<template>
  <div class="my-pagination">
    <a href="javascript:;" :class="{ disabled: currentPage === 1 }" @click="changePage(false)">上一頁</a>
    <span v-if="currentPage > 3">...</span>
    <a
      href="javascript:;" 
      v-for="item in list"
      :key="item"
      :class="{ active: currentPage === item }"
      @click="changePage(item)"
      >{{ item }}</a
    >
    <span v-if="currentPage < pages - 2">...</span>
    <a href="javascript:;" :class="{ disabled: currentPage === pages }" @click="changePage(true)">下一頁</a>
  </div>
</template>
<script>
import { computed, ref } from 'vue-demi'
export default {
  name: 'MyPagination',
  props: {
    total: {
      type: Number,
      default: 80
    },
    pagesize: {
      type: Number,
      default: 10
    }
  },
  setup(props, { emit, attrs }) {
    // 當前頁
    const currentPage = ref(attrs.currentPage)
    // 計算總頁數(shù)
    const pages = computed(() => Math.ceil(props.total / props.pagesize))
    // 頁碼顯示組合
    const list = computed(() => {
      const result = []
      // 總頁數(shù)小于等于5頁的時候
      if (pages <= 5) {
        for (let i = 1; i <= pages; i++) {
          result.push(i)
        }
      } else {
        // 總頁數(shù)大于5頁的時候
        // 控制兩個極端那邊的省略號的有無，頁碼的顯示個數(shù)與選中頁碼居中
        if (currentPage.value <= 2) {
          for (let i = 1; i <= 5; i++) {
            result.push(i)
          }
        } else if (currentPage.value >= 3 && currentPage.value <= pages.value - 2) {
          for (let i = currentPage.value - 2; i <= currentPage.value + 2; i++) {
            result.push(i)
          }
        } else if (currentPage.value > pages.value - 2) {
          for (let i = pages.value - 4; i <= pages.value; i++) {
            result.push(i)
          }
        }
      }
      return result
    })
    // 點擊上一頁下一頁頁碼改變頁碼
    const changePage = type => {
      // 點擊上一頁按鈕
      if (type === false) {
        if (currentPage.value <= 1) return
        currentPage.value -= 1
      } else if (type === true) {
        // 點擊下一頁按鈕
        if (currentPage.value >= pages.value) return
        currentPage.value += 1
      } else {
        // 點擊頁碼
        currentPage.value = type
      }
      // 傳給父組件當前頁碼，可以在該事件中做相關操作
      emit('change-page', currentPage.value)
    }
    return { currentPage, pages, list, changePage }
  }
}
</script>
<style scoped lang="less">
.my-pagination {
  display: flex;
  justify-content: center;
  padding: 30px;
  > a {
    display: inline-block;
    padding: 5px 10px;
    border: 1px solid #e4e4e4;
    border-radius: 4px;
    margin-right: 10px;
    &:hover {
      color: @xtxColor;
    }
    &.active {
      background: @xtxColor;
      color: #fff;
      border-color: @xtxColor;
    }
    &.disabled {
      cursor: not-allowed;
      opacity: 0.4;
      &:hover {
        color: #333;
      }
    }
  }
  > span {
    margin-right: 10px;
  }
}
</style>

<XtxPagination 
:total="total" 
:pagesize="reqParams.pagesize" 
:currentPage="1" 
@change-page="changePage" />