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

import 'core/constants.dart';
import 'providers/auth_provider.dart';
import 'providers/settings_provider.dart';
import 'screens/auth/login_screen.dart';
import 'screens/chat/chat_screen.dart';
import 'screens/chat/conversations_list_screen.dart';
import 'screens/notes/note_detail_screen.dart';
import 'screens/notes/note_edit_screen.dart';
import 'screens/notes/notes_list_screen.dart';
import 'screens/quick_capture/quick_capture_screen.dart';
import 'screens/settings/settings_screen.dart';
import 'screens/setup/setup_screen.dart';
import 'screens/splash/splash_screen.dart';
import 'screens/tasks/task_edit_screen.dart';
import 'screens/tasks/tasks_list_screen.dart';

// ChangeNotifier that fires when auth or server URL changes,
// used as GoRouter.refreshListenable so the router re-evaluates redirects
// without being recreated.
class _RouterNotifier extends ChangeNotifier {
  _RouterNotifier(Ref ref) {
    ref.listen(authProvider, (_, _) => notifyListeners());
    ref.listen(serverUrlProvider, (_, _) => notifyListeners());
  }
}

final routerProvider = Provider<GoRouter>((ref) {
  final notifier = _RouterNotifier(ref);

  return GoRouter(
    refreshListenable: notifier,
    initialLocation: Routes.splash,
    redirect: (context, state) {
      final location = state.matchedLocation;
      final serverUrl = ref.read(serverUrlProvider);
      final authStatus = ref.read(authProvider);

      if (serverUrl == null || serverUrl.isEmpty) {
        if (location != Routes.setup) return Routes.setup;
        return null;
      }

      if (authStatus == AuthStatus.unauthenticated) {
        if (location != Routes.login && location != Routes.setup) {
          return Routes.login;
        }
        return null;
      }

      return null;
    },
    routes: [
      GoRoute(
        path: Routes.splash,
        builder: (_, _) => const SplashScreen(),
      ),
      GoRoute(
        path: Routes.setup,
        builder: (_, _) => const SetupScreen(),
      ),
      GoRoute(
        path: Routes.login,
        builder: (_, _) => const LoginScreen(),
      ),
      GoRoute(
        path: Routes.quickCapture,
        builder: (_, _) => const QuickCaptureScreen(),
      ),
      GoRoute(
        path: Routes.settings,
        builder: (_, _) => const SettingsScreen(),
      ),
      GoRoute(
        path: Routes.noteNew,
        builder: (_, _) => const NoteEditScreen(),
      ),
      GoRoute(
        path: Routes.noteDetail,
        builder: (_, state) => NoteDetailScreen(
          noteId: int.parse(state.pathParameters['id']!),
        ),
      ),
      GoRoute(
        path: Routes.noteEdit,
        builder: (_, state) => NoteEditScreen(
          noteId: int.parse(state.pathParameters['id']!),
        ),
      ),
      GoRoute(
        path: Routes.taskNew,
        builder: (_, _) => const TaskEditScreen(),
      ),
      GoRoute(
        path: Routes.taskEdit,
        builder: (_, state) => TaskEditScreen(
          taskId: int.parse(state.pathParameters['id']!),
        ),
      ),
      GoRoute(
        path: Routes.chat,
        builder: (_, state) => ChatScreen(
          conversationId: int.parse(state.pathParameters['id']!),
        ),
      ),
      ShellRoute(
        builder: (context, state, child) => _Shell(child: child),
        routes: [
          GoRoute(
            path: Routes.notes,
            builder: (_, _) => const NotesListScreen(),
          ),
          GoRoute(
            path: Routes.tasks,
            builder: (_, _) => const TasksListScreen(),
          ),
          GoRoute(
            path: Routes.conversations,
            builder: (_, _) => const ConversationsListScreen(),
          ),
        ],
      ),
    ],
  );
});

class _Shell extends ConsumerWidget {
  final Widget child;
  const _Shell({required this.child});

  static const _tabs = [Routes.notes, Routes.tasks, Routes.conversations];

  int _tabIndex(String location) {
    for (var i = 0; i < _tabs.length; i++) {
      if (location.startsWith(_tabs[i])) return i;
    }
    return 0;
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final location = GoRouterState.of(context).matchedLocation;
    final index = _tabIndex(location);

    return Scaffold(
      body: child,
      bottomNavigationBar: NavigationBar(
        selectedIndex: index,
        onDestinationSelected: (i) => context.go(_tabs[i]),
        destinations: const [
          NavigationDestination(icon: Icon(Icons.note), label: 'Notes'),
          NavigationDestination(icon: Icon(Icons.check_box), label: 'Tasks'),
          NavigationDestination(
              icon: Icon(Icons.chat_bubble), label: 'Chat'),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        heroTag: 'shell_fab',
        onPressed: () => context.push(Routes.quickCapture),
        child: const Icon(Icons.add),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
    );
  }
}

class FabledApp extends ConsumerWidget {
  const FabledApp({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final router = ref.watch(routerProvider);

    return MaterialApp.router(
      title: 'Fabled',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.indigo),
        useMaterial3: true,
      ),
      darkTheme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: Colors.indigo,
          brightness: Brightness.dark,
        ),
        useMaterial3: true,
      ),
      routerConfig: router,
    );
  }
}