packages/wyatt_cloud_messaging_bloc_firebase/lib/src/data/data_sources/cloud_messaging_firebase_data_source.dart

@@ -6,6 +6,8 @@ import 'package:firebase_messaging/firebase_messaging.dart'
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 import 'package:wyatt_cloud_messaging_bloc_base/wyatt_cloud_messaging_bloc.dart';
 
+typedef CloudMessagingStreamController = StreamController<RemoteNotification>;
+
 class CloudMessagingFirebaseDataSource extends CloudMessagingRemoteDataSource {
   final FirebaseMessaging _firebaseMessagingInstance =
       FirebaseMessaging.instance;
@@ -18,8 +20,36 @@ class CloudMessagingFirebaseDataSource extends CloudMessagingRemoteDataSource {
   }
 
   @override
-  Future<Stream<RemoteNotification>> onNotificationBackground() {
-    throw UnimplementedError();
+  Future<Stream<RemoteNotification>> onNotificationBackground() async {
+    final backgroundStreamController = CloudMessagingStreamController();
+
+    Future<void> getLastBackgroundNotification() async {
+      final lastNotification =
+          await _firebaseMessagingInstance.getInitialMessage();
+      if (lastNotification != null) {
+        backgroundStreamController.add(
+          RemoteNotification(
+            title: lastNotification.notification?.title,
+            body: lastNotification.notification?.body,
+            data: lastNotification.data,
+          ),
+        );
+      }
+
+      FirebaseMessaging.onMessageOpenedApp.listen((notification) {
+        backgroundStreamController.add(
+          RemoteNotification(
+            title: notification.notification?.title,
+            body: notification.notification?.body,
+            data: notification.data,
+          ),
+        );
+      });
+    }
+
+    unawaited(getLastBackgroundNotification());
+
+    return backgroundStreamController.stream;
   }
 
   @override
@@ -47,8 +77,8 @@ class CloudMessagingFirebaseDataSource extends CloudMessagingRemoteDataSource {
       iOS: DarwinInitializationSettings(),
     );
 
-    final StreamController<RemoteNotification> foregroundStream =
-        StreamController<RemoteNotification>();
+    final CloudMessagingStreamController foregroundStream =
+        CloudMessagingStreamController();
 
     await _localNotificationInstance.initialize(
       initializationSettings,