'use strict';

// 拖边缘改大小的纯计算部分单独放一个文件：
// 这段几何运算是最容易出错、但在无边框窗口里只能靠真鼠标才能触发的地方，
// 拆出来之后可以在 node 里直接跑用例，不必等到 Windows 上肉眼试。

const MIN_SIZE = { width: 260, height: 150 };

function computeBounds(start, dir, dx, dy, min) {
  const limit = min || MIN_SIZE;
  let x = start.x;
  let y = start.y;
  let width = start.width;
  let height = start.height;

  if (dir.includes('e')) width += dx;
  if (dir.includes('s')) height += dy;
  if (dir.includes('w')) {
    width -= dx;
    x += dx;
  }
  if (dir.includes('n')) {
    height -= dy;
    y += dy;
  }

  // 顶到最小尺寸后继续拖，被拖的那条边要停住，而不是把整个窗口推走
  if (width < limit.width) {
    if (dir.includes('w')) x = start.x + start.width - limit.width;
    width = limit.width;
  }
  if (height < limit.height) {
    if (dir.includes('n')) y = start.y + start.height - limit.height;
    height = limit.height;
  }

  return { x: Math.round(x), y: Math.round(y), width: Math.round(width), height: Math.round(height) };
}

if (typeof module !== 'undefined' && module.exports) {
  module.exports = { computeBounds, MIN_SIZE };
}