Refactor: extract native event to package

app/lib/event/native_event.dart

@@ -3,7 +3,7 @@ import 'dart:convert';
 
 import 'package:logging/logging.dart';
 import 'package:nc_photos/stream_extension.dart';
-import 'package:nc_photos_plugin/nc_photos_plugin.dart';
+import 'package:np_platform_message_relay/np_platform_message_relay.dart';
 
 class NativeEventListener<T> {
   NativeEventListener(this.listener);
@@ -26,7 +26,7 @@ class NativeEventListener<T> {
   }
 
   static final _mappedStream =
-      NativeEvent.stream.whereType<NativeEventObject>().map((ev) {
+      MessageRelay.stream.whereType<Message>().map((ev) {
     switch (ev.event) {
       case FileExifUpdatedEvent._id:
         return FileExifUpdatedEvent.fromEvent(ev);
@@ -39,20 +39,21 @@ class NativeEventListener<T> {
   final void Function(T) listener;
   StreamSubscription<T>? _subscription;
 
-  final _log = Logger("event.native_event.NativeEventListener<${T.runtimeType}>");
+  final _log =
+      Logger("event.native_event.NativeEventListener<${T.runtimeType}>");
 }
 
 class FileExifUpdatedEvent {
   const FileExifUpdatedEvent(this.fileIds);
 
-  factory FileExifUpdatedEvent.fromEvent(NativeEventObject ev) {
+  factory FileExifUpdatedEvent.fromEvent(Message ev) {
     assert(ev.event == _id);
     assert(ev.data != null);
     final dataJson = jsonDecode(ev.data!) as Map;
     return FileExifUpdatedEvent((dataJson["fileIds"] as List).cast<int>());
   }
 
-  NativeEventObject toEvent() => NativeEventObject(
+  Message toEvent() => Message(
         _id,
         jsonEncode({
           "fileIds": fileIds,

app/lib/service.dart

@@ -24,6 +24,7 @@ import 'package:nc_photos_plugin/nc_photos_plugin.dart';
 import 'package:np_async/np_async.dart';
 import 'package:np_codegen/np_codegen.dart';
 import 'package:np_geocoder/np_geocoder.dart';
+import 'package:np_platform_message_relay/np_platform_message_relay.dart';
 
 part 'service.g.dart';
 
@@ -237,7 +238,7 @@ class _MetadataTask {
     }
     if (_processedIds.isNotEmpty) {
       unawaited(
-        NativeEvent.fire(FileExifUpdatedEvent(_processedIds).toEvent()),
+        MessageRelay.broadcast(FileExifUpdatedEvent(_processedIds).toEvent()),
       );
       _processedIds = [];
     }
@@ -319,7 +320,7 @@ class _MetadataTask {
 
     _processedIds.add(file.fileId!);
     if (_processedIds.length >= 10) {
-      NativeEvent.fire(FileExifUpdatedEvent(_processedIds).toEvent());
+      MessageRelay.broadcast(FileExifUpdatedEvent(_processedIds).toEvent());
       _processedIds = [];
     }
   }

app/pubspec.lock

@@ -1032,6 +1032,13 @@ packages:
       relative: true
     source: path
     version: "0.0.1"
+  np_platform_message_relay:
+    dependency: "direct main"
+    description:
+      path: "../np_platform_message_relay"
+      relative: true
+    source: path
+    version: "0.0.1"
   np_platform_permission:
     dependency: "direct main"
     description:

app/pubspec.yaml

@@ -115,6 +115,8 @@ dependencies:
     path: ../np_platform_lock
   np_platform_log:
     path: ../np_platform_log
+  np_platform_message_relay:
+    path: ../np_platform_message_relay
   np_platform_permission:
     path: ../np_platform_permission
   np_platform_raw_image:

np_platform_message_relay/.gitignore

@@ -0,0 +1,30 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
+/pubspec.lock
+**/doc/api/
+.dart_tool/
+.packages
+build/

np_platform_message_relay/.metadata

@@ -0,0 +1,30 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled.
+
+version:
+  revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+  channel: stable
+
+project_type: plugin
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: android
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'

np_platform_message_relay/analysis_options.yaml

@@ -0,0 +1 @@
+include: package:np_lints/np.yaml

np_platform_message_relay/android/.gitignore

@@ -0,0 +1,9 @@
+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures
+.cxx

np_platform_message_relay/android/build.gradle

@@ -0,0 +1,52 @@
+group 'com.nkming.nc_photos.np_platform_message_relay'
+version '1.0-SNAPSHOT'
+
+buildscript {
+    ext.kotlin_version = '1.8.20'
+    repositories {
+        google()
+        mavenCentral()
+		gradlePluginPortal()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:7.4.2'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+
+android {
+    namespace 'com.nkming.nc_photos.np_platform_message_relay'
+   	compileSdk 31
+
+    defaultConfig {
+   		minSdk 21
+   	}
+
+    buildTypes {
+   		release {
+   			minifyEnabled false
+   		}
+   	}
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+}
+
+dependencies {
+    implementation "androidx.annotation:annotation:1.6.0"
+}

np_platform_message_relay/android/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.2-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

np_platform_message_relay/android/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'np_platform_message_relay'

np_platform_message_relay/android/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="com.nkming.nc_photos.np_platform_message_relay">
+</manifest>

np_platform_message_relay/android/src/main/kotlin/com/nkming/nc_photos/np_platform_message_relay/K.kt

@@ -0,0 +1,7 @@
+package com.nkming.nc_photos.np_platform_message_relay
+
+internal interface K {
+	companion object {
+		const val LIB_ID = "com.nkming.nc_photos.np_platform_message_relay"
+	}
+}

np_platform_message_relay/android/src/main/kotlin/com/nkming/nc_photos/np_platform_message_relay/MessageRelayChannelHandler.kt

@@ -1,28 +1,14 @@
-package com.nkming.nc_photos.plugin
+package com.nkming.nc_photos.np_platform_message_relay
 
 import io.flutter.plugin.common.EventChannel
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
 
-internal class NativeEventChannelHandler : MethodChannel.MethodCallHandler,
+internal class MessageRelayChannelHandler : MethodChannel.MethodCallHandler,
 	EventChannel.StreamHandler {
 	companion object {
-		const val EVENT_CHANNEL = "${K.LIB_ID}/native_event"
+		const val EVENT_CHANNEL = "${K.LIB_ID}/message_relay_event"
-		const val METHOD_CHANNEL = "${K.LIB_ID}/native_event_method"
+		const val METHOD_CHANNEL = "${K.LIB_ID}/message_relay_method"
-
-		/**
-		 * Fire native events on the native side
-		 */
-		fun fire(eventObj: NativeEvent) {
-			synchronized(eventSinks) {
-				for (s in eventSinks.values) {
-					s.success(buildMap {
-						put("event", eventObj.getId())
-						eventObj.getData()?.also { put("data", it) }
-					})
-				}
-			}
-		}
 
 		private val eventSinks = mutableMapOf<Int, EventChannel.EventSink>()
 		private var nextId = 0
@@ -30,9 +16,9 @@ internal class NativeEventChannelHandler : MethodChannel.MethodCallHandler,
 
 	override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
 		when (call.method) {
-			"fire" -> {
+			"broadcast" -> {
 				try {
-					fire(
+					broadcast(
 						call.argument("event")!!, call.argument("data"), result
 					)
 				} catch (e: Throwable) {
@@ -54,7 +40,7 @@ internal class NativeEventChannelHandler : MethodChannel.MethodCallHandler,
 		}
 	}
 
-	private fun fire(
+	private fun broadcast(
 		event: String, data: String?, result: MethodChannel.Result
 	) {
 		synchronized(eventSinks) {

np_platform_message_relay/android/src/main/kotlin/com/nkming/nc_photos/np_platform_message_relay/NpPlatformMessageRelayPlugin.kt

@@ -0,0 +1,34 @@
+package com.nkming.nc_photos.np_platform_message_relay
+
+import androidx.annotation.NonNull
+import io.flutter.embedding.engine.plugins.FlutterPlugin
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.MethodChannel
+
+class NpPlatformMessageRelayPlugin : FlutterPlugin {
+	override fun onAttachedToEngine(
+		@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding
+	) {
+		val messageRelayHandler = MessageRelayChannelHandler()
+		eventChannel = EventChannel(
+			flutterPluginBinding.binaryMessenger,
+			MessageRelayChannelHandler.EVENT_CHANNEL
+		)
+		eventChannel.setStreamHandler(messageRelayHandler)
+		methodChannel = MethodChannel(
+			flutterPluginBinding.binaryMessenger,
+			MessageRelayChannelHandler.METHOD_CHANNEL
+		)
+		methodChannel.setMethodCallHandler(messageRelayHandler)
+	}
+
+	override fun onDetachedFromEngine(
+		@NonNull binding: FlutterPlugin.FlutterPluginBinding
+	) {
+		eventChannel.setStreamHandler(null)
+		methodChannel.setMethodCallHandler(null)
+	}
+
+	private lateinit var eventChannel: EventChannel
+	private lateinit var methodChannel: MethodChannel
+}

np_platform_message_relay/lib/np_platform_message_relay.dart

@@ -0,0 +1,3 @@
+library np_platform_message_relay;
+
+export 'src/message_relay.dart';

np_platform_message_relay/lib/src/k.dart

@@ -0,0 +1 @@
+const libId = "com.nkming.nc_photos.np_platform_message_relay";

np_platform_message_relay/lib/src/message_relay.dart

@@ -0,0 +1,59 @@
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+import 'package:logging/logging.dart';
+import 'package:np_codegen/np_codegen.dart';
+import 'package:np_platform_message_relay/src/k.dart' as k;
+
+part 'message_relay.g.dart';
+
+class Message {
+  const Message(this.event, this.data);
+
+  static Message fromJson(Map<String, dynamic> json) {
+    return Message(json["event"], json["data"]);
+  }
+
+  Map<String, dynamic> toJson() => {
+        "event": event,
+        if (data != null) "data": data,
+      };
+
+  final String event;
+  final String? data;
+}
+
+/// Relay messages via native side
+///
+/// Typically used to broadcast messages across different Flutter engines (e.g.,
+/// main isolate <-> background isolates)
+///
+/// Beware that the isolate that broadcasted the message will also receive the
+/// message if subscribed
+@npLog
+class MessageRelay {
+  static Future<void> broadcast(Message msg) =>
+      _methodChannel.invokeMethod("broadcast", msg.toJson());
+
+  static Stream<Message> get stream =>
+      _eventChannel.receiveBroadcastStream().map(_toEvent).whereNotNull();
+
+  static Message? _toEvent(dynamic ev) {
+    try {
+      return Message.fromJson((ev as Map).cast<String, dynamic>());
+    } catch (e, stackTrace) {
+      _log.severe("Failed while parsing native events", e, stackTrace);
+      return null;
+    }
+  }
+
+  static const _eventChannel = EventChannel("${k.libId}/message_relay_event");
+  static const _methodChannel =
+      MethodChannel("${k.libId}/message_relay_method");
+
+  static final _log = _$MessageRelayNpLog.log;
+}
+
+extension<T> on Stream<T?> {
+  Stream<T> whereNotNull() => where((e) => e != null).cast<T>();
+}

np_platform_message_relay/lib/src/message_relay.g.dart

@@ -0,0 +1,14 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'message_relay.dart';
+
+// **************************************************************************
+// NpLogGenerator
+// **************************************************************************
+
+extension _$MessageRelayNpLog on MessageRelay {
+  // ignore: unused_element
+  Logger get _log => log;
+
+  static final log = Logger("src.message_relay.MessageRelay");
+}

np_platform_message_relay/pubspec.yaml

@@ -0,0 +1,30 @@
+name: np_platform_message_relay
+description: A new Flutter plugin project.
+version: 0.0.1
+homepage:
+publish_to: none
+
+environment:
+  sdk: '>=2.19.6 <3.0.0'
+  flutter: ">=3.3.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+  logging: ^1.1.1
+  np_codegen:
+    path: ../codegen
+
+dev_dependencies:
+  build_runner: ^2.2.1
+  np_codegen_build:
+    path: ../codegen_build
+  np_lints:
+    path: ../np_lints
+
+flutter:
+  plugin:
+    platforms:
+      android:
+        package: com.nkming.nc_photos.np_platform_message_relay
+        pluginClass: NpPlatformMessageRelayPlugin

plugin/android/src/main/kotlin/com/nkming/nc_photos/plugin/NativeEvent.kt

@@ -1,6 +0,0 @@
-package com.nkming.nc_photos.plugin
-
-internal interface NativeEvent {
-	fun getId(): String
-	fun getData(): String? = null
-}

plugin/android/src/main/kotlin/com/nkming/nc_photos/plugin/NcPhotosPlugin.kt

@@ -60,18 +60,6 @@ class NcPhotosPlugin : FlutterPlugin, ActivityAware,
 			PreferenceChannelHandler.METHOD_CHANNEL
 		)
 		preferenceMethodChannel.setMethodCallHandler(preferenceChannelHandler)
-
-		val nativeEventHandler = NativeEventChannelHandler()
-		nativeEventChannel = EventChannel(
-			flutterPluginBinding.binaryMessenger,
-			NativeEventChannelHandler.EVENT_CHANNEL
-		)
-		nativeEventChannel.setStreamHandler(nativeEventHandler)
-		nativeEventMethodChannel = MethodChannel(
-			flutterPluginBinding.binaryMessenger,
-			NativeEventChannelHandler.METHOD_CHANNEL
-		)
-		nativeEventMethodChannel.setMethodCallHandler(nativeEventHandler)
 	}
 
 	override fun onDetachedFromEngine(
@@ -82,8 +70,6 @@ class NcPhotosPlugin : FlutterPlugin, ActivityAware,
 		mediaStoreMethodChannel.setMethodCallHandler(null)
 		contentUriMethodChannel.setMethodCallHandler(null)
 		preferenceMethodChannel.setMethodCallHandler(null)
-		nativeEventChannel.setStreamHandler(null)
-		nativeEventMethodChannel.setMethodCallHandler(null)
 	}
 
 	override fun onAttachedToActivity(binding: ActivityPluginBinding) {
@@ -136,8 +122,6 @@ class NcPhotosPlugin : FlutterPlugin, ActivityAware,
 	private lateinit var mediaStoreMethodChannel: MethodChannel
 	private lateinit var contentUriMethodChannel: MethodChannel
 	private lateinit var preferenceMethodChannel: MethodChannel
-	private lateinit var nativeEventChannel: EventChannel
-	private lateinit var nativeEventMethodChannel: MethodChannel
 
 	private lateinit var mediaStoreChannelHandler: MediaStoreChannelHandler
 }

plugin/lib/nc_photos_plugin.dart

@@ -3,6 +3,5 @@ library nc_photos_plugin;
 export 'src/content_uri.dart';
 export 'src/exception.dart';
 export 'src/media_store.dart';
-export 'src/native_event.dart';
 export 'src/notification.dart';
 export 'src/preference.dart';

plugin/lib/src/native_event.dart

@@ -1,34 +0,0 @@
-import 'dart:async';
-
-import 'package:flutter/services.dart';
-import 'package:nc_photos_plugin/src/k.dart' as k;
-
-class NativeEventObject {
-  NativeEventObject(this.event, this.data);
-
-  final String event;
-  final String? data;
-}
-
-class NativeEvent {
-  static Future<void> fire(NativeEventObject ev) =>
-      _methodChannel.invokeMethod("fire", <String, dynamic>{
-        "event": ev.event,
-        if (ev.data != null) "data": ev.data,
-      });
-
-  static Stream get stream => _eventStream;
-
-  static const _eventChannel = EventChannel("${k.libId}/native_event");
-  static const _methodChannel = MethodChannel("${k.libId}/native_event_method");
-
-  static final _eventStream = _eventChannel
-      .receiveBroadcastStream()
-      .map((event) {
-        if (event is Map) {
-          return NativeEventObject(event["event"], event["data"]);
-        } else {
-          return event;
-        }
-      });
-}