<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.$nextTick(() => {
        if (!this.target || this.binded) return;
        this.triggerShowFn = this.contextMenuHandler.bind(this);
        this.target.addEventListener("contextmenu", this.triggerShowFn);
      });
    },
    // 取消绑定事件
    unbindEvents() {
      if (!this.target) return;
      this.target.removeEventListener("contextmenu", this.triggerShowFn);
    },
    // 绑定隐藏菜单事件
    bindHideEvents() {
      this.triggerHideFn = this.clickDocumentHandler.bind(this);
      document.addEventListener("mousedown", this.triggerHideFn);
      document.addEventListener("mousewheel", this.triggerHideFn);
    },
    // 取消绑定隐藏菜单事件
    unbindHideEvents() {
      document.removeEventListener("mousedown", this.triggerHideFn);
      document.removeEventListener("mousewheel", this.triggerHideFn);
    },
    // 鼠标按压事件处理器
    clickDocumentHandler(e) {
      this.$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>