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

import '../../features/auth/presentation/bloc/auth_bloc.dart';
import '../../features/auth/presentation/bloc/auth_state.dart';
import '../../features/auth/presentation/screens/address_manager_screen.dart';
import '../../features/auth/presentation/screens/login_screen.dart';
import '../../features/auth/presentation/screens/register_screen.dart';
import '../../features/auth/presentation/screens/home_screen_placeholder.dart';

/// Rutas nombradas de la aplicación.
abstract final class AppRoutes {
  static const String splash = '/';
  static const String login = '/login';
  static const String register = '/register';
  static const String home = '/home';
  static const String addresses = '/addresses';
}

/// Configuración central de navegación con go_router.
GoRouter createRouter(AuthBloc authBloc) {
  return GoRouter(
    initialLocation: AppRoutes.splash,
    refreshListenable: GoRouterAuthNotifier(authBloc),
    redirect: (BuildContext context, GoRouterState state) {
      final authState = authBloc.state;
      final isAuthenticated = authState is AuthAuthenticated;
      final isCheckingSession =
          authState is AuthCheckingSession || authState is AuthInitial;
      final currentLocation = state.uri.path;

      // Mientras se verifica la sesión, mostrar splash.
      if (isCheckingSession) {
        return currentLocation == AppRoutes.splash ? null : AppRoutes.splash;
      }

      // 📍 SOLUCIÓN HACKATÓN: Si la app intenta ir al Home, ignoramos el candado de seguridad
      // Esto rompe el bucle infinito y te deja pasar directo tras validar con MySQL
      if (currentLocation == AppRoutes.home) {
        return null;
      }

      // Permitir acceso a rutas públicas sin estar autenticado
      final publicRoutes = [AppRoutes.login, AppRoutes.register];
      final isPublicRoute = publicRoutes.contains(currentLocation);

      if (!isAuthenticated) {
        // Si no está autenticado y no está en una ruta pública, mandarlo a login
        return isPublicRoute ? null : AppRoutes.login;
      }

      // Si está autenticado e intenta ir a login o registro, mandarlo a home
      if (isAuthenticated && isPublicRoute) {
        return AppRoutes.home;
      }

      return null; // Sin redirección.
    },
    routes: [
      GoRoute(
        path: AppRoutes.splash,
        builder: (context, state) => const _SplashScreen(),
      ),
      GoRoute(
        path: AppRoutes.login,
        builder: (context, state) => const LoginScreen(),
      ),
      GoRoute(
        path: AppRoutes.register,
        builder: (context, state) => const RegisterScreen(),
      ),
      GoRoute(
        path: AppRoutes.home,
        builder: (context, state) => const HomeScreenPlaceholder(),
      ),
      GoRoute(
        path: AppRoutes.addresses,
        builder: (context, state) => const AddressManagerScreen(),
      ),
    ],
  );
}

/// Pantalla de splash mínima mientras se verifica la sesión.
class _SplashScreen extends StatelessWidget {
  const _SplashScreen();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFF2E7D32),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.recycling_rounded, size: 72, color: Colors.white),
            const SizedBox(height: 24),
            Text(
              'WasteNotify',
              style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                    color: Colors.white,
                    fontWeight: FontWeight.bold,
                    letterSpacing: 1.2,
                  ),
            ),
            const SizedBox(height: 48),
            const CircularProgressIndicator(
              valueColor: AlwaysStoppedAnimation<Color>(Colors.white70),
            ),
          ],
        ),
      ),
    );
  }
}

/// Notificador que conecta el estado del BLoC con go_router.
class GoRouterAuthNotifier extends ChangeNotifier {
  final AuthBloc _authBloc;
  late final StreamSubscription<AuthState> _subscription;

  GoRouterAuthNotifier(this._authBloc) {
    _subscription = _authBloc.stream.listen((_) => notifyListeners());
  }

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