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

/// Resize edge zones for frameless windows.
class WindowResizeZones extends StatelessWidget {
  final Widget child;

  const WindowResizeZones({super.key, required this.child});

  static const _edgeSize = 4.0;
  static const _cornerSize = 10.0;

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        child,

        // Top edge
        _ResizeEdge(
          edge: ResizeEdge.top,
          top: 0, left: _cornerSize, right: _cornerSize, height: _edgeSize,
        ),
        // Bottom edge
        _ResizeEdge(
          edge: ResizeEdge.bottom,
          bottom: 0, left: _cornerSize, right: _cornerSize, height: _edgeSize,
        ),
        // Left edge
        _ResizeEdge(
          edge: ResizeEdge.left,
          left: 0, top: _cornerSize, bottom: _cornerSize, width: _edgeSize,
        ),
        // Right edge
        _ResizeEdge(
          edge: ResizeEdge.right,
          right: 0, top: _cornerSize, bottom: _cornerSize, width: _edgeSize,
        ),

        // Corners
        _ResizeCorner(edge: ResizeEdge.topLeft, top: 0, left: 0),
        _ResizeCorner(edge: ResizeEdge.topRight, top: 0, right: 0),
        _ResizeCorner(edge: ResizeEdge.bottomLeft, bottom: 0, left: 0),
        _ResizeCorner(edge: ResizeEdge.bottomRight, bottom: 0, right: 0),
      ],
    );
  }
}

class _ResizeEdge extends StatelessWidget {
  final ResizeEdge edge;
  final double? top, bottom, left, right, width, height;

  const _ResizeEdge({
    required this.edge,
    this.top, this.bottom, this.left, this.right,
    this.width, this.height,
  });

  MouseCursor _cursor(ResizeEdge e) {
    return switch (e) {
      ResizeEdge.top || ResizeEdge.bottom => SystemMouseCursors.resizeRow,
      ResizeEdge.left || ResizeEdge.right => SystemMouseCursors.resizeColumn,
      _ => SystemMouseCursors.basic,
    };
  }

  @override
  Widget build(BuildContext context) {
    return Positioned(
      top: top, bottom: bottom, left: left, right: right,
      width: width, height: height,
      child: MouseRegion(
        cursor: _cursor(edge),
        child: GestureDetector(
          behavior: HitTestBehavior.opaque,
          onPanStart: (_) => windowManager.startResizing(edge),
        ),
      ),
    );
  }
}

class _ResizeCorner extends StatelessWidget {
  final ResizeEdge edge;
  final double? top, bottom, left, right;

  const _ResizeCorner({
    required this.edge,
    this.top, this.bottom, this.left, this.right,
  });

  MouseCursor _cursor(ResizeEdge e) {
    return switch (e) {
      ResizeEdge.topLeft || ResizeEdge.bottomRight =>
        SystemMouseCursors.resizeDownLeft,
      ResizeEdge.topRight || ResizeEdge.bottomLeft =>
        SystemMouseCursors.resizeDownRight,
      _ => SystemMouseCursors.basic,
    };
  }

  @override
  Widget build(BuildContext context) {
    return Positioned(
      top: top, bottom: bottom, left: left, right: right,
      width: WindowResizeZones._cornerSize,
      height: WindowResizeZones._cornerSize,
      child: MouseRegion(
        cursor: _cursor(edge),
        child: GestureDetector(
          behavior: HitTestBehavior.opaque,
          onPanStart: (_) => windowManager.startResizing(edge),
        ),
      ),
    );
  }
}