export default {
  bind(el, binding, vnode) {
    if (
      el.querySelector(".el-dialog__header") &&
      el.querySelector(".el-dialog")
    ) {
      const dialogHeaderEl = el.querySelector(".el-dialog__header");
      const dragDom = el.querySelector(".el-dialog");
      dialogHeaderEl.style.cssText += ";cursor:move;";
      dragDom.style.cssText += ";top:0;";

      const getStyle = (function () {
        if (window.document.currentStyle) {
          return (dom, attr) => dom.currentStyle[attr];
        } else {
          return (dom, attr) => getComputedStyle(dom, false)[attr];
        }
      })();

      dialogHeaderEl.onmousedown = (e) => {
        const disX = e.clientX - dialogHeaderEl.offsetLeft;
        const disY = e.clientY - dialogHeaderEl.offsetTop;

        const dragDomWidth = dragDom.offsetWidth;
        const dragDomHeight = dragDom.offsetHeight;

        const screenWidth = document.body.clientWidth;
        const screenHeight = document.body.clientHeight;

        const minDragDomLeft = dragDom.offsetLeft;
        const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;

        const minDragDomTop = dragDom.offsetTop;
        const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomHeight;

        let styL = getStyle(dragDom, "left");
        let styT = getStyle(dragDom, "top");

        if (styL.includes("%")) {
          styL = +document.body.clientWidth * (+styL / 100);
          styT = +document.body.clientHeight * (+styT / 100);
        } else {
          styL = +styL.replace(/\px/g, "");
          styT = +styT.replace(/\px/g, "");
        }

        document.onmousemove = function (e) {
          let left = e.clientX - disX;
          let top = e.clientY - disY;

          if (-left > minDragDomLeft) {
            left = -minDragDomLeft;
          } else if (left > maxDragDomLeft) {
            left = maxDragDomLeft;
          }

          if (-top > minDragDomTop) {
            top = -minDragDomTop;
          } else if (top > maxDragDomTop) {
            top = maxDragDomTop;
          }

          dragDom.style.cssText += `;left:${left + styL}px;top:${
            top + styT
          }px;`;

          vnode.child.$emit("dragDialog");
        };

        document.onmouseup = function (e) {
          document.onmousemove = null;
          document.onmouseup = null;
        };
      };
    }
  },
};