import 'dart:async';
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'core/auth/auth_bloc.dart';
import 'features/auth/screens/welcome_screen.dart';
import 'features/auth/screens/display_name_screen.dart';
import 'features/auth/screens/register_screen.dart';
import 'features/auth/screens/otp_screen.dart';
import 'features/auth/screens/force_register_screen.dart';
import 'features/splash/splash_screen.dart';
import 'features/home/home_screen.dart';
import 'features/chat/screens/searching_screen.dart';
import 'features/chat/screens/bestie_found_screen.dart';
import 'features/chat/screens/no_bestie_screen.dart';
import 'features/chat/screens/chat_screen.dart';
import 'features/chat/screens/chat_history_screen.dart';
import 'features/chat/screens/chat_transcript_screen.dart';

/// Converts a BLoC stream into a ChangeNotifier for GoRouter's refreshListenable.
class _BlocRefreshNotifier extends ChangeNotifier {
  late final StreamSubscription _subscription;

  _BlocRefreshNotifier(AuthBloc bloc) {
    _subscription = bloc.stream.listen((_) => notifyListeners());
  }

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

GoRouter buildRouter(AuthBloc authBloc) {
  return GoRouter(
    initialLocation: '/splash',
    refreshListenable: _BlocRefreshNotifier(authBloc),
    redirect: (context, state) {
      final authState = authBloc.state;
      final isSplash = state.matchedLocation == '/splash';
      final isAuthRoute = state.matchedLocation.startsWith('/auth') ||
          state.matchedLocation == '/welcome';

      // Show splash while loading
      if (authState is AuthLoading) return isSplash ? null : '/splash';

      if (authState is AuthAuthenticated || authState is AuthAnonymous) {
        return (isSplash || isAuthRoute) ? '/home' : null;
      }
      if (authState is AuthForceRegister) return '/auth/force-register';
      if (!isAuthRoute && !isSplash) return '/welcome';
      if (isSplash) return '/welcome';
      return null;
    },
    routes: [
      GoRoute(path: '/splash', builder: (_, __) => const SplashScreen()),
      GoRoute(path: '/welcome', builder: (_, __) => const WelcomeScreen()),
      GoRoute(path: '/auth/display-name', builder: (_, __) => const DisplayNameScreen()),
      GoRoute(path: '/auth/register', builder: (_, __) => const RegisterScreen()),
      GoRoute(path: '/auth/otp', builder: (context, state) => OtpScreen(phone: state.extra as String)),
      GoRoute(path: '/auth/force-register', builder: (_, __) => const ForceRegisterScreen()),
      GoRoute(path: '/home', builder: (_, __) => const HomeScreen()),
      GoRoute(path: '/chat/searching', builder: (_, __) => const SearchingScreen()),
      GoRoute(path: '/chat/found', builder: (context, state) {
        final extra = state.extra as Map<String, dynamic>;
        return BestieFoundScreen(
          sessionId: extra['sessionId'] as String,
          mitraName: extra['mitraName'] as String,
        );
      }),
      GoRoute(path: '/chat/no-bestie', builder: (_, __) => const NoBestieScreen()),
      GoRoute(path: '/chat/session/:sessionId', builder: (context, state) {
        final extra = state.extra;
        final mitraName = extra is String
            ? extra
            : (extra is Map<String, dynamic> ? extra['mitraName'] as String? : null);
        return ChatScreen(
          sessionId: state.pathParameters['sessionId']!,
          mitraName: mitraName ?? 'Bestie',
        );
      }),
      GoRoute(path: '/chat/history', builder: (_, __) => const ChatHistoryScreen()),
      GoRoute(path: '/chat/history/:sessionId', builder: (context, state) {
        return ChatTranscriptScreen(sessionId: state.pathParameters['sessionId']!);
      }),
    ],
  );
}