import 'package:flutter/material.dart';
import 'package:mobile_scanner/mobile_scanner.dart';
import 'package:inventory_system/screens/admin/scan/scan_result.dart';
import 'package:inventory_system/screens/title_bar.dart';
import 'package:inventory_system/screens/nav_bar.dart';
import 'package:inventory_system/screens/bottom_nav_bar.dart';

class ScanScreen extends StatefulWidget {
  const ScanScreen({super.key});

  @override
  State<ScanScreen> createState() => _ScanScreenState();
}

class _ScanScreenState extends State<ScanScreen> {
  int _selectedIndex = 1;
  bool _isProcessing = false;

  void _onDetect(BarcodeCapture capture) async {
    if (_isProcessing) return;

    final codes = capture.barcodes;
    if (codes.isEmpty) return;

    final value = codes.first.rawValue;
    if (value == null || value.isEmpty) return;

    _isProcessing = true;

    await Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => ScanResultScreen(scannedCode: value.trim()),
      ),
    );

    // brief debounce to avoid flood
    await Future.delayed(const Duration(milliseconds: 500));
    _isProcessing = false;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFFF5F5F7),
      appBar: const TitleBar(title: 'Scan Item'),
      drawer: const NavBar(isAdmin: true, selectedScreen: AppScreen.item),
      body: Stack(
        fit: StackFit.expand,
        children: [
          // 1. Add Padding around the camera view
          Padding(
            padding: const EdgeInsets.all(38.38), // Adjust the padding as you need
            child: ClipRRect(
              // 2. (Optional) Add rounded corners to the camera view
              borderRadius: BorderRadius.circular(24.0),
              child: MobileScanner(
                fit: BoxFit.cover, // Use BoxFit.cover for a better aspect ratio
                onDetect: _onDetect,
              ),
            ),
          ),
          _ScannerOverlay(),
          Positioned(
            bottom: 16,
            left: 0,
            right: 0,
            child: Text(
              'Place the code inside the frame',
              textAlign: TextAlign.center,
              style: TextStyle(
                color: Colors.white,
                fontSize: 16,
                fontWeight: FontWeight.bold,
                shadows: [
                  Shadow(
                    blurRadius: 10.0,
                    color: Colors.black.withOpacity(0.5),
                    offset: const Offset(0, 0),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),      bottomNavigationBar: BottomNavBar(
        selectedIndex: _selectedIndex,
        onItemTapped: (index) {
          setState(() => _selectedIndex = index);
          if (index == 0) {
            Navigator.pop(context);
          }
        },
      ),
    );
  }
}

class _ScannerOverlay extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return IgnorePointer(
      child: CustomPaint(
        painter: _OverlayPainter(),
        size: Size.infinite,
      ),
    );
  }
}

class _OverlayPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.white
      ..style = PaintingStyle.stroke
      ..strokeWidth = 3;

    final double padding = 48;
    final rect = RRect.fromRectAndRadius(
      Rect.fromLTWH(padding, padding, size.width - padding * 2, size.height - padding * 2),
      const Radius.circular(12),
    );

    final bg = Paint()..color = Colors.black.withOpacity(0.5);
    final clearPaint = Paint()..blendMode = BlendMode.clear;
    final path = Path()..addRRect(rect);

    canvas.saveLayer(Offset.zero & size, Paint());
    canvas.drawRect(Offset.zero & size, bg);
    canvas.drawPath(path, clearPaint);
    canvas.restore();

    canvas.drawRRect(rect, paint);
  }

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