import 'package:flutter/material.dart';
import 'package:supabase_flutter/supabase_flutter.dart';

// ── Supabase credentials ──────────────────────────────────────────────
const _supabaseUrl = 'https://yaopcyubateifnicpywp.supabase.co';
// TODO: Paste your anon key from Supabase Dashboard → Settings → API.
const _supabaseAnonKey = 'YOUR_ANON_KEY';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Supabase.initialize(
    url: _supabaseUrl,
    anonKey: _supabaseAnonKey,
  );

  runApp(const HWHubApp());
}

/// Convenience accessor used throughout the app.
final supabase = Supabase.instance.client;

// ── Root App Widget ───────────────────────────────────────────────────
class HWHubApp extends StatelessWidget {
  const HWHubApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'HW Hub',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const AuthGate(),
    );
  }
}

// ── Auth Gate ─────────────────────────────────────────────────────────
// Listens to Supabase auth state changes (including deep-link callbacks
// for password resets) and routes to Login or Home.
class AuthGate extends StatefulWidget {
  const AuthGate({super.key});

  @override
  State<AuthGate> createState() => _AuthGateState();
}

class _AuthGateState extends State<AuthGate> {
  bool _isLoading = true;
  Session? _session;

  @override
  void initState() {
    super.initState();

    // 1. Check for an existing session on cold start.
    _session = supabase.auth.currentSession;

    // 2. Listen for auth state changes (sign-in, sign-out,
    //    password-recovery deep link, token refresh, etc.)
    supabase.auth.onAuthStateChange.listen(
      (AuthState authState) {
        if (!mounted) return;
        setState(() {
          _session = authState.session;
        });

        // If the user just clicked a password-reset link from their email,
        // Supabase fires a PASSWORD_RECOVERY event. We can navigate them
        // to a "set new password" screen here.
        if (authState.event == AuthChangeEvent.passwordRecovery) {
          _showResetPasswordDialog();
        }
      },
      onError: (error) {
        if (!mounted) return;
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Auth error: $error'), backgroundColor: Colors.red),
        );
      },
    );

    // Done checking – remove the loading state.
    setState(() => _isLoading = false);
  }

  /// Shows a dialog so the user can type a new password after clicking
  /// the "Reset Password" link from their email.
  Future<void> _showResetPasswordDialog() async {
    final passwordController = TextEditingController();

    await showDialog<void>(
      context: context,
      barrierDismissible: false,
      builder: (ctx) => AlertDialog(
        title: const Text('Set New Password'),
        content: TextField(
          controller: passwordController,
          obscureText: true,
          decoration: const InputDecoration(
            labelText: 'New password',
            border: OutlineInputBorder(),
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(),
            child: const Text('Cancel'),
          ),
          ElevatedButton(
            onPressed: () async {
              final newPassword = passwordController.text.trim();
              if (newPassword.length < 6) {
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(content: Text('Password must be at least 6 characters.')),
                );
                return;
              }
              try {
                await supabase.auth.updateUser(
                  UserAttributes(password: newPassword),
                );
                if (!ctx.mounted) return;
                Navigator.of(ctx).pop();
                if (!mounted) return;
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(content: Text('Password updated successfully!')),
                );
              } on AuthException catch (e) {
                if (!mounted) return;
                ScaffoldMessenger.of(context).showSnackBar(
                  SnackBar(content: Text(e.message), backgroundColor: Colors.red),
                );
              }
            },
            child: const Text('Save'),
          ),
        ],
      ),
    );

    passwordController.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (_isLoading) {
      return const Scaffold(
        body: Center(child: CircularProgressIndicator()),
      );
    }

    if (_session != null) {
      return const HomeScreen();
    }

    return const LoginScreen();
  }
}

// ── Login Screen ──────────────────────────────────────────────────────
class LoginScreen extends StatefulWidget {
  const LoginScreen({super.key});

  @override
  State<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  bool _isLoading = false;

  /// Sign in with email + password.
  Future<void> _signIn() async {
    final email = _emailController.text.trim();
    final password = _passwordController.text;
    if (email.isEmpty || password.isEmpty) return;

    setState(() => _isLoading = true);

    try {
      await supabase.auth.signInWithPassword(
        email: email,
        password: password,
      );
      // AuthGate listener will pick up the new session automatically.
    } on AuthException catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message), backgroundColor: Colors.red),
      );
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  /// Send a password-reset email. The link in the email uses the
  /// hwcollector://login deep link so it opens back in the app,
  /// which triggers the PASSWORD_RECOVERY event in AuthGate.
  Future<void> _forgotPassword() async {
    final email = _emailController.text.trim();
    if (email.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Enter your email first.')),
      );
      return;
    }

    try {
      await supabase.auth.resetPasswordForEmail(
        email,
        redirectTo: 'hwcollector://login',
      );
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Password reset email sent! Check your inbox.')),
      );
    } on AuthException catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(e.message), backgroundColor: Colors.red),
      );
    }
  }

  @override
  void dispose() {
    _emailController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.symmetric(horizontal: 32),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              const Icon(Icons.directions_car, size: 72, color: Colors.deepPurple),
              const SizedBox(height: 16),
              const Text(
                'Hot Wheels Tracker',
                style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
              ),
              const SizedBox(height: 32),
              TextField(
                controller: _emailController,
                keyboardType: TextInputType.emailAddress,
                decoration: const InputDecoration(
                  labelText: 'Email',
                  border: OutlineInputBorder(),
                ),
              ),
              const SizedBox(height: 12),
              TextField(
                controller: _passwordController,
                obscureText: true,
                decoration: const InputDecoration(
                  labelText: 'Password',
                  border: OutlineInputBorder(),
                ),
                onSubmitted: (_) => _signIn(),
              ),
              const SizedBox(height: 8),
              Align(
                alignment: Alignment.centerRight,
                child: TextButton(
                  onPressed: _forgotPassword,
                  child: const Text('Forgot Password?'),
                ),
              ),
              const SizedBox(height: 8),
              SizedBox(
                width: double.infinity,
                child: ElevatedButton(
                  onPressed: _isLoading ? null : _signIn,
                  child: _isLoading
                      ? const SizedBox(
                          height: 20,
                          width: 20,
                          child: CircularProgressIndicator(strokeWidth: 2),
                        )
                      : const Text('Sign In'),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

// ── Home Screen (placeholder) ─────────────────────────────────────────
class HomeScreen extends StatelessWidget {
  const HomeScreen({super.key});

  @override
  Widget build(BuildContext context) {
    final user = supabase.auth.currentUser;

    return Scaffold(
      appBar: AppBar(
        title: const Text('Garage is Online! 🏎️'),
        actions: [
          IconButton(
            icon: const Icon(Icons.logout),
            onPressed: () async {
              await supabase.auth.signOut();
            },
          ),
        ],
      ),
      body: Center(
        child: Text(
          'Signed in as ${user?.email ?? 'unknown'}',
          style: Theme.of(context).textTheme.titleMedium,
        ),
      ),
    );
  }
}