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

import '../utils/app_lock_service.dart';
import '../utils/app_theme.dart';

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

  final Widget child;

  @override
  State<AppLockOverlay> createState() => _AppLockOverlayState();
}

class _AppLockOverlayState extends State<AppLockOverlay>
    with WidgetsBindingObserver {
  bool _shouldRelockOnResume = false;

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

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

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final service = AppLockService.instance;
    if (!service.isEnabled) return;

    if (state == AppLifecycleState.inactive ||
        state == AppLifecycleState.paused ||
        state == AppLifecycleState.hidden) {
      _shouldRelockOnResume = true;
      return;
    }

    if (state == AppLifecycleState.resumed && _shouldRelockOnResume) {
      _shouldRelockOnResume = false;
      service.lock();
    }
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: AppLockService.instance,
      builder: (context, _) {
        final service = AppLockService.instance;
        return Stack(
          fit: StackFit.expand,
          children: [
            widget.child,
            if (service.initialized && service.isLocked)
              const Positioned.fill(child: _AppLockBarrier()),
          ],
        );
      },
    );
  }
}

class _AppLockBarrier extends StatelessWidget {
  const _AppLockBarrier();

  @override
  Widget build(BuildContext context) {
    return PopScope(
      canPop: false,
      child: Material(
        color: AppTheme.darkBg.withValues(alpha: 0.96),
        child: Stack(
          fit: StackFit.expand,
          children: [
            Positioned.fill(
              child: CustomPaint(
                painter: _LockBackgroundPainter(),
              ),
            ),
            const SafeArea(
              child: Center(
                child: Padding(
                  padding: EdgeInsets.all(20),
                  child: _AppLockCard(),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class _AppLockCard extends StatefulWidget {
  const _AppLockCard();

  @override
  State<_AppLockCard> createState() => _AppLockCardState();
}

class _AppLockCardState extends State<_AppLockCard> {
  final TextEditingController _controller = TextEditingController();
  bool _isVerifying = false;
  String? _errorText;

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

  Future<void> _unlock() async {
    if (_isVerifying) return;

    FocusScope.of(context).unfocus();
    final passcode = _controller.text.trim();
    if (passcode.isEmpty) {
      setState(() => _errorText = 'رمز برنامه را وارد کنید.');
      return;
    }

    setState(() {
      _isVerifying = true;
      _errorText = null;
    });

    final isValid = await AppLockService.instance.verifyPasscode(passcode);

    if (!mounted) return;
    setState(() {
      _isVerifying = false;
      _errorText = isValid ? null : 'رمز واردشده درست نیست.';
    });

    if (isValid) {
      _controller.clear();
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return ConstrainedBox(
      constraints: const BoxConstraints(maxWidth: 420),
      child: AppTheme.glassWrapper(
        radius: 28,
        sigma: 14,
        child: Padding(
          padding: const EdgeInsets.fromLTRB(24, 28, 24, 24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Container(
                width: 76,
                height: 76,
                decoration: BoxDecoration(
                  shape: BoxShape.circle,
                  gradient: LinearGradient(
                    colors: [
                      theme.primaryColor.withValues(alpha: 0.95),
                      AppTheme.accentCyan.withValues(alpha: 0.95),
                    ],
                  ),
                  boxShadow: [
                    BoxShadow(
                      color: theme.primaryColor.withValues(alpha: 0.28),
                      blurRadius: 20,
                      spreadRadius: 1,
                    ),
                  ],
                ),
                child: const Icon(
                  Icons.lock_rounded,
                  size: 38,
                  color: Colors.white,
                ),
              ),
              const SizedBox(height: 18),
              const Text(
                'قفل برنامه فعال است',
                style: TextStyle(
                  fontSize: 22,
                  fontWeight: FontWeight.bold,
                  color: Colors.white,
                ),
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 10),
              const Text(
                'برای ورود به صبا، رمز برنامه را وارد کنید.',
                style: TextStyle(
                  fontSize: 14,
                  height: 1.6,
                  color: Colors.white70,
                ),
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 24),
              TextField(
                controller: _controller,
                autofocus: true,
                keyboardType: TextInputType.number,
                textInputAction: TextInputAction.done,
                obscureText: true,
                obscuringCharacter: '•',
                inputFormatters: [
                  FilteringTextInputFormatter.digitsOnly,
                  LengthLimitingTextInputFormatter(8),
                ],
                onSubmitted: (_) => _unlock(),
                decoration: InputDecoration(
                  labelText: 'رمز برنامه',
                  hintText: '۴ تا ۸ رقم',
                  errorText: _errorText,
                  filled: true,
                  fillColor: Colors.white.withValues(alpha: 0.06),
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(16),
                  ),
                ),
              ),
              const SizedBox(height: 18),
              SizedBox(
                width: double.infinity,
                child: ElevatedButton.icon(
                  onPressed: _isVerifying ? null : _unlock,
                  style: ElevatedButton.styleFrom(
                    padding: const EdgeInsets.symmetric(vertical: 15),
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(16),
                    ),
                  ),
                  icon: _isVerifying
                      ? const SizedBox(
                          width: 18,
                          height: 18,
                          child: CircularProgressIndicator(strokeWidth: 2),
                        )
                      : const Icon(Icons.lock_open_rounded),
                  label:
                      Text(_isVerifying ? 'در حال بررسی...' : 'ورود به برنامه'),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _LockBackgroundPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final purplePaint = Paint()
      ..shader = RadialGradient(
        colors: [
          AppTheme.accentPurple.withValues(alpha: 0.22),
          AppTheme.accentPurple.withValues(alpha: 0),
        ],
      ).createShader(
        Rect.fromCircle(
          center: Offset(size.width * 0.18, size.height * 0.2),
          radius: size.width * 0.55,
        ),
      );

    final cyanPaint = Paint()
      ..shader = RadialGradient(
        colors: [
          AppTheme.accentCyan.withValues(alpha: 0.14),
          AppTheme.accentCyan.withValues(alpha: 0),
        ],
      ).createShader(
        Rect.fromCircle(
          center: Offset(size.width * 0.82, size.height * 0.78),
          radius: size.width * 0.6,
        ),
      );

    canvas.drawCircle(
      Offset(size.width * 0.18, size.height * 0.2),
      size.width * 0.55,
      purplePaint,
    );
    canvas.drawCircle(
      Offset(size.width * 0.82, size.height * 0.78),
      size.width * 0.6,
      cyanPaint,
    );
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}