NearbyParentFragment.kt: add helper methods for user location overlays and accuracy data.

Before this commit, the code used to create the user location overlays was in multiple places.
Additionally, there was no easy way to access the location accuracy.

This commit places the user location overlay creation code into helper methods, as well as adding
a new location accuracy getter method. These methods can now be used to refactor other parts of the file.

app/src/main/java/fr/free/nrw/commons/nearby/fragments/NearbyParentFragment.kt

@@ -2710,35 +2710,76 @@ class NearbyParentFragment : CommonsDaggerSupportFragment(),
                     else -> i++
                 }
             }
-
-            // Add disk overlay
-            ScaleDiskOverlay(context, it, 2000, UnitOfMeasure.foot).apply {
-                setCirclePaint2(Paint().apply {
-                    color = Color.rgb(128, 128, 128)
-                    style = Paint.Style.STROKE
-                    strokeWidth = 2f
-                })
-                setCirclePaint1(Paint().apply {
-                    color = Color.argb(40, 128, 128, 128)
-                    style = Paint.Style.FILL_AND_STROKE
-                })
-                setDisplaySizeMin(900)
-                setDisplaySizeMax(1700)
-                overlays.add(this)
-            }
-
-            // Add marker
-            Marker(binding?.map).apply {
-                position = it
-                setAnchor(Marker.ANCHOR_CENTER, Marker.ANCHOR_BOTTOM)
-                icon = getDrawable(context, R.drawable.current_location_marker)
-                title = "Your Location"
-                textLabelFontSize = 24
-                overlays.add(this)
-            }
         }
     }
 
+    /**
+     * @return The accuracy of the current location with a confidence at the 68th percentile.
+     * Units are in meters. Returning 0 may indicate failure.
+     */
+    private fun getCurrentLocationAccuracy(): Float {
+        var accuracy = 0f
+        val lastLocation = locationManager.getLastLocation()
+        if (lastLocation != null) {
+            accuracy = lastLocation.accuracy
+        }
+
+        return accuracy
+    }
+
+    /**
+     * Creates the current location overlay
+     *
+     * @param geoPoint The GeoPoint where the current location overlay will be placed.
+     *
+     * @return The current location overlay as a Marker
+     */
+    private fun createCurrentLocationOverlay(geoPoint: GeoPoint): Marker {
+        val currentLocationOverlay = Marker(
+            binding!!.map
+        )
+        currentLocationOverlay.position = geoPoint
+        currentLocationOverlay.icon =
+            getDrawable(
+                this.requireContext(),
+                fr.free.nrw.commons.R.drawable.current_location_marker
+            )
+        currentLocationOverlay.title = "Your Location"
+        currentLocationOverlay.textLabelFontSize = 24
+        currentLocationOverlay.setAnchor(0.5f, 0.5f)
+
+        return currentLocationOverlay
+    }
+
+    /**
+     * Creates the location error overlay to show the user how accurate the current location
+     * overlay is. The edge of the disk is the 95% confidence interval.
+     *
+     * @param context The Android context
+     * @param point The user's location as a GeoPoint
+     * @param value The radius of the disk
+     * @param unitOfMeasure The unit of measurement of the value/disk radius.
+     *
+     * @return The location error overlay as a ScaleDiskOverlay.
+     */
+    private fun createCurrentLocationErrorOverlay(context: Context?, point: GeoPoint, value: Int,
+                                           unitOfMeasure: UnitOfMeasure): ScaleDiskOverlay {
+        val scaleDisk = ScaleDiskOverlay(context, point, value, unitOfMeasure)
+
+        scaleDisk.setCirclePaint2(Paint().apply {
+            color = Color.rgb(128, 128, 128)
+            style = Paint.Style.STROKE
+            strokeWidth = 2f
+        })
+
+        scaleDisk.setCirclePaint1(Paint().apply {
+            color = Color.argb(40, 128, 128, 128)
+            style = Paint.Style.FILL_AND_STROKE
+        })
+
+        return scaleDisk
+    }
+
     private fun moveCameraToPosition(geoPoint: GeoPoint) {
         binding!!.map.controller.animateTo(geoPoint)
     }