<template>
  <div :style="style" style="display: block;" v-show="show"
    @mousedown.stop
    @contextmenu.prevent
  >
    <slot></slot>
  </div>
</template>

<script>
export default {
  name: 'context-menu',
  data() {
    return {
      target: null,
      triggerShowFn: () => {},
      triggerHideFn: () => {},
      x: null,
      y: null,
      style: {},
      binded: false
    };
  },
  props: {
    // target: null,
    show: Boolean
  },
  mounted() {
    // console.log(this.$parent.$el);
    this.target = this.$parent.$el;
    this.bindEvents();
  },
  watch: {
    show(show) {
      if (show) {
        this.bindHideEvents();
      } else {
        this.unbindHideEvents();
      }
    },
    target(target) {
      this.bindEvents();
    }
  },
  methods: {
    // 初始化事件
    bindEvents() {
      this.$nextTick(() => {
        if (!this.target || this.binded) return;
        this.triggerShowFn = this.contextMenuHandler.bind(this);
        this.target.addEventListener('contextmenu', this.triggerShowFn);
        this.binded = true;
      });
    },
    // 取消绑定事件
    unbindEvents() {
      if (!this.target) return;
      this.target.removeEventListener('contextmenu', this.triggerShowFn);
    },
    // 绑定隐藏菜单事件
    bindHideEvents() {
      this.triggerHideFn = this.clickDocumentHandler.bind(this);
      document.addEventListener('mousedown', this.triggerHideFn);
      document.addEventListener('mousewheel', this.triggerHideFn);
    },
    // 取消绑定隐藏菜单事件
    unbindHideEvents() {
      document.removeEventListener('mousedown', this.triggerHideFn);
      document.removeEventListener('mousewheel', this.triggerHideFn);
    },
    // 鼠标按压事件处理器
    clickDocumentHandler(e) {
      this.$emit('update:show', false);
    },
    // 右键事件事件处理
    contextMenuHandler(e) {
      this.x = e.clientX;
      this.y = e.clientY;
      this.layout();
      this.$emit('update:show', true);
      e.preventDefault();
    },
    // 布局
    layout() {
      this.style = {
        left: this.x + 'px',
        top: this.y + 'px'
      };
    }
  }
};
</script>