import 'package:flutter/material.dart';
import 'package:flutter_web_plugins/flutter_web_plugins.dart';
import 'package:provider/provider.dart';
import 'package:go_router/go_router.dart';
import 'package:qpay/navbar.dart';
import 'package:qpay/screens/confirm/confirm_screen.dart';
import 'package:qpay/screens/gateway/gateway_redirect.dart';
import 'package:qpay/screens/gateway/gateway_screen.dart';
import 'package:qpay/screens/gateway/gateway_web_screen.dart';
import 'package:qpay/screens/home/home_screen.dart';
import 'package:qpay/screens/history/history_screen.dart';
import 'package:qpay/screens/integration/integration_screen.dart';
import 'package:qpay/screens/onboarding/complete_screen.dart';
import 'package:qpay/screens/onboarding/landing/landing_screen.dart';
import 'package:qpay/screens/onboarding/login/login_screen.dart';
import 'package:qpay/screens/onboarding/onboarding_controller.dart';
import 'package:qpay/screens/onboarding/password/password_screen.dart';
import 'package:qpay/screens/onboarding/phone/phone_screen.dart';
import 'package:qpay/screens/onboarding/register/register_screen.dart';
import 'package:qpay/screens/onboarding/verify/verify_screen.dart';
import 'package:qpay/screens/pay/pay_screen.dart';
import 'package:qpay/screens/poll/poll_screen.dart';
import 'package:qpay/screens/splash_screen.dart';
import 'package:qpay/screens/receipt/receipt_screen.dart';
import 'package:qpay/screens/recipient/recipients_screen.dart';
import 'package:qpay/screens/transaction_controller.dart';
import 'package:qpay/screens/profile_screen.dart';
import 'package:qpay/theme/app_theme.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';
import 'package:firebase_core/firebase_core.dart';
import 'firebase_options.dart';

const String testEnv = 'assets/.env.test';
const String liveEnv = 'assets/.env.live';
const String appEnv = String.fromEnvironment('APP_ENV', defaultValue: 'test');

String resolveEnvFile(String env) {
  switch (env.toLowerCase()) {
    case 'live':
      return liveEnv;
    case 'test':
    default:
      return testEnv;
  }
}

/// Tracks whether the splash animation is complete so that
/// GoRouter's redirect can show the splash first, then release
/// navigation to the originally intended URL.
class SplashState extends ChangeNotifier {
  bool _complete = false;
  /// The route the user originally intended to visit before being
  /// redirected to /splash. Set by the redirect callback on first
  /// invocation.
  String? _intendedRoute;
  bool get complete => _complete;
  String? get intendedRoute => _intendedRoute;

  /// Called by the redirect to store the intended destination and
  /// return the splash route.
  String? guard(String attemptedRoute) {
    if (_complete) return null;
    // Avoid saving the splash route itself.
    if (attemptedRoute == '/splash') return null;
    _intendedRoute = attemptedRoute;
    return '/splash';
  }

  void finish() {
    _complete = true;
    notifyListeners();
  }
}

final SplashState splashState = SplashState();

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  usePathUrlStrategy();
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);

  await dotenv.load(fileName: resolveEnvFile(appEnv));
  runApp(
    MultiProvider(
      providers: [
        ChangeNotifierProvider<TransactionController>(
          create: (_) => TransactionController(),
        ),
        ChangeNotifierProvider<OnboardingController>(
          create: (_) => OnboardingController(),
        ),
      ],
      child: const MyApp(),
    ),
  );
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      title: 'Velocity',
      theme: AppTheme.lightTheme,
      themeMode: ThemeMode.light,
      debugShowCheckedModeBanner: false,
      routerConfig: GoRouter(
        initialLocation: '/',
        refreshListenable: splashState,
        errorBuilder: (context, state) => Scaffold(
          body: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                const Text('Page not found', style: TextStyle(fontSize: 20)),
                const SizedBox(height: 16),
                ElevatedButton(
                  onPressed: () => context.go('/'),
                  child: const Text('Go Home'),
                ),
              ],
            ),
          ),
        ),
        redirect: (context, state) {
          // Before splash is complete: redirect everything to /splash,
          // but save the original intended destination.
          final guardResult = splashState.guard(state.uri.path);
          if (guardResult != null) return guardResult;

          // Once splash is complete: if we're still on /splash, navigate
          // to the intended destination (or home as fallback).
          if (splashState.complete && state.uri.path == '/splash') {
            return splashState.intendedRoute ?? '/';
          }

          return null;
        },
        routes: [
          // Splash route sits outside the ShellRoute so it renders
          // without the bottom nav bar or side rail.
          GoRoute(
            path: '/splash',
            builder: (context, state) => const SplashScreen(),
          ),
          ShellRoute(
            builder: (context, state, child) {
              final location = GoRouterState.of(context).uri.toString();
              if (location.startsWith('/onboarding/')) {
                return child;
              }
              return ScaffoldWithNavBar(child: child);
            },
            routes: [
              GoRoute(
                path: '/',
                builder: (context, state) => const HomeScreen(),
              ),
              GoRoute(
                path: '/home',
                builder: (context, state) => const HomeScreen(),
              ),
              GoRoute(
                path: '/make-payment',
                builder: (context, state) => const PayScreen(),
              ),
              GoRoute(
                path: '/confirm',
                builder: (context, state) => const ConfirmScreen(),
              ),
              GoRoute(
                path: '/gateway',
                builder: (context, state) => const GatewayScreen(),
              ),
              GoRoute(
                path: '/gateway-web',
                builder: (context, state) => const GatewayWebScreen(),
              ),
              GoRoute(
                path: '/gateway-redirect',
                builder: (context, state) => const GatewayRedirectScreen(),
              ),
              GoRoute(
                path: '/poll/:id',
                builder: (context, state) => PollScreen(
                  transactionId: state.pathParameters['id'],
                ),
              ),
              GoRoute(
                path: '/poll',
                builder: (context, state) => const PollScreen(),
              ),
              GoRoute(
                path: '/receipt',
                builder: (context, state) => const ReceiptScreen(),
              ),
              GoRoute(
                path: '/integration',
                builder: (context, state) => const IntegrationScreen(),
              ),
              GoRoute(
                path: '/recipients',
                builder: (context, state) => const RecipientsScreen(),
              ),
              GoRoute(
                path: '/history',
                builder: (context, state) => const HistoryScreen(),
              ),
              GoRoute(
                path: '/profile',
                builder: (context, state) => const ProfileScreen(),
              ),
              GoRoute(
                path: '/onboarding/landing',
                builder: (context, state) => const LandingScreen(),
              ),
              GoRoute(
                path: '/onboarding/register',
                builder: (context, state) => const RegisterScreen(),
              ),
              GoRoute(
                path: '/onboarding/phone',
                builder: (context, state) => const PhoneScreen(),
              ),
              GoRoute(
                path: '/onboarding/verify',
                builder: (context, state) => const VerifyScreen(),
              ),
              GoRoute(
                path: '/onboarding/password',
                builder: (context, state) => const PasswordScreen(),
              ),
              GoRoute(
                path: '/onboarding/login',
                builder: (context, state) => const LoginScreen(),
              ),
              GoRoute(
                path: '/onboarding/complete',
                builder: (context, state) => const CompleteScreen(),
              ),
            ],
          ),
        ],
      ),
    );
  }
}