import 'dart:convert';
import 'package:workmanager/workmanager.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:odoo_rpc/odoo_rpc.dart';

@pragma('vm:entry-point')
void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) async {
    try {
      final prefs = await SharedPreferences.getInstance();
      final url = prefs.getString('odoo_url');
      final sessionStr = prefs.getString('odoo_session');
      final lastNotificationId = prefs.getInt('last_notification_id') ?? 0;

      if (url == null || sessionStr == null) {
        return Future.value(true); // Cannot fetch if not logged in
      }

      final sessionArgs = json.decode(sessionStr);
      final session = OdooSession.fromJson(sessionArgs);
      final client = OdooClient(url, sessionId: session);
      
      final response = await client.callRPC(
        '/api/loyalty/fetch_notifications', 
        'call', 
        {'last_id': lastNotificationId}
      );

      if (response != null && response['status'] == 'success') {
        final notifications = response['data'] as List;
        if (notifications.isNotEmpty) {
          int highestId = lastNotificationId;
          
          final flnp = FlutterLocalNotificationsPlugin();
          const androidSettings = AndroidInitializationSettings('@mipmap/ic_launcher');
          const initSettings = InitializationSettings(android: androidSettings);
          await flnp.initialize(settings: initSettings);

          for (final notif in notifications) {
            final int notifId = notif['id'];
            if (notifId > highestId) highestId = notifId;
            
            const androidConfig = AndroidNotificationDetails(
              'loyalty_channel', 'Promos',
              importance: Importance.max, priority: Priority.high
            );
            await flnp.show(
              id: notifId, 
              title: notif['title'], 
              body: notif['body'], 
              notificationDetails: const NotificationDetails(android: androidConfig)
            );
          }
          await prefs.setInt('last_notification_id', highestId);
        }
      }
    } catch (e) {
      print('Background Fetch Error: $e');
    }
    return Future.value(true);
  });
}