/**
 * 函数防抖
 */
export function debounce(fn, delay) {
  // 记录上一次的延时器
  var timer = null;
  var delay = delay || 200;
  return function() {
    var args = arguments;
    var that = this;
    // 清除上一次延时器
    clearTimeout(timer);
    timer = setTimeout(function() {
      fn.apply(that, args);
    }, delay);
  };
}

// 图片旋转处理 -> base64
export const rotateBase64Img = (src, edg, callback) => {
  try {
    const canvas = document.createElement("canvas");
    const ctx = canvas.getContext("2d");

    let imgW = 0; // 图片宽度
    let imgH = 0; // 图片高度
    let size = 0; // canvas初始大小

    if (edg % 90 !== 0) {
      throw new Error("旋转角度必须是90的倍数!");
    }

    edg < 0 && (edg = (edg % 360) + 360);
    const quadrant = (edg / 90) % 4; // 旋转象限
    const cutCoor = { sx: 0, sy: 0, ex: 0, ey: 0 }; // 裁剪坐标

    const image = new Image();
    image.src = src;
    image.crossOrigin = "anonymous";

    image.onload = function() {
      imgW = image.width;
      imgH = image.height;
      size = imgW > imgH ? imgW : imgH;

      canvas.width = size * 2;
      canvas.height = size * 2;
      switch (quadrant) {
        case 0:
          cutCoor.sx = size;
          cutCoor.sy = size;
          cutCoor.ex = size + imgW;
          cutCoor.ey = size + imgH;
          break;
        case 1:
          cutCoor.sx = size - imgH;
          cutCoor.sy = size;
          cutCoor.ex = size;
          cutCoor.ey = size + imgW;
          break;
        case 2:
          cutCoor.sx = size - imgW;
          cutCoor.sy = size - imgH;
          cutCoor.ex = size;
          cutCoor.ey = size;
          break;
        case 3:
          cutCoor.sx = size;
          cutCoor.sy = size - imgW;
          cutCoor.ex = size + imgH;
          cutCoor.ey = size + imgW;
          break;
      }

      ctx.translate(size, size);
      ctx.rotate((edg * Math.PI) / 180);
      ctx.drawImage(image, 0, 0);

      const imgData = ctx.getImageData(
        cutCoor.sx,
        cutCoor.sy,
        cutCoor.ex,
        cutCoor.ey
      );
      if (quadrant % 2 === 0) {
        canvas.width = imgW;
        canvas.height = imgH;
      } else {
        canvas.width = imgH;
        canvas.height = imgW;
      }
      ctx.putImageData(imgData, 0, 0);

      if (typeof callback === "function") {
        callback(canvas.toDataURL("image/png", 0.7));
      }
    };
  } catch (e) {
    console.log(e);
  }
};
