import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:mobile_scanner/mobile_scanner.dart';

import '../providers/scanner_provider.dart';

/// Widget that provides barcode scanning functionality using device camera
class BarcodeScannerWidget extends ConsumerStatefulWidget {
  const BarcodeScannerWidget({super.key});

  @override
  ConsumerState<BarcodeScannerWidget> createState() => _BarcodeScannerWidgetState();
}

class _BarcodeScannerWidgetState extends ConsumerState<BarcodeScannerWidget>
    with WidgetsBindingObserver {
  late MobileScannerController _controller;
  bool _isStarted = false;
  String? _lastScannedCode;
  DateTime? _lastScanTime;
  bool _isTorchOn = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _controller = MobileScannerController(
      formats: [
        BarcodeFormat.code128,
      ],
      facing: CameraFacing.back,
      torchEnabled: false,
    );
    _startScanner();
  }

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

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);

    switch (state) {
      case AppLifecycleState.paused:
        _stopScanner();
        break;
      case AppLifecycleState.resumed:
        _startScanner();
        break;
      case AppLifecycleState.detached:
      case AppLifecycleState.inactive:
      case AppLifecycleState.hidden:
        break;
    }
  }

  Future<void> _startScanner() async {
    if (!_isStarted && mounted) {
      try {
        await _controller.start();
        setState(() {
          _isStarted = true;
        });
      } catch (e) {
        debugPrint('Failed to start scanner: $e');
      }
    }
  }

  Future<void> _stopScanner() async {
    if (_isStarted) {
      try {
        await _controller.stop();
        setState(() {
          _isStarted = false;
        });
      } catch (e) {
        debugPrint('Failed to stop scanner: $e');
      }
    }
  }

  void _onBarcodeDetected(BarcodeCapture capture) {
    final List<Barcode> barcodes = capture.barcodes;

    if (barcodes.isNotEmpty) {
      final barcode = barcodes.first;
      final code = barcode.rawValue;

      if (code != null && code.isNotEmpty) {
        // Prevent duplicate scans within 2 seconds
        final now = DateTime.now();
        if (_lastScannedCode == code &&
            _lastScanTime != null &&
            now.difference(_lastScanTime!).inSeconds < 2) {
          return;
        }

        _lastScannedCode = code;
        _lastScanTime = now;

        // Update scanner provider with new barcode
        ref.read(scannerProvider.notifier).updateBarcode(code);

        // Provide haptic feedback
        _provideHapticFeedback();
      }
    }
  }

  void _provideHapticFeedback() {
    // Haptic feedback is handled by the system
    // You can add custom vibration here if needed
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        color: Colors.black,
        borderRadius: BorderRadius.circular(0),
      ),
      child: Stack(
        children: [
          // Camera View
          ClipRRect(
            borderRadius: BorderRadius.circular(0),
            child: MobileScanner(
              controller: _controller,
              onDetect: _onBarcodeDetected,
            ),
          ),

          // Overlay with scanner frame
          _buildScannerOverlay(context),

          // Control buttons
          _buildControlButtons(context),
        ],
      ),
    );
  }

  /// Build scanner overlay with frame and guidance
  Widget _buildScannerOverlay(BuildContext context) {
    return Container(
      decoration: const BoxDecoration(
        color: Colors.transparent,
      ),
      child: Stack(
        children: [
          // Dark overlay with cutout
          Container(
            color: Colors.black.withOpacity(0.5),
            child: Center(
              child: Container(
                width: 250,
                height: 150,
                decoration: BoxDecoration(
                  border: Border.all(
                    color: Theme.of(context).colorScheme.primary,
                    width: 2,
                  ),
                  borderRadius: BorderRadius.circular(12),
                ),
                child: ClipRRect(
                  borderRadius: BorderRadius.circular(10),
                  child: Container(
                    color: Colors.transparent,
                  ),
                ),
              ),
            ),
          ),

          // Instructions
          Positioned(
            bottom: 60,
            left: 0,
            right: 0,
            child: Container(
              padding: const EdgeInsets.symmetric(horizontal: 32, vertical: 16),
              child: Text(
                'Position barcode within the frame',
                style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                      color: Colors.white,
                      fontWeight: FontWeight.w500,
                    ),
                textAlign: TextAlign.center,
              ),
            ),
          ),
        ],
      ),
    );
  }

  /// Build control buttons (torch, camera switch)
  Widget _buildControlButtons(BuildContext context) {
    return Positioned(
      top: 16,
      right: 16,
      child: Column(
        children: [
          // Torch Toggle
          Container(
            decoration: BoxDecoration(
              color: Colors.black.withOpacity(0.6),
              shape: BoxShape.circle,
            ),
            child: IconButton(
              icon: Icon(
                _isTorchOn ? Icons.flash_on : Icons.flash_off,
                color: Colors.white,
              ),
              onPressed: _toggleTorch,
            ),
          ),
          const SizedBox(height: 12),

          // Camera Switch
          Container(
            decoration: BoxDecoration(
              color: Colors.black.withOpacity(0.6),
              shape: BoxShape.circle,
            ),
            child: IconButton(
              icon: const Icon(
                Icons.cameraswitch,
                color: Colors.white,
              ),
              onPressed: _switchCamera,
            ),
          ),
        ],
      ),
    );
  }

  /// Build error widget when camera fails
  Widget _buildErrorWidget(MobileScannerException error) {
    return Container(
      color: Colors.black,
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(
              Icons.camera_alt_outlined,
              size: 64,
              color: Theme.of(context).colorScheme.error,
            ),
            const SizedBox(height: 16),
            Text(
              'Camera Error',
              style: Theme.of(context).textTheme.titleMedium?.copyWith(
                    color: Colors.white,
                  ),
            ),
            const SizedBox(height: 8),
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 32),
              child: Text(
                _getErrorMessage(error),
                style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                      color: Colors.white70,
                    ),
                textAlign: TextAlign.center,
              ),
            ),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: _restartScanner,
              child: const Text('Retry'),
            ),
          ],
        ),
      ),
    );
  }

  /// Build placeholder while camera is loading
  Widget _buildPlaceholderWidget() {
    return Container(
      color: Colors.black,
      child: const Center(
        child: CircularProgressIndicator(
          color: Colors.white,
        ),
      ),
    );
  }

  /// Get user-friendly error message
  String _getErrorMessage(MobileScannerException error) {
    switch (error.errorCode) {
      case MobileScannerErrorCode.permissionDenied:
        return 'Camera permission is required to scan barcodes. Please enable camera access in settings.';
      case MobileScannerErrorCode.unsupported:
        return 'Your device does not support barcode scanning.';
      default:
        return 'Unable to access camera. Please check your device settings and try again.';
    }
  }

  /// Toggle torch/flashlight
  void _toggleTorch() async {
    try {
      await _controller.toggleTorch();
      setState(() {
        _isTorchOn = !_isTorchOn;
      });
    } catch (e) {
      debugPrint('Failed to toggle torch: $e');
    }
  }

  /// Switch between front and back camera
  void _switchCamera() async {
    try {
      await _controller.switchCamera();
    } catch (e) {
      debugPrint('Failed to switch camera: $e');
    }
  }

  /// Restart scanner after error
  void _restartScanner() async {
    try {
      await _controller.stop();
      await _controller.start();
      setState(() {
        _isStarted = true;
      });
    } catch (e) {
      debugPrint('Failed to restart scanner: $e');
    }
  }
}