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

class BarcodeOverlay extends CustomPainter {
  BarcodeOverlay({
    required this.barcodeCorners,
    required this.barcodeSize,
    required this.boxFit,
    required this.cameraPreviewSize,
  });

  final List<Offset> barcodeCorners;
  final Size barcodeSize;
  final BoxFit boxFit;
  final Size cameraPreviewSize;

  @override
  void paint(Canvas canvas, Size size) {
    if (barcodeCorners.isEmpty ||
        barcodeSize.isEmpty ||
        cameraPreviewSize.isEmpty) {
      return;
    }

    final adjustedSize = applyBoxFit(boxFit, cameraPreviewSize, size);

    double verticalPadding = size.height - adjustedSize.destination.height;
    double horizontalPadding = size.width - adjustedSize.destination.width;
    if (verticalPadding > 0) {
      verticalPadding = verticalPadding / 2;
    } else {
      verticalPadding = 0;
    }

    if (horizontalPadding > 0) {
      horizontalPadding = horizontalPadding / 2;
    } else {
      horizontalPadding = 0;
    }

    final double ratioWidth;
    final double ratioHeight;

    if (!kIsWeb && defaultTargetPlatform == TargetPlatform.iOS) {
      ratioWidth = barcodeSize.width / adjustedSize.destination.width;
      ratioHeight = barcodeSize.height / adjustedSize.destination.height;
    } else {
      ratioWidth = cameraPreviewSize.width / adjustedSize.destination.width;
      ratioHeight = cameraPreviewSize.height / adjustedSize.destination.height;
    }

    final List<Offset> adjustedOffset = [
      for (final offset in barcodeCorners)
        Offset(
          offset.dx / ratioWidth + horizontalPadding,
          offset.dy / ratioHeight + verticalPadding,
        ),
    ];

    final cutoutPath = Path()..addPolygon(adjustedOffset, true);

    final backgroundPaint = Paint()
      ..color = Colors.red.withOpacity(1.0)
      ..style = PaintingStyle.fill
      ..blendMode = BlendMode.dstOut;

    canvas.drawPath(cutoutPath, backgroundPaint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    return false;
  }
}