Request user to disable battery optimization for Syncthing

lint.xml

@@ -15,6 +15,9 @@
 	<!-- We don't care about Google App Indexing -->
 	<issue id="GoogleAppIndexingWarning" severity="ignore" />
 
+	<!-- Disabling battery optimizations is optional, so this warning doesn't apply to us -->
+	<issue id="BatteryLife" severity="ignore" />
+
 	<!-- Ignore types in translations (not handled by us) -->
 	<issue id="Typos">
 		<ignore path="src/main/res/values-ar" />

src/main/AndroidManifest.xml

@@ -13,6 +13,7 @@
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.READ_SYNC_SETTINGS" />
+    <uses-permission android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS"/>
 
     <application
         android:allowBackup="false"

src/main/java/com/nutomic/syncthingandroid/activities/MainActivity.java

@@ -1,16 +1,23 @@
 package com.nutomic.syncthingandroid.activities;
 
 import android.annotation.SuppressLint;
+import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.ComponentName;
+import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.IBinder;
+import android.os.PowerManager;
+import android.preference.PreferenceManager;
+import android.provider.Settings;
 import android.support.design.widget.TabLayout;
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
@@ -23,8 +30,13 @@ import android.support.v7.app.ActionBarDrawerToggle;
 import android.util.DisplayMetrics;
 import android.util.Log;
 import android.util.TypedValue;
-import android.view.*;
+import android.view.KeyEvent;
+import android.view.LayoutInflater;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.ViewGroup;
 import android.widget.TextView;
+
 import com.nutomic.syncthingandroid.R;
 import com.nutomic.syncthingandroid.fragments.DeviceListFragment;
 import com.nutomic.syncthingandroid.fragments.DrawerFragment;
@@ -84,6 +96,7 @@ public class MainActivity extends SyncthingActivity
             case ACTIVE:
                 dismissDisabledDialog();
                 dismissLoadingDialog();
+                showBatteryOptimizationDialogIfNecessary();
                 mDrawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);
                 mDrawerFragment.requestGuiUpdate();
                 if (new Date().getTime() > getFirstStartTime() + USAGE_REPORTING_DIALOG_DELAY &&
@@ -103,6 +116,31 @@ public class MainActivity extends SyncthingActivity
         }
     }
 
+    @TargetApi(23)
+    private void showBatteryOptimizationDialogIfNecessary() {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
+        PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
+        boolean dontShowAgain = sp.getBoolean("battery_optimization_dont_show_again", false);
+        if (dontShowAgain || Build.VERSION.SDK_INT < Build.VERSION_CODES.M ||
+                pm.isIgnoringBatteryOptimizations(getPackageName())) {
+            return;
+        }
+
+        new AlertDialog.Builder(this)
+                .setTitle(R.string.dialog_disable_battery_optimization_title)
+                .setMessage(R.string.dialog_disable_battery_optimization_message)
+                .setPositiveButton(R.string.dialog_disable_battery_optimization_turn_off, (d, i) -> {
+                    Intent intent = new Intent(Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS);
+                    intent.setData(Uri.parse("package:" + getPackageName()));
+                    startActivity(intent);
+                })
+                .setNeutralButton(R.string.dialog_disable_battery_optimization_later, null)
+                .setNegativeButton(R.string.dialog_disable_battery_optimization_dont_show_again, (d, i) -> {
+                    sp.edit().putBoolean("battery_optimization_dont_show_again", true).apply();
+                })
+                .show();
+    }
+
     private void dismissDisabledDialog() {
         if (mDisabledDialog != null) {
             mDisabledDialog.dismiss();

src/main/res/values/strings.xml

@@ -57,6 +57,12 @@ Please report any problems you encounter via Github.</string>
 
     <string name="folder_rejected">Device %1$s wants to share folder %2$s</string>
 
+    <string name="dialog_disable_battery_optimization_title">Battery Optimization</string>
+    <string name="dialog_disable_battery_optimization_message">Android may stop synchronization after some time. To prevent this, turn off battery optimization</string>
+    <string name="dialog_disable_battery_optimization_later">Later</string>
+    <string name="dialog_disable_battery_optimization_dont_show_again">Don\'t show again</string>
+    <string name="dialog_disable_battery_optimization_turn_off">Turn off for Syncthing</string>
+
     <!-- FoldersFragment -->