feat(linux): Get the isolate implementation somewhat working

android/src/main/kotlin/org/moxxy/moxxy_native/notifications/NotificationsApi.kt

@@ -20,13 +20,13 @@ private fun wrapError(exception: Throwable): List<Any?> {
     return listOf(
       exception.code,
       exception.message,
-            exception.details,
+      exception.details
     )
   } else {
     return listOf(
       exception.javaClass.simpleName,
       exception.toString(),
-            "Cause: " + exception.cause + ", Stacktrace: " + Log.getStackTraceString(exception),
+      "Cause: " + exception.cause + ", Stacktrace: " + Log.getStackTraceString(exception)
     )
   }
 }
@@ -40,14 +40,13 @@ private fun wrapError(exception: Throwable): List<Any?> {
 class FlutterError (
   val code: String,
   override val message: String? = null,
-    val details: Any? = null,
+  val details: Any? = null
 ) : Throwable()
 
 enum class NotificationIcon(val raw: Int) {
   WARNING(0),
   ERROR(1),
-    NONE(2),
-    ;
+  NONE(2);
 
   companion object {
     fun ofRaw(raw: Int): NotificationIcon? {
@@ -59,8 +58,7 @@ enum class NotificationIcon(val raw: Int) {
 enum class NotificationEventType(val raw: Int) {
   MARKASREAD(0),
   REPLY(1),
-    OPEN(2),
-    ;
+  OPEN(2);
 
   companion object {
     fun ofRaw(raw: Int): NotificationEventType? {
@@ -72,8 +70,7 @@ enum class NotificationEventType(val raw: Int) {
 enum class NotificationChannelImportance(val raw: Int) {
   MIN(0),
   HIGH(1),
-    DEFAULT(2),
-    ;
+  DEFAULT(2);
 
   companion object {
     fun ofRaw(raw: Int): NotificationChannelImportance? {
@@ -88,7 +85,7 @@ data class NotificationMessageContent(
   val body: String? = null,
   /** The path and mime type of the media to show. */
   val mime: String? = null,
-    val path: String? = null,
+  val path: String? = null
 
 ) {
   companion object {
@@ -122,7 +119,7 @@ data class NotificationMessage(
   /** Milliseconds since epoch. */
   val timestamp: Long,
   /** The path to the avatar to use */
-    val avatarPath: String? = null,
+  val avatarPath: String? = null
 
 ) {
   companion object {
@@ -166,7 +163,7 @@ data class MessagingNotification(
   /** The id for notification grouping. */
   val groupId: String? = null,
   /** Additional data to include. */
-    val extra: Map<String?, String?>? = null,
+  val extra: Map<String?, String?>? = null
 
 ) {
   companion object {
@@ -210,7 +207,7 @@ data class RegularNotification(
   /** The id of the notification. */
   val id: Long,
   /** The icon to use. */
-    val icon: NotificationIcon,
+  val icon: NotificationIcon
 
 ) {
   companion object {
@@ -252,7 +249,7 @@ data class NotificationEvent(
    */
   val payload: String? = null,
   /** Extra data. Only set when type == NotificationType.reply. */
-    val extra: Map<String?, String?>? = null,
+  val extra: Map<String?, String?>? = null
 
 ) {
   companion object {
@@ -284,7 +281,7 @@ data class NotificationI18nData(
   /** The content of the "mark as read" button. */
   val markAsRead: String,
   /** The text to show when *you* reply. */
-    val you: String,
+  val you: String
 
 ) {
   companion object {
@@ -308,7 +305,7 @@ data class NotificationI18nData(
 /** Generated class from Pigeon that represents data sent in messages. */
 data class NotificationGroup (
   val id: String,
-    val description: String,
+  val description: String
 
 ) {
   companion object {
@@ -336,7 +333,7 @@ data class NotificationChannel(
   val showBadge: Boolean,
   val groupId: String? = null,
   val vibration: Boolean,
-    val enableLights: Boolean,
+  val enableLights: Boolean
 
 ) {
   companion object {
@@ -366,7 +363,6 @@ data class NotificationChannel(
     )
   }
 }
-
 @Suppress("UNCHECKED_CAST")
 private object MoxxyNotificationsApiCodec : StandardMessageCodec() {
   override fun readValueOfType(type: Byte, buffer: ByteBuffer): Any? {
@@ -472,7 +468,6 @@ interface MoxxyNotificationsApi {
     val codec: MessageCodec<Any?> by lazy {
       MoxxyNotificationsApiCodec
     }
-
     /** Sets up an instance of `MoxxyNotificationsApi` to handle messages through the `binaryMessenger`. */
     @Suppress("UNCHECKED_CAST")
     fun setUp(binaryMessenger: BinaryMessenger, api: MoxxyNotificationsApi?) {

lib/pigeon/background_service.g.dart

@@ -20,10 +20,10 @@ class MoxxyBackgroundServiceApi {
 
   Future<String> getExtraData() async {
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
-        'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.getExtraData', codec,
+        'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.getExtraData',
+        codec,
         binaryMessenger: _binaryMessenger);
-    final List<Object?>? replyList =
-        await channel.send(null) as List<Object?>?;
+    final List<Object?>? replyList = await channel.send(null) as List<Object?>?;
     if (replyList == null) {
       throw PlatformException(
         code: 'channel-error',
@@ -47,7 +47,8 @@ class MoxxyBackgroundServiceApi {
 
   Future<void> setNotificationBody(String arg_body) async {
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
-        'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.setNotificationBody', codec,
+        'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.setNotificationBody',
+        codec,
         binaryMessenger: _binaryMessenger);
     final List<Object?>? replyList =
         await channel.send(<Object?>[arg_body]) as List<Object?>?;
@@ -69,7 +70,8 @@ class MoxxyBackgroundServiceApi {
 
   Future<void> sendData(String arg_data) async {
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
-        'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.sendData', codec,
+        'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.sendData',
+        codec,
         binaryMessenger: _binaryMessenger);
     final List<Object?>? replyList =
         await channel.send(<Object?>[arg_data]) as List<Object?>?;
@@ -93,8 +95,7 @@ class MoxxyBackgroundServiceApi {
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
         'dev.flutter.pigeon.moxxy_native.MoxxyBackgroundServiceApi.stop', codec,
         binaryMessenger: _binaryMessenger);
-    final List<Object?>? replyList =
-        await channel.send(null) as List<Object?>?;
+    final List<Object?>? replyList = await channel.send(null) as List<Object?>?;
     if (replyList == null) {
       throw PlatformException(
         code: 'channel-error',

lib/src/service/background/isolate.dart

@@ -0,0 +1,53 @@
+import 'dart:convert';
+import 'dart:isolate';
+import 'dart:ui';
+import 'package:logging/logging.dart';
+import 'package:moxlib/moxlib.dart';
+import 'package:moxxy_native/src/service/background/base.dart';
+import 'package:moxxy_native/src/service/config.dart';
+import 'package:moxxy_native/src/service/datasender/types.dart';
+import 'package:uuid/uuid.dart';
+
+class IsolateBackgroundService extends BackgroundService {
+  IsolateBackgroundService(this._sendPort);
+  final SendPort _sendPort;
+  final ReceivePort receivePort = ReceivePort();
+
+  /// A logger.
+  final Logger _log = Logger('IsolateBackgroundService');
+
+  @override
+  Future<void> send(BackgroundEvent event, {String? id}) async {
+    final data = DataWrapper(
+      id ?? const Uuid().v4(),
+      event,
+    );
+
+    _sendPort.send(jsonEncode(data.toJson()));
+  }
+
+  @override
+  Future<void> init(
+    ServiceConfig config,
+  ) async {
+    // Ensure that the Dart executor is ready to use plugins
+    // NOTE: We're not allowed to use this here. Maybe reusing the RootIsolateToken
+    //       (See IsolateForegroundService) helps?
+    // WidgetsFlutterBinding.ensureInitialized();
+    DartPluginRegistrant.ensureInitialized();
+
+    // Register the channel for Foreground -> Service communication
+    receivePort.listen((data) async {
+      // TODO(Unknown): Maybe do something smarter like pigeon and use Lists instead of Maps
+      await config
+          .handleData(jsonDecode(data! as String) as Map<String, dynamic>);
+    });
+
+    // Start execution
+    _log.finest('Setup complete. Calling main entrypoint...');
+    await config.entrypoint(config.initialLocale);
+  }
+
+  @override
+  void setNotificationBody(String body) {}
+}

lib/src/service/datasender/isolate.dart

@@ -0,0 +1,15 @@
+import 'dart:convert';
+import 'dart:isolate';
+import 'package:moxlib/moxlib.dart';
+import 'package:moxxy_native/src/service/datasender/types.dart';
+
+class IsolateForegroundServiceDataSender
+    extends AwaitableDataSender<BackgroundCommand, BackgroundEvent> {
+  IsolateForegroundServiceDataSender(this._port);
+  final SendPort _port;
+
+  @override
+  Future<void> sendDataImpl(DataWrapper<JsonImplementation> data) async {
+    _port.send(jsonEncode(data.toJson()));
+  }
+}

lib/src/service/datasender/types.dart

@@ -1,8 +1,4 @@
-import 'dart:io';
 import 'package:moxlib/moxlib.dart';
-import 'package:moxxy_native/pigeon/service.g.dart';
-import 'package:moxxy_native/src/service/datasender/pigeon.dart';
-import 'package:moxxy_native/src/service/exceptions.dart';
 
 typedef ForegroundServiceDataSender
     = AwaitableDataSender<BackgroundCommand, BackgroundEvent>;
@@ -10,11 +6,3 @@ typedef ForegroundServiceDataSender
 abstract class BackgroundCommand implements JsonImplementation {}
 
 abstract class BackgroundEvent implements JsonImplementation {}
-
-ForegroundServiceDataSender getForegroundDataSender(MoxxyServiceApi api) {
-  if (Platform.isAndroid) {
-    return PigeonForegroundServiceDataSender(api);
-  } else {
-    throw UnsupportedPlatformException();
-  }
-}

lib/src/service/entrypoints/base.dart

@@ -0,0 +1,28 @@
+import 'dart:io';
+import 'package:moxxy_native/src/service/config.dart';
+import 'package:moxxy_native/src/service/entrypoints/isolate.dart';
+import 'package:moxxy_native/src/service/entrypoints/pigeon.dart';
+import 'package:moxxy_native/src/service/exceptions.dart';
+
+typedef PlatformEntrypointCallback = Future<void> Function(dynamic);
+
+ServiceConfig getServiceConfig(
+  HandleEventCallback srvHandleData,
+  HandleEventCallback uiHandleData,
+  String initialLocale,
+) {
+  PlatformEntrypointCallback entrypoint;
+  if (Platform.isAndroid) {
+    entrypoint = pigeonEntrypoint;
+  } else if (Platform.isLinux || Platform.isWindows || Platform.isMacOS) {
+    entrypoint = isolateEntrypoint;
+  } else {
+    throw UnsupportedPlatformException();
+  }
+
+  return ServiceConfig(
+    entrypoint,
+    srvHandleData,
+    initialLocale,
+  );
+}

lib/src/service/entrypoints/isolate.dart

@@ -0,0 +1,30 @@
+import 'dart:isolate';
+import 'package:flutter/services.dart';
+import 'package:get_it/get_it.dart';
+import 'package:moxxy_native/src/service/background/base.dart';
+import 'package:moxxy_native/src/service/background/isolate.dart';
+import 'package:moxxy_native/src/service/config.dart';
+
+@pragma('vm:entry-point')
+Future<void> isolateEntrypoint(dynamic parameters) async {
+  parameters as List<dynamic>;
+
+  final sendPort = parameters[0] as SendPort;
+  final config = ServiceConfig.fromString(parameters[1] as String);
+
+  // This allows us to use the root isolate's method channels.
+  // See https://medium.com/flutter/introducing-background-isolate-channels-7a299609cad8
+  BackgroundIsolateBinaryMessenger.ensureInitialized(
+    parameters[2] as RootIsolateToken,
+  );
+
+  // Set up the background service
+  final srv = IsolateBackgroundService(sendPort);
+  GetIt.I.registerSingleton<BackgroundService>(srv);
+
+  // Reply back with the new send port
+  sendPort.send(srv.receivePort.sendPort);
+
+  // Run the entrypoint
+  await srv.init(config);
+}

lib/src/service/entrypoints/pigeon.dart

@@ -8,7 +8,7 @@ import 'package:moxxy_native/src/service/config.dart';
 /// An entrypoint that should be used when the service runs
 /// in a new Flutter Engine.
 @pragma('vm:entry-point')
-Future<void> pigeonEntrypoint() async {
+Future<void> pigeonEntrypoint(dynamic _) async {
   // ignore: avoid_print
   print('androidEntrypoint: Called on new FlutterEngine');
 

lib/src/service/foreground/base.dart

@@ -3,6 +3,7 @@ import 'package:moxlib/moxlib.dart';
 import 'package:moxxy_native/src/service/config.dart';
 import 'package:moxxy_native/src/service/datasender/types.dart';
 import 'package:moxxy_native/src/service/exceptions.dart';
+import 'package:moxxy_native/src/service/foreground/isolate.dart';
 import 'package:moxxy_native/src/service/foreground/pigeon.dart';
 
 /// Wrapper API that is only available to the UI isolate.
@@ -40,6 +41,8 @@ ForegroundService getForegroundService() {
   if (_service == null) {
     if (Platform.isAndroid) {
       _service = PigeonForegroundService();
+    } else if (Platform.isLinux || Platform.isWindows || Platform.isMacOS) {
+      _service = IsolateForegroundService();
     } else {
       throw UnsupportedPlatformException();
     }

lib/src/service/foreground/isolate.dart

@@ -0,0 +1,98 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:isolate';
+import 'dart:ui';
+import 'package:logging/logging.dart';
+import 'package:moxxy_native/src/service/config.dart';
+import 'package:moxxy_native/src/service/datasender/isolate.dart';
+import 'package:moxxy_native/src/service/datasender/types.dart';
+import 'package:moxxy_native/src/service/entrypoints/isolate.dart';
+import 'package:moxxy_native/src/service/foreground/base.dart';
+
+class IsolateForegroundService extends ForegroundService {
+  /// The port on which we receive data from the isolate.
+  final ReceivePort _receivePort = ReceivePort();
+
+  /// The port on which we send data to the isolate.
+  late final SendPort _sendPort;
+
+  /// A completer that indicates when _sendPort has been set.
+  /// For more notes, see the comment in [start].
+  Completer<void>? _sendPortCompleter = Completer<void>();
+
+  /// The data sender backing this class.
+  late final IsolateForegroundServiceDataSender _dataSender;
+
+  /// A logger.
+  final Logger _log = Logger('IsolateForegroundService');
+
+  @override
+  Future<void> attach(
+    HandleEventCallback handleData,
+  ) async {
+    _receivePort.asBroadcastStream().listen((data) async {
+      if (data is SendPort) {
+        // Set the send port.
+        _sendPort = data;
+
+        // Resolve the waiting future.
+        assert(
+          _sendPortCompleter != null,
+          '_sendPort should only be received once!',
+        );
+        _sendPortCompleter?.complete();
+        return;
+      }
+
+      await handleData(
+        jsonDecode(data! as String) as Map<String, dynamic>,
+      );
+    });
+  }
+
+  @override
+  Future<void> start(
+    ServiceConfig config,
+    HandleEventCallback uiHandleData,
+  ) async {
+    // Listen for events
+    await attach(uiHandleData);
+
+    await Isolate.spawn(
+      isolateEntrypoint,
+      [
+        _receivePort.sendPort,
+        config.toString(),
+        RootIsolateToken.instance!,
+      ],
+    );
+
+    // Wait for [_sendPort] to get set.
+    // The issue is that [_receivePort] provides a stream that only one listener can listen to.
+    // This means that we cannot do `await _receivePort.first`. To work around this, we just cram
+    // an approximation of `_receivePort.first` into the actual listener.
+    await _sendPortCompleter!.future;
+    _sendPortCompleter = null;
+
+    // Create the data sender
+    _dataSender = IsolateForegroundServiceDataSender(_sendPort);
+    _log.finest('Background service started...');
+  }
+
+  @override
+  Future<bool> isRunning() async => false;
+
+  @override
+  ForegroundServiceDataSender getDataSender() => _dataSender;
+
+  @override
+  Future<BackgroundEvent?> send(
+    BackgroundCommand command, {
+    bool awaitable = true,
+  }) {
+    return _dataSender.sendData(
+      command,
+      awaitable: awaitable,
+    );
+  }
+}