Feature/notifications

android/app/build.gradle

@@ -30,10 +30,13 @@ if (keystorePropertiesFile.exists()) {
 
 android {
     namespace "com.hjiangsu.thunder"
-    compileSdkVersion flutter.compileSdkVersion
+    // Use variable for version requested by background_fetch and flutter_local_notifications
+    compileSdkVersion rootProject.ext.compileSdkVersion
     ndkVersion flutter.ndkVersion
 
     compileOptions {
+        // The following line is required by flutter_local_notifications
+        coreLibraryDesugaringEnabled true
         sourceCompatibility JavaVersion.VERSION_1_8
         targetCompatibility JavaVersion.VERSION_1_8
     }
@@ -52,9 +55,12 @@ android {
         // You can update the following values to match your application needs.
         // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-gradle-build-configuration.
         minSdkVersion 21
-        targetSdkVersion flutter.targetSdkVersion
+        // Use variable for version requested by background_fetch and flutter_local_notifications
+        targetSdkVersion rootProject.ext.targetSdkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
+        // The following line is required by flutter_local_notifications
+        multiDexEnabled true
     }
 
     signingConfigs {
@@ -80,4 +86,9 @@ flutter {
     source '../..'
 }
 
-dependencies {}
+dependencies {
+    // The following 3 dependencies are required by flutter_local_notifications
+    coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.2.2'
+    implementation 'androidx.window:window:1.0.0'
+    implementation 'androidx.window:window-java:1.0.0'
+}

android/app/src/debug/AndroidManifest.xml

@@ -4,4 +4,8 @@
          to allow setting breakpoints, to provide hot reload, etc.
     -->
     <uses-permission android:name="android.permission.INTERNET"/>
+
+    <!-- In Debug mode, request the EXACT_ALARM permission. -->
+    <!-- This allows us to run background_fetch at lower intervals for the sake of quicker testing. -->
+    <uses-permission android:minSdkVersion="34" android:name="android.permission.USE_EXACT_ALARM" />
 </manifest>

android/app/src/main/AndroidManifest.xml

@@ -1,12 +1,16 @@
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+<!-- The tools namespace is needed by background_fetch --> 
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
+          xmlns:tools="http://schemas.android.com/tools"
     package="com.baseflow.permissionhandler">
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
     <uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
     <uses-permission android:name="android.permission.READ_MEDIA_VIDEO" />
     <uses-permission android:name="android.permission.VIBRATE" />
+    <!-- The tools:replace line is needed by background_fetch -->
     <application
+        tools:replace="android:label"
         android:label="Thunder"
         android:name="${applicationName}"
         android:usesCleartextTraffic="true"

android/build.gradle

@@ -1,12 +1,20 @@
 buildscript {
     ext.kotlin_version = '1.7.10'
+    // Versions recommended/needed by flutter_local_notifications and background_fetch
+    // These can be upgraded over time.
+    ext {
+        compileSdkVersion   = 33
+        targetSdkVersion    = 33
+        appCompatVersion    = "1.6.1"
+    }
     repositories {
         google()
         mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.3.0'
+        // flutter_local_notifications requires gradle version 7.3.1
+        classpath 'com.android.tools.build:gradle:7.3.1'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
@@ -15,6 +23,10 @@ allprojects {
     repositories {
         google()
         mavenCentral()
+        // The following section is required by background_fetch
+        maven {
+            url "${project(':background_fetch').projectDir}/libs"
+        }
     }
 }
 

lib/core/enums/full_name_separator.dart

@@ -11,25 +11,28 @@ enum FullNameSeparator {
   const FullNameSeparator(this.label);
 }
 
-String generateUserFullName(BuildContext context, name, instance) {
-  final ThunderState thunderState = context.read<ThunderBloc>().state;
-  return switch (thunderState.userSeparator) {
+String generateUserFullName(BuildContext? context, name, instance, {FullNameSeparator? userSeparator}) {
+  assert(context != null || userSeparator != null);
+  userSeparator ??= context!.read<ThunderBloc>().state.userSeparator;
+  return switch (userSeparator) {
     FullNameSeparator.dot => '$name · $instance',
     FullNameSeparator.at => '$name@$instance',
   };
 }
 
-String generateUserFullNameSuffix(BuildContext context, instance) {
-  final ThunderState thunderState = context.read<ThunderBloc>().state;
-  return switch (thunderState.userSeparator) {
+String generateUserFullNameSuffix(BuildContext? context, instance, {FullNameSeparator? userSeparator}) {
+  assert(context != null || userSeparator != null);
+  userSeparator ??= context!.read<ThunderBloc>().state.userSeparator;
+  return switch (userSeparator) {
     FullNameSeparator.dot => ' · $instance',
     FullNameSeparator.at => '@$instance',
   };
 }
 
-String generateCommunityFullName(BuildContext context, name, instance) {
-  final ThunderState thunderState = context.read<ThunderBloc>().state;
-  return switch (thunderState.communitySeparator) {
+String generateCommunityFullName(BuildContext? context, name, instance, {FullNameSeparator? communitySeparator}) {
+  assert(context != null || communitySeparator != null);
+  communitySeparator ??= context!.read<ThunderBloc>().state.communitySeparator;
+  return switch (communitySeparator) {
     FullNameSeparator.dot => '$name · $instance',
     FullNameSeparator.at => '$name@$instance',
   };

lib/core/enums/local_settings.dart

@@ -18,6 +18,7 @@ enum LocalSettings {
   useDisplayNamesForUsers(name: 'setting_use_display_names_for_users', label: 'Show User Display Names'),
   markPostAsReadOnMediaView(name: 'setting_general_mark_post_read_on_media_view', label: 'Mark Read After Viewing Media'),
   showInAppUpdateNotification(name: 'setting_notifications_show_inapp_update', label: 'Get notified of new GitHub releases'),
+  enableInboxNotifications(name: 'setting_enable_inbox_notifications', label: ''),
   scoreCounters(name: 'setting_score_counters', label: "Display User Scores"),
   appLanguageCode(name: 'setting_app_language_code', label: 'App Language'),
 

lib/l10n/app_en.arb

@@ -69,6 +69,10 @@
   "@back": {},
   "backButton": "Back button",
   "@backButton": {},
+  "backgroundCheckWarning": "Note that notification checks will consume additional battery",
+  "@backgroundCheckWarning": {
+    "description": "Warning for enabling notifications"
+  },
   "backToTop": "Back To Top",
   "@backToTop": {},
   "blockCommunity": "Block Community",
@@ -285,6 +289,10 @@
   "@dimReadPosts": {
     "description": "Description of the effect on read posts."
   },
+  "disable": "Disable",
+  "@disable": {
+    "description": "Action for disabling something"
+  },
   "dismissRead": "Dismiss Read",
   "@dismissRead": {},
   "displayUserScore": "Display User Scores (Karma).",
@@ -317,6 +325,10 @@
   "@enableFeedFab": {
     "description": "Enable the Floating Action Button for the feed"
   },
+  "enableInboxNotifications": "Enable Inbox Notifications (Experimental)",
+  "@enableInboxNotifications": {
+    "description": "Setting name for inbox notifications"
+  },
   "enablePostFab": "Enable Floating Button on Posts",
   "@enablePostFab": {
     "description": "Enable the Floating Action Button for the post"
@@ -587,6 +599,14 @@
   "@notificationsBehaviourSettings": {
     "description": "Subcategory in Setting -> General"
   },
+  "notificationsNotAllowed": "Notifications are not allowed for Thunder in system settings",
+  "@notificationsNotAllowed": {
+    "description": "Description for when notifications are now allowed for app"
+  },
+  "notificationsWarningDialog": "Notifications are an experimental feature which may not function correctly on all devices.\n\n· Checks will occur every ~15 minutes and will consume additional battery.\n\n· Disable battery optimizations for a higher likelihood of successful notifications.\n\nSee the following page for more information.",
+  "@notificationsWarningDialog": {
+    "description": "The content of the warning dialog for the notifications feature"
+  },
   "off": "off",
   "@off": {},
   "ok": "OK",
@@ -965,6 +985,10 @@
   "@unblockInstance": {
     "description": "Tooltip for unblocking an instance"
   },
+  "understandEnable": "I Understand, Enable",
+  "@understandEnable": {
+    "description": "Action for acknowledging and enabling something"
+  },
   "unexpectedError": "Unexpected Error",
   "@unexpectedError": {},
   "unsubscribe": "Unsubscribe",
@@ -1017,6 +1041,10 @@
   "@visitInstance": {},
   "visitUserProfile": "Visit User Profile",
   "@visitUserProfile": {},
+  "warning": "Warning",
+  "@warning": {
+    "description": "Heading for warning dialogs"
+  },
   "xDownvotes": "{x} downvotes",
   "@xDownvotes": {},
   "xScore": "{x} score",

lib/main.dart

@@ -1,18 +1,22 @@
+import 'dart:async';
 import 'dart:io';
 
+import 'package:background_fetch/background_fetch.dart';
 import 'package:dart_ping_ios/dart_ping_ios.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 // External Packages
 import 'package:flutter_bloc/flutter_bloc.dart';
 import "package:flutter_displaymode/flutter_displaymode.dart";
+import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:flutter_native_splash/flutter_native_splash.dart';
 import 'package:l10n_esperanto/l10n_esperanto.dart';
 import 'package:overlay_support/overlay_support.dart';
 import 'package:dynamic_color/dynamic_color.dart';
 import 'package:flex_color_scheme/flex_color_scheme.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 import 'package:thunder/account/bloc/account_bloc.dart';
 import 'package:thunder/community/bloc/anonymous_subscriptions_bloc.dart';
 import 'package:thunder/community/bloc/community_bloc.dart';
@@ -31,6 +35,7 @@ import 'package:thunder/thunder/thunder.dart';
 import 'package:thunder/user/bloc/user_bloc.dart';
 import 'package:thunder/utils/global_context.dart';
 import 'package:flutter/foundation.dart';
+import 'package:thunder/utils/notifications.dart';
 
 void main() async {
   WidgetsBinding widgetsBinding = WidgetsFlutterBinding.ensureInitialized();
@@ -47,12 +52,38 @@ void main() async {
     DartPingIOS.register();
   }
 
+  // Initialize local notifications. Note that this doesn't request permissions or actually send any notifications.
+  // It's just hooking up callbacks and settings.
+  final FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
+  // Initialize the Android-specific settings, using the splash asset as the notification icon.
+  const AndroidInitializationSettings initializationSettingsAndroid = AndroidInitializationSettings('splash');
+  const InitializationSettings initializationSettings = InitializationSettings(android: initializationSettingsAndroid);
+  await flutterLocalNotificationsPlugin.initialize(initializationSettings, onDidReceiveNotificationResponse: onDidReceiveNotificationResponse);
+
+  // See if Thunder is launching because a notification was tapped. If so, we want to jump right to the appropriate page.
+  final NotificationAppLaunchDetails? notificationAppLaunchDetails = await flutterLocalNotificationsPlugin.getNotificationAppLaunchDetails();
+  if (notificationAppLaunchDetails?.didNotificationLaunchApp == true && notificationAppLaunchDetails!.notificationResponse?.payload == repliesGroupKey) {
+    thunderPageController = PageController(initialPage: 3);
+  }
+
+  // Initialize background fetch (this is async and can go run on its own).
+  final SharedPreferences prefs = (await UserPreferences.instance).sharedPreferences;
+  if (!kIsWeb && Platform.isAndroid && (prefs.getBool(LocalSettings.enableInboxNotifications.name) ?? false)) {
+    initBackgroundFetch();
+  }
+
   final String initialInstance = (await UserPreferences.instance).sharedPreferences.getString(LocalSettings.currentAnonymousInstance.name) ?? 'lemmy.ml';
   LemmyClient.instance.changeBaseUrl(initialInstance);
 
   runApp(const ThunderApp());
+
   // Set high refresh rate after app initialization
   FlutterDisplayMode.setHighRefreshRate();
+
+  // Register to receive BackgroundFetch events after app is terminated.
+  if (!kIsWeb && Platform.isAndroid && (prefs.getBool(LocalSettings.enableInboxNotifications.name) ?? false)) {
+    initHeadlessBackgroundFetch();
+  }
 }
 
 class ThunderApp extends StatelessWidget {
@@ -168,3 +199,86 @@ class ThunderApp extends StatelessWidget {
     );
   }
 }
+
+// ---------------- START LOCAL NOTIFICATION STUFF ---------------- //
+
+/// This seems to a notification callback handler that is only need for iOS.
+void onDidReceiveLocalNotification(int id, String? title, String? body, String? payload) {}
+
+/// This is the notification handler that runs when a notification is tapped while the app is running.
+void onDidReceiveNotificationResponse(NotificationResponse details) {
+  switch (details.payload) {
+    case repliesGroupKey:
+      // Navigate to the inbox page
+      thunderPageController.jumpToPage(3);
+      break;
+    default:
+      break;
+  }
+}
+
+// ---------------- END LOCAL NOTIFICATION STUFF ---------------- //
+
+// ---------------- START BACKGROUND FETCH STUFF ---------------- //
+
+/// This method handles "headless" callbacks,
+/// i.e., whent the app is not running
+@pragma('vm:entry-point')
+void backgroundFetchHeadlessTask(HeadlessTask task) async {
+  if (task.timeout) {
+    BackgroundFetch.finish(task.taskId);
+    return;
+  }
+  // Run the poll!
+  await pollRepliesAndShowNotifications();
+  BackgroundFetch.finish(task.taskId);
+}
+
+/// The method initializes background fetching while the app is running
+Future<void> initBackgroundFetch() async {
+  await BackgroundFetch.configure(
+    BackgroundFetchConfig(
+      minimumFetchInterval: 15,
+      stopOnTerminate: false,
+      startOnBoot: true,
+      enableHeadless: true,
+      requiredNetworkType: NetworkType.NONE,
+      requiresBatteryNotLow: false,
+      requiresStorageNotLow: false,
+      requiresCharging: false,
+      requiresDeviceIdle: false,
+      // Uncomment this line (and set the minimumFetchInterval to 1) for quicker testing.
+      //forceAlarmManager: true,
+    ),
+    // This is the callback that handles background fetching while the app is running.
+    (String taskId) async {
+      // Run the poll!
+      await pollRepliesAndShowNotifications();
+      BackgroundFetch.finish(taskId);
+    },
+    // This is the timeout callback.
+    (String taskId) async {
+      BackgroundFetch.finish(taskId);
+    },
+  );
+}
+
+void disableBackgroundFetch() async {
+  await BackgroundFetch.configure(
+    BackgroundFetchConfig(
+      minimumFetchInterval: 15,
+      stopOnTerminate: true,
+      startOnBoot: false,
+      enableHeadless: false,
+    ),
+    () {},
+    () {},
+  );
+}
+
+// This method initializes background fetching while the app is not running
+void initHeadlessBackgroundFetch() async {
+  BackgroundFetch.registerHeadlessTask(backgroundFetchHeadlessTask);
+}
+
+// ---------------- END BACKGROUND FETCH STUFF ---------------- //

lib/routes.dart

@@ -20,19 +20,21 @@ import 'package:thunder/settings/settings.dart';
 import 'package:thunder/thunder/thunder.dart';
 import 'package:thunder/user/pages/user_settings_page.dart';
 
+PageController thunderPageController = PageController(initialPage: 0);
+
 final GoRouter router = GoRouter(
   debugLogDiagnostics: true,
   routes: <GoRoute>[
     GoRoute(
       name: 'home',
       path: '/',
-      builder: (BuildContext context, GoRouterState state) => const Thunder(),
+      builder: (BuildContext context, GoRouterState state) => Thunder(pageController: thunderPageController),
       routes: const <GoRoute>[],
     ),
     GoRoute(
       name: 'settings',
       path: '/settings',
-      builder: (BuildContext context, GoRouterState state) => SettingsPage(),
+      builder: (BuildContext context, GoRouterState state) => const SettingsPage(),
       routes: <GoRoute>[
         GoRoute(
           name: 'general',