Implement Background Sync Polling with Workmanager

frontend/lib/core/services/background_sync_service.dart

@@ -0,0 +1,63 @@
+import 'dart:math' as math;
+import 'package:dio/dio.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:workmanager/workmanager.dart';
+import 'notification_service.dart';
+
+@pragma('vm:entry-point')
+void callbackDispatcher() {
+  Workmanager().executeTask((task, inputData) async {
+    try {
+      // 1. Retrieve the saved base URL and Auth Token
+      final prefs = await SharedPreferences.getInstance();
+      final baseUrl = prefs.getString('server_url');
+      if (baseUrl == null) return true; // No server known, wait till next run
+
+      const storage = FlutterSecureStorage();
+      final token = await storage.read(key: 'jwt_token');
+      if (token == null) return true; // Not logged in
+
+      // 2. Fetch recent notifications from server
+      final dio = Dio(BaseOptions(
+        baseUrl: baseUrl,
+        connectTimeout: const Duration(seconds: 5),
+        receiveTimeout: const Duration(seconds: 5),
+        headers: {'Authorization': 'Bearer $token'},
+      ));
+
+      final response = await dio.get('/notifications/recent');
+      final list = (response.data as List).cast<Map<String, dynamic>>();
+
+      if (list.isNotEmpty) {
+        // 3. Find the last seen notification ID
+        final highestOldId = prefs.getInt('last_seen_notification_id') ?? 0;
+        
+        // Find new ones
+        final newNotes = list.where((e) => (e['id'] as int) > highestOldId).toList();
+        
+        if (newNotes.isNotEmpty) {
+          final notificationService = NotificationService();
+          await notificationService.initialize(); // Ensure it's ready in this isolate
+
+          // 4. Show local notification for each new one
+          for (var note in newNotes) {
+            await notificationService.showNotification(
+              title: note['title'] ?? 'New Notification',
+              body: note['message'] ?? '',
+            );
+          }
+
+          // 5. Update highest seen ID in prefs
+          final newHighestId = list.map((e) => e['id'] as int).reduce(math.max);
+          await prefs.setInt('last_seen_notification_id', math.max(highestOldId, newHighestId));
+        }
+      }
+
+      return Future.value(true);
+    } catch (e) {
+      print('Background fetch failed: $e');
+      return Future.value(false); // Retries on false
+    }
+  });
+}

frontend/lib/main.dart

@@ -12,7 +12,9 @@ import 'ui/screens/splash/splash_screen.dart';
 import 'core/theme/app_theme.dart'; // Add this import
 import 'core/constants/app_colors.dart';
 import 'core/services/notification_service.dart';
+import 'core/services/background_sync_service.dart';
 import 'ui/shared/widgets/inactivity_wrapper.dart';
+import 'package:workmanager/workmanager.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -47,6 +49,22 @@ void main() async {
   
   await NotificationService().initialize();
   
+  if (!kIsWeb && (Platform.isAndroid || Platform.isIOS)) {
+    Workmanager().initialize(
+      callbackDispatcher,
+      isInDebugMode: false,
+    );
+    // Register periodic task
+    Workmanager().registerPeriodicTask(
+      "1",
+      "background_sync_task",
+      frequency: const Duration(minutes: 15),
+      constraints: Constraints(
+        networkType: NetworkType.connected,
+      ),
+    );
+  }
+  
   runApp(const ProviderScope(child: TisRmsApp()));
 }
 

frontend/lib/ui/providers/notification_provider.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../domain/repositories/notification_repository.dart';
 import '../../domain/entities/notification_model.dart';
 import '../../core/services/notification_service.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 import 'dart:math' as math;
 
 final notificationRepositoryProvider = Provider<NotificationRepository>((ref) {
@@ -52,6 +53,12 @@ class NotificationNotifier extends AsyncNotifier<List<NotificationModel>> {
         }
       }
 
+      if (list.isNotEmpty) {
+        final highestId = list.map((e) => e.id).reduce(math.max);
+        final prefs = await SharedPreferences.getInstance();
+        await prefs.setInt('last_seen_notification_id', highestId);
+      }
+
       state = AsyncData(list);
     } catch (e, st) {
       state = AsyncError(e, st);

frontend/pubspec.lock

@@ -1549,6 +1549,38 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.11.0"
+  workmanager:
+    dependency: "direct main"
+    description:
+      name: workmanager
+      sha256: "065673b2a465865183093806925419d311a9a5e0995aa74ccf8920fd695e2d10"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.0+3"
+  workmanager_android:
+    dependency: transitive
+    description:
+      name: workmanager_android
+      sha256: "9ae744db4ef891f5fcd2fb8671fccc712f4f96489a487a1411e0c8675e5e8cb7"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.0+2"
+  workmanager_apple:
+    dependency: transitive
+    description:
+      name: workmanager_apple
+      sha256: "1cc12ae3cbf5535e72f7ba4fde0c12dd11b757caf493a28e22d684052701f2ca"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.1+2"
+  workmanager_platform_interface:
+    dependency: transitive
+    description:
+      name: workmanager_platform_interface
+      sha256: f40422f10b970c67abb84230b44da22b075147637532ac501729256fcea10a47
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.1+1"
   xdg_directories:
     dependency: transitive
     description:

frontend/pubspec.yaml

@@ -60,6 +60,7 @@ dependencies:
   pdf: ^3.12.0
   intl: ^0.20.3
   flutter_local_notifications: ^17.2.2
+  workmanager: ^0.9.0+3
 
 dev_dependencies:
   flutter_test: