<template>
  <div>
    <ul   :total="total" :pageSize="pageSize" :pageNum="pageNum">
      <li @click="leftRight(1)">
        <上一页
      </li>
      <li @click="pageClick(item)" :style="{color:item==page?'red':'black'}" v-for="item in arr" :key="item">{{item}}
      </li>
      <li @click="leftRight(2)">下一页></li>
    </ul>
  </div>
</template>

<script>
  export default {
    props: {
      total: {
        type: Number,
        default: 0
      },
      pageSize: {
        type: Number,
        default: 10
      },
      pageNum: {
        type: Number,
        default: 1
      },
    },
    data() {
      return {
        length: 0,
        page: 1,
        arr: [],
      }
    },
    mounted() {
      this.getLength()
    },
    methods: {
      getLength() {//获取页码大小并初始化页面
        let shuzu = [];
        if (this.total % this.pageSize == 0) {
          this.length = this.total / this.pageSize;
        } else {
          this.length = parseInt(this.total / this.pageSize) + 1;

        }
        // console.log(this.length + 'this.length')
        if (this.length >= 10) {
          shuzu.length = 10
        } else {
          shuzu.length = this.length
        }
        for (let i = 0; i <shuzu.length; i++) {
          shuzu[i] = i + 1
        }
        this.arr = shuzu
      },
      getpage(page) {
        let shuzu = [];
        let j = 0
        let str = 0
        if (page + 5 <= this.length) {
          str = page + 5
          j = page - 5
        } else {
          str = page + (this.length - page)
          j = str - 10
        }

        for (let i = j+1; i <= str; i++) {
          shuzu.push(i)
        }
        this.arr = shuzu
      },
      pageClick(page) {
        this.page = page
        // console.log(this.arr.length)
        if (page <= this.arr.length / 2 || this.length <= 10) {
          alert('1')
          this.getLength()
        } else {
          this.getpage(page)
        }
        this.pageNumChange(this.page)
      },
      leftRight(e){
        switch (e){
          case 1:
            if(this.page==1){
              this.page=1
            }
            else {
              this.page-=1
            }
            this.pageClick(this.page)
            break;
          case 2:
            if(this.page==this.length){
              this.page=this.length
            }else {
              this.page+=1
            }
            this.pageClick(this.page)
            break;
        }
        this.pageNumChange(this.page)
      },
      pageNumChange(page){
        this.$emit('pageNumChange',page)
      }
    }
  }
</script>

<style scoped>
  * {
    margin: 0;
    padding: 0;
  }

  ul > li {
    -ms-user-select:none;
    margin:0 2px;
    display: inline-block;
    border: 1px black solid;
    min-width: 20px;
    height: 20px;
    border-radius: 2px;
    cursor: pointer;
    vertical-align: middle;
  }

  li:hover {
    border: 1px cornflowerblue solid;
  }
</style>