import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:login_vault_app/auth_service.dart';
import 'package:login_vault_app/dashboard_screen.dart';
import 'package:login_vault_app/theme_provider.dart';

/// First screen: register (if not yet), or re-authenticate (if registered).
/// If a valid session exists, skip straight to the Dashboard.
class AuthScreen extends StatefulWidget {
  final AuthService auth;
  const AuthScreen({super.key, required this.auth});

  @override
  State<AuthScreen> createState() => _AuthScreenState();
}

class _AuthScreenState extends State<AuthScreen> {
  final _emailCtrl = TextEditingController();
  final _passCtrl = TextEditingController();
  bool _isLogin = true;
  bool _busy = false;
  String? _error;
  String? _bioMsg;
  bool _biometricAvailable = false;
  bool _biometricEnabled = false;

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

  /// Decide login vs register based on whether an account exists.
  Future<void> _initMode() async {
    final registered = await widget.auth.isRegistered();
    if (!mounted) return;
    final avail = await widget.auth.canUseBiometrics();
    final enabled = await widget.auth.isBiometricEnabled();
    setState(() {
      _isLogin = registered;
      _biometricAvailable = avail;
      _biometricEnabled = enabled;
    });
    // If already registered and biometric is enabled, prompt fingerprint
    // automatically (unless a valid session already skips to dashboard).
    if (registered && enabled) {
      final timeout = await widget.auth.getTimeoutMinutes();
      final valid = await widget.auth.hasValidSession(timeout);
      if (!valid) {
        _promptBiometricOnOpen();
        return; // skip silent-auth path; biometric handles entry
      }
    }
    _trySilentAuth();
  }

  /// Auto-prompt fingerprint on open when enabled; on success go to dashboard
  /// (email may be empty for google-less accounts, fallback to stored email).
  Future<void> _promptBiometricOnOpen() async {
    final (ok, err) = await widget.auth.authenticateWithBiometrics();
    if (!mounted) return;
    if (ok) {
      final email = await widget.auth.getEmail() ?? '';
      _goToDashboard(email);
    } else {
      // fingerprint failed/cancelled -> let user login manually
      setState(() {
        _bioMsg = 'Gagal verifikasi sidik jari. Silakan masuk manual.';
      });
    }
  }

  /// On open: if a valid session is present, go straight to Dashboard.
  Future<void> _trySilentAuth() async {
    final timeout = await widget.auth.getTimeoutMinutes();
    final valid = await widget.auth.hasValidSession(timeout);
    if (valid && mounted) {
      final email = await widget.auth.getEmail() ?? '';
      _goToDashboard(email);
    }
  }

  void _goToDashboard(String email) {
    if (!mounted) return;
    widget.auth.openSession(); // refresh session timestamp
    Navigator.of(context).pushReplacement(
      MaterialPageRoute(
        builder: (_) => DashboardScreen(
          auth: widget.auth,
          theme: Provider.of<ThemeProvider>(context, listen: false),
          email: email,
        ),
      ),
    );
  }

  Future<void> _submit() async {
    setState(() => _busy = true);
    final email = _emailCtrl.text.trim();
    final pass = _passCtrl.text;
    if (email.isEmpty || pass.isEmpty) {
      setState(() => _error = 'Email & password wajib diisi');
      _busy = false;
      return;
    }
    try {
      if (_isLogin) {
        final stored = await widget.auth.getAppPassword();
        final ok = await widget.auth.verifyPassword(pass);
        if (stored == null) {
          setState(() => _error = 'Belum terdaftar, silakan registrasi');
        } else if (!ok) {
          setState(() => _error = 'Password aplikasi salah');
        } else {
          _goToDashboard(email);
        }
      } else {
        await widget.auth.registerWithEmail(email, pass);
        _goToDashboard(email);
      }
    } catch (e) {
      setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Login Vault')),
      body: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(_isLogin ? 'Masuk' : 'Daftar',
                style: Theme.of(context).textTheme.headlineSmall),
            const SizedBox(height: 16),
            TextField(
              controller: _emailCtrl,
              keyboardType: TextInputType.emailAddress,
              decoration: const InputDecoration(
                  labelText: 'Email', border: OutlineInputBorder()),
            ),
            const SizedBox(height: 12),
            TextField(
              controller: _passCtrl,
              obscureText: true,
              decoration: const InputDecoration(
                  labelText: 'Password aplikasi', border: OutlineInputBorder()),
            ),
            const SizedBox(height: 8),
            if (_error != null)
              Text(_error!, style: const TextStyle(color: Colors.red)),
            if (_bioMsg != null)
              Padding(
                padding: const EdgeInsets.only(bottom: 8),
                child: Text(_bioMsg!,
                    style: const TextStyle(color: Colors.grey)),
              ),
            const SizedBox(height: 12),
            _busy
                ? const CircularProgressIndicator()
                : Column(
                    children: [
                      ElevatedButton(
                        onPressed: _submit,
                        child: Text(_isLogin ? 'Masuk' : 'Daftar'),
                      ),
                      // Biometric retry button (only when enabled + registered)
                      if (_isLogin &&
                          _biometricAvailable &&
                          _biometricEnabled)
                        TextButton.icon(
                          onPressed: () {
                            setState(() => _bioMsg = null);
                            _promptBiometricOnOpen();
                          },
                          icon: const Icon(Icons.fingerprint),
                          label: const Text('Gunakan Sidik Jari'),
                        ),
                    ],
                  ),
          ],
        ),
      ),
    );
  }
}