<template>
  <div id="dropMenu"
       :style="style"
       style="display: block;"
       v-show="show"
       @mousedown.stop   
       @contextmenu.prevent><!--阻止冒泡事件 阻止右键的默认事件-->
    <slot></slot>
  </div>
</template>
<script>
export default {
  data() {
    return {
      triggerShowFn: () => {},
      triggerHideFn: () => {},
      x: null,
      y: null,
      style: {},
      binded: false
    }
  },
  props: {
    target: null,
    show: Boolean
  },
  mounted() {
    this.bindEvents()
  },
  watch: {
    show(show) {
      if (show) {
        this.bindHideEvents()
      } else {
        this.unbindHideEvents()
      }
    },
    target(target) {
      this.bindEvents()
    }
  },
  methods: {
    // 初始化事件
    bindEvents() {
      this.$nextTick(() => {
        var that = this
        if (!this.target || this.binded) return
        console.log(this);
        this.triggerShowFn = this.contextMenuHandler.bind(this)
        this.target.addEventListener('contextmenu', this.triggerShowFn)
        //this.binded = true
      })
    },
    // 取消绑定事件
    unbindEvents() {
      if (!this.target) return
      this.target.removeEventListener('contextmenu', this.triggerShowFn)
    },
    // 绑定隐藏菜单事件
    bindHideEvents() {
      this.triggerHideFn = this.clickDocumentHandler.bind(this)
      document.addEventListener('mousedown', this.triggerHideFn)
      document.addEventListener('mousewheel', this.triggerHideFn)
    },
    // 取消绑定隐藏菜单事件
    unbindHideEvents() {
      document.removeEventListener('mousedown', this.triggerHideFn)
      document.removeEventListener('mousewheel', this.triggerHideFn)
    },
    // 鼠标按压事件处理器
    clickDocumentHandler(e) {
      this.$emit('update:show', false) //隐藏
    },
    // 右键事件事件处理
    contextMenuHandler(e) {

      e.target.click()//这个是因为我需要获取tree节点的数据，所以我通过点击事件去获取数据
      this.x = e.clientX 
      this.y = e.clientY - 110
      this.layout()
      this.$emit('update:show', true)  //显示
      e.preventDefault()
      e.stopPropagation()

      this.$emit('targetElement', e.target) //我还要获取右键的DOM元素进行操作
    },
    // 布局
    layout() {
      this.style = {
        left: this.x + 'px',
        top: this.y + 'px'
      }
    }
  }
}
</script>
<style lang="scss">
#dropMenu {
  position: absolute;
  margin: 0;
  padding: 0;
  width: 120px;
  height: auto;
  border: 1px solid #ccc;
  border-radius: 4px;
  ul {
    list-style: none;
    margin: 0;
    padding: 0;
    li {
      width: 100%;
      text-align: center;
      height: 30px;
      line-height: 30px;
      background: #fff;
      margin-bottom: 1px;
      font-size:16px;
      
      cursor: pointer;

      li:hover {
  color: deeppink;
  text-decoration: underline;
  }
    }
    
  }
}
</style>