.wikimedia.org / (none)</li>
+ *     <li>Test Wikipedia: HTTPS / test.wikipedia.org / test</li>
+ *     <li>Võro Wikipedia: HTTPS / fiu-vro.wikipedia.org / fiu-vro</li>
+ *     <li>Simple English Wikipedia: HTTPS / simple.wikipedia.org / simple</li>
+ *     <li>Simple English Wikipedia (beta cluster mirror): HTTP / simple.wikipedia.beta.wmflabs.org / simple</li>
+ *     <li>Development: HTTP / 192.168.1.11:8080 / (none)</li>
+ * </ul>
+ *
+ * <strong>As shown above, the language code or mapping is part of the authority:</strong>
+ * <ul>
+ *     <lh>Validity: authority / language code</lh>
+ *     <li>Correct: "test.wikipedia.org" / "test"</li>
+ *     <li>Correct: "wikipedia.org", ""</li>
+ *     <li>Correct: "no.wikipedia.org", "nb"</li>
+ *     <li>Incorrect: "wikipedia.org", "test"</li>
+ * </ul>
+ */
+public class WikiSite implements Parcelable {
+    public static final String DEFAULT_SCHEME = "https";
+    private static String DEFAULT_BASE_URL = Service.WIKIPEDIA_URL;
+
+    public static final Parcelable.Creator<WikiSite> CREATOR = new Parcelable.Creator<WikiSite>() {
+        @Override
+        public WikiSite createFromParcel(Parcel in) {
+            return new WikiSite(in);
+        }
+
+        @Override
+        public WikiSite[] newArray(int size) {
+            return new WikiSite[size];
+        }
+    };
+
+    // todo: remove @SerializedName. this is now in the TypeAdapter and a "uri" case may be added
+    @SerializedName("domain") @NonNull private final Uri uri;
+    @NonNull private String languageCode;
+
+    public static boolean supportedAuthority(@NonNull String authority) {
+        return authority.endsWith(Uri.parse(DEFAULT_BASE_URL).getAuthority());
+    }
+
+    public static void setDefaultBaseUrl(@NonNull String url) {
+        DEFAULT_BASE_URL = TextUtils.isEmpty(url) ? Service.WIKIPEDIA_URL : url;
+    }
+
+    public static WikiSite forLanguageCode(@NonNull String languageCode) {
+        Uri uri = ensureScheme(Uri.parse(DEFAULT_BASE_URL));
+        return new WikiSite((languageCode.isEmpty()
+                ? "" : (languageCodeToSubdomain(languageCode) + ".")) + uri.getAuthority(),
+                languageCode);
+    }
+
+    public WikiSite(@NonNull Uri uri) {
+        Uri tempUri = ensureScheme(uri);
+        String authority = tempUri.getAuthority();
+        if (("wikipedia.org".equals(authority) || "www.wikipedia.org".equals(authority))
+                && tempUri.getPath() != null && tempUri.getPath().startsWith("/wiki")) {
+            // Special case for Wikipedia only: assume English subdomain when none given.
+            authority = "en.wikipedia.org";
+        }
+        String langVariant = UriUtil.getLanguageVariantFromUri(tempUri);
+        if (!TextUtils.isEmpty(langVariant)) {
+            languageCode = langVariant;
+        } else {
+            languageCode = authorityToLanguageCode(authority);
+        }
+        this.uri = new Uri.Builder()
+                .scheme(tempUri.getScheme())
+                .encodedAuthority(authority)
+                .build();
+    }
+
+    public WikiSite(@NonNull String url) {
+        this(url.startsWith("http") ? Uri.parse(url) : url.startsWith("//")
+                ? Uri.parse(DEFAULT_SCHEME + ":" + url) : Uri.parse(DEFAULT_SCHEME + "://" + url));
+    }
+
+    public WikiSite(@NonNull String authority, @NonNull String languageCode) {
+        this(authority);
+        this.languageCode = languageCode;
+    }
+
+    @NonNull
+    public String scheme() {
+        return TextUtils.isEmpty(uri.getScheme()) ? DEFAULT_SCHEME : uri.getScheme();
+    }
+
+    /**
+     * @return The complete wiki authority including language subdomain but not including scheme,
+     *         authentication, port, nor trailing slash.
+     *
+     * @see <a href='https://en.wikipedia.org/wiki/Uniform_Resource_Locator#Syntax'>URL syntax</a>
+     */
+    @NonNull
+    public String authority() {
+        return uri.getAuthority();
+    }
+
+    /**
+     * Like {@link #authority()} but with a "m." between the language subdomain and the rest of the host.
+     * Examples:
+     *
+     * <ul>
+     *     <li>English Wikipedia: en.m.wikipedia.org</li>
+     *     <li>Chinese Wikipedia: zh.m.wikipedia.org</li>
+     *     <li>Meta-Wiki: meta.m.wikimedia.org</li>
+     *     <li>Test Wikipedia: test.m.wikipedia.org</li>
+     *     <li>Võro Wikipedia: fiu-vro.m.wikipedia.org</li>
+     *     <li>Simple English Wikipedia: simple.m.wikipedia.org</li>
+     *     <li>Simple English Wikipedia (beta cluster mirror): simple.m.wikipedia.beta.wmflabs.org</li>
+     *     <li>Development: m.192.168.1.11</li>
+     * </ul>
+     */
+    @NonNull
+    public String mobileAuthority() {
+        return authorityToMobile(authority());
+    }
+
+    /**
+     * @return The canonical "desktop" form of the authority. For example, if the authority
+     * is in a "mobile" form, e.g. en.m.wikipedia.org, this will become en.wikipedia.org.
+     */
+    @NonNull
+    public String desktopAuthority() {
+        return authority().replace(".m.", ".");
+    }
+
+    @NonNull
+    public String subdomain() {
+        return languageCodeToSubdomain(languageCode);
+    }
+
+    /**
+     * @return A path without an authority for the segment including a leading "/".
+     */
+    @NonNull
+    public String path(@NonNull String segment) {
+        return "/w/" + segment;
+    }
+
+
+    @NonNull public Uri uri() {
+        return uri;
+    }
+
+    /**
+     * @return The canonical URL. e.g., https://en.wikipedia.org.
+     */
+    @NonNull public String url() {
+        return uri.toString();
+    }
+
+    /**
+     * @return The canonical URL for segment. e.g., https://en.wikipedia.org/w/foo.
+     */
+    @NonNull public String url(@NonNull String segment) {
+        return url() + path(segment);
+    }
+
+    /**
+     * @return The wiki language code which may differ from the language subdomain. Empty if
+     *         language code is unknown. Ex: "en", "zh-hans", ""
+     *
+     * @see AppLanguageLookUpTable
+     */
+    @NonNull
+    public String languageCode() {
+        return languageCode;
+    }
+
+    // TODO: this method doesn't have much to do with WikiSite. Move to PageTitle?
+    /**
+     * Create a PageTitle object from an internal link string.
+     *
+     * @param internalLink Internal link target text (eg. /wiki/Target).
+     *                     Should be URL decoded before passing in
+     * @return A {@link PageTitle} object representing the internalLink passed in.
+     */
+    public PageTitle titleForInternalLink(String internalLink) {
+        // Strip the /wiki/ from the href
+        return new PageTitle(UriUtil.removeInternalLinkPrefix(internalLink), this);
+    }
+
+    // TODO: this method doesn't have much to do with WikiSite. Move to PageTitle?
+    /**
+     * Create a PageTitle object from a Uri, taking into account any fragment (section title) in the link.
+     * @param uri Uri object to be turned into a PageTitle.
+     * @return {@link PageTitle} object that corresponds to the given Uri.
+     */
+    public PageTitle titleForUri(Uri uri) {
+        String path = uri.getPath();
+        if (!TextUtils.isEmpty(uri.getFragment())) {
+            path += "#" + uri.getFragment();
+        }
+        return titleForInternalLink(path);
+    }
+
+    @NonNull public String dbName() {
+        return subdomain().replaceAll("-", "_") + "wiki";
+    }
+
+    // Auto-generated
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        WikiSite wiki = (WikiSite) o;
+
+        if (!uri.equals(wiki.uri)) {
+            return false;
+        }
+        return languageCode.equals(wiki.languageCode);
+    }
+
+    // Auto-generated
+    @Override
+    public int hashCode() {
+        int result = uri.hashCode();
+        result = 31 * result + languageCode.hashCode();
+        return result;
+    }
+
+    // Auto-generated
+    @Override
+    public String toString() {
+        return "WikiSite{"
+                + "uri=" + uri
+                + ", languageCode='" + languageCode + '\''
+                + '}';
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
+        dest.writeParcelable(uri, 0);
+        dest.writeString(languageCode);
+    }
+
+    protected WikiSite(@NonNull Parcel in) {
+        this.uri = in.readParcelable(Uri.class.getClassLoader());
+        this.languageCode = in.readString();
+    }
+
+    @NonNull
+    private static String languageCodeToSubdomain(@NonNull String languageCode) {
+        switch (languageCode) {
+            case AppLanguageLookUpTable.SIMPLIFIED_CHINESE_LANGUAGE_CODE:
+            case AppLanguageLookUpTable.TRADITIONAL_CHINESE_LANGUAGE_CODE:
+            case AppLanguageLookUpTable.CHINESE_CN_LANGUAGE_CODE:
+            case AppLanguageLookUpTable.CHINESE_HK_LANGUAGE_CODE:
+            case AppLanguageLookUpTable.CHINESE_MO_LANGUAGE_CODE:
+            case AppLanguageLookUpTable.CHINESE_SG_LANGUAGE_CODE:
+            case AppLanguageLookUpTable.CHINESE_TW_LANGUAGE_CODE:
+                return AppLanguageLookUpTable.CHINESE_LANGUAGE_CODE;
+            case AppLanguageLookUpTable.NORWEGIAN_BOKMAL_LANGUAGE_CODE:
+                return AppLanguageLookUpTable.NORWEGIAN_LEGACY_LANGUAGE_CODE; // T114042
+            default:
+                return languageCode;
+        }
+    }
+
+    @NonNull private static String authorityToLanguageCode(@NonNull String authority) {
+        String[] parts = authority.split("\\.");
+        final int minLengthForSubdomain = 3;
+        if (parts.length < minLengthForSubdomain
+                || parts.length == minLengthForSubdomain && parts[0].equals("m")) {
+            // ""
+            // wikipedia.org
+            // m.wikipedia.org
+            return "";
+        }
+        return parts[0];
+    }
+
+    @NonNull private static Uri ensureScheme(@NonNull Uri uri) {
+        if (TextUtils.isEmpty(uri.getScheme())) {
+            return uri.buildUpon().scheme(DEFAULT_SCHEME).build();
+        }
+        return uri;
+    }
+
+    /** @param authority Host and optional port. */
+    @NonNull private String authorityToMobile(@NonNull String authority) {
+        if (authority.startsWith("m.") || authority.contains(".m.")) {
+            return authority;
+        }
+        return authority.replaceFirst("^" + subdomain() + "\\.?", "$0m.");
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/CreateAccountResponse.java

@@ -0,0 +1,42 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+public class CreateAccountResponse extends MwResponse {
+    @SuppressWarnings("unused") @Nullable private Result createaccount;
+
+    @Nullable public String status() {
+        return createaccount.status();
+    }
+
+    @Nullable public String user() {
+        return createaccount.user();
+    }
+
+    @Nullable public String message() {
+        return createaccount.message();
+    }
+
+    public boolean hasResult() {
+        return createaccount != null;
+    }
+
+    public static class Result {
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String status;
+        @SuppressWarnings("unused") @Nullable private String message;
+        @SuppressWarnings("unused") @Nullable private String username;
+
+        @NonNull public String status() {
+            return status;
+        }
+
+        @Nullable public String user() {
+            return username;
+        }
+
+        @Nullable public String message() {
+            return message;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/EditorTaskCounts.java

@@ -0,0 +1,113 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.json.GsonUtil;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+@SuppressWarnings("unused")
+public class EditorTaskCounts {
+    @Nullable private JsonElement counts;
+    @Nullable @SerializedName("targets_passed") private JsonElement targetsPassed;
+    @Nullable private JsonElement targets;
+
+    @NonNull
+    public Map<String, Integer> getDescriptionEditsPerLanguage() {
+        Map<String, Integer> editsPerLanguage = null;
+        if (counts != null && !(counts instanceof JsonArray)) {
+            editsPerLanguage = GsonUtil.getDefaultGson().fromJson(counts, Counts.class).appDescriptionEdits;
+        }
+        return editsPerLanguage == null ? Collections.emptyMap() : editsPerLanguage;
+    }
+
+    @NonNull
+    public List<Integer> getDescriptionEditTargetsPassed() {
+        List<Integer> passedList = null;
+        if (targetsPassed != null && !(targetsPassed instanceof JsonArray)) {
+            passedList = GsonUtil.getDefaultGson().fromJson(targetsPassed, Targets.class).appDescriptionEdits;
+        }
+        return passedList == null ? Collections.emptyList() : passedList;
+    }
+
+    public int getDescriptionEditTargetsPassedCount() {
+        List<Integer> targetList = getDescriptionEditTargets();
+        List<Integer> passedList = getDescriptionEditTargetsPassed();
+        int count = 0;
+        if (!targetList.isEmpty() && !passedList.isEmpty()) {
+            for (int target : targetList) {
+                if (passedList.contains(target)) {
+                    count++;
+                }
+            }
+        }
+        return count;
+    }
+
+    @NonNull
+    public List<Integer> getDescriptionEditTargets() {
+        List<Integer> targetList = null;
+        if (targets != null && !(targets instanceof JsonArray)) {
+            targetList = GsonUtil.getDefaultGson().fromJson(targets, Targets.class).appDescriptionEdits;
+        }
+        return targetList == null ? Collections.emptyList() : targetList;
+    }
+
+    @NonNull
+    public Map<String, Integer> getCaptionEditsPerLanguage() {
+        Map<String, Integer> editsPerLanguage = null;
+        if (counts != null && !(counts instanceof JsonArray)) {
+            editsPerLanguage = GsonUtil.getDefaultGson().fromJson(counts, Counts.class).appCaptionEdits;
+        }
+        return editsPerLanguage == null ? Collections.emptyMap() : editsPerLanguage;
+    }
+
+    @NonNull
+    public List<Integer> getCaptionEditTargetsPassed() {
+        List<Integer> passedList = null;
+        if (targetsPassed != null && !(targetsPassed instanceof JsonArray)) {
+            passedList = GsonUtil.getDefaultGson().fromJson(targetsPassed, Targets.class).appCaptionEdits;
+        }
+        return passedList == null ? Collections.emptyList() : passedList;
+    }
+
+    public int getCaptionEditTargetsPassedCount() {
+        List<Integer> targetList = getCaptionEditTargets();
+        List<Integer> passedList = getCaptionEditTargetsPassed();
+        int count = 0;
+        if (!targetList.isEmpty() && !passedList.isEmpty()) {
+            for (int target : targetList) {
+                if (passedList.contains(target)) {
+                    count++;
+                }
+            }
+        }
+        return count;
+    }
+
+    @NonNull
+    public List<Integer> getCaptionEditTargets() {
+        List<Integer> targetList = null;
+        if (targets != null && !(targets instanceof JsonArray)) {
+            targetList = GsonUtil.getDefaultGson().fromJson(targets, Targets.class).appCaptionEdits;
+        }
+        return targetList == null ? Collections.emptyList() : targetList;
+    }
+
+    public class Counts {
+        @Nullable @SerializedName("app_description_edits") private Map<String, Integer> appDescriptionEdits;
+        @Nullable @SerializedName("app_caption_edits") private Map<String, Integer> appCaptionEdits;
+    }
+
+    public class Targets {
+        @Nullable @SerializedName("app_description_edits") private List<Integer> appDescriptionEdits;
+        @Nullable @SerializedName("app_caption_edits") private List<Integer> appCaptionEdits;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/GeoSearchItem.java

@@ -0,0 +1,32 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+
+@SuppressWarnings("unused")
+public class GeoSearchItem {
+    @Nullable private String title;
+    @SerializedName("lat") private double latitude;
+    @SerializedName("lon") private double longitude;
+    @SerializedName("dist") private double distance;
+
+    @NonNull public String getTitle() {
+        return StringUtils.defaultString(title);
+    }
+
+    public double getLatitude() {
+        return latitude;
+    }
+
+    public double getLongitude() {
+        return longitude;
+    }
+
+    public double getDistance() {
+        return distance;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/ImageDetails.java

@@ -0,0 +1,17 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+
+public class ImageDetails {
+
+    @SuppressWarnings("unused") private String name;
+    @SuppressWarnings("unused") private String title;
+
+    @NonNull public String getName() {
+        return name;
+    }
+
+    @NonNull public String getTitle() {
+        return title;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/ListUserResponse.java

@@ -0,0 +1,44 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.collection.ArraySet;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+@SuppressWarnings("unused")
+public class ListUserResponse {
+    @SerializedName("name") @Nullable private String name;
+    private long userid;
+    @Nullable private List<String> groups;
+    @Nullable private String cancreate;
+    @Nullable private List<UserResponseCreateError> cancreateerror;
+
+    @Nullable public String name() {
+        return name;
+    }
+
+    public boolean canCreate() {
+        return cancreate != null;
+    }
+
+    @NonNull public Set<String> getGroups() {
+        return groups != null ? new ArraySet<>(groups) : Collections.emptySet();
+    }
+
+    public static class UserResponseCreateError {
+        @Nullable private String message;
+        @Nullable private String code;
+        @Nullable private String type;
+
+        @NonNull public String message() {
+            return StringUtils.defaultString(message);
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwAuthManagerInfo.java

@@ -0,0 +1,47 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.model.BaseModel;
+
+import java.util.List;
+import java.util.Map;
+
+class MwAuthManagerInfo extends BaseModel {
+    @SuppressWarnings("unused,NullableProblems") @NonNull private List<Request> requests;
+
+    @NonNull List<Request> requests() {
+        return requests;
+    }
+
+    static class Request {
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String id;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private Map<String, String> metadata;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String required;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String provider;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String account;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private Map<String, Field> fields;
+
+        @NonNull String id() {
+            return id;
+        }
+
+        @NonNull Map<String, Field> fields() {
+            return fields;
+        }
+    }
+
+    static class Field {
+        @SuppressWarnings("unused") @Nullable private String type;
+        @SuppressWarnings("unused") @Nullable private String value;
+        @SuppressWarnings("unused") @Nullable private String label;
+        @SuppressWarnings("unused") @Nullable private String help;
+        @SuppressWarnings("unused") private boolean optional;
+        @SuppressWarnings("unused") private boolean sensitive;
+
+        @Nullable String value() {
+            return value;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwException.java

@@ -0,0 +1,24 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+public class MwException extends RuntimeException {
+    @SuppressWarnings("unused") @NonNull private final MwServiceError error;
+
+    public MwException(@NonNull MwServiceError error) {
+        this.error = error;
+    }
+
+    @NonNull public MwServiceError getError() {
+        return error;
+    }
+
+    @Nullable public String getTitle() {
+        return error.getTitle();
+    }
+
+    @Override @Nullable public String getMessage() {
+        return error.getDetails();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwPostResponse.java

@@ -0,0 +1,21 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.Nullable;
+
+public class MwPostResponse extends MwResponse {
+    @Nullable @SuppressWarnings("unused") private String options;
+    @SuppressWarnings("unused") private int success;
+
+    public boolean success(@Nullable String result) {
+        return "success".equals(result);
+    }
+
+    @Nullable public String getOptions() {
+        return options;
+    }
+
+    public int getSuccessVal() {
+        return success;
+    }
+}
+

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwQueryLogEvent.java

@@ -0,0 +1,107 @@
+package org.wikipedia.dataclient.mwapi;
+
+import org.wikipedia.model.BaseModel;
+import org.wikipedia.util.DateUtil;
+
+import java.text.ParseException;
+import java.util.Date;
+import java.util.List;
+
+@SuppressWarnings("unused")
+public class MwQueryLogEvent extends BaseModel {
+    private int logid;
+    private int ns;
+    private int index;
+    private String title;
+    private int pageid;
+    private Params params;
+    private String type;
+    private String action;
+    private String user;
+    private int userid;
+    private String timestamp;
+    private String comment;
+    private String parsedcomment;
+    private List<String> tags;
+
+    public int logid() {
+        return logid;
+    }
+
+    public int ns() {
+        return ns;
+    }
+
+    public int index() {
+        return index;
+    }
+
+    public String title() {
+        return title;
+    }
+
+    public int pageid() {
+        return pageid;
+    }
+
+    public String type() {
+        return type;
+    }
+
+    public String action() {
+        return action;
+    }
+
+    public String user() {
+        return user;
+    }
+
+    public int userid() {
+        return userid;
+    }
+
+    public String timestamp() {
+        return timestamp;
+    }
+
+    public Date date(){
+        try {
+            return DateUtil.iso8601DateParse(timestamp);
+        } catch (ParseException e) {
+            return null;
+        }
+    }
+
+    public String comment() {
+        return comment;
+    }
+
+    public String parsedcomment() {
+        return parsedcomment;
+    }
+
+    public List<String> tags() {
+        return tags;
+    }
+
+    public boolean isDeleted() {
+        return pageid==0;
+    }
+
+    public Params params() {
+        return params;
+    }
+
+    public static class Params{
+        private String img_sha1;
+        private String img_timestamp;
+
+        public String img_sha1() {
+            return img_sha1;
+        }
+
+        public String img_timestamp() {
+            return img_timestamp;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwQueryPage.java

@@ -0,0 +1,237 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.gallery.ImageInfo;
+import org.wikipedia.gallery.VideoInfo;
+import org.wikipedia.model.BaseModel;
+import org.wikipedia.page.Namespace;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A class representing a standard page object as returned by the MediaWiki API.
+ */
+public class MwQueryPage extends BaseModel {
+    @SuppressWarnings("unused") private int pageid;
+    @SuppressWarnings("unused") private int ns;
+    @SuppressWarnings("unused") private int index;
+    @SuppressWarnings("unused,NullableProblems") @NonNull private String title;
+    @SuppressWarnings("unused") @Nullable private List<LangLink> langlinks;
+    @SuppressWarnings("unused") @Nullable private List<Revision> revisions;
+    @SuppressWarnings("unused") @Nullable private List<Coordinates> coordinates;
+    @SuppressWarnings("unused") @Nullable private List<Category> categories;
+    @SuppressWarnings("unused") @Nullable private PageProps pageprops;
+    @SuppressWarnings("unused") @Nullable private PageTerms terms;
+    @SuppressWarnings("unused") @Nullable private String extract;
+    @SuppressWarnings("unused") @Nullable private Thumbnail thumbnail;
+    @SuppressWarnings("unused") @Nullable private String description;
+    @SuppressWarnings("unused") @SerializedName("descriptionsource") @Nullable private String descriptionSource;
+    @SuppressWarnings("unused") @SerializedName("imageinfo") @Nullable private List<ImageInfo> imageInfo;
+    @SuppressWarnings("unused") @SerializedName("videoinfo") @Nullable private List<VideoInfo> videoInfo;
+    @Nullable private String redirectFrom;
+    @Nullable private String convertedFrom;
+    @Nullable private String convertedTo;
+
+    @NonNull public String title() {
+        return title;
+    }
+
+    public int index() {
+        return index;
+    }
+
+    @NonNull public Namespace namespace() {
+        return Namespace.of(ns);
+    }
+
+    @Nullable public List<LangLink> langLinks() {
+        return langlinks;
+    }
+
+    @Nullable public List<Revision> revisions() {
+        return revisions;
+    }
+
+    @Nullable public List<Category> categories() {
+        return categories;
+    }
+
+    @Nullable public List<Coordinates> coordinates() {
+        // TODO: Handle null values in lists during deserialization, perhaps with a new
+        // @RequiredElements annotation and corresponding TypeAdapter
+        if (coordinates != null) {
+            coordinates.removeAll(Collections.singleton(null));
+        }
+        return coordinates;
+    }
+
+    public List<String> labels() {
+        return terms != null && terms.label != null ? terms.label : Collections.emptyList();
+    }
+
+    public int pageId() {
+        return pageid;
+    }
+
+    @Nullable public PageProps pageProps() {
+        return pageprops;
+    }
+
+    @Nullable public String extract() {
+        return extract;
+    }
+
+    @Nullable public String thumbUrl() {
+        return thumbnail != null ? thumbnail.source() : null;
+    }
+
+    @Nullable public String description() {
+        return description;
+    }
+
+    @Nullable
+    public String descriptionSource() {
+        return descriptionSource;
+    }
+
+    @Nullable public ImageInfo imageInfo() {
+        return imageInfo != null ? imageInfo.get(0) : null;
+    }
+
+    @Nullable public VideoInfo videoInfo() {
+        return videoInfo != null ? videoInfo.get(0) : null;
+    }
+
+    @Nullable public String redirectFrom() {
+        return redirectFrom;
+    }
+
+    public void redirectFrom(@Nullable String from) {
+        redirectFrom = from;
+    }
+
+    @Nullable public String convertedFrom() {
+        return convertedFrom;
+    }
+
+    public void convertedFrom(@Nullable String from) {
+        convertedFrom = from;
+    }
+
+    @Nullable public String convertedTo() {
+        return convertedTo;
+    }
+
+    public void convertedTo(@Nullable String to) {
+        convertedTo = to;
+    }
+
+    public void appendTitleFragment(@Nullable String fragment) {
+        title += "#" + fragment;
+    }
+
+    public static class Revision {
+        @SerializedName("revid") private long revisionId;
+        private String user;
+        @SuppressWarnings("unused,NullableProblems") @SerializedName("contentformat") @NonNull private String contentFormat;
+        @SuppressWarnings("unused,NullableProblems") @SerializedName("contentmodel") @NonNull private String contentModel;
+        @SuppressWarnings("unused,NullableProblems") @SerializedName("timestamp") @NonNull private String timeStamp;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String content;
+
+        @NonNull public String content() {
+            return content;
+        }
+
+        @NonNull public String timeStamp() {
+            return StringUtils.defaultString(timeStamp);
+        }
+
+        public long getRevisionId() {
+            return revisionId;
+        }
+
+        @NonNull
+        public String getUser() {
+            return StringUtils.defaultString(user);
+        }
+    }
+
+    public static class LangLink {
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String lang;
+        @NonNull public String lang() {
+            return lang;
+        }
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String title;
+        @NonNull public String title() {
+            return title;
+        }
+    }
+
+    public static class Coordinates {
+        @SuppressWarnings("unused") @Nullable private Double lat;
+        @SuppressWarnings("unused") @Nullable private Double lon;
+
+        @Nullable public Double lat() {
+            return lat;
+        }
+        @Nullable public Double lon() {
+            return lon;
+        }
+    }
+
+    static class Thumbnail {
+        @SuppressWarnings("unused") private String source;
+        @SuppressWarnings("unused") private int width;
+        @SuppressWarnings("unused") private int height;
+        String source() {
+            return source;
+        }
+    }
+
+    public static class PageProps {
+        @SuppressWarnings("unused") @SerializedName("wikibase_item") @Nullable private String wikiBaseItem;
+        @SuppressWarnings("unused") @Nullable private String displaytitle;
+        @SuppressWarnings("unused") @Nullable private String disambiguation;
+
+        @Nullable public String getDisplayTitle() {
+            return displaytitle;
+        }
+
+        @NonNull public String getWikiBaseItem() {
+            return StringUtils.defaultString(wikiBaseItem);
+        }
+
+        public boolean isDisambiguation() {
+            return disambiguation != null;
+        }
+    }
+
+    public static class Category {
+        @SuppressWarnings("unused") private int ns;
+        @SuppressWarnings("unused,NullableProblems") @Nullable private String title;
+        @SuppressWarnings("unused") private boolean hidden;
+
+        public int ns() {
+            return ns;
+        }
+
+        @NonNull public String title() {
+            return StringUtils.defaultString(title);
+        }
+
+        public boolean hidden() {
+            return hidden;
+        }
+    }
+
+    public static class PageTerms {
+        @SuppressWarnings("unused") private List<String> alias;
+        @SuppressWarnings("unused") private List<String> label;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwQueryResponse.java

@@ -0,0 +1,37 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+import com.google.gson.annotations.SerializedName;
+
+import java.util.Map;
+
+public class MwQueryResponse extends MwResponse {
+
+    @SuppressWarnings("unused") @SerializedName("batchcomplete") private boolean batchComplete;
+
+    @SuppressWarnings("unused") @SerializedName("continue") @Nullable private Map<String, String> continuation;
+
+    @Nullable private MwQueryResult query;
+
+    public boolean batchComplete() {
+        return batchComplete;
+    }
+
+    @Nullable public Map<String, String> continuation() {
+        return continuation;
+    }
+
+    @Nullable public MwQueryResult query() {
+        return query;
+    }
+
+    public boolean success() {
+        return query != null;
+    }
+
+    @VisibleForTesting protected void setQuery(@Nullable MwQueryResult query) {
+        this.query = query;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwQueryResult.java

@@ -0,0 +1,314 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.gallery.ImageInfo;
+import org.wikipedia.gallery.VideoInfo;
+import org.wikipedia.json.PostProcessingTypeAdapter;
+import org.wikipedia.model.BaseModel;
+import org.wikipedia.notifications.Notification;
+import org.wikipedia.page.PageTitle;
+import org.wikipedia.settings.SiteInfo;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@SuppressWarnings("unused")
+public class MwQueryResult extends BaseModel implements PostProcessingTypeAdapter.PostProcessable {
+    @Nullable private List<MwQueryPage> pages;
+    @Nullable private List<Redirect> redirects;
+    @Nullable private List<ConvertedTitle> converted;
+    @SerializedName("userinfo") private UserInfo userInfo;
+    @Nullable private List<ListUserResponse> users;
+    @Nullable private Tokens tokens;
+    @SerializedName("authmanagerinfo") @Nullable private MwAuthManagerInfo amInfo;
+    @Nullable private MarkReadResponse echomarkread;
+    @Nullable private MarkReadResponse echomarkseen;
+    @Nullable private NotificationList notifications;
+    @Nullable private Map<String, Notification.UnreadNotificationWikiItem> unreadnotificationpages;
+    @SerializedName("general") @Nullable private SiteInfo generalSiteInfo;
+    @Nullable private List<RecentChange> recentchanges;
+    @SerializedName("wikimediaeditortaskscounts") @Nullable private EditorTaskCounts editorTaskCounts;
+    @SerializedName("allimages") @Nullable private List<ImageDetails> allImages;
+    @SerializedName("geosearch") @Nullable private List<GeoSearchItem> geoSearch;
+    @Nullable private List<MwQueryLogEvent> logevents;
+
+
+    @Nullable public List<MwQueryPage> pages() {
+        return pages;
+    }
+
+    @Nullable public MwQueryPage firstPage() {
+        if (pages != null && pages.size() > 0) {
+            return pages.get(0);
+        }
+        return null;
+    }
+
+    @NonNull
+    public List<ImageDetails> allImages() {
+        return allImages == null ? Collections.emptyList() : allImages;
+    }
+
+    @NonNull
+    public List<GeoSearchItem> geoSearch() {
+        return geoSearch == null ? Collections.emptyList() : geoSearch;
+    }
+
+    @Nullable public UserInfo userInfo() {
+        return userInfo;
+    }
+
+    @Nullable public String csrfToken() {
+        return tokens != null ? tokens.csrf() : null;
+    }
+
+    @Nullable public String createAccountToken() {
+        return tokens != null ? tokens.createAccount() : null;
+    }
+
+    @Nullable public String loginToken() {
+        return tokens != null ? tokens.login() : null;
+    }
+
+    @Nullable public NotificationList notifications() {
+        return notifications;
+    }
+
+    @Nullable public Map<String, Notification.UnreadNotificationWikiItem> unreadNotificationWikis() {
+        return unreadnotificationpages;
+    }
+
+    @Nullable public MarkReadResponse getEchoMarkSeen() {
+        return echomarkseen;
+    }
+
+    @Nullable public String captchaId() {
+        String captchaId = null;
+        if (amInfo != null) {
+            for (MwAuthManagerInfo.Request request : amInfo.requests()) {
+                if ("CaptchaAuthenticationRequest".equals(request.id())) {
+                    captchaId = request.fields().get("captchaId").value();
+                }
+            }
+        }
+        return captchaId;
+    }
+
+    @Nullable public List<RecentChange> getRecentChanges() {
+        return recentchanges;
+    }
+
+    @Nullable public ListUserResponse getUserResponse(@NonNull String userName) {
+        if (users != null) {
+            for (ListUserResponse user : users) {
+                // MediaWiki user names are case sensitive, but the first letter is always capitalized.
+                if (StringUtils.capitalize(userName).equals(user.name())) {
+                    return user;
+                }
+            }
+        }
+        return null;
+    }
+
+    @NonNull public Map<String, ImageInfo> images() {
+        Map<String, ImageInfo> result = new HashMap<>();
+        if (pages != null) {
+            for (MwQueryPage page : pages) {
+                if (page.imageInfo() != null) {
+                    result.put(page.title(), page.imageInfo());
+                }
+            }
+        }
+        return result;
+    }
+
+    @NonNull public Map<String, VideoInfo> videos() {
+        Map<String, VideoInfo> result = new HashMap<>();
+        if (pages != null) {
+            for (MwQueryPage page : pages) {
+                if (page.videoInfo() != null) {
+                    result.put(page.title(), page.videoInfo());
+                }
+            }
+        }
+        return result;
+    }
+
+    @NonNull public List<PageTitle> langLinks() {
+        List<PageTitle> result = new ArrayList<>();
+        if (pages == null || pages.isEmpty() || pages.get(0).langLinks() == null) {
+            return result;
+        }
+        // noinspection ConstantConditions
+        for (MwQueryPage.LangLink link : pages.get(0).langLinks()) {
+            PageTitle title = new PageTitle(link.title(), WikiSite.forLanguageCode(link.lang()));
+            result.add(title);
+        }
+        return result;
+    }
+
+    @NonNull public List<NearbyPage> nearbyPages(@NonNull WikiSite wiki) {
+        List<NearbyPage> result = new ArrayList<>();
+        if (pages != null) {
+            for (MwQueryPage page : pages) {
+                NearbyPage nearbyPage = new NearbyPage(page, wiki);
+                if (nearbyPage.getLocation() != null) {
+                    result.add(nearbyPage);
+                }
+            }
+        }
+        return result;
+    }
+
+    @Nullable public SiteInfo siteInfo() {
+        return generalSiteInfo;
+    }
+
+    @Nullable public EditorTaskCounts editorTaskCounts() {
+        return editorTaskCounts;
+    }
+
+    @Override
+    public void postProcess() {
+        resolveConvertedTitles();
+        resolveRedirectedTitles();
+    }
+
+    private void resolveRedirectedTitles() {
+        if (redirects == null || pages == null) {
+            return;
+        }
+        for (MwQueryPage page : pages) {
+            for (MwQueryResult.Redirect redirect : redirects) {
+                // TODO: Looks like result pages and redirects can also be matched on the "index"
+                // property.  Confirm in the API docs and consider updating.
+                if (page.title().equals(redirect.to())) {
+                    page.redirectFrom(redirect.from());
+                    if (redirect.toFragment() != null) {
+                        page.appendTitleFragment(redirect.toFragment());
+                    }
+                }
+            }
+        }
+    }
+
+    private void resolveConvertedTitles() {
+        if (converted == null || pages == null) {
+            return;
+        }
+        // noinspection ConstantConditions
+        for (MwQueryResult.ConvertedTitle convertedTitle : converted) {
+            // noinspection ConstantConditions
+            for (MwQueryPage page : pages) {
+                if (page.title().equals(convertedTitle.to())) {
+                    page.convertedFrom(convertedTitle.from());
+                    page.convertedTo(convertedTitle.to());
+                }
+            }
+        }
+    }
+
+    @Nullable
+    public List<MwQueryLogEvent> logevents() {
+        return logevents;
+    }
+
+    private static class Redirect {
+        @SuppressWarnings("unused") private int index;
+        @SuppressWarnings("unused") @Nullable private String from;
+        @SuppressWarnings("unused") @Nullable private String to;
+        @SuppressWarnings("unused") @SerializedName("tofragment") @Nullable private String toFragment;
+
+        @Nullable public String to() {
+            return to;
+        }
+
+        @Nullable public String from() {
+            return from;
+        }
+
+        @Nullable public String toFragment() {
+            return toFragment;
+        }
+    }
+
+    public static class ConvertedTitle {
+        @SuppressWarnings("unused") @Nullable private String from;
+        @SuppressWarnings("unused") @Nullable private String to;
+
+        @Nullable public String to() {
+            return to;
+        }
+
+        @Nullable public String from() {
+            return from;
+        }
+    }
+
+    private static class Tokens {
+        @SuppressWarnings("unused,NullableProblems") @SerializedName("csrftoken")
+        @Nullable private String csrf;
+        @SuppressWarnings("unused,NullableProblems") @SerializedName("createaccounttoken")
+        @Nullable private String createAccount;
+        @SuppressWarnings("unused,NullableProblems") @SerializedName("logintoken")
+        @Nullable private String login;
+
+        @Nullable private String csrf() {
+            return csrf;
+        }
+
+        @Nullable private String createAccount() {
+            return createAccount;
+        }
+
+        @Nullable private String login() {
+            return login;
+        }
+    }
+
+    public static class MarkReadResponse {
+        @SuppressWarnings("unused") @Nullable private String result;
+        @SuppressWarnings("unused,NullableProblems") @Nullable private String timestamp;
+
+        @Nullable public String getResult() {
+            return result;
+        }
+
+        @Nullable public String getTimestamp() {
+            return timestamp;
+        }
+    }
+
+    public static class NotificationList {
+        @SuppressWarnings("unused") private int count;
+        @SuppressWarnings("unused") private int rawcount;
+        @SuppressWarnings("unused") @Nullable private Notification.SeenTime seenTime;
+        @SuppressWarnings("unused") @Nullable private List<Notification> list;
+        @SuppressWarnings("unused") @SerializedName("continue") @Nullable private String continueStr;
+
+        @Nullable public List<Notification> list() {
+            return list;
+        }
+
+        @Nullable public String getContinue() {
+            return continueStr;
+        }
+
+        public int getCount() {
+            return count;
+        }
+
+        @Nullable public Notification.SeenTime getSeenTime() {
+            return seenTime;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwResponse.java

@@ -0,0 +1,23 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.json.PostProcessingTypeAdapter;
+import org.wikipedia.model.BaseModel;
+
+import java.util.List;
+
+public abstract class MwResponse extends BaseModel implements PostProcessingTypeAdapter.PostProcessable {
+    @SuppressWarnings({"unused"}) @Nullable private List<MwServiceError> errors;
+    @SuppressWarnings("unused,NullableProblems") @SerializedName("servedby") @NonNull private String servedBy;
+
+    @Override
+    public void postProcess() {
+        if (errors != null && !errors.isEmpty()) {
+            throw new MwException(errors.get(0));
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/MwServiceError.java

@@ -0,0 +1,74 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.dataclient.ServiceError;
+import org.wikipedia.model.BaseModel;
+
+import java.util.List;
+
+/**
+ * Gson POJO for a MediaWiki API error.
+ */
+public class MwServiceError extends BaseModel implements ServiceError {
+    @SuppressWarnings("unused") @Nullable private String code;
+    @SuppressWarnings("unused") @Nullable private String text;
+    @SuppressWarnings("unused") @Nullable private Data data;
+
+    @Override @NonNull public String getTitle() {
+        return StringUtils.defaultString(code);
+    }
+
+    @Override @NonNull public String getDetails() {
+        return StringUtils.defaultString(text);
+    }
+
+    public boolean badToken() {
+        return "badtoken".equals(code);
+    }
+
+    public boolean badLoginState() {
+        return "assertuserfailed".equals(code);
+    }
+
+    public boolean hasMessageName(@NonNull String messageName) {
+        if (data != null && data.messages() != null) {
+            for (Message msg : data.messages()) {
+                if (messageName.equals(msg.name)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    @Nullable public String getMessageHtml(@NonNull String messageName) {
+        if (data != null && data.messages() != null) {
+            for (Message msg : data.messages()) {
+                if (messageName.equals(msg.name)) {
+                    return msg.html();
+                }
+            }
+        }
+        return null;
+    }
+
+    private static final class Data {
+        @SuppressWarnings("unused") @Nullable private List<Message> messages;
+
+        @Nullable private List<Message> messages() {
+            return messages;
+        }
+    }
+
+    private static final class Message {
+        @SuppressWarnings("unused") @Nullable private String name;
+        @SuppressWarnings("unused") @Nullable private String html;
+
+        @NonNull private String html() {
+            return StringUtils.defaultString(html);
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/NearbyPage.java

@@ -0,0 +1,67 @@
+package org.wikipedia.dataclient.mwapi;
+
+import android.location.Location;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.page.PageTitle;
+
+import java.util.List;
+
+public class NearbyPage {
+    @NonNull private PageTitle title;
+    @Nullable private Location location;
+
+    /** calculated externally */
+    private int distance;
+
+    public NearbyPage(@NonNull MwQueryPage page, @NonNull WikiSite wiki) {
+        title = new PageTitle(page.title(), wiki);
+        title.setThumbUrl(page.thumbUrl());
+        List<MwQueryPage.Coordinates> coordinates = page.coordinates();
+        if (coordinates == null || coordinates.isEmpty()) {
+            return;
+        }
+        if (coordinates.get(0).lat() != null && coordinates.get(0).lon() != null) {
+            location = new Location(title.getPrefixedText());
+            location.setLatitude(coordinates.get(0).lat());
+            location.setLongitude(coordinates.get(0).lon());
+        }
+    }
+
+    public NearbyPage(@NonNull PageTitle title, @Nullable Location location) {
+        this.title = title;
+        this.location = location;
+    }
+
+    @NonNull public PageTitle getTitle() {
+        return title;
+    }
+
+    @Nullable public Location getLocation() {
+        return location;
+    }
+
+    @Override public String toString() {
+        return "NearbyPage{"
+                + "title='" + title + '\''
+                + ", thumbUrl='" + title.getThumbUrl() + '\''
+                + ", location=" + location + '\''
+                + ", distance='" + distance
+                + '}';
+    }
+
+    /**
+     * Returns the distance from the point where the device is.
+     * Calculated later and can change. Needs to be set first by #setDistance!
+     */
+    public int getDistance() {
+        return distance;
+    }
+
+    public void setDistance(int distance) {
+        this.distance = distance;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/RecentChange.java

@@ -0,0 +1,42 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+
+@SuppressWarnings("unused")
+public class RecentChange {
+    @Nullable private String type;
+    @Nullable private String title;
+    private long pageid;
+    private long revid;
+    @SerializedName("old_revid") private long oldRevisionId;
+    @Nullable private String timestamp;
+
+    @NonNull public String getType() {
+        return StringUtils.defaultString(type);
+    }
+
+    @NonNull public String getTitle() {
+        return StringUtils.defaultString(title);
+    }
+
+    public long getPageId() {
+        return pageid;
+    }
+
+    public long getRevId() {
+        return revid;
+    }
+
+    public long getOldRevisionId() {
+        return oldRevisionId;
+    }
+
+    public String getTimestamp() {
+        return StringUtils.defaultString(timestamp);
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/SiteMatrix.java

@@ -0,0 +1,60 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+
+import com.google.gson.JsonObject;
+
+import org.wikipedia.json.GsonUtil;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class SiteMatrix extends MwResponse {
+    @SuppressWarnings("unused,NullableProblems") @NonNull private JsonObject sitematrix;
+
+    public JsonObject siteMatrix() {
+        return sitematrix;
+    }
+
+    @SuppressWarnings("unused,NullableProblems")
+    public class SiteInfo {
+        @NonNull
+        private String code;
+        @NonNull
+        private String name;
+        @NonNull
+        private String localname;
+
+        @NonNull
+        public String code() {
+            return code;
+        }
+
+        @NonNull
+        public String name() {
+            return name;
+        }
+
+        @NonNull
+        public String localName() {
+            return localname;
+        }
+    }
+
+    public static List<SiteInfo> getSites(@NonNull SiteMatrix siteMatrix) {
+        List<SiteInfo> sites = new ArrayList<>();
+        // We have to parse the Json manually because the list of SiteInfo objects
+        // contains a "count" member that prevents it from being able to deserialize
+        // as a list automatically.
+        for (String key : siteMatrix.siteMatrix().keySet()) {
+            if (key.equals("count")) {
+                continue;
+            }
+            SiteInfo info = GsonUtil.getDefaultGson().fromJson(siteMatrix.siteMatrix().get(key), SiteInfo.class);
+            if (info != null) {
+                sites.add(info);
+            }
+        }
+        return sites;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/UserInfo.java

@@ -0,0 +1,84 @@
+package org.wikipedia.dataclient.mwapi;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.util.HashMap;
+import java.util.Map;
+
+@SuppressWarnings("unused")
+public class UserInfo {
+    @NonNull
+    private String name;
+    @NonNull
+    private int id;
+
+    //Block information
+    private int blockid;
+    private String blockedby;
+    private int blockedbyid;
+    private String blockreason;
+    private String blocktimestamp;
+    private String blockexpiry;
+
+    // Object type is any JSON type.
+    @SuppressWarnings("MismatchedQueryAndUpdateOfCollection")
+    @Nullable
+    private Map<String, ?> options;
+
+    public int id() {
+        return id;
+    }
+
+    @NonNull
+    public Map<String, String> userjsOptions() {
+        Map<String, String> map = new HashMap<>();
+        if (options != null) {
+            for (Map.Entry<String, ?> entry : options.entrySet()) {
+                if (entry.getKey().startsWith("userjs-")) {
+                    // T161866 entry.valueOf() should always return a String but doesn't
+                    map.put(entry.getKey(), entry.getValue() == null ? "" : String.valueOf(entry.getValue()));
+                }
+            }
+        }
+        return map;
+    }
+
+    @NonNull
+    public int blockid() {
+        return blockid;
+    }
+
+    @NonNull
+    public String blockedby() {
+        if (blockedby != null)
+            return blockedby;
+        else return "";
+    }
+
+    @NonNull
+    public int blockedbyid() {
+        return blockedbyid;
+    }
+
+    @NonNull
+    public String blockreason() {
+        if (blockreason != null)
+            return blockreason;
+        else return "";
+    }
+
+    @NonNull
+    public String blocktimestamp() {
+        if (blocktimestamp != null)
+            return blocktimestamp;
+        else return "";
+    }
+
+    @NonNull
+    public String blockexpiry() {
+        if (blockexpiry != null)
+            return blockexpiry;
+        else return "";
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/page/MwMobileViewPageLead.java

@@ -0,0 +1,281 @@
+package org.wikipedia.dataclient.mwapi.page;
+
+import android.location.Location;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.dataclient.mwapi.MwQueryPage;
+import org.wikipedia.dataclient.mwapi.MwResponse;
+import org.wikipedia.dataclient.page.PageLead;
+import org.wikipedia.dataclient.page.PageLeadProperties;
+import org.wikipedia.dataclient.page.Protection;
+import org.wikipedia.page.Namespace;
+import org.wikipedia.page.Page;
+import org.wikipedia.page.PageProperties;
+import org.wikipedia.page.PageTitle;
+import org.wikipedia.page.Section;
+import org.wikipedia.util.StringUtil;
+import org.wikipedia.util.UriUtil;
+
+import java.util.Collections;
+import java.util.List;
+
+import static org.wikipedia.dataclient.Service.PREFERRED_THUMB_SIZE;
+import static org.wikipedia.util.ImageUrlUtil.getUrlForSize;
+
+/**
+ * Gson POJO for loading the first stage of page content.
+ */
+public class MwMobileViewPageLead extends MwResponse implements PageLead {
+    @SuppressWarnings("unused") private Mobileview mobileview;
+
+    /** Note: before using this check that #getMobileview != null */
+    @Override
+    public Page toPage(@NonNull PageTitle title) {
+        return new Page(adjustPageTitle(title, title.getPrefixedText()),
+                mobileview.getSections(),
+                mobileview.toPageProperties(),
+                false);
+    }
+
+    private PageTitle adjustPageTitle(@NonNull PageTitle title, @NonNull String originalPrefixedText) {
+        if (mobileview.getRedirected() != null) {
+            // Handle redirects properly.
+            title = new PageTitle(mobileview.getRedirected(), title.getWikiSite(),
+                    title.getThumbUrl());
+        } else if (mobileview.getNormalizedTitle() != null) {
+            // We care about the normalized title only if we were not redirected
+            title = new PageTitle(mobileview.getNormalizedTitle(), title.getWikiSite(),
+                    title.getThumbUrl());
+        }
+
+        if (mobileview.getDisplayTitle() != null
+                && !StringUtil.removeHTMLTags(title.getDisplayText()).equals(StringUtil.removeHTMLTags(mobileview.getDisplayTitle()))) {
+            title = new PageTitle(StringUtil.removeHTMLTags(mobileview.getDisplayTitle()), title.getWikiSite(),
+                    title.getThumbUrl());
+        }
+
+        if (mobileview.getDisplayTitle() != null
+                && !mobileview.getDisplayTitle().equals(originalPrefixedText)
+                && mobileview.getNormalizedTitle() == null) {
+            // Sometimes the MW api will not give us the "converted" or "redirected" title if switching between Chinese variants
+            // Ticket: https://phabricator.wikimedia.org/T206891#4672777
+            // We can the original prefixed title text (the one we used for calling API) to build the PageTitle
+            title = new PageTitle(originalPrefixedText, title.getWikiSite(), title.getThumbUrl());
+        }
+
+        if (mobileview.getRedirected() != null) {
+            title.setConvertedText(mobileview.getRedirected());
+        }
+
+        title.setDescription(mobileview.getDescription());
+        return title;
+    }
+
+    @Override @NonNull public String getLeadSectionContent() {
+        if (mobileview != null) {
+            return mobileview.getSections().get(0).getContent();
+        }
+        return "";
+    }
+
+    @Nullable
+    @Override
+    public String getTitlePronunciationUrl() {
+        return null;
+    }
+
+    @Nullable @Override public String getLeadImageUrl(int leadImageWidth) {
+        return mobileview == null ? null : mobileview.getLeadImageUrl(leadImageWidth);
+    }
+
+    @Nullable @Override public String getThumbUrl() {
+        return mobileview == null ? null : mobileview.getThumbUrl();
+    }
+
+    @Nullable @Override public String getDescription() {
+        return mobileview == null ? null : mobileview.getDescription();
+    }
+
+    @Nullable
+    @Override
+    public Location getGeo() {
+        return null;
+    }
+
+    @VisibleForTesting
+    public Mobileview getMobileview() {
+        return mobileview;
+    }
+
+
+    /**
+     * Almost everything is in this inner class.
+     */
+    public static class Mobileview implements PageLeadProperties {
+        @SuppressWarnings("unused") private int id;
+        @SuppressWarnings("unused") private int namespace;
+        @SuppressWarnings("unused") private long revision;
+        @SuppressWarnings("unused") @Nullable private String lastmodified;
+        @SuppressWarnings("unused") @Nullable private String displaytitle;
+        @SuppressWarnings("unused") @Nullable private String redirected;
+        @SuppressWarnings("unused") @Nullable private String normalizedtitle;
+        @SuppressWarnings("unused") private int languagecount;
+        @SuppressWarnings("unused") private boolean editable;
+        @SuppressWarnings("unused") private boolean mainpage;
+        @SuppressWarnings("unused") private boolean disambiguation;
+        @SuppressWarnings("unused") @Nullable private String description;
+        @SuppressWarnings("unused") @Nullable private String descriptionsource;
+        @SuppressWarnings("unused") @SerializedName("image") @Nullable private PageImage pageImage;
+        @SuppressWarnings("unused") @SerializedName("thumb") @Nullable private PageImageThumb leadImage;
+        @SuppressWarnings("unused") @Nullable private Protection protection;
+        @SuppressWarnings("unused") @Nullable private List<Section> sections;
+        @SuppressWarnings("unused") @Nullable private MwQueryPage.PageProps pageprops;
+
+        /** Converter */
+        public PageProperties toPageProperties() {
+            return new PageProperties(this);
+        }
+
+        @Override
+        public int getId() {
+            return id;
+        }
+
+        @Override @NonNull public Namespace getNamespace() {
+            return Namespace.of(namespace);
+        }
+
+        @Override
+        public long getRevision() {
+            return revision;
+        }
+
+        @Override
+        @Nullable
+        public String getLastModified() {
+            return lastmodified;
+        }
+
+        @Override
+        public int getLanguageCount() {
+            return languagecount;
+        }
+
+        @Override
+        @Nullable
+        public String getDisplayTitle() {
+            return displaytitle;
+        }
+
+        @Override
+        @Nullable
+        public String getTitlePronunciationUrl() {
+            return null;
+        }
+
+        @Override
+        @Nullable
+        public Location getGeo() {
+            return null;
+        }
+
+        @Override
+        @Nullable
+        public String getRedirected() {
+            return redirected;
+        }
+
+        @Override
+        @Nullable
+        public String getNormalizedTitle() {
+            return normalizedtitle;
+        }
+
+        @Nullable
+        public String getDescription() {
+            return description;
+        }
+
+        @Override
+        @Nullable
+        public String getLeadImageUrl(int leadImageWidth) {
+            return leadImage != null ? leadImage.getUrl() : null;
+        }
+
+        @Override
+        @Nullable
+        public String getThumbUrl() {
+            return leadImage != null ? UriUtil.resolveProtocolRelativeUrl(getUrlForSize(leadImage.getUrl(), PREFERRED_THUMB_SIZE)) : null;
+        }
+
+        @Override
+        @Nullable
+        public String getLeadImageFileName() {
+            return pageImage != null ? pageImage.getFileName() : null;
+        }
+
+        @Override
+        @Nullable
+        public String getWikiBaseItem() {
+            return pageprops != null && pageprops.getWikiBaseItem() != null ? pageprops.getWikiBaseItem() : null;
+        }
+
+        @Override
+        @Nullable
+        public String getDescriptionSource() {
+            return descriptionsource;
+        }
+
+        @Override
+        @Nullable
+        public String getFirstAllowedEditorRole() {
+            return protection != null ? protection.getFirstAllowedEditorRole() : null;
+        }
+
+        @Override
+        public boolean isEditable() {
+            return editable;
+        }
+
+        @Override
+        public boolean isMainPage() {
+            return mainpage;
+        }
+
+        @Override
+        public boolean isDisambiguation() {
+            return disambiguation;
+        }
+
+        @Override @NonNull public List<Section> getSections() {
+            return sections == null ? Collections.emptyList() : sections;
+        }
+    }
+
+    /**
+     * For the lead image File: page name
+     */
+    public static class PageImage {
+        @SuppressWarnings("unused") @SerializedName("file") private String fileName;
+
+        public String getFileName() {
+            return fileName;
+        }
+    }
+
+    /**
+     * For the lead image URL
+     */
+    public static class PageImageThumb {
+        @SuppressWarnings("unused") private String url;
+
+        public String getUrl() {
+            return url;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/page/MwMobileViewPageRemaining.java

@@ -0,0 +1,21 @@
+package org.wikipedia.dataclient.mwapi.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.page.PageRemaining;
+import org.wikipedia.page.Section;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Gson POJO for loading remaining page content.
+ */
+public class MwMobileViewPageRemaining implements PageRemaining {
+    @SuppressWarnings("unused") @Nullable private MwMobileViewPageLead.Mobileview mobileview;
+
+    @NonNull @Override public List<Section> sections() {
+        return mobileview == null ? Collections.emptyList() : mobileview.getSections();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/page/MwPageClient.java

@@ -0,0 +1,54 @@
+package org.wikipedia.dataclient.mwapi.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.ServiceFactory;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.dataclient.page.PageClient;
+import org.wikipedia.dataclient.page.PageSummary;
+
+import io.reactivex.Observable;
+import okhttp3.CacheControl;
+import okhttp3.Request;
+import retrofit2.Response;
+
+/**
+ * Retrofit web service client for MediaWiki PHP API.
+ */
+public class MwPageClient implements PageClient {
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Observable<? extends PageSummary> summary(@NonNull WikiSite wiki, @NonNull String title, @Nullable String referrerUrl) {
+        return ServiceFactory.get(wiki).getSummary(referrerUrl, title, wiki.languageCode());
+    }
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Observable<Response<MwMobileViewPageLead>> lead(@NonNull WikiSite wiki,
+                                                                              @Nullable CacheControl cacheControl,
+                                                                              @Nullable String saveOfflineHeader,
+                                                                              @Nullable String referrerUrl,
+                                                                              @NonNull String title,
+                                                                              int leadImageWidth) {
+        return ServiceFactory.get(wiki).getLeadSection(cacheControl == null ? null : cacheControl.toString(),
+                saveOfflineHeader, referrerUrl, title, leadImageWidth, wiki.languageCode());
+    }
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Observable<Response<MwMobileViewPageRemaining>> sections(@NonNull WikiSite wiki,
+                                                                                       @Nullable CacheControl cacheControl,
+                                                                                       @Nullable String saveOfflineHeader,
+                                                                                       @NonNull String title) {
+        return ServiceFactory.get(wiki).getRemainingSections(cacheControl == null ? null : cacheControl.toString(),
+                saveOfflineHeader, title, wiki.languageCode());
+    }
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Request sectionsUrl(@NonNull WikiSite wiki,
+                                                  @Nullable CacheControl cacheControl,
+                                                  @Nullable String saveOfflineHeader,
+                                                  @NonNull String title) {
+        return ServiceFactory.get(wiki).getRemainingSectionsUrl(cacheControl == null ? null : cacheControl.toString(),
+                saveOfflineHeader, title, wiki.languageCode()).request();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/mwapi/page/MwQueryPageSummary.java

@@ -0,0 +1,83 @@
+package org.wikipedia.dataclient.mwapi.page;
+
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.mwapi.MwQueryResponse;
+import org.wikipedia.dataclient.page.PageSummary;
+import org.wikipedia.page.Namespace;
+
+/**
+ * Useful for link previews coming from MW API.
+ */
+public class MwQueryPageSummary extends MwQueryResponse implements PageSummary {
+    @Override @Nullable public String getTitle() {
+        if (query() == null || query().firstPage() == null) {
+            return null;
+        }
+        return query().firstPage().title();
+    }
+
+    @Override @Nullable public String getDisplayTitle() {
+        if (query() == null || query().firstPage() == null) {
+            return null;
+        }
+        return (query().firstPage().pageProps() != null && !TextUtils.isEmpty(query().firstPage().pageProps().getDisplayTitle()))
+                ? query().firstPage().pageProps().getDisplayTitle() : query().firstPage().title();
+    }
+
+    @Override @Nullable public String getConvertedTitle() {
+        if (query() == null || query().firstPage() == null) {
+            return null;
+        }
+        return (query().firstPage().convertedTo() != null && !TextUtils.isEmpty(query().firstPage().convertedTo()))
+                ? query().firstPage().convertedTo() : query().firstPage().title();
+    }
+
+    @Override @Nullable
+    public String getExtract() {
+        if (query() == null || query().firstPage() == null) {
+            return null;
+        }
+        return query().firstPage().extract();
+    }
+
+    @Override @Nullable
+    public String getExtractHtml() {
+        return getExtract();
+    }
+
+    @Override @Nullable
+    public String getThumbnailUrl() {
+        if (query() == null || query().firstPage() == null) {
+            return null;
+        }
+        return query().firstPage().thumbUrl();
+    }
+
+    @Override @NonNull
+    public Namespace getNamespace() {
+        if (query() == null || query().firstPage() == null) {
+            return Namespace.MAIN;
+        }
+        return query().firstPage().namespace();
+    }
+
+    @NonNull @Override
+    public String getType() {
+        if (query() != null && query().firstPage() != null && query().firstPage().pageProps() != null
+                && query().firstPage().pageProps().isDisambiguation()) {
+            return TYPE_DISAMBIGUATION;
+        }
+        return TYPE_STANDARD;
+    }
+
+    @Override public int getPageId() {
+        if (query() == null || query().firstPage() == null) {
+            return 0;
+        }
+        return query().firstPage().pageId();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/okhttp/AvailableInputStream.java

@@ -0,0 +1,74 @@
+package org.wikipedia.dataclient.okhttp;
+
+import androidx.annotation.NonNull;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * This is a subclass of InputStream that implements the available() method reliably enough
+ * to satisfy WebResourceResponses or other consumers like BufferedInputStream that depend
+ * on available() to return a meaningful value.
+ *
+ * The problem is that the InputStream provided by OkHttp's body().byteStream() returns zero
+ * when calling available() prior to making any read() calls, which means that it will break
+ * any consumers that wrap a BufferedInputStream onto this stream, or any other wrapper that
+ * relies on a consistent implementation of available().
+ *
+ * This is initialized with the original InputStream plus its total size, which must be known
+ * at the time of instantiation.  You may then call the read() and skip() methods in the usual
+ * way, and then be able to call available() and get the number of bytes left to read.
+ */
+public class AvailableInputStream extends InputStream {
+    private InputStream stream;
+    private long available;
+
+    public AvailableInputStream(InputStream stream, long available) {
+        this.stream = stream;
+        this.available = available;
+    }
+
+    @Override public int read() throws IOException {
+        decreaseAvailable(1);
+        return stream.read();
+    }
+
+    @Override public int read(@NonNull byte[] b) throws IOException {
+        int ret = stream.read(b);
+        if (ret > 0) {
+            decreaseAvailable(ret);
+        }
+        return ret;
+    }
+
+    @Override public int read(@NonNull byte[] b, int off, int len) throws IOException {
+        int ret = stream.read(b, off, len);
+        if (ret > 0) {
+            decreaseAvailable(ret);
+        }
+        return ret;
+    }
+
+    @Override public long skip(long n) throws IOException {
+        long ret = stream.skip(n);
+        if (ret > 0) {
+            decreaseAvailable(ret);
+        }
+        return ret;
+    }
+
+    @Override public int available() throws IOException {
+        int ret = stream.available();
+        if (ret == 0 && available > 0) {
+            return (int) available;
+        }
+        return ret;
+    }
+
+    private void decreaseAvailable(long n) {
+        available -= n;
+        if (available < 0) {
+            available = 0;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/okhttp/HttpStatusException.java

@@ -0,0 +1,54 @@
+package org.wikipedia.dataclient.okhttp;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.ServiceError;
+import org.wikipedia.dataclient.restbase.RbServiceError;
+import org.wikipedia.util.log.L;
+
+import java.io.IOException;
+
+import okhttp3.Response;
+
+public class HttpStatusException extends IOException {
+    private final int code;
+    private final String url;
+    @Nullable private ServiceError serviceError;
+
+    public HttpStatusException(@NonNull Response rsp) {
+        this.code = rsp.code();
+        this.url = rsp.request().url().uri().toString();
+        try {
+            if (rsp.body() != null && rsp.body().contentType() != null
+                    && rsp.body().contentType().toString().contains("json")) {
+                serviceError = RbServiceError.create(rsp.body().string());
+            }
+        } catch (Exception e) {
+            L.e(e);
+        }
+    }
+
+    public HttpStatusException(@Nullable ServiceError error) {
+        serviceError = error;
+        code = 0;
+        url = "";
+    }
+
+    public int code() {
+        return code;
+    }
+
+    public ServiceError serviceError() {
+        return serviceError;
+    }
+
+    @Override
+    public String getMessage() {
+        String str = "Code: " + Integer.toString(code) + ", URL: " + url;
+        if (serviceError != null) {
+            str += ", title: " + serviceError.getTitle() + ", detail: " + serviceError.getDetails();
+        }
+        return str;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/okhttp/TestStubInterceptor.kt

@@ -0,0 +1,23 @@
+package org.wikipedia.dataclient.okhttp
+
+import okhttp3.Interceptor
+import okhttp3.Response
+import java.io.IOException
+
+class TestStubInterceptor : Interceptor {
+    interface Callback {
+        @Throws(IOException::class)
+        fun getResponse(request: Interceptor.Chain): Response
+    }
+
+    @Throws(IOException::class)
+    override fun intercept(chain: Interceptor.Chain): Response {
+        return if (CALLBACK != null) {
+            CALLBACK!!.getResponse(chain)
+        } else chain.proceed(chain.request())
+    }
+
+    companion object {
+        var CALLBACK: Callback? = null
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/okhttp/UnsuccessfulResponseInterceptor.kt

@@ -0,0 +1,16 @@
+package org.wikipedia.dataclient.okhttp
+
+import okhttp3.Interceptor
+import okhttp3.Response
+import java.io.IOException
+
+class UnsuccessfulResponseInterceptor : Interceptor {
+    @Throws(IOException::class)
+    override fun intercept(chain: Interceptor.Chain): Response {
+        val rsp = chain.proceed(chain.request())
+        if (rsp.isSuccessful) {
+            return rsp
+        }
+        throw HttpStatusException(rsp)
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/okhttp/util/HttpUrlUtil.java

@@ -0,0 +1,23 @@
+package org.wikipedia.dataclient.okhttp.util;
+
+import androidx.annotation.NonNull;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import okhttp3.HttpUrl;
+
+public final class HttpUrlUtil {
+    private static final List<String> RESTBASE_SEGMENT_IDENTIFIERS = Arrays.asList("rest_v1", "v1");
+
+    public static boolean isRestBase(@NonNull HttpUrl url) {
+        return !Collections.disjoint(url.encodedPathSegments(), RESTBASE_SEGMENT_IDENTIFIERS);
+    }
+
+    public static boolean isMobileView(@NonNull HttpUrl url) {
+        return "mobileview".equals(url.queryParameter("action"));
+    }
+
+    private HttpUrlUtil() { }
+}

data-client/src/main/java/org/wikipedia/dataclient/page/PageClient.java

@@ -0,0 +1,60 @@
+package org.wikipedia.dataclient.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.WikiSite;
+
+import io.reactivex.Observable;
+import okhttp3.CacheControl;
+import okhttp3.Request;
+import retrofit2.Response;
+
+/**
+ * Generic interface for Page content service.
+ * Usually we would use direct Retrofit Callbacks here but since we have two ways of
+ * getting to the data (MW API and RESTBase) we add this layer of indirection -- until we drop one.
+ */
+public interface PageClient {
+    /**
+     * Gets a page summary for a given title -- for link previews
+     *
+     * @param title the page title to be used including prefix
+     */
+    @NonNull <T extends PageSummary> Observable<T> summary(@NonNull WikiSite wiki,
+                                                           @NonNull String title,
+                                                           @Nullable String referrerUrl);
+
+    /**
+     * Gets the lead section and initial metadata of a given title.
+     *
+     * @param title the page title with prefix if necessary
+     * @param leadThumbnailWidth one of the bucket widths for the lead image
+     */
+    @NonNull <T extends PageLead> Observable<Response<T>> lead(@NonNull WikiSite wiki,
+                                                               @Nullable CacheControl cacheControl,
+                                                               @Nullable String saveOfflineHeader,
+                                                               @Nullable String referrerUrl,
+                                                               @NonNull String title,
+                                                               int leadThumbnailWidth);
+
+    /**
+     * Gets the remaining sections of a given title.
+     *
+     * @param title the page title to be used including prefix
+     */
+    @NonNull <T extends PageRemaining> Observable<Response<T>> sections(@NonNull WikiSite wiki,
+                                                                        @Nullable CacheControl cacheControl,
+                                                                        @Nullable String saveOfflineHeader,
+                                                                        @NonNull String title);
+
+    /**
+     * Gets the remaining sections request url of a given title.
+     *
+     * @param title the page title to be used including prefix
+     */
+    @NonNull Request sectionsUrl(@NonNull WikiSite wiki,
+                               @Nullable CacheControl cacheControl,
+                               @Nullable String saveOfflineHeader,
+                               @NonNull String title);
+}

data-client/src/main/java/org/wikipedia/dataclient/page/PageLead.java

@@ -0,0 +1,26 @@
+package org.wikipedia.dataclient.page;
+
+import android.location.Location;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.page.Page;
+import org.wikipedia.page.PageTitle;
+
+/**
+ * Gson POJI for loading the first stage of page content.
+ */
+public interface PageLead {
+    /** Note: before using this check that #hasError is false */
+    Page toPage(PageTitle title);
+
+    @NonNull String getLeadSectionContent();
+
+    @Nullable String getTitlePronunciationUrl();
+    @Nullable String getLeadImageUrl(int leadImageWidth);
+    @Nullable String getThumbUrl();
+    @Nullable String getDescription();
+
+    @Nullable Location getGeo();
+}

data-client/src/main/java/org/wikipedia/dataclient/page/PageLeadProperties.java

@@ -0,0 +1,73 @@
+package org.wikipedia.dataclient.page;
+
+import android.location.Location;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.page.Namespace;
+import org.wikipedia.page.Section;
+
+import java.util.List;
+
+/**
+ * The main properties of a page
+ */
+public interface PageLeadProperties {
+
+    int getId();
+
+    @NonNull Namespace getNamespace();
+
+    long getRevision();
+
+    @Nullable
+    String getLastModified();
+
+    int getLanguageCount();
+
+    @Nullable
+    String getDisplayTitle();
+
+    @Nullable
+    String getTitlePronunciationUrl();
+
+    @Nullable
+    Location getGeo();
+
+    @Nullable
+    String getRedirected();
+
+    @Nullable
+    String getNormalizedTitle();
+
+    @Nullable
+    String getWikiBaseItem();
+
+    @Nullable
+    String getDescriptionSource();
+
+    /**
+     * @return Nullable URL with no scheme. For example, foo.bar.com/ instead of
+     *         http://foo.bar.com/.
+     */
+    @Nullable
+    String getLeadImageUrl(int leadImageWidth);
+
+    @Nullable
+    String getThumbUrl();
+
+    @Nullable
+    String getLeadImageFileName();
+
+    @Nullable
+    String getFirstAllowedEditorRole();
+
+    boolean isEditable();
+
+    boolean isMainPage();
+
+    boolean isDisambiguation();
+
+    @NonNull List<Section> getSections();
+}

data-client/src/main/java/org/wikipedia/dataclient/page/PageRemaining.java

@@ -0,0 +1,14 @@
+package org.wikipedia.dataclient.page;
+
+import androidx.annotation.NonNull;
+
+import org.wikipedia.page.Section;
+
+import java.util.List;
+
+/**
+ * Gson POJI for loading remaining page content.
+ */
+public interface PageRemaining {
+    @NonNull List<Section> sections();
+}

data-client/src/main/java/org/wikipedia/dataclient/page/PageSummary.java

@@ -0,0 +1,26 @@
+package org.wikipedia.dataclient.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.page.Namespace;
+
+/**
+ * Represents a summary of a page, useful for page previews.
+ */
+public interface PageSummary {
+    String TYPE_STANDARD = "standard";
+    String TYPE_DISAMBIGUATION = "disambiguation";
+    String TYPE_MAIN_PAGE = "mainpage";
+    String TYPE_NO_EXTRACT = "no-extract";
+
+    @NonNull String getType();
+    @Nullable String getTitle();
+    @Nullable String getDisplayTitle();
+    @Nullable String getConvertedTitle();
+    @Nullable String getExtract();
+    @Nullable String getExtractHtml();
+    @Nullable String getThumbnailUrl();
+    @NonNull Namespace getNamespace();
+    int getPageId();
+}

data-client/src/main/java/org/wikipedia/dataclient/page/Protection.java

@@ -0,0 +1,23 @@
+package org.wikipedia.dataclient.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.util.Collections;
+import java.util.Set;
+
+/** Protection settings for a page */
+public class Protection {
+    @SuppressWarnings("MismatchedReadAndWriteOfArray") @NonNull private Set<String> edit = Collections.emptySet();
+
+    // TODO should send them all, but callers need to be updated, too, (future patch)
+    @Nullable
+    public String getFirstAllowedEditorRole() {
+        return edit.isEmpty() ? null : edit.iterator().next();
+    }
+
+    @NonNull
+    public Set<String> getEditRoles() {
+        return Collections.unmodifiableSet(edit);
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/RbDefinition.java

@@ -0,0 +1,56 @@
+package org.wikipedia.dataclient.restbase;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.json.annotations.Required;
+
+import java.util.Map;
+
+public class RbDefinition {
+    @Required @NonNull private Map<String, Usage[]> usagesByLang;
+
+    public RbDefinition(@NonNull Map<String, RbDefinition.Usage[]> usages) {
+        usagesByLang = usages;
+    }
+
+    @Nullable public Usage[] getUsagesForLang(String langCode) {
+        return usagesByLang.get(langCode);
+    }
+
+    public static class Usage {
+        @Required @NonNull private String partOfSpeech;
+        @Required @NonNull private Definition[] definitions;
+
+        public Usage(@NonNull String partOfSpeech, @NonNull Definition[] definitions) {
+            this.partOfSpeech = partOfSpeech;
+            this.definitions = definitions;
+        }
+
+        @NonNull public String getPartOfSpeech() {
+            return partOfSpeech;
+        }
+
+        @NonNull public Definition[] getDefinitions() {
+            return definitions;
+        }
+    }
+
+    public static class Definition {
+        @Required @NonNull private String definition;
+        @Nullable private String[] examples;
+
+        public Definition(@NonNull String definition, @Nullable String[] examples) {
+            this.definition = definition;
+            this.examples = examples;
+        }
+
+        @NonNull public String getDefinition() {
+            return definition;
+        }
+
+        @Nullable public String[] getExamples() {
+            return examples;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/RbRelatedPages.java

@@ -0,0 +1,33 @@
+package org.wikipedia.dataclient.restbase;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.restbase.page.RbPageSummary;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class RbRelatedPages {
+    @SuppressWarnings("unused") @Nullable private List<RbPageSummary> pages;
+
+    @Nullable
+    public List<RbPageSummary> getPages() {
+        return pages;
+    }
+
+    @NonNull
+    public List<RbPageSummary> getPages(int limit) {
+        List<RbPageSummary> list = new ArrayList<>();
+        if (getPages() != null) {
+            for (RbPageSummary page : getPages()) {
+                list.add(page);
+                if (limit == list.size()) {
+                    break;
+                }
+            }
+        }
+
+        return list;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/RbServiceError.java

@@ -0,0 +1,35 @@
+package org.wikipedia.dataclient.restbase;
+
+import androidx.annotation.NonNull;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.dataclient.ServiceError;
+import org.wikipedia.json.GsonUnmarshaller;
+import org.wikipedia.model.BaseModel;
+
+/**
+ * Gson POJO for a RESTBase API error.
+ */
+public class RbServiceError extends BaseModel implements ServiceError {
+    @SuppressWarnings("unused") private String type;
+    @SuppressWarnings("unused") private String title;
+    @SuppressWarnings("unused") private String detail;
+    @SuppressWarnings("unused") private String method;
+    @SuppressWarnings("unused") private String uri;
+
+    public static RbServiceError create(@NonNull String rspBody) {
+        return GsonUnmarshaller.unmarshal(RbServiceError.class, rspBody);
+    }
+
+    @Override
+    @NonNull
+    public String getTitle() {
+        return StringUtils.defaultString(title);
+    }
+
+    @Override
+    @NonNull
+    public String getDetails() {
+        return StringUtils.defaultString(detail);
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/page/RbPageClient.java

@@ -0,0 +1,60 @@
+package org.wikipedia.dataclient.restbase.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.ServiceFactory;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.dataclient.page.PageClient;
+import org.wikipedia.dataclient.page.PageSummary;
+
+import io.reactivex.Observable;
+import okhttp3.CacheControl;
+import okhttp3.Request;
+import retrofit2.Response;
+
+// todo: consolidate with MwPageClient or just use the Services directly!
+/**
+ * Retrofit web service client for RESTBase Nodejs API.
+ */
+public class RbPageClient implements PageClient {
+
+    // todo: RbPageSummary should specify an @Required annotation that throws a JsonParseException
+    //       when the body is null rather than requiring all clients to check for a null body. There
+    //       may be some abandoned demo patches that already have this functionality. It should be
+    //       part of the Gson augmentation package and eventually cut into a separate lib. Repeat
+    //       everywhere a Response.body() == null check occurs that throws
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Observable<? extends PageSummary> summary(@NonNull WikiSite wiki, @NonNull String title, @Nullable String referrerUrl) {
+        return ServiceFactory.getRest(wiki).getSummary(referrerUrl, title);
+    }
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Observable<Response<RbPageLead>> lead(@NonNull WikiSite wiki,
+                                                                    @Nullable CacheControl cacheControl,
+                                                                    @Nullable String saveOfflineHeader,
+                                                                    @Nullable String referrerUrl,
+                                                                    @NonNull String title,
+                                                                    int leadThumbnailWidth) {
+        return ServiceFactory.getRest(wiki).getLeadSection(cacheControl == null ? null : cacheControl.toString(),
+                saveOfflineHeader, referrerUrl, title);
+    }
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Observable<Response<RbPageRemaining>> sections(@NonNull WikiSite wiki,
+                                                                             @Nullable CacheControl cacheControl,
+                                                                             @Nullable String saveOfflineHeader,
+                                                                             @NonNull String title) {
+        return ServiceFactory.getRest(wiki).getRemainingSections(cacheControl == null ? null : cacheControl.toString(),
+                saveOfflineHeader, title);
+    }
+
+    @SuppressWarnings("unchecked")
+    @NonNull @Override public Request sectionsUrl(@NonNull WikiSite wiki,
+                                                  @Nullable CacheControl cacheControl,
+                                                  @Nullable String saveOfflineHeader,
+                                                  @NonNull String title) {
+        return ServiceFactory.getRest(wiki).getRemainingSectionsUrl(cacheControl == null ? null : cacheControl.toString(),
+                saveOfflineHeader, title).request();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/page/RbPageLead.java

@@ -0,0 +1,268 @@
+package org.wikipedia.dataclient.restbase.page;
+
+import android.location.Location;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.dataclient.page.PageLead;
+import org.wikipedia.dataclient.page.PageLeadProperties;
+import org.wikipedia.dataclient.page.Protection;
+import org.wikipedia.page.GeoTypeAdapter;
+import org.wikipedia.page.Namespace;
+import org.wikipedia.page.Page;
+import org.wikipedia.page.PageProperties;
+import org.wikipedia.page.PageTitle;
+import org.wikipedia.page.Section;
+import org.wikipedia.util.UriUtil;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import static org.wikipedia.dataclient.Service.PREFERRED_THUMB_SIZE;
+
+/**
+ * Gson POJO for loading the first stage of page content.
+ */
+@SuppressWarnings("unused")
+public class RbPageLead implements PageLead, PageLeadProperties {
+    private int ns;
+    private int id;
+    private long revision;
+    @Nullable private String lastmodified;
+    @Nullable private String displaytitle;
+    @Nullable private String redirected;
+    @Nullable private String normalizedtitle;
+    @Nullable @SerializedName("wikibase_item") private String wikiBaseItem;
+    @Nullable @SerializedName("pronunciation") private TitlePronunciation titlePronunciation;
+    @Nullable @JsonAdapter(GeoTypeAdapter.class) private Location geo;
+    private int languagecount;
+    private boolean editable;
+    private boolean mainpage;
+    private boolean disambiguation;
+    @Nullable private String description;
+    @Nullable @SerializedName("description_source") private String descriptionSource;
+    @Nullable private Image image;
+    @Nullable private Protection protection;
+    @Nullable private List<Section> sections;
+
+    /** Note: before using this check that #getMobileview != null */
+    @Override
+    public Page toPage(PageTitle title) {
+        return new Page(adjustPageTitle(title),
+                getSections(),
+                toPageProperties(),
+                true);
+    }
+
+    PageTitle adjustPageTitle(PageTitle title) {
+        if (redirected != null) {
+            // Handle redirects properly.
+            title = new PageTitle(redirected, title.getWikiSite(), title.getThumbUrl());
+        } else if (normalizedtitle != null) {
+            // We care about the normalized title only if we were not redirected
+            title = new PageTitle(normalizedtitle, title.getWikiSite(), title.getThumbUrl());
+        }
+        title.setDescription(description);
+        return title;
+    }
+
+    @Override
+    public String getLeadSectionContent() {
+        if (sections != null) {
+            return sections.get(0).getContent();
+        } else {
+            return "";
+        }
+    }
+
+    /** Converter */
+    private PageProperties toPageProperties() {
+        return new PageProperties(this);
+    }
+
+    @Override
+    public int getId() {
+        return id;
+    }
+
+    @NonNull @Override public Namespace getNamespace() {
+        return Namespace.of(ns);
+    }
+
+    @Override
+    public long getRevision() {
+        return revision;
+    }
+
+    @Override
+    @Nullable
+    public String getLastModified() {
+        return lastmodified;
+    }
+
+    @Override
+    @Nullable
+    public String getTitlePronunciationUrl() {
+        return titlePronunciation == null
+                ? null
+                : UriUtil.resolveProtocolRelativeUrl(titlePronunciation.getUrl());
+    }
+
+    @Override
+    @Nullable
+    public Location getGeo() {
+        return geo;
+    }
+
+    @Override
+    public int getLanguageCount() {
+        return languagecount;
+    }
+
+    @Override
+    @Nullable
+    public String getDisplayTitle() {
+        return displaytitle;
+    }
+
+    @Override
+    @Nullable
+    public String getRedirected() {
+        return redirected;
+    }
+
+    @Override
+    @Nullable
+    public String getNormalizedTitle() {
+        return normalizedtitle;
+    }
+
+    @Override
+    @Nullable
+    public String getWikiBaseItem() {
+        return wikiBaseItem;
+    }
+
+    @Override
+    @Nullable
+    public String getDescription() {
+        return description;
+    }
+
+    @Override
+    @Nullable
+    public String getDescriptionSource() {
+        return descriptionSource;
+    }
+
+    @Override
+    @Nullable
+    public String getLeadImageUrl(int leadImageWidth) {
+        return image != null ? image.getUrl(leadImageWidth) : null;
+    }
+
+    @Override
+    @Nullable
+    public String getThumbUrl() {
+        return image != null ? image.getUrl(PREFERRED_THUMB_SIZE) : null;
+    }
+
+    @Override
+    @Nullable
+    public String getLeadImageFileName() {
+        return image != null ? image.getFileName() : null;
+    }
+
+    @Override
+    @Nullable
+    public String getFirstAllowedEditorRole() {
+        return protection != null ? protection.getFirstAllowedEditorRole() : null;
+    }
+
+    @Override
+    public boolean isEditable() {
+        return editable;
+    }
+
+    public Set<String> getEditRoles() {
+        return protection != null ? protection.getEditRoles() : Collections.emptySet();
+    }
+
+    @Override
+    public boolean isMainPage() {
+        return mainpage;
+    }
+
+    @Override
+    public boolean isDisambiguation() {
+        return disambiguation;
+    }
+
+    @Override @NonNull public List<Section> getSections() {
+        return sections == null ? Collections.emptyList() : sections;
+    }
+
+    /**
+     * For the lead image File: page name
+     */
+    public static class TitlePronunciation {
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String url;
+
+        @NonNull
+        public String getUrl() {
+            return url;
+        }
+    }
+
+    /**
+     * For the lead image File: page name
+     */
+    public static class Image {
+        @SuppressWarnings("unused") @SerializedName("file") private String fileName;
+        @SuppressWarnings("unused") private ThumbUrls urls;
+
+        public String getFileName() {
+            return fileName;
+        }
+
+        @Nullable
+        public String getUrl(int width) {
+            return urls != null ? urls.get(width) : null;
+        }
+    }
+
+    /**
+     * For the lead image URLs
+     */
+    public static class ThumbUrls {
+        private static final int SMALL = 320;
+        private static final int MEDIUM = 640;
+        private static final int LARGE = 800;
+        private static final int XL = 1024;
+        @SuppressWarnings("unused") @SerializedName("320") private String small;
+        @SuppressWarnings("unused") @SerializedName("640") private String medium;
+        @SuppressWarnings("unused") @SerializedName("800") private String large;
+        @SuppressWarnings("unused") @SerializedName("1024") private String xl;
+
+        @Nullable
+        public String get(int width) {
+            switch (width) {
+                case SMALL:
+                    return small;
+                case MEDIUM:
+                    return medium;
+                case LARGE:
+                    return large;
+                case XL:
+                    return xl;
+                default:
+                    return null;
+            }
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/page/RbPageRemaining.java

@@ -0,0 +1,24 @@
+package org.wikipedia.dataclient.restbase.page;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.page.PageRemaining;
+import org.wikipedia.page.Section;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Gson POJO for loading remaining page content.
+ */
+public class RbPageRemaining implements PageRemaining {
+    @SuppressWarnings("unused") @Nullable private List<Section> sections;
+
+    @NonNull @Override public List<Section> sections() {
+        if (sections == null) {
+            return Collections.emptyList();
+        }
+        return sections;
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/restbase/page/RbPageSummary.java

@@ -0,0 +1,136 @@
+package org.wikipedia.dataclient.restbase.page;
+
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.dataclient.page.PageSummary;
+import org.wikipedia.json.annotations.Required;
+import org.wikipedia.page.Namespace;
+import org.wikipedia.page.PageTitle;
+
+/**
+ * A standardized page summary object constructed by RESTBase, used for link previews and as the
+ * base class for various feed content (see the FeedPageSummary class).
+ *
+ * N.B.: The "title" field here sent by RESTBase is the *normalized* page title.  However, in the
+ * FeedPageSummary subclass, "title" becomes the un-normalized, raw title, and the normalized title
+ * is sent as "normalizedtitle".
+ */
+@SuppressWarnings("unused")
+public class RbPageSummary implements PageSummary {
+    @Nullable private String type;
+    @SuppressWarnings("NullableProblems") @Required @NonNull private String title;
+    @Nullable private String normalizedtitle;
+    @SuppressWarnings("NullableProblems") @NonNull private String displaytitle;
+    @Nullable private NamespaceContainer namespace;
+    @Nullable private String extract;
+    @Nullable @SerializedName("extract_html") private String extractHtml;
+    @Nullable private String description;
+    @Nullable private Thumbnail thumbnail;
+    @Nullable @SerializedName("originalimage") private Thumbnail originalImage;
+    @Nullable private String lang;
+    private int pageid;
+    @Nullable @SerializedName("wikibase_item") private String wikiBaseItem;
+
+    @Override @NonNull
+    public String getTitle() {
+        return title;
+    }
+
+    @Override @NonNull
+    public String getDisplayTitle() {
+        return displaytitle;
+    }
+
+    @Override @NonNull
+    public String getConvertedTitle() {
+        return title;
+    }
+
+    @Override @NonNull
+    public Namespace getNamespace() {
+        return namespace == null ? Namespace.MAIN : Namespace.of(namespace.id());
+    }
+
+    @Override @NonNull
+    public String getType() {
+        return TextUtils.isEmpty(type) ? TYPE_STANDARD : type;
+    }
+
+    @Override @Nullable
+    public String getExtract() {
+        return extract;
+    }
+
+    @Override @Nullable
+    public String getExtractHtml() {
+        return extractHtml;
+    }
+
+    @Override @Nullable
+    public String getThumbnailUrl() {
+        return thumbnail == null ? null : thumbnail.getUrl();
+    }
+
+    @Nullable
+    public String getDescription() {
+        return description;
+    }
+
+    @NonNull
+    public String getNormalizedTitle() {
+        return normalizedtitle == null ? title : normalizedtitle;
+    }
+
+    @Nullable
+    public String getOriginalImageUrl() {
+        return originalImage == null ? null : originalImage.getUrl();
+    }
+
+    @Nullable
+    public String getWikiBaseItem() {
+        return wikiBaseItem;
+    }
+
+    @NonNull
+    public PageTitle getPageTitle(@NonNull WikiSite wiki) {
+        return new PageTitle(getTitle(), wiki, getThumbnailUrl(), getDescription());
+    }
+
+    public int getPageId() {
+        return pageid;
+    }
+
+    public String getLang() {
+        return lang;
+    }
+
+    /**
+     * For the thumbnail URL of the page
+     */
+    private static class Thumbnail {
+        @SuppressWarnings("unused") private String source;
+
+        public String getUrl() {
+            return source;
+        }
+    }
+
+    private static class NamespaceContainer {
+        @SuppressWarnings("unused") private int id;
+        @SuppressWarnings("unused") @Nullable private String text;
+
+        public int id() {
+            return id;
+        }
+    }
+
+    @Override public String toString() {
+        return getTitle();
+    }
+}

data-client/src/main/java/org/wikipedia/dataclient/retrofit/RetrofitException.java

@@ -0,0 +1,75 @@
+package org.wikipedia.dataclient.retrofit;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.io.IOException;
+
+import retrofit2.Response;
+
+/**
+ *  This is RetrofitError converted to Retrofit 2
+ */
+public class RetrofitException extends RuntimeException {
+    public static RetrofitException httpError(Response<?> response) {
+        return httpError(response.raw().request().url().toString(), response);
+    }
+
+    public static RetrofitException httpError(String url, Response<?> response) {
+        String message = response.code() + " " + response.message();
+        return new RetrofitException(message, url, response.code(), Kind.HTTP, null);
+    }
+
+    public static RetrofitException httpError(@NonNull okhttp3.Response response) {
+        String message = response.code() + " " + response.message();
+        return new RetrofitException(message, response.request().url().toString(), response.code(), Kind.HTTP,
+                null);
+    }
+
+    public static RetrofitException networkError(IOException exception) {
+        return new RetrofitException(exception.getMessage(), null, null, Kind.NETWORK, exception);
+    }
+
+    public static RetrofitException unexpectedError(Throwable exception) {
+        return new RetrofitException(exception.getMessage(), null, null, Kind.UNEXPECTED, exception);
+    }
+
+    /** Identifies the event kind which triggered a {@link RetrofitException}. */
+    public enum Kind {
+        /** An {@link IOException} occurred while communicating to the server. */
+        NETWORK,
+        /** A non-200 HTTP status code was received from the server. */
+        HTTP,
+        /**
+         * An internal error occurred while attempting to execute a request. It is best practice to
+         * re-throw this exception so your application crashes.
+         */
+        UNEXPECTED
+    }
+
+    private final String url;
+    @Nullable private final Integer code;
+    private final Kind kind;
+
+    RetrofitException(String message, String url, @Nullable Integer code, Kind kind, Throwable exception) {
+        super(message, exception);
+        this.url = url;
+        this.code = code;
+        this.kind = kind;
+    }
+
+    /** The request URL which produced the error. */
+    public String getUrl() {
+        return url;
+    }
+
+    /** HTTP status code. */
+    @Nullable public Integer getCode() {
+        return code;
+    }
+
+    /** The event kind which triggered this error. */
+    public Kind getKind() {
+        return kind;
+    }
+}

data-client/src/main/java/org/wikipedia/edit/Edit.java

@@ -0,0 +1,79 @@
+package org.wikipedia.edit;
+
+import androidx.annotation.Nullable;
+
+import org.wikipedia.dataclient.mwapi.MwPostResponse;
+
+public class Edit extends MwPostResponse {
+    @SuppressWarnings("unused,") @Nullable private Result edit;
+
+    @Nullable public Result edit() {
+        return edit;
+    }
+
+    boolean hasEditResult() {
+        return edit != null;
+    }
+
+    public class Result {
+        @SuppressWarnings("unused") @Nullable private String result;
+        @SuppressWarnings("unused") private int newrevid;
+        @SuppressWarnings("unused") @Nullable private Captcha captcha;
+        @SuppressWarnings("unused") @Nullable private String code;
+        @SuppressWarnings("unused") @Nullable private String info;
+        @SuppressWarnings("unused") @Nullable private String warning;
+        @SuppressWarnings("unused") @Nullable private String spamblacklist;
+
+        @Nullable String status() {
+            return result;
+        }
+
+        public int newRevId() {
+            return newrevid;
+        }
+
+        public boolean editSucceeded() {
+            return "Success".equals(result);
+        }
+
+        @Nullable String captchaId() {
+            return captcha == null ? null : captcha.id();
+        }
+
+        public boolean hasEditErrorCode() {
+            return code != null;
+        }
+
+        boolean hasCaptchaResponse() {
+            return captcha != null;
+        }
+
+        @Nullable public String code() {
+            return code;
+        }
+
+        @Nullable public String info() {
+            return info;
+        }
+
+        @Nullable public String warning() {
+            return warning;
+        }
+
+        @Nullable String spamblacklist() {
+            return spamblacklist;
+        }
+
+        boolean hasSpamBlacklistResponse() {
+            return spamblacklist != null;
+        }
+    }
+
+    private static class Captcha {
+        @SuppressWarnings("unused") @Nullable private String id;
+
+        @Nullable String id() {
+            return id;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/edit/EditAbuseFilterResult.java

@@ -0,0 +1,79 @@
+package org.wikipedia.edit;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import androidx.annotation.Nullable;
+
+public class EditAbuseFilterResult extends EditResult {
+    static final int TYPE_WARNING = 1;
+    static final int TYPE_ERROR = 2;
+
+    @Nullable private final String code;
+    @Nullable private final String info;
+    @Nullable private final String warning;
+
+    EditAbuseFilterResult(@Nullable String code, @Nullable String info, @Nullable String warning) {
+        super("Failure");
+        this.code = code;
+        this.info = info;
+        this.warning = warning;
+    }
+
+    private EditAbuseFilterResult(Parcel in) {
+        super(in);
+        code = in.readString();
+        info = in.readString();
+        warning = in.readString();
+    }
+
+    @Nullable public String getCode() {
+        return code;
+    }
+
+    @Nullable public String getInfo() {
+        return info;
+    }
+
+    @Nullable public String getWarning() {
+        return warning;
+    }
+
+    @Override public void writeToParcel(Parcel dest, int flags) {
+        super.writeToParcel(dest, flags);
+        dest.writeString(code);
+        dest.writeString(info);
+        dest.writeString(warning);
+    }
+
+    public int getType() {
+        if (code != null && code.startsWith("abusefilter-warning")) {
+            return TYPE_WARNING;
+        } else if (code != null && code.startsWith("abusefilter-disallowed")) {
+            return TYPE_ERROR;
+        } else if (info != null && info.startsWith("Hit AbuseFilter")) {
+            // This case is here because, unfortunately, an admin can create an abuse filter which
+            // emits an arbitrary error code over the API.
+            // TODO: More properly handle the case where the AbuseFilter throws an arbitrary error.
+            // Oh, and, you know, also fix the AbuseFilter API to not throw arbitrary error codes.
+            return TYPE_ERROR;
+        } else {
+            // We have no understanding of what kind of abuse filter response we got. It's safest
+            // to simply treat these as an error.
+            return TYPE_ERROR;
+        }
+    }
+
+    public static final Parcelable.Creator<EditAbuseFilterResult> CREATOR
+            = new Parcelable.Creator<EditAbuseFilterResult>() {
+        @Override
+        public EditAbuseFilterResult createFromParcel(Parcel in) {
+            return new EditAbuseFilterResult(in);
+        }
+
+        @Override
+        public EditAbuseFilterResult[] newArray(int size) {
+            return new EditAbuseFilterResult[size];
+        }
+    };
+}

data-client/src/main/java/org/wikipedia/edit/EditClient.java

@@ -0,0 +1,72 @@
+package org.wikipedia.edit;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+import org.wikipedia.captcha.CaptchaResult;
+import org.wikipedia.dataclient.Service;
+import org.wikipedia.dataclient.ServiceFactory;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.page.PageTitle;
+
+import java.io.IOException;
+
+import retrofit2.Call;
+import retrofit2.Response;
+
+public class EditClient {
+    public interface Callback {
+        void success(@NonNull Call<Edit> call, @NonNull EditResult result);
+        void failure(@NonNull Call<Edit> call, @NonNull Throwable caught);
+    }
+
+    @SuppressWarnings("checkstyle:parameternumber")
+    public Call<Edit> request(@NonNull WikiSite wiki, @NonNull PageTitle title, int section,
+                              @NonNull String text, @NonNull String token, @NonNull String summary,
+                              @Nullable String baseTimeStamp, boolean loggedIn, @Nullable String captchaId,
+                              @Nullable String captchaWord, @NonNull Callback cb) {
+        return request(ServiceFactory.get(wiki), title, section, text, token, summary,
+                baseTimeStamp, loggedIn, captchaId, captchaWord, cb);
+    }
+
+    @VisibleForTesting @SuppressWarnings("checkstyle:parameternumber")
+    Call<Edit> request(@NonNull Service service, @NonNull PageTitle title, int section,
+                       @NonNull String text, @NonNull String token, @NonNull String summary,
+                       @Nullable String baseTimeStamp, boolean loggedIn, @Nullable String captchaId,
+                       @Nullable String captchaWord, @NonNull final Callback cb) {
+        Call<Edit> call = service.postEditSubmit(title.getPrefixedText(), section, summary, loggedIn ? "user" : null,
+                text, baseTimeStamp, token, captchaId, captchaWord);
+        call.enqueue(new retrofit2.Callback<Edit>() {
+            @Override
+            public void onResponse(@NonNull Call<Edit> call, @NonNull Response<Edit> response) {
+                if (response.body().hasEditResult()) {
+                    handleEditResult(response.body().edit(), call, cb);
+                } else {
+                    cb.failure(call, new IOException("An unknown error occurred."));
+                }
+            }
+
+            @Override
+            public void onFailure(@NonNull Call<Edit> call, @NonNull Throwable t) {
+                cb.failure(call, t);
+            }
+        });
+        return call;
+    }
+
+    private void handleEditResult(@NonNull Edit.Result result, @NonNull Call<Edit> call,
+                                  @NonNull Callback cb) {
+        if (result.editSucceeded()) {
+            cb.success(call, new EditSuccessResult(result.newRevId()));
+        } else if (result.hasEditErrorCode()) {
+            cb.success(call, new EditAbuseFilterResult(result.code(), result.info(), result.warning()));
+        } else if (result.hasSpamBlacklistResponse()) {
+            cb.success(call, new EditSpamBlacklistResult(result.spamblacklist()));
+        } else if (result.hasCaptchaResponse()) {
+            cb.success(call, new CaptchaResult(result.captchaId()));
+        } else {
+            cb.failure(call, new IOException("Received unrecognized edit response"));
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/edit/EditResult.java

@@ -0,0 +1,32 @@
+package org.wikipedia.edit;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import org.wikipedia.model.BaseModel;
+
+public abstract class EditResult extends BaseModel implements Parcelable {
+    private final String result;
+
+    public EditResult(String result) {
+        this.result = result;
+    }
+
+    protected EditResult(Parcel in) {
+        this.result = in.readString();
+    }
+
+    public String getResult() {
+        return result;
+    }
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeString(result);
+    }
+}

data-client/src/main/java/org/wikipedia/edit/EditSpamBlacklistResult.java

@@ -0,0 +1,40 @@
+package org.wikipedia.edit;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+public class EditSpamBlacklistResult extends EditResult {
+    private final String domain;
+    public EditSpamBlacklistResult(String domain) {
+        super("Failure");
+        this.domain = domain;
+    }
+
+    protected EditSpamBlacklistResult(Parcel in) {
+        super(in);
+        domain = in.readString();
+    }
+
+    public String getDomain() {
+        return domain;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        super.writeToParcel(dest, flags);
+        dest.writeString(domain);
+    }
+
+    public static final Parcelable.Creator<EditSpamBlacklistResult> CREATOR
+            = new Parcelable.Creator<EditSpamBlacklistResult>() {
+        @Override
+        public EditSpamBlacklistResult createFromParcel(Parcel in) {
+            return new EditSpamBlacklistResult(in);
+        }
+
+        @Override
+        public EditSpamBlacklistResult[] newArray(int size) {
+            return new EditSpamBlacklistResult[size];
+        }
+    };
+}

data-client/src/main/java/org/wikipedia/edit/EditSuccessResult.java

@@ -0,0 +1,34 @@
+package org.wikipedia.edit;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+public class EditSuccessResult extends EditResult {
+    private final int revID;
+    public EditSuccessResult(int revID) {
+        super("Success");
+        this.revID = revID;
+    }
+
+    private EditSuccessResult(Parcel in) {
+        super(in);
+        revID = in.readInt();
+    }
+
+    public int getRevID() {
+        return revID;
+    }
+
+    public static final Parcelable.Creator<EditSuccessResult> CREATOR
+            = new Parcelable.Creator<EditSuccessResult>() {
+        @Override
+        public EditSuccessResult createFromParcel(Parcel in) {
+            return new EditSuccessResult(in);
+        }
+
+        @Override
+        public EditSuccessResult[] newArray(int size) {
+            return new EditSuccessResult[size];
+        }
+    };
+}

data-client/src/main/java/org/wikipedia/edit/preview/EditPreview.java

@@ -0,0 +1,29 @@
+package org.wikipedia.edit.preview;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.dataclient.mwapi.MwPostResponse;
+
+public class EditPreview extends MwPostResponse {
+    @SuppressWarnings("unused") @Nullable private Parse parse;
+
+    boolean hasPreviewResult() {
+        return parse != null;
+    }
+
+    @Nullable String result() {
+        return parse != null ? parse.text() : null;
+    }
+
+    private static class Parse {
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String title;
+        @SuppressWarnings("unused") @SerializedName("pageid") private int pageId;
+        @SuppressWarnings("unused,NullableProblems") @NonNull private String text;
+        @NonNull String text() {
+            return text;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/feed/aggregated/AggregatedFeedContent.java

@@ -0,0 +1,46 @@
+package org.wikipedia.feed.aggregated;
+
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.dataclient.restbase.page.RbPageSummary;
+import org.wikipedia.feed.image.FeaturedImage;
+import org.wikipedia.feed.mostread.MostReadArticles;
+import org.wikipedia.feed.news.NewsItem;
+import org.wikipedia.feed.onthisday.OnThisDay;
+
+import java.util.List;
+
+public class AggregatedFeedContent {
+    @SuppressWarnings("unused") @Nullable private RbPageSummary tfa;
+    @SuppressWarnings("unused") @Nullable private List<NewsItem> news;
+    @SuppressWarnings("unused") @SerializedName("mostread") @Nullable private MostReadArticles mostRead;
+    @SuppressWarnings("unused") @Nullable private FeaturedImage image;
+    @SuppressWarnings("unused") @Nullable private List<OnThisDay.Event> onthisday;
+
+    @Nullable
+    public List<OnThisDay.Event> onthisday() {
+        return onthisday;
+    }
+
+    @Nullable
+    public RbPageSummary tfa() {
+        return tfa;
+    }
+
+    @Nullable
+    List<NewsItem> news() {
+        return news;
+    }
+
+    @Nullable
+    MostReadArticles mostRead() {
+        return mostRead;
+    }
+
+    @Nullable
+    FeaturedImage potd() {
+        return image;
+    }
+}

data-client/src/main/java/org/wikipedia/feed/announcement/Announcement.java

@@ -0,0 +1,164 @@
+package org.wikipedia.feed.announcement;
+
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.json.annotations.Required;
+import org.wikipedia.model.BaseModel;
+import org.wikipedia.util.DateUtil;
+
+import java.text.ParseException;
+import java.util.Collections;
+import java.util.Date;
+import java.util.List;
+
+import static org.apache.commons.lang3.StringUtils.defaultString;
+
+public class Announcement extends BaseModel {
+    public static final String SURVEY = "survey";
+    public static final String FUNDRAISING = "fundraising";
+
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String id;
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String type;
+    @SuppressWarnings("unused,NullableProblems") @SerializedName("start_time") @Required @NonNull private String startTime;
+    @SuppressWarnings("unused,NullableProblems") @SerializedName("end_time") @Required @NonNull private String endTime;
+    @SuppressWarnings("unused") @NonNull private List<String> platforms = Collections.emptyList();
+    @SuppressWarnings("unused") @NonNull private List<String> countries = Collections.emptyList();
+    @SuppressWarnings("unused") @SerializedName("caption_HTML") @Nullable private String footerCaption;
+    @SuppressWarnings("unused") @SerializedName("image_url") @Nullable private String imageUrl;
+    @SuppressWarnings("unused") @SerializedName("image_height") @Nullable private String imageHeight;
+    @SuppressWarnings("unused") @SerializedName("logged_in") @Nullable private Boolean loggedIn;
+    @SuppressWarnings("unused") @SerializedName("reading_list_sync_enabled") @Nullable private Boolean readingListSyncEnabled;
+    @SuppressWarnings("unused") @Nullable private Boolean beta;
+    @SuppressWarnings("unused") @SerializedName("min_version") @Nullable private String minVersion;
+    @SuppressWarnings("unused") @SerializedName("max_version") @Nullable private String maxVersion;
+
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String text;
+    @SuppressWarnings("unused") @Nullable private Action action;
+    @SuppressWarnings("unused") @SerializedName("negative_text") @Nullable private String negativeText;
+
+    public Announcement() { }
+
+    public Announcement(@NonNull String id, @NonNull String text, @NonNull String imageUrl,
+                        @NonNull Action action, @NonNull String negativeText) {
+        this.id = id;
+        this.text = text;
+        this.imageUrl = imageUrl;
+        this.action = action;
+        this.negativeText = negativeText;
+    }
+
+    @NonNull String id() {
+        return id;
+    }
+
+    @NonNull String type() {
+        return type;
+    }
+
+    @Nullable Date startTime() {
+        try {
+            return DateUtil.iso8601DateParse(startTime);
+        } catch (ParseException e) {
+            return null;
+        }
+    }
+
+    @Nullable Date endTime() {
+        try {
+            return DateUtil.iso8601DateParse(endTime);
+        } catch (ParseException e) {
+            return null;
+        }
+    }
+
+    @NonNull List<String> platforms() {
+        return platforms;
+    }
+
+    @NonNull List<String> countries() {
+        return countries;
+    }
+
+    @NonNull String text() {
+        return text;
+    }
+
+    boolean hasAction() {
+        return action != null;
+    }
+
+    @NonNull String actionTitle() {
+        return action != null ? action.title() : "";
+    }
+
+    @NonNull String actionUrl() {
+        return action != null ? action.url() : "";
+    }
+
+    boolean hasFooterCaption() {
+        return !TextUtils.isEmpty(footerCaption);
+    }
+
+    @NonNull String footerCaption() {
+        return defaultString(footerCaption);
+    }
+
+    boolean hasImageUrl() {
+        return !TextUtils.isEmpty(imageUrl);
+    }
+
+    @NonNull String imageUrl() {
+        return defaultString(imageUrl);
+    }
+
+    @NonNull String imageHeight() {
+        return defaultString(imageHeight);
+    }
+
+    @Nullable String negativeText() {
+        return negativeText;
+    }
+
+    @Nullable Boolean loggedIn() {
+        return loggedIn;
+    }
+
+    @Nullable Boolean readingListSyncEnabled() {
+        return readingListSyncEnabled;
+    }
+
+    @Nullable Boolean beta() {
+        return beta;
+    }
+
+    @Nullable String minVersion() {
+        return minVersion;
+    }
+
+    @Nullable String maxVersion() {
+        return maxVersion;
+    }
+
+    public static class Action {
+        @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String title;
+        @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String url;
+
+        public Action(@NonNull String title, @NonNull String url) {
+            this.title = title;
+            this.url = url;
+        }
+
+        @NonNull String title() {
+            return title;
+        }
+
+        @NonNull String url() {
+            return url;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/feed/announcement/AnnouncementList.java

@@ -0,0 +1,21 @@
+package org.wikipedia.feed.announcement;
+
+import androidx.annotation.NonNull;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.wikipedia.model.BaseModel;
+
+import java.util.Collections;
+import java.util.List;
+
+public class AnnouncementList extends BaseModel {
+
+    @SuppressWarnings("unused") @SerializedName("announce") @NonNull private List<Announcement> items = Collections.emptyList();
+
+    @NonNull
+    List<Announcement> items() {
+        return items;
+    }
+
+}

data-client/src/main/java/org/wikipedia/feed/announcement/GeoIPCookie.java

@@ -0,0 +1,41 @@
+package org.wikipedia.feed.announcement;
+
+import android.location.Location;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+public class GeoIPCookie {
+
+    @NonNull private final String country;
+    @NonNull private final String region;
+    @NonNull private final String city;
+    @Nullable private final Location location;
+
+    GeoIPCookie(@NonNull String country, @NonNull String region, @NonNull String city, @Nullable Location location) {
+        this.country = country;
+        this.region = region;
+        this.city = city;
+        this.location = location;
+    }
+
+    @NonNull
+    public String country() {
+        return country;
+    }
+
+    @NonNull
+    public String region() {
+        return region;
+    }
+
+    @NonNull
+    public String city() {
+        return city;
+    }
+
+    @Nullable
+    public Location location() {
+        return location;
+    }
+}

data-client/src/main/java/org/wikipedia/feed/announcement/GeoIPCookieUnmarshaller.java

@@ -0,0 +1,60 @@
+package org.wikipedia.feed.announcement;
+
+import android.location.Location;
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+
+import org.wikipedia.dataclient.SharedPreferenceCookieManager;
+
+/*
+This currently supports the "v4" version of the GeoIP cookie.
+For some info about the format and contents of the cookie:
+https://phabricator.wikimedia.org/diffusion/ECNO/browse/master/resources/subscribing/ext.centralNotice.geoIP.js
+ */
+public final class GeoIPCookieUnmarshaller {
+    private static final String COOKIE_NAME = "GeoIP";
+
+    private enum Component {
+        COUNTRY, REGION, CITY, LATITUDE, LONGITUDE, VERSION
+    }
+
+    @NonNull
+    public static GeoIPCookie unmarshal() {
+        return unmarshal(SharedPreferenceCookieManager.getInstance().getCookieByName(COOKIE_NAME));
+    }
+
+    @VisibleForTesting
+    @NonNull
+    static GeoIPCookie unmarshal(@Nullable String cookie) throws IllegalArgumentException {
+        if (TextUtils.isEmpty(cookie)) {
+            throw new IllegalArgumentException("Cookie is empty.");
+        }
+        String[] components = cookie.split(":");
+        if (components.length < Component.values().length) {
+            throw new IllegalArgumentException("Cookie is malformed.");
+        } else if (!components[Component.VERSION.ordinal()].equals("v4")) {
+            throw new IllegalArgumentException("Incorrect cookie version.");
+        }
+        Location location = null;
+        if (!TextUtils.isEmpty(components[Component.LATITUDE.ordinal()])
+                && !TextUtils.isEmpty(components[Component.LONGITUDE.ordinal()])) {
+            location = new Location("");
+            try {
+                location.setLatitude(Double.parseDouble(components[Component.LATITUDE.ordinal()]));
+                location.setLongitude(Double.parseDouble(components[Component.LONGITUDE.ordinal()]));
+            } catch (NumberFormatException e) {
+                throw new IllegalArgumentException("Location is malformed.");
+            }
+        }
+        return new GeoIPCookie(components[Component.COUNTRY.ordinal()],
+                components[Component.REGION.ordinal()],
+                components[Component.CITY.ordinal()],
+                location);
+    }
+
+    private GeoIPCookieUnmarshaller() {
+    }
+}

data-client/src/main/java/org/wikipedia/feed/configure/FeedAvailability.java

@@ -0,0 +1,37 @@
+package org.wikipedia.feed.configure;
+
+import androidx.annotation.NonNull;
+
+import com.google.gson.annotations.SerializedName;
+
+import java.util.Collections;
+import java.util.List;
+
+@SuppressWarnings("unused")
+public class FeedAvailability {
+    @SerializedName("todays_featured_article") private List<String> featuredArticle;
+    @SerializedName("most_read") private List<String> mostRead;
+    @SerializedName("picture_of_the_day") private List<String> featuredPicture;
+    @SerializedName("in_the_news") private List<String> news;
+    @SerializedName("on_this_day") private List<String> onThisDay;
+
+    @NonNull public List<String> featuredArticle() {
+        return featuredArticle != null ? featuredArticle : Collections.emptyList();
+    }
+
+    @NonNull public List<String> mostRead() {
+        return mostRead != null ? mostRead : Collections.emptyList();
+    }
+
+    @NonNull public List<String> featuredPicture() {
+        return featuredPicture != null ? featuredPicture : Collections.emptyList();
+    }
+
+    @NonNull public List<String> news() {
+        return news != null ? news : Collections.emptyList();
+    }
+
+    @NonNull public List<String> onThisDay() {
+        return onThisDay != null ? onThisDay : Collections.emptyList();
+    }
+}

data-client/src/main/java/org/wikipedia/feed/image/FeaturedImage.java

@@ -0,0 +1,34 @@
+package org.wikipedia.feed.image;
+
+import androidx.annotation.NonNull;
+
+import org.wikipedia.gallery.GalleryItem;
+import org.wikipedia.gallery.ImageInfo;
+import org.wikipedia.json.PostProcessingTypeAdapter;
+import org.wikipedia.json.annotations.Required;
+
+public final class FeaturedImage extends GalleryItem implements PostProcessingTypeAdapter.PostProcessable {
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String title;
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private ImageInfo image;
+
+    private int age;
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    @NonNull
+    public String title() {
+        return title;
+    }
+
+    @Override
+    public void postProcess() {
+        setTitle(title);
+        getOriginal().setSource(image.getSource());
+    }
+}

data-client/src/main/java/org/wikipedia/feed/model/UtcDate.java

@@ -0,0 +1,49 @@
+package org.wikipedia.feed.model;
+
+import androidx.annotation.NonNull;
+
+import java.util.Calendar;
+
+import static java.util.TimeZone.getTimeZone;
+
+public class UtcDate {
+    @NonNull private Calendar cal;
+    @NonNull private String year;
+    @NonNull private String month;
+    @NonNull private String date;
+
+    public UtcDate(int age) {
+        this.cal = Calendar.getInstance(getTimeZone("UTC"));
+        cal.add(Calendar.DATE, -age);
+        this.year = Integer.toString(cal.get(Calendar.YEAR));
+        this.month = pad(Integer.toString(cal.get(Calendar.MONTH) + 1));
+        this.date = pad(Integer.toString(cal.get(Calendar.DATE)));
+    }
+
+    @NonNull
+    public Calendar baseCalendar() {
+        return cal;
+    }
+
+    @NonNull
+    public String year() {
+        return year;
+    }
+
+    @NonNull
+    public String month() {
+        return month;
+    }
+
+    @NonNull
+    public String date() {
+        return date;
+    }
+
+    private String pad(String value) {
+        if (value.length() == 1) {
+            return "0" + value;
+        }
+        return value;
+    }
+}

data-client/src/main/java/org/wikipedia/feed/mostread/MostReadArticles.java

@@ -0,0 +1,22 @@
+package org.wikipedia.feed.mostread;
+
+import androidx.annotation.NonNull;
+
+import org.wikipedia.dataclient.restbase.page.RbPageSummary;
+import org.wikipedia.json.annotations.Required;
+
+import java.util.Date;
+import java.util.List;
+
+public final class MostReadArticles {
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private Date date;
+    @SuppressWarnings("unused,NullableProblems") @Required @NonNull private List<RbPageSummary> articles;
+
+    @NonNull public Date date() {
+        return date;
+    }
+
+    @NonNull public List<RbPageSummary> articles() {
+        return articles;
+    }
+}

data-client/src/main/java/org/wikipedia/feed/news/NewsItem.java

@@ -0,0 +1,56 @@
+package org.wikipedia.feed.news;
+
+import android.net.Uri;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.dataclient.restbase.page.RbPageSummary;
+import org.wikipedia.json.annotations.Required;
+
+import java.util.Collections;
+import java.util.List;
+
+import static org.wikipedia.dataclient.Service.PREFERRED_THUMB_SIZE;
+import static org.wikipedia.util.ImageUrlUtil.getUrlForSize;
+
+public final class NewsItem {
+    @SuppressWarnings("unused") @Required @Nullable private String story;
+    @SuppressWarnings("unused") @Nullable private List<RbPageSummary> links
+            = Collections.emptyList();
+
+    @NonNull String story() {
+        return StringUtils.defaultString(story);
+    }
+
+    @NonNull public List<RbPageSummary> links() {
+        return links != null ? links : Collections.emptyList();
+    }
+
+    @Nullable public Uri thumb() {
+        Uri uri = getFirstImageUri(links());
+        return uri != null ? getUrlForSize(uri, PREFERRED_THUMB_SIZE) : null;
+    }
+
+    @Nullable Uri featureImage() {
+        return getFirstImageUri(links());
+    }
+
+    /**
+     * Iterate through the CardPageItems associated with the news story's links and return the first
+     * thumb URI found.
+     */
+    @Nullable private Uri getFirstImageUri(List<RbPageSummary> links) {
+        for (RbPageSummary link : links) {
+            if (link == null) {
+                continue;
+            }
+            String thumbnail = link.getThumbnailUrl();
+            if (thumbnail != null) {
+                return Uri.parse(thumbnail);
+            }
+        }
+        return null;
+    }
+}

data-client/src/main/java/org/wikipedia/feed/onthisday/OnThisDay.java

@@ -0,0 +1,80 @@
+package org.wikipedia.feed.onthisday;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.dataclient.restbase.page.RbPageSummary;
+import org.wikipedia.json.annotations.Required;
+import org.wikipedia.util.StringUtil;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+
+public class OnThisDay {
+
+    @SuppressWarnings("unused") @Nullable private List<Event> selected;
+    @SuppressWarnings("unused") @Nullable private List<Event> events;
+    @SuppressWarnings("unused") @Nullable private List<Event> births;
+    @SuppressWarnings("unused") @Nullable private List<Event> deaths;
+    @SuppressWarnings("unused") @Nullable private List<Event> holidays;
+
+    @NonNull public List<Event> selectedEvents() {
+        return selected != null ? selected : Collections.emptyList();
+    }
+
+    @NonNull public List<Event> events() {
+        ArrayList<Event> allEvents = new ArrayList<>();
+        if (events != null) {
+            allEvents.addAll(events);
+        }
+        if (births != null) {
+            allEvents.addAll(births);
+        }
+        if (deaths != null) {
+            allEvents.addAll(deaths);
+        }
+        if (holidays != null) {
+            allEvents.addAll(holidays);
+        }
+        Collections.sort(allEvents, (e1, e2) -> Integer.compare(e2.year(), e1.year()));
+        return allEvents;
+    }
+
+    public static class Event {
+        @SuppressWarnings("unused,NullableProblems") @Required @NonNull private String text;
+        @SuppressWarnings("unused") private int year;
+        @SuppressWarnings("unused,NullableProblems") @Required @NonNull private List<RbPageSummary> pages;
+
+        @NonNull
+        public CharSequence text() {
+            List<String> pageTitles = new ArrayList<>();
+            for (RbPageSummary page : pages) {
+                pageTitles.add((StringUtil.fromHtml(StringUtils.defaultString(page.getNormalizedTitle()))).toString());
+            }
+            return StringUtil.boldenSubstrings(text, pageTitles);
+        }
+
+        public int year() {
+            return year;
+        }
+
+        @Nullable
+        public List<RbPageSummary> pages() {
+            Iterator iterator = pages.iterator();
+            while ((iterator.hasNext())) {
+                if (iterator.next() == null) {
+                    iterator.remove();
+                }
+            }
+            return pages;
+        }
+    }
+
+    public void setSelected(@Nullable List<Event> selected) {
+        this.selected = selected;
+    }
+
+}

data-client/src/main/java/org/wikipedia/gallery/ArtistInfo.java

@@ -0,0 +1,16 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+public class ArtistInfo extends TextInfo {
+
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String name;
+    @SuppressWarnings("unused,NullableProblems") @Nullable @SerializedName("user_page") private String userPage;
+
+    @Nullable
+    public String getName() {
+        return name;
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/ExtMetadata.java

@@ -0,0 +1,102 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+
+@SuppressWarnings("unused")
+public class ExtMetadata {
+    @SerializedName("DateTime") @Nullable private Values dateTime;
+    @SerializedName("ObjectName") @Nullable private Values objectName;
+    @SerializedName("CommonsMetadataExtension") @Nullable private Values commonsMetadataExtension;
+    @SerializedName("Categories") @Nullable private Values categories;
+    @SerializedName("Assessments") @Nullable private Values assessments;
+    @SerializedName("GPSLatitude") @Nullable private Values gpsLatitude;
+    @SerializedName("GPSLongitude") @Nullable private Values gpsLongitude;
+    @SerializedName("ImageDescription") @Nullable private Values imageDescription;
+    @SerializedName("DateTimeOriginal") @Nullable private Values dateTimeOriginal;
+    @SerializedName("Artist") @Nullable private Values artist;
+    @SerializedName("Credit") @Nullable private Values credit;
+    @SerializedName("Permission") @Nullable private Values permission;
+    @SerializedName("AuthorCount") @Nullable private Values authorCount;
+    @SerializedName("LicenseShortName") @Nullable private Values licenseShortName;
+    @SerializedName("UsageTerms") @Nullable private Values usageTerms;
+    @SerializedName("LicenseUrl") @Nullable private Values licenseUrl;
+    @SerializedName("AttributionRequired") @Nullable private Values attributionRequired;
+    @SerializedName("Copyrighted") @Nullable private Values copyrighted;
+    @SerializedName("Restrictions") @Nullable private Values restrictions;
+    @SerializedName("License") @Nullable private Values license;
+
+    @NonNull public String licenseShortName() {
+        return StringUtils.defaultString(licenseShortName == null ? null : licenseShortName.value());
+    }
+
+    @NonNull public String licenseUrl() {
+        return StringUtils.defaultString(licenseUrl == null ? null : licenseUrl.value());
+    }
+
+    @NonNull public String license() {
+        return StringUtils.defaultString(license == null ? null : license.value());
+    }
+
+    @NonNull public String imageDescription() {
+        return StringUtils.defaultString(imageDescription == null ? null : imageDescription.value());
+    }
+
+    @NonNull public String imageDescriptionSource() {
+        return StringUtils.defaultString(imageDescription == null ? null : imageDescription.source());
+    }
+
+    @NonNull public String objectName() {
+        return StringUtils.defaultString(objectName == null ? null : objectName.value());
+    }
+
+    @NonNull public String usageTerms() {
+        return StringUtils.defaultString(usageTerms == null ? null : usageTerms.value());
+    }
+
+    @NonNull public String dateTimeOriginal() {
+        return StringUtils.defaultString(dateTimeOriginal == null ? null : dateTimeOriginal.value());
+    }
+
+    @NonNull public String dateTime() {
+        return StringUtils.defaultString(dateTime == null ? null : dateTime.value());
+    }
+
+    @NonNull public String artist() {
+        return StringUtils.defaultString(artist == null ? null : artist.value());
+    }
+
+    @NonNull public String getCategories() {
+        return StringUtils.defaultString(categories == null ? null : categories.value());
+    }
+
+    @NonNull public String getGpsLatitude() {
+        return StringUtils.defaultString(gpsLatitude == null ? null : gpsLatitude.value());
+    }
+
+    @NonNull public String getGpsLongitude() {
+        return StringUtils.defaultString(gpsLongitude == null ? null : gpsLongitude.value());
+    }
+
+    @NonNull public String credit() {
+        return StringUtils.defaultString(credit == null ? null : credit.value());
+    }
+
+    public class Values {
+        @Nullable private String value;
+        @Nullable private String source;
+        @Nullable private String hidden;
+
+        @Nullable public String value() {
+            return value;
+        }
+
+        @Nullable public String source() {
+            return source;
+        }
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/Gallery.java

@@ -0,0 +1,35 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Gallery {
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String revision;
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String tid;
+    @SuppressWarnings("unused") @Nullable private List<GalleryItem> items;
+
+    @Nullable
+    public List<GalleryItem> getAllItems() {
+        return items;
+    }
+
+    @NonNull
+    public List<GalleryItem> getItems(@NonNull String... types) {
+        List<GalleryItem> list = new ArrayList<>();
+        if (items != null) {
+            for (GalleryItem item : items) {
+                if (item.isShowInGallery()) {
+                    for (String type : types) {
+                        if (item.getType().contains(type)) {
+                            list.add(item);
+                        }
+                    }
+                }
+            }
+        }
+        return list;
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/GalleryItem.java

@@ -0,0 +1,194 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+import org.wikipedia.dataclient.Service;
+import org.wikipedia.util.ImageUrlUtil;
+import org.wikipedia.util.StringUtil;
+
+import java.io.Serializable;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@SuppressWarnings("unused")
+public class GalleryItem implements Serializable {
+    public static final int PREFERRED_GALLERY_IMAGE_SIZE = 1280;
+
+    @SerializedName("section_id") private int sectionId;
+    @SuppressWarnings("NullableProblems") @NonNull private String type;
+    @Nullable @SerializedName("audio_type") private String audioType;
+    @Nullable private TextInfo caption;
+    private boolean showInGallery;
+    @SuppressWarnings("NullableProblems") @NonNull private Titles titles;
+    @Nullable private ImageInfo thumbnail;
+    @Nullable private ImageInfo original;
+    @Nullable private List<VideoInfo> sources;
+    @Nullable @SerializedName("file_page") private String filePage;
+    @Nullable private ArtistInfo artist;
+    private double duration;
+    @SuppressWarnings("NullableProblems") @NonNull private ImageLicense license;
+    @Nullable private TextInfo description;
+    @Nullable @SerializedName("wb_entity_id") private String entityId;
+    @Nullable @SerializedName("structured") private StructuredData structuredData;
+
+    public GalleryItem() {
+    }
+
+    public GalleryItem(@NonNull String title) {
+        this.type = "*/*";
+        this.titles = new Titles(title, StringUtil.addUnderscores(title), title);
+        this.original = new ImageInfo();
+        this.thumbnail = new ImageInfo();
+        this.description = new TextInfo();
+        this.license = new ImageLicense();
+    }
+
+    @NonNull
+    public String getType() {
+        return StringUtils.defaultString(type);
+    }
+
+    @NonNull
+    public String getAudioType() {
+        return StringUtils.defaultString(audioType);
+    }
+
+    @Nullable
+    public TextInfo getCaption() {
+        return caption;
+    }
+
+    public boolean isShowInGallery() {
+        return showInGallery;
+    }
+
+    @NonNull
+    public Titles getTitles() {
+        return titles;
+    }
+
+    protected void setTitle(@NonNull String title) {
+        titles = new Titles(title, StringUtil.addUnderscores(title), title);
+    }
+
+    @NonNull
+    public ImageInfo getThumbnail() {
+        if (thumbnail == null) {
+            thumbnail = new ImageInfo();
+        }
+        return thumbnail;
+    }
+
+    @NonNull
+    public String getThumbnailUrl() {
+        return getThumbnail().getSource();
+    }
+
+    @NonNull
+    public String getPreferredSizedImageUrl() {
+        return ImageUrlUtil.getUrlForPreferredSize(getThumbnailUrl(), PREFERRED_GALLERY_IMAGE_SIZE);
+    }
+
+    @NonNull
+    public ImageInfo getOriginal() {
+        if (original == null) {
+            original = new ImageInfo();
+        }
+        return original;
+    }
+
+    @Nullable
+    public List<VideoInfo> getSources() {
+        return sources;
+    }
+
+    @Nullable
+    public VideoInfo getOriginalVideoSource() {
+        // The getSources has different levels of source,
+        // should have an option that allows user to chose which quality to play
+        return sources == null || sources.size() == 0
+                ? null : sources.get(sources.size() - 1);
+    }
+
+    public double getDuration() {
+        return duration;
+    }
+
+    @NonNull
+    public String getFilePage() {
+        // return the base url of Wiki Commons for WikiSite() if the file_page is null.
+        return filePage == null ? Service.COMMONS_URL : StringUtils.defaultString(filePage);
+    }
+
+    public void setFilePage(@NonNull String filePage) {
+        this.filePage = filePage;
+    }
+
+    @Nullable
+    public ArtistInfo getArtist() {
+        return artist;
+    }
+
+    public void setArtist(@Nullable ArtistInfo artist) {
+        this.artist = artist;
+    }
+
+    @NonNull
+    public ImageLicense getLicense() {
+        return license;
+    }
+
+    public void setLicense(@NonNull ImageLicense license) {
+        this.license = license;
+    }
+
+    @NonNull
+    public TextInfo getDescription() {
+        if (description == null) {
+            description = new TextInfo();
+        }
+        return description;
+    }
+
+    @NonNull
+    public Map<String, String> getStructuredCaptions() {
+        return (structuredData != null && structuredData.captions != null) ? structuredData.captions : Collections.emptyMap();
+    }
+
+    public static class Titles implements Serializable {
+        @Nullable private String canonical;
+        @Nullable private String normalized;
+        @Nullable private String display;
+
+        Titles(@NonNull String display, @NonNull String canonical, @NonNull String normalized) {
+            this.display = display;
+            this.canonical = canonical;
+            this.normalized = normalized;
+        }
+
+        @NonNull
+        public String getCanonical() {
+            return StringUtils.defaultString(canonical);
+        }
+
+        @NonNull
+        public String getNormalized() {
+            return StringUtils.defaultString(normalized);
+        }
+
+        @NonNull
+        public String getDisplay() {
+            return StringUtils.defaultString(display);
+        }
+    }
+
+    public static class StructuredData implements Serializable {
+        @Nullable private HashMap<String, String> captions;
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/ImageInfo.java

@@ -0,0 +1,76 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.Serializable;
+
+/**
+ * Gson POJO for a standard image info object as returned by the API ImageInfo module
+ */
+@SuppressWarnings("unused")
+public class ImageInfo implements Serializable {
+    private int size;
+    private int width;
+    private int height;
+    @Nullable private String source;
+    @SerializedName("thumburl") @Nullable private String thumbUrl;
+    @SerializedName("thumbwidth") private int thumbWidth;
+    @SerializedName("thumbheight") private int thumbHeight;
+    @SerializedName("url") @Nullable private String originalUrl;
+    @SerializedName("descriptionurl") @Nullable private String descriptionUrl;
+    @SerializedName("descriptionshorturl") @Nullable private String descriptionShortUrl;
+    @SerializedName("mime") @Nullable private String mimeType;
+    @SerializedName("extmetadata")@Nullable private ExtMetadata metadata;
+    @Nullable private String user;
+    @Nullable private String timestamp;
+
+    @NonNull
+    public String getSource() {
+        return StringUtils.defaultString(source);
+    }
+
+    public void setSource(@Nullable String source) {
+        this.source = source;
+    }
+
+    public int getSize() {
+        return size;
+    }
+
+    public int getWidth() {
+        return width;
+    }
+
+    public int getHeight() {
+        return height;
+    }
+
+    @NonNull public String getMimeType() {
+        return StringUtils.defaultString(mimeType, "*/*");
+    }
+
+    @NonNull public String getThumbUrl() {
+        return StringUtils.defaultString(thumbUrl);
+    }
+
+    @NonNull public String getOriginalUrl() {
+        return StringUtils.defaultString(originalUrl);
+    }
+
+    @NonNull public String getUser() {
+        return StringUtils.defaultString(user);
+    }
+
+    @NonNull public String getTimestamp() {
+        return StringUtils.defaultString(timestamp);
+    }
+
+    @Nullable public ExtMetadata getMetadata() {
+        return metadata;
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/ImageLicense.java

@@ -0,0 +1,67 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.NonNull;
+
+import com.google.gson.annotations.SerializedName;
+
+import java.io.Serializable;
+import java.util.Locale;
+
+import static org.apache.commons.lang3.StringUtils.defaultString;
+
+public class ImageLicense implements Serializable {
+    private static final String CREATIVE_COMMONS_PREFIX = "cc";
+    private static final String PUBLIC_DOMAIN_PREFIX = "pd";
+    private static final String CC_BY_SA = "ccbysa";
+
+    @NonNull @SerializedName("type") private final String license;
+    @NonNull @SerializedName("code") private final String licenseShortName;
+    @NonNull @SerializedName("url") private final String licenseUrl;
+
+    public ImageLicense(@NonNull ExtMetadata metadata) {
+        this.license = metadata.license();
+        this.licenseShortName = metadata.licenseShortName();
+        this.licenseUrl = metadata.licenseUrl();
+    }
+
+    private ImageLicense(@NonNull String license, @NonNull String licenseShortName, @NonNull String licenseUrl) {
+        this.license = license;
+        this.licenseShortName = licenseShortName;
+        this.licenseUrl = licenseUrl;
+    }
+
+    public ImageLicense() {
+        this("", "", "");
+    }
+
+    @NonNull public String getLicenseName() {
+        return license;
+    }
+
+    @NonNull public String getLicenseShortName() {
+        return licenseShortName;
+    }
+
+    @NonNull public String getLicenseUrl() {
+        return licenseUrl;
+    }
+
+    public boolean isLicenseCC() {
+        return defaultString(license).toLowerCase(Locale.ENGLISH).startsWith(CREATIVE_COMMONS_PREFIX)
+                || defaultString(licenseShortName).toLowerCase(Locale.ENGLISH).startsWith(CREATIVE_COMMONS_PREFIX);
+    }
+
+    public boolean isLicensePD() {
+        return defaultString(license).toLowerCase(Locale.ENGLISH).startsWith(PUBLIC_DOMAIN_PREFIX)
+                || defaultString(licenseShortName).toLowerCase(Locale.ENGLISH).startsWith(PUBLIC_DOMAIN_PREFIX);
+    }
+
+    public boolean isLicenseCCBySa() {
+        return defaultString(license).toLowerCase(Locale.ENGLISH).replace("-", "").startsWith(CC_BY_SA)
+                || defaultString(licenseShortName).toLowerCase(Locale.ENGLISH).replace("-", "").startsWith(CC_BY_SA);
+    }
+
+    public boolean hasLicenseInfo() {
+        return !(license.isEmpty() && licenseShortName.isEmpty() && licenseUrl.isEmpty());
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/TextInfo.java

@@ -0,0 +1,29 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.io.Serializable;
+
+public class TextInfo implements Serializable {
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String html;
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String text;
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String lang;
+
+    @NonNull
+    public String getHtml() {
+        return StringUtils.defaultString(html);
+    }
+
+    @NonNull
+    public String getText() {
+        return StringUtils.defaultString(text);
+    }
+
+    @NonNull
+    public String getLang() {
+        return StringUtils.defaultString(lang);
+    }
+}

data-client/src/main/java/org/wikipedia/gallery/VideoInfo.java

@@ -0,0 +1,16 @@
+package org.wikipedia.gallery;
+
+import androidx.annotation.Nullable;
+
+import com.google.gson.annotations.SerializedName;
+
+import java.util.List;
+
+/**
+ * Gson POJO for a standard video info object as returned by the API VideoInfo module
+ */
+public class VideoInfo extends ImageInfo {
+    @SuppressWarnings("unused") @Nullable private List<String> codecs;
+    @SuppressWarnings("unused,NullableProblems") @Nullable private String name;
+    @SuppressWarnings("unused,NullableProblems") @Nullable @SerializedName("short_name") private String shortName;
+}

data-client/src/main/java/org/wikipedia/json/CookieManagerTypeAdapter.java

@@ -0,0 +1,53 @@
+package org.wikipedia.json;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+import org.wikipedia.dataclient.SharedPreferenceCookieManager;
+import org.wikipedia.dataclient.WikiSite;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import okhttp3.Cookie;
+import okhttp3.HttpUrl;
+
+public class CookieManagerTypeAdapter extends TypeAdapter<SharedPreferenceCookieManager> {
+    @Override public void write(JsonWriter out, SharedPreferenceCookieManager cookies) throws IOException {
+        Map<String, List<Cookie>> map = cookies.getCookieJar();
+        out.beginObject();
+        for (String key : map.keySet()) {
+            out.name(key).beginArray();
+            for (Cookie cookie : map.get(key)) {
+                out.value(cookie.toString());
+            }
+            out.endArray();
+        }
+        out.endObject();
+    }
+
+    @Override public SharedPreferenceCookieManager read(JsonReader in) throws IOException {
+        Map<String, List<Cookie>> map = new HashMap<>();
+        in.beginObject();
+        while (in.hasNext()) {
+            String key = in.nextName();
+            List<Cookie> list = new ArrayList<>();
+            map.put(key, list);
+            in.beginArray();
+            HttpUrl url = HttpUrl.parse(WikiSite.DEFAULT_SCHEME + "://" + key);
+            while (in.hasNext()) {
+                String str = in.nextString();
+                if (url != null) {
+                    list.add(Cookie.parse(url, str));
+                }
+            }
+            in.endArray();
+        }
+        in.endObject();
+        return new SharedPreferenceCookieManager(map);
+    }
+}

data-client/src/main/java/org/wikipedia/json/GsonMarshaller.java

@@ -0,0 +1,18 @@
+package org.wikipedia.json;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.Gson;
+
+public final class GsonMarshaller {
+    public static String marshal(@Nullable Object object) {
+        return marshal(GsonUtil.getDefaultGson(), object);
+    }
+
+    public static String marshal(@NonNull Gson gson, @Nullable Object object) {
+        return gson.toJson(object);
+    }
+
+    private GsonMarshaller() { }
+}

data-client/src/main/java/org/wikipedia/json/GsonUnmarshaller.java

@@ -0,0 +1,32 @@
+package org.wikipedia.json;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+public final class GsonUnmarshaller {
+    /** @return Unmarshalled object. */
+    public static <T> T unmarshal(Class<T> clazz, @Nullable String json) {
+        return unmarshal(GsonUtil.getDefaultGson(), clazz, json);
+    }
+
+    /** @return Unmarshalled collection of objects. */
+    public static <T> T unmarshal(TypeToken<T> typeToken, @Nullable String json) {
+        return unmarshal(GsonUtil.getDefaultGson(), typeToken, json);
+    }
+
+    /** @return Unmarshalled object. */
+    public static <T> T unmarshal(@NonNull Gson gson, Class<T> clazz, @Nullable String json) {
+        return gson.fromJson(json, clazz);
+    }
+
+    /** @return Unmarshalled collection of objects. */
+    public static <T> T unmarshal(@NonNull Gson gson, TypeToken<T> typeToken, @Nullable String json) {
+        // From the manual: "Fairly hideous...  Unfortunately, no way to get around this in Java".
+        return gson.fromJson(json, typeToken.getType());
+    }
+
+    private GsonUnmarshaller() { }
+}

data-client/src/main/java/org/wikipedia/json/GsonUtil.java

@@ -0,0 +1,38 @@
+package org.wikipedia.json;
+
+import android.net.Uri;
+
+import androidx.annotation.VisibleForTesting;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+import org.wikipedia.dataclient.SharedPreferenceCookieManager;
+import org.wikipedia.dataclient.WikiSite;
+import org.wikipedia.page.Namespace;
+
+public final class GsonUtil {
+    private static final String DATE_FORMAT = "MMM dd, yyyy HH:mm:ss";
+
+    private static final GsonBuilder DEFAULT_GSON_BUILDER = new GsonBuilder()
+            .setDateFormat(DATE_FORMAT)
+            .registerTypeHierarchyAdapter(Uri.class, new UriTypeAdapter().nullSafe())
+            .registerTypeHierarchyAdapter(Namespace.class, new NamespaceTypeAdapter().nullSafe())
+            .registerTypeAdapter(WikiSite.class, new WikiSiteTypeAdapter().nullSafe())
+            .registerTypeAdapter(SharedPreferenceCookieManager.class, new CookieManagerTypeAdapter().nullSafe())
+            .registerTypeAdapterFactory(new RequiredFieldsCheckOnReadTypeAdapterFactory())
+            .registerTypeAdapterFactory(new PostProcessingTypeAdapter());
+
+    private static final Gson DEFAULT_GSON = DEFAULT_GSON_BUILDER.create();
+
+    public static Gson getDefaultGson() {
+        return DEFAULT_GSON;
+    }
+
+    @VisibleForTesting
+    public static GsonBuilder getDefaultGsonBuilder() {
+        return DEFAULT_GSON_BUILDER;
+    }
+
+    private GsonUtil() { }
+}