<template>
  <el-autocomplete
    ref="autocomplete"
    value-key="value"
    v-scrollLoad="selectLoadMore"
    v-loading="loading"
    v-model="state"
    :fetch-suggestions="querySearch"
    :placeholder="placeholder"
    :trigger-on-focus="false"
    @select="handleSelect"
  ></el-autocomplete>
</template>
 
<script>
export default {
  name: 'InputLoadMore',
  props: {
    // 封装的查数据方法
    getOptionFn: {
      require: true
    },
    // 后端定义的联想的key
    searchKey: {
      type: String,
      require: true
    },
    // v-model的绑定值
    value: {
      type: String,
      require: true
    },
    // placehoder
    placeholder: {
      type: String,
      default: '请输入'
    }
  },
  data() {
    return {
      state: '',
      loading: false,
      page: 1,
      pageTotal: 0
    }
  },
  watch: {
    state(val) {
      this.$emit('input', val)
    },
    value(val) {
      this.state = val
    }
  },
  directives: {
    // 自定义指令，监听下拉框的滚动，滚动到底部就加载下一页
    scrollLoad: {
      bind(el, binding, vnode) {
        let wrapDom = el.querySelector('.el-autocomplete-suggestion__wrap')
        let listDom = el.querySelector('.el-autocomplete-suggestion__wrap  .el-autocomplete-suggestion__list')
        wrapDom.addEventListener(
          'scroll',
          e => {
            // 注意load的使用，节流
            let condition = wrapDom.offsetHeight + wrapDom.scrollTop + 10 - listDom.offsetHeight
            if (condition > 0 && !vnode.context.loading) {
              //滚动到底部则执行滚动方法load，binding.value就是v-scrollLoad绑定的值，加()表示执行绑定的方法
              binding.value()
            }
          },
          false
        )
      }
    }
  },
  methods: {
    async querySearch(queryString, cb) {
      this.page = 1
      this.loading = true
      try {
        let { result } = await this.getOptionFn({
          page: 1,
          pageSize: 50,
          [this.searchKey]: queryString
        })
        // 根据实际情况修改下面的代码，展示数据
        if (result.rows) {
          let arr = []
          result.rows.forEach(item => {
            arr.push({ value: item })
          })
          cb(arr)
        } else {
          cb([])
        }
        this.pageTotal = result.total || 0
      } catch(e) {
        // console.log(e)
      } finally {
        this.loading = false
      }
    },
    handleSelect(item) {},
    // 加载更多
    async selectLoadMore() {
      if(Number(this.pageTotal) <= this.$refs['autocomplete'].$data.suggestions.length) {
        return
      }
      this.page = this.page + 1
      this.loading = true
      try {
        let { result } = await this.getOptionFn({
          page: this.page,
          pageSize: 50,
          [this.searchKey]: this.state
        })
        // 根据实际情况修改下面的代码，展示数据
        if (result.rows) {
          const arr = result.rows.map(item => {
            return { value: item }
          })
          // 将数据添加到下拉列表
          this.$refs['autocomplete'].$data.suggestions = this.$refs['autocomplete'].$data.suggestions.concat(arr)
        }
        this.pageTotal = result.total || 0
      } catch(e) {
        // console.log(e)
      } finally {
        this.loading = false
      }
    }
  }
}
</script>
</script>

// 自定义指令，监听下拉框的滚动，滚动到底部就加载下一页
    scrollLoad: {
      bind(el, binding, vnode) {
        let wrapDom = el.querySelector('.el-autocomplete-suggestion__wrap')
        let listDom = el.querySelector('.el-autocomplete-suggestion__wrap  .el-autocomplete-suggestion__list')
        wrapDom.addEventListener(
          'scroll',
          e => {
            // 注意load的使用，节流
            let condition = wrapDom.offsetHeight + wrapDom.scrollTop + 10 - listDom.offsetHeight
            if (condition > 0 && !vnode.context.loading) {
              //滚动到底部则执行滚动方法load，binding.value就是v-scrollLoad绑定的值，加()表示执行绑定的方法
              binding.value()
            }
          },
          false
        )
      }

this.$refs['autocomplete'].$data.suggestions // 下拉的列表

if(Number(this.pageTotal) <= this.$refs['autocomplete'].$data.suggestions.length) {
    return
  }