import 'package:flutter/foundation.dart';
import 'package:geolocator/geolocator.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:workmanager/workmanager.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';

/// Unique task name for the background location update.
const _taskName = 'com.tasq.backgroundLocationUpdate';

/// Top-level callback required by Workmanager. Must be a top-level or static
/// function.
@pragma('vm:entry-point')
void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) async {
    try {
      // Re-initialize Supabase in the isolate
      await dotenv.load();
      final url = dotenv.env['SUPABASE_URL'] ?? '';
      final anonKey = dotenv.env['SUPABASE_ANON_KEY'] ?? '';
      if (url.isEmpty || anonKey.isEmpty) return Future.value(true);

      await Supabase.initialize(url: url, anonKey: anonKey);
      final client = Supabase.instance.client;

      // Must have an active session
      final session = client.auth.currentSession;
      if (session == null) return Future.value(true);

      final serviceEnabled = await Geolocator.isLocationServiceEnabled();
      if (!serviceEnabled) return Future.value(true);

      final permission = await Geolocator.checkPermission();
      if (permission == LocationPermission.denied ||
          permission == LocationPermission.deniedForever) {
        return Future.value(true);
      }

      final position = await Geolocator.getCurrentPosition(
        locationSettings: const LocationSettings(
          accuracy: LocationAccuracy.high,
        ),
      );

      await client.rpc(
        'update_live_position',
        params: {'p_lat': position.latitude, 'p_lng': position.longitude},
      );
    } catch (e) {
      debugPrint('Background location update error: $e');
    }
    return Future.value(true);
  });
}

/// Initialize Workmanager and register periodic background location task.
Future<void> initBackgroundLocationService() async {
  await Workmanager().initialize(callbackDispatcher, isInDebugMode: false);
}

/// Register a periodic task to report location every ~15 minutes
/// (Android minimum for periodic Workmanager tasks).
Future<void> startBackgroundLocationUpdates() async {
  await Workmanager().registerPeriodicTask(
    _taskName,
    _taskName,
    frequency: const Duration(minutes: 15),
    constraints: Constraints(networkType: NetworkType.connected),
    existingWorkPolicy: ExistingWorkPolicy.keep,
  );
}

/// Cancel the periodic background location task.
Future<void> stopBackgroundLocationUpdates() async {
  await Workmanager().cancelByUniqueName(_taskName);
}