import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../features/auth/presentation/login_screen.dart';
import '../../features/household/presentation/household_screen.dart';
import '../../features/locations/presentation/location_detail_screen.dart';
import '../../features/locations/presentation/locations_screen.dart';
import '../../features/plants/domain/plant.dart';
import '../../features/plants/presentation/plant_detail_screen.dart';
import '../../features/plants/presentation/plant_diagnoses_screen.dart';
import '../../features/plants/presentation/plant_form_screen.dart';
import '../../features/plants/presentation/plants_screen.dart';
import '../../features/settings/presentation/settings_screen.dart';
import '../../features/today/presentation/today_screen.dart';
import '../firebase/firebase_providers.dart';

/// Zentrale Routen-Definition. Die Pfade werden auch vom Drawer genutzt,
/// deshalb hier als Konstanten.
abstract final class AppRoutes {
  static const today = '/';
  static const login = '/login';
  static const plants = '/plants';
  static const plantAdd = '/plants/add';
  static const plantEdit = '/plants/edit';
  static const locations = '/locations';
  static const household = '/household';
  static const settings = '/settings';

  /// Untersuchungs-Seite einer Pflanze.
  static String plantDiagnoses(String plantId) =>
      '/plants/$plantId/diagnoses';

  /// Detailseite eines Stellplatzes (Foto, Standort-Analyse, Eignung).
  static String locationDetail(String locationId) => '/locations/$locationId';
}

/// Übersetzt einen Stream in ein Listenable, damit der Router bei
/// Login/Logout sofort neu auswertet, wohin umgeleitet werden muss.
class _StreamListenable extends ChangeNotifier {
  _StreamListenable(Stream<dynamic> stream) {
    _subscription = stream.listen((_) => notifyListeners());
  }

  late final StreamSubscription<dynamic> _subscription;

  @override
  void dispose() {
    _subscription.cancel();
    super.dispose();
  }
}

final appRouterProvider = Provider<GoRouter>((ref) {
  final auth = ref.watch(firebaseAuthProvider);
  final refreshListenable = _StreamListenable(auth.authStateChanges());
  ref.onDispose(refreshListenable.dispose);

  final router = GoRouter(
    initialLocation: AppRoutes.today,
    refreshListenable: refreshListenable,
    redirect: (context, state) {
      final loggedIn = auth.currentUser != null;
      final onLoginScreen = state.matchedLocation == AppRoutes.login;
      if (!loggedIn) return onLoginScreen ? null : AppRoutes.login;
      if (onLoginScreen) return AppRoutes.today;
      return null;
    },
    routes: [
      GoRoute(
        path: AppRoutes.login,
        builder: (context, state) => const LoginScreen(),
      ),
      GoRoute(
        path: AppRoutes.today,
        builder: (context, state) => const TodayScreen(),
      ),
      GoRoute(
        path: AppRoutes.plants,
        builder: (context, state) => const PlantsScreen(),
      ),
      GoRoute(
        path: AppRoutes.plantAdd,
        builder: (context, state) => const PlantFormScreen(),
      ),
      GoRoute(
        path: AppRoutes.plantEdit,
        builder: (context, state) =>
            PlantFormScreen(existing: state.extra as Plant?),
      ),
      GoRoute(
        path: '/plants/:id',
        builder: (context, state) =>
            PlantDetailScreen(plantId: state.pathParameters['id']!),
      ),
      GoRoute(
        path: '/plants/:id/diagnoses',
        builder: (context, state) =>
            PlantDiagnosesScreen(plantId: state.pathParameters['id']!),
      ),
      GoRoute(
        path: AppRoutes.locations,
        builder: (context, state) => const LocationsScreen(),
      ),
      GoRoute(
        path: '/locations/:id',
        builder: (context, state) =>
            LocationDetailScreen(locationId: state.pathParameters['id']!),
      ),
      GoRoute(
        path: AppRoutes.household,
        builder: (context, state) => const HouseholdScreen(),
      ),
      GoRoute(
        path: AppRoutes.settings,
        builder: (context, state) => const SettingsScreen(),
      ),
    ],
  );
  ref.onDispose(router.dispose);
  return router;
});