<template>
  <div class="text-expand" ref="textExpand">
    <div v-if="!(showPopover && showPopoverJudge)">
      <span class="text-expand-content" :style="expandStyle">
        {{ (text === null || text === undefined || text === '') ? '--' : text }}
      </span>
      <div class="expander">
        <span
          v-if="showBtn && showBtnJudge"
        >
          <span
            v-if="!showFull"
            class="action action-expand"
            @click.stop="showFullFn(true)"
          >
            展开
            <i v-if="showBtnIcon" class="iconfont iconxiajiantou" />
          </span>
          <span
            v-else
            class="action action-pack"
            @click.stop="showFullFn(false)"
          >
            收起
            <i v-if="showBtnIcon" class="iconfont iconshangjiantou" />
          </span>
        </span>
      </div>
    </div>
    <el-popover
      v-else
      :placement="popoverPlace"
      trigger="hover">
      <div class="popover-content">
        {{ text }}
      </div>
      <span class="text-expand-content" :style="expandStyle" slot="reference">{{ text }}</span>
    </el-popover>
  </div>
</template>
<script>
export default {
  name: "TextExpand",
  props: {
    text: { // 文本内容
      type: String,
      default: () => ''
    },
    expand: { // 折叠显示行数
      type: Number,
      default: () => 3
    },
    showBtn: { // 展开、折叠按钮
      type: Boolean,
      default: true
    },
    showBtnIcon: { // 展开、折叠icon
      type: Boolean,
      default: true
    },
    showPopover: { // popover显示全文本
      type: Boolean,
      default: false
    },
    popoverPlace: { // popover位置
      type: String,
      default: 'bottom'
    }
  },
  data () {
    return {
      showFull: false, // 是否展示全文本
      expandStyle: '',
      showBtnJudge: false, // 判断是否需要折叠展示按钮
      showPopoverJudge: false // 判断是否需要折叠展示popover
    }
  },
  watch: {
    text: function (val) {
      this.judgeExpand()
    }
  },
  mounted () { 
    this.judgeExpand()
  },
  methods: {
    showFullFn (value) {
      this.expandStyle = value ? '' : `display: -webkit-box;word-break: break-all;-webkit-line-clamp: ${this.expand};-webkit-box-orient: vertical;text-overflow: ellipsis;overflow: hidden;`
      this.showFull = value
    },
    judgeExpand () { // 判断是否需要折叠
      this.$nextTick(() => {
        const { expand } = this;
        const textExpandStyle = window.getComputedStyle(this.$refs.textExpand)
        const textExpandHeight = parseFloat(textExpandStyle.height) //获取总高度
        const textExpandLineHeight = parseFloat(textExpandStyle.lineHeight) //获取行高
        // 计算行高
        const rects = Math.ceil(textExpandHeight / textExpandLineHeight)
        if (rects <= expand) { // 不需要折叠展示
          this.showBtnJudge = false
          this.showPopoverJudge = false
        } else {
          this.showBtnJudge = true
          this.showPopoverJudge = true
          this.expandStyle = `display: -webkit-box;word-break: break-all;-webkit-line-clamp: ${this.expand};-webkit-box-orient: vertical;text-overflow: ellipsis;overflow: hidden;`
        }
      })
    }

  }
}
</script>
<style lang="less" scoped>
.text-expand{
  &-content{
    word-break: break-all;
    white-space: pre-wrap;
  }
  .expander {
    text-align: left;
    margin-top: 6px;
    .action {
      display: inline-block;
      font-size: 14px;
      color: #0281F0;
      cursor: pointer;
      i {
        display: inline;
        font-size: 12px;
      }
    }
    .action.action-pack {
      margin-left: 0;
    }
  }
}
.popover-content{
  max-width: 40vw;
  max-height: 30vh;
  overflow: hidden;
  word-break: break-all;
  overflow-y: auto;
}
</style>