Name uniqueness checking

Follows sequence 'Foo.jpeg', 'Foo 2.jpeg', 'Foo 3.jpeg' etc until one is
found that doesn't exist, then we send up the upload. This avoids most
typical conflicts scenarios.

Still can produce a conflict if you start uploads near-simultaneously,
but this is better than none.

commons/src/main/java/org/wikimedia/commons/UploadService.java

@@ -1,7 +1,10 @@
 package org.wikimedia.commons;
 
 import java.io.*;
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import android.graphics.*;
 import android.os.Bundle;
@@ -186,6 +189,7 @@ public class UploadService extends HandlerService<Contribution> {
         this.startForeground(NOTIFICATION_UPLOAD_IN_PROGRESS, curProgressNotification.build());
 
         try {
+            String filename = findUniqueFilename(contribution.getFilename());
             if(!api.validateLogin()) {
                 // Need to revalidate!
                 if(app.revalidateAuthToken()) {
@@ -204,7 +208,7 @@ public class UploadService extends HandlerService<Contribution> {
                     String.format(getString(R.string.upload_progress_notification_title_finishing), contribution.getDisplayTitle()),
                     contribution
             );
-            result = api.upload(contribution.getFilename(), file, contribution.getDataLength(), contribution.getPageContents(), contribution.getEditSummary(), notificationUpdater);
+            result = api.upload(filename, file, contribution.getDataLength(), contribution.getPageContents(), contribution.getEditSummary(), notificationUpdater);
 
 
             Log.d("Commons", "Response is" + Utils.getStringFromDOM(result.getDocument()));
@@ -271,4 +275,49 @@ public class UploadService extends HandlerService<Contribution> {
         contribution.setState(Contribution.STATE_FAILED);
         contribution.save();
     }
+
+    private String findUniqueFilename(String fileName) {
+        return findUniqueFilename(fileName, 1);
+    }
+
+    private String findUniqueFilename(String fileName, int sequenceNumber) {
+        String sequenceFileName;
+        if (sequenceNumber == 1) {
+            sequenceFileName = fileName;
+        } else {
+            if (fileName.indexOf('.') == -1) {
+                // We really should have appended a file type suffix already.
+                // But... we might not.
+                sequenceFileName = fileName + " " + sequenceNumber;
+            } else {
+                Pattern regex = Pattern.compile("^(.*)(\\..+?)$");
+                Matcher regexMatcher = regex.matcher(fileName);
+                sequenceFileName = regexMatcher.replaceAll("$1 " + sequenceNumber + "$2");
+            }
+        }
+        Log.d("Commons", "checking for uniqueness of name " + sequenceFileName);
+
+        if (fileExistsWithName(sequenceFileName)) {
+            return findUniqueFilename(fileName, sequenceNumber + 1);
+        } else {
+            return sequenceFileName;
+        }
+    }
+
+    private boolean fileExistsWithName(String fileName) {
+        MWApi api = app.getApi();
+        ApiResult result;
+
+        try {
+            result = api.action("query")
+                    .param("prop", "imageinfo")
+                    .param("titles", "File:" + fileName)
+                    .get();
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        ArrayList<ApiResult> nodes = result.getNodes("/api/query/pages/page/imageinfo");
+        return nodes.size() > 0;
+    }
 }