Add ability for local push notifications on Android (#1000)

* Add inbox message notifications

* Improve appearance of notifications
 - Show more text in expanded body
 - Show post name and community
 - Render markdown/html

* Do not show unformatted markdown

* Show notification experimental warning

* added release build configuration

* Remove multiDexEnabled due to SDK >= 21

* Refactor some code

* Make setState more clear

---------

Co-authored-by: Hamlet Jiang Su <hamlet.jiangsu@outlook.com>

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
     }
@@ -52,7 +55,8 @@ 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
     }
@@ -68,9 +72,9 @@ android {
 
     buildTypes {
         release {
-            // TODO: Add your own signing config for the release build.
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            // signingConfig signingConfigs.debug
+            minifyEnabled true
+            shrinkResources true
+            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
             signingConfig signingConfigs.release
         }
     }
@@ -80,4 +84,9 @@ 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/proguard-rules.pro

@@ -0,0 +1,32 @@
+##---------------Begin: proguard configuration for Gson  ----------
+# Gson uses generic type information stored in a class file when working with fields. Proguard
+# removes such information by default, so configure it to keep all of it.
+-keepattributes Signature
+
+# For using GSON @Expose annotation
+-keepattributes *Annotation*
+
+# Gson specific classes
+-dontwarn sun.misc.**
+#-keep class com.google.gson.stream.** { *; }
+
+# Application classes that will be serialized/deserialized over Gson
+-keep class com.google.gson.examples.android.model.** { <fields>; }
+
+# Prevent proguard from stripping interface information from TypeAdapter, TypeAdapterFactory,
+# JsonSerializer, JsonDeserializer instances (so they can be used in @JsonAdapter)
+-keep class * extends com.google.gson.TypeAdapter
+-keep class * implements com.google.gson.TypeAdapterFactory
+-keep class * implements com.google.gson.JsonSerializer
+-keep class * implements com.google.gson.JsonDeserializer
+
+# Prevent R8 from leaving Data object members always null
+-keepclassmembers,allowobfuscation class * {
+  @com.google.gson.annotations.SerializedName <fields>;
+}
+
+# Retain generic signatures of TypeToken and its subclasses with R8 version 3.0 and higher.
+-keep,allowobfuscation,allowshrinking class com.google.gson.reflect.TypeToken
+-keep,allowobfuscation,allowshrinking class * extends com.google.gson.reflect.TypeToken
+
+##---------------End: proguard configuration for Gson  ----------

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

@@ -1,13 +1,17 @@
-<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 -->
     <!-- requestLegacyExternalStorage is required for saving media to an album in API 29 -->
     <application
+        tools:replace="android:label"
         android:label="Thunder"
         android:name="${applicationName}"
         android:icon="@mipmap/launcher_icon"

android/app/src/main/res/raw/keep.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:tools="http://schemas.android.com/tools" tools:keep="@drawable/*" />

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"
+        }
     }
 }
 

ios/Podfile.lock

@@ -1,4 +1,6 @@
 PODS:
+  - background_fetch (1.2.1):
+    - Flutter
   - device_info_plus (0.0.1):
     - Flutter
   - Flutter (1.0.0)
@@ -10,6 +12,8 @@ PODS:
     - Flutter
   - flutter_keyboard_visibility (0.0.1):
     - Flutter
+  - flutter_local_notifications (0.0.1):
+    - Flutter
   - flutter_native_splash (0.0.1):
     - Flutter
   - FMDB (2.7.5):
@@ -45,12 +49,14 @@ PODS:
     - Flutter
 
 DEPENDENCIES:
+  - background_fetch (from `.symlinks/plugins/background_fetch/ios`)
   - device_info_plus (from `.symlinks/plugins/device_info_plus/ios`)
   - Flutter (from `Flutter`)
   - flutter_custom_tabs_ios (from `.symlinks/plugins/flutter_custom_tabs_ios/ios`)
   - flutter_file_dialog (from `.symlinks/plugins/flutter_file_dialog/ios`)
   - flutter_icmp_ping (from `.symlinks/plugins/flutter_icmp_ping/ios`)
   - flutter_keyboard_visibility (from `.symlinks/plugins/flutter_keyboard_visibility/ios`)
+  - flutter_local_notifications (from `.symlinks/plugins/flutter_local_notifications/ios`)
   - flutter_native_splash (from `.symlinks/plugins/flutter_native_splash/ios`)
   - gal (from `.symlinks/plugins/gal/darwin`)
   - image_picker_ios (from `.symlinks/plugins/image_picker_ios/ios`)
@@ -70,6 +76,8 @@ SPEC REPOS:
     - FMDB
 
 EXTERNAL SOURCES:
+  background_fetch:
+    :path: ".symlinks/plugins/background_fetch/ios"
   device_info_plus:
     :path: ".symlinks/plugins/device_info_plus/ios"
   Flutter:
@@ -82,6 +90,8 @@ EXTERNAL SOURCES:
     :path: ".symlinks/plugins/flutter_icmp_ping/ios"
   flutter_keyboard_visibility:
     :path: ".symlinks/plugins/flutter_keyboard_visibility/ios"
+  flutter_local_notifications:
+    :path: ".symlinks/plugins/flutter_local_notifications/ios"
   flutter_native_splash:
     :path: ".symlinks/plugins/flutter_native_splash/ios"
   gal:
@@ -110,12 +120,14 @@ EXTERNAL SOURCES:
     :path: ".symlinks/plugins/webview_flutter_wkwebview/ios"
 
 SPEC CHECKSUMS:
+  background_fetch: 896944864b038d2837fc750d470e9841e1e6a363
   device_info_plus: c6fb39579d0f423935b0c9ce7ee2f44b71b9fce6
   Flutter: f04841e97a9d0b0a8025694d0796dd46242b2854
   flutter_custom_tabs_ios: 62439c843b2691aae516fd50119a01eb9755fff7
   flutter_file_dialog: 4c014a45b105709a27391e266c277d7e588e9299
   flutter_icmp_ping: 2b159955eee0c487c766ad83fec224ae35e7c935
   flutter_keyboard_visibility: 0339d06371254c3eb25eeb90ba8d17dca8f9c069
+  flutter_local_notifications: 0c0b1ae97e741e1521e4c1629a459d04b9aec743
   flutter_native_splash: 52501b97d1c0a5f898d687f1646226c1f93c56ef
   FMDB: 2ce00b547f966261cd18927a3ddb07cb6f3db82a
   gal: 61e868295d28fe67ffa297fae6dacebf56fd53e1

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

@@ -20,6 +20,7 @@ enum LocalSettings {
   useDisplayNamesForUsers(name: 'setting_use_display_names_for_users', key: 'showUserDisplayNames'),
   markPostAsReadOnMediaView(name: 'setting_general_mark_post_read_on_media_view', key: 'markPostAsReadOnMediaView'),
   showInAppUpdateNotification(name: 'setting_notifications_show_inapp_update', key: 'showInAppUpdateNotifications'),
+  enableInboxNotifications(name: 'setting_enable_inbox_notifications', key: 'enableInboxNotifications'),
   scoreCounters(name: 'setting_score_counters', key: "showScoreCounters"),
   appLanguageCode(name: 'setting_app_language_code', key: 'appLanguage'),
 
@@ -159,6 +160,7 @@ extension LocalizationExt on AppLocalizations {
       'showUserDisplayNames': showUserDisplayNames,
       'markPostAsReadOnMediaView': markPostAsReadOnMediaView,
       'showInAppUpdateNotifications': showInAppUpdateNotifications,
+      'enableInboxNotifications': enableInboxNotifications,
       'showScoreCounters': showScoreCounters,
       'appLanguage': appLanguage,
       'compactView': compactView,

lib/l10n/app_en.arb

@@ -71,6 +71,10 @@
   "@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": {},
   "base": "Base",
@@ -357,6 +361,10 @@
   "@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).",
@@ -393,6 +401,10 @@
   "@enableFeedFab": {
     "description": "Enable the Floating Action Button for the feed"
   },
+  "enableInboxNotifications": "Enable Inbox Notifications (Experimental)",
+  "@enableInboxNotifications": {
+    "description": "Setting name for inbox notifications"
+  },
   "enableFloatingButtonOnFeeds": "Enable Floating Button On Feeds",
   "@enableFloatingButtonOnFeeds": {
     "description": "Setting for enable floating button on feeds"
@@ -739,6 +751,14 @@
   "@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",
@@ -1265,6 +1285,10 @@
   "@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",
@@ -1333,6 +1357,10 @@
   "@visitInstance": {},
   "visitUserProfile": "Visit User Profile",
   "@visitUserProfile": {},
+  "warning": "Warning",
+  "@warning": {
+    "description": "Heading for warning dialogs"
+  },
   "xDownvotes": "{x} downvotes",
   "@xDownvotes": {},
   "xScore": "{x} score",