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

import '../services/security_service.dart';

class AppLockGate extends StatefulWidget {
  const AppLockGate({
    super.key,
    required this.securityService,
    required this.child,
  });

  final SecurityService securityService;
  final Widget child;

  @override
  State<AppLockGate> createState() => _AppLockGateState();
}

class _AppLockGateState extends State<AppLockGate> with WidgetsBindingObserver {
  bool _checking = true;
  bool _locked = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _loadLockState();
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.paused || state == AppLifecycleState.inactive) {
      _lockIfNeeded();
    }
  }

  Future<void> _loadLockState() async {
    final enabled = await widget.securityService.isPinEnabled();
    if (!mounted) return;
    setState(() {
      _locked = enabled;
      _checking = false;
    });
  }

  Future<void> _lockIfNeeded() async {
    final enabled = await widget.securityService.isPinEnabled();
    if (!mounted || !enabled) return;
    setState(() => _locked = true);
  }

  void _unlock() {
    setState(() => _locked = false);
  }

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

    if (_locked) {
      return PinUnlockScreen(
        securityService: widget.securityService,
        onUnlocked: _unlock,
      );
    }

    return widget.child;
  }
}

class PinUnlockScreen extends StatefulWidget {
  const PinUnlockScreen({
    super.key,
    required this.securityService,
    required this.onUnlocked,
  });

  final SecurityService securityService;
  final VoidCallback onUnlocked;

  @override
  State<PinUnlockScreen> createState() => _PinUnlockScreenState();
}

class _PinUnlockScreenState extends State<PinUnlockScreen> {
  final _pinController = TextEditingController();
  bool _checking = false;
  bool _checkingBiometric = false;
  bool _biometricEnabled = false;
  bool _biometricAvailable = false;
  bool _biometricAttempted = false;
  String? _error;

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

  @override
  void dispose() {
    _pinController.dispose();
    super.dispose();
  }

  Future<void> _loadBiometricState() async {
    final enabled = await widget.securityService.isBiometricEnabled();
    final available = await widget.securityService.isBiometricAvailable();

    if (!mounted) return;
    setState(() {
      _biometricEnabled = enabled;
      _biometricAvailable = available;
    });

    if (enabled && available && !_biometricAttempted) {
      _biometricAttempted = true;
      await Future.delayed(const Duration(milliseconds: 250));
      if (mounted) await _unlockWithBiometrics();
    }
  }

  Future<void> _unlockWithBiometrics() async {
    setState(() {
      _checkingBiometric = true;
      _error = null;
    });

    final ok = await widget.securityService.authenticateWithBiometrics();

    if (!mounted) return;

    if (ok) {
      widget.onUnlocked();
    } else {
      setState(() {
        _checkingBiometric = false;
        _error = 'Empreinte refusée ou annulée. Utilise le PIN.';
      });
    }
  }

  Future<void> _unlock() async {
    setState(() {
      _checking = true;
      _error = null;
    });

    final ok = await widget.securityService.verifyPin(_pinController.text.trim());

    if (!mounted) return;

    if (ok) {
      _pinController.clear();
      widget.onUnlocked();
    } else {
      HapticFeedback.vibrate();
      setState(() {
        _checking = false;
        _error = 'PIN incorrect.';
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final showBiometric = _biometricEnabled && _biometricAvailable;

    return Scaffold(
      body: SafeArea(
        child: Center(
          child: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 420),
            child: ListView(
              shrinkWrap: true,
              padding: const EdgeInsets.all(24),
              children: [
                Icon(showBiometric ? Icons.fingerprint : Icons.lock, size: 64),
                const SizedBox(height: 16),
                Text(
                  'FIN65 verrouillé',
                  textAlign: TextAlign.center,
                  style: Theme.of(context).textTheme.headlineSmall,
                ),
                const SizedBox(height: 8),
                Text(
                  showBiometric
                      ? 'Déverrouille avec ton empreinte ou ton PIN.'
                      : 'Entre ton PIN pour accéder aux données locales.',
                  textAlign: TextAlign.center,
                ),
                if (showBiometric) ...[
                  const SizedBox(height: 24),
                  FilledButton.icon(
                    onPressed: _checkingBiometric ? null : _unlockWithBiometrics,
                    icon: _checkingBiometric
                        ? const SizedBox(
                            width: 18,
                            height: 18,
                            child: CircularProgressIndicator(strokeWidth: 2),
                          )
                        : const Icon(Icons.fingerprint),
                    label: Text(_checkingBiometric ? 'Vérification...' : 'Utiliser l’empreinte'),
                  ),
                ],
                const SizedBox(height: 24),
                TextField(
                  controller: _pinController,
                  autofocus: !showBiometric,
                  obscureText: true,
                  keyboardType: TextInputType.number,
                  maxLength: 8,
                  decoration: InputDecoration(
                    labelText: 'PIN',
                    border: const OutlineInputBorder(),
                    errorText: _error,
                    counterText: '',
                  ),
                  onSubmitted: (_) => _checking ? null : _unlock(),
                ),
                const SizedBox(height: 12),
                OutlinedButton.icon(
                  onPressed: _checking ? null : _unlock,
                  icon: _checking
                      ? const SizedBox(
                          width: 18,
                          height: 18,
                          child: CircularProgressIndicator(strokeWidth: 2),
                        )
                      : const Icon(Icons.lock_open),
                  label: Text(_checking ? 'Vérification...' : 'Déverrouiller avec le PIN'),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}