import Vue from 'vue'
 
// v-dialogDrag: 弹窗拖拽
Vue.directive('dialogDrag', {
  bind (el, binding, vnode, oldVnode) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header')
    const dragDom = el.querySelector('.el-dialog')
    dialogHeaderEl.style.cursor = 'move'
 
    // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
    const sty = dragDom.currentStyle || window.getComputedStyle(dragDom, null)
 
    dialogHeaderEl.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop
      const screenWidth = document.body.clientWidth; // body当前宽度
      const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取)
      const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
      const dragDomheight = dragDom.offsetHeight; // 对话框高度
      const minDragDomLeft = dragDom.offsetLeft;
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;
      const minDragDomTop = dragDom.offsetTop;
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;
 
      // 获取到的值带px 正则匹配替换
      let styL, styT
 
      // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
      if (sty.left.includes('%')) {
        styL = +document.body.clientWidth * (+sty.left.replace(/\%/g, '') / 100)
        styT = +document.body.clientHeight * (+sty.top.replace(/\%/g, '') / 100)
      } else {
        styL = +sty.left.replace(/\px/g, '')
        styT = +sty.top.replace(/\px/g, '')
      }
 
      document.onmousemove = function (e) {
        // 获取body的页面可视宽高
        // var clientHeight = document.documentElement.clientHeight || document.body.clientHeight
        // var clientWidth = document.documentElement.clientWidth || document.body.clientWidth
 
        // 通过事件委托，计算移动的距离
        var l = e.clientX - disX
        var t = e.clientY - disY
 
        // 边界处理
        if (-l > minDragDomLeft) {
          l = -minDragDomLeft;
        } else if (l > maxDragDomLeft) {
          l = maxDragDomLeft;
        }
        if (-t > minDragDomTop) {
          t = -minDragDomTop;
        } else if (t > maxDragDomTop) {
          t = maxDragDomTop;
        }
        // 移动当前元素
        dragDom.style.left = `${l + styL}px`
        dragDom.style.top = `${t + styT}px`
 
        // 将此时的位置传出去
        // binding.value({x:e.pageX,y:e.pageY})
      }
 
      document.onmouseup = function (e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
})