import 'package:flutter/material.dart';

class OutsideDimMask extends StatelessWidget {
  final double opacity;
  const OutsideDimMask({super.key, this.opacity = 0.6});

  @override
  Widget build(BuildContext context) {
    const a5Ratio = 148 / 210;

    return LayoutBuilder(
      builder: (context, constraints) {
        final width = constraints.maxWidth;
        final height = constraints.maxHeight;

        double frameWidth;
        double frameHeight;

        if (width / height > a5Ratio) {
          frameHeight = height;
          frameWidth = height * a5Ratio;
        } else {
          frameWidth = width;
          frameHeight = width / a5Ratio;
        }

        final left = (width - frameWidth) / 2;
        final top = (height - frameHeight) / 2;

        return Stack(
          children: [
            // Top
            Positioned(
              left: 0,
              right: 0,
              top: 0,
              height: top,
              child: Container(color: Colors.black.withOpacity(opacity)),
            ),
            // Bottom
            Positioned(
              left: 0,
              right: 0,
              bottom: 0,
              height: top,
              child: Container(color: Colors.black.withOpacity(opacity)),
            ),
            // Left
            Positioned(
              left: 0,
              top: top,
              width: left,
              height: frameHeight,
              child: Container(color: Colors.black.withOpacity(opacity)),
            ),
            // Right
            Positioned(
              right: 0,
              top: top,
              width: left,
              height: frameHeight,
              child: Container(color: Colors.black.withOpacity(opacity)),
            ),
          ],
        );
      },
    );
  }
}