<template>
  <div class="standard-table">
    <div class="alert">
      <a-alert type="info" :show-icon="true">
        <div slot="message">
          已选择&nbsp;<a style="font-weight: 600">{{ selectedRows.length }}</a>&nbsp;&nbsp;
          <template v-for="(item, index) in needTotalList" v-if="item.needTotal">
            {{ item.title }} 总计&nbsp;
            <a :key="index" style="font-weight: 600">
              {{ item.customRender ? item.customRender(item.total) : item.total }}
            </a>&nbsp;&nbsp;
          </template>
          <a style="margin-left: 24px" @click="onClearSelected">清空</a>
        </div>
      </a-alert>
    </div>
    <a-table
      :size="size"
      :bordered="bordered"
      :loading="loading"
      :columns="columns"
      :dataSource="current"
      :rowKey="rowKey"
      :pagination="pagination"
      :rowSelection="{ selectedRowKeys: selectedRowKeys, onChange: updateSelect }"
    >
    </a-table>
  </div>
</template>

<script>
export default {
  name: "StandardTable",
  // props: ['bordered', 'loading', 'columns', 'data', 'rowKey', 'pagination', 'selectedRows'],
  props: {

    /**
     * 数据加载函数，返回值必须是 Promise
     * 默认情况下必须传递 data 参数；
     *    如果使用本地数据渲染表格，业务代码中将获取本地数据包装为 Promise 即可。
     *
     * currentData 用于向外暴露表格当前渲染的数据，
     * 业务开发中也可以直接修改 currentData，从而重新渲染表格（仅推荐用于客户端排序、数据过滤等场景）
     */
    data: {
      type: Function,
      required: true
    },
    dataSource: {
      type: Array,
      default() {
        return []
      }
    },
    columns: {
      type: Array,
      required: true
    },
    /*      pagination: {
            type: Object,
            default () {
              return {}
            }
          },*/
    pageSize: {
      type: Number,
      default: 10
    },
    pageNum: {
      type: Number,
      default: 1
    },
    pageSizeOptions: {
      type: Array,
      default() {
        return ['10', '20', '30', '40', '50']
      }
    },
    responseParamsName: {
      type: Object,
      default() {
        return {}
      }
    },
    bordered: {
      type: Boolean,
      default: false
    },
    /**
     * 表格大小风格，default, middle, small
     */
    size: {
      type: String,
      default: 'default'
    },
    rowKey: {
      type: String,
      default: ''
    },
    selectedRows: {
      type: Array,
      default: null
    }
  },
  data() {
    return {
      needTotalList: [],
      selectedRowKeys: [],

      loading: true,

      total: 0,
      pageNumber: this.pageNum,
      currentPageSize: this.pageSize,
      defaultCurrent: 1,
      sortParams: {},

      current: [],
      pagination: {},
      paramsName: {},
    }
  },
  created() {
    //数据请求参数配置
    this.paramsName = Object.assign(
      {},
      {
        pageNumber: "pageNo",
        pageSize: "pageSize",
        total: "totalCount",
        results: "data",
        sortColumns: "sortColumns"
      },
      this.responseParamsName
    );

    this.needTotalList = this.initTotalList(this.columns)

    // load data
    this.loadData({pageNum: this.pageNumber})
  },
  methods: {
    updateSelect(selectedRowKeys, selectedRows) {
      this.selectedRowKeys = selectedRowKeys
      let list = this.needTotalList
      this.needTotalList = list.map(item => {
        return {
          ...item,
          total: selectedRows.reduce((sum, val) => {
            return sum + val[item.dataIndex]
          }, 0)
        }
      })
      this.$emit('change', selectedRowKeys, selectedRows)
    },
    initTotalList(columns) {
      const totalList = []
      columns.forEach(column => {
        if (column.needTotal) {
          totalList.push({...column, total: 0})
        }
      })
      return totalList
    },

    loadData(params) {
      let that = this
      that.loading = true
      params = Object.assign({}, params)
      const remoteParams = Object.assign({}, that.sortParams)
      remoteParams[that.paramsName.pageNumber] = params.pageNum || that.pageNumber
      remoteParams[that.paramsName.pageSize] = params.pageSize || that.currentPageSize

      if (params.pageNum) {
        that.pageNumber = params.pageNum
      }
      if (params.pageSize) {
        that.currentPageSize = params.pageSize
      }

      let dataPromise = that.data(remoteParams)

      dataPromise.then(response => {
        if (!response) {
          that.loading = false
          return
        }
        let results = response[that.paramsName.results]
        results = (results instanceof Array && results) || []

        that.current = results

        that.$emit("update:currentData", that.current.slice())
        that.$emit("dataloaded", that.current.slice())

        that.total = response[that.paramsName.total] * 1
        that.pagination = that.pager()
        that.loading = false
      }, () => {
        // error callback
        that.loading = false
      })
    },
    // eslint-disable-next-line
    onPagerChange(page, pageSize) {
      this.pageNumber = page
      this.loadData({pageNum: page})
    },
    onPagerSizeChange(current, size) {
      this.currentPageSize = size
      /*
      if (current === this.pageNumber) this.loadData()
      console.log('page-size-change', current, size)
      */
    },
    onClearSelected() {
      this.selectedRowKeys = []
      this.updateSelect([], [])
    },
    pager() {
      return {
        total: this.total,
        showTotal: total => `共有 ${total} 条`,
        showSizeChanger: true,
        pageSizeOptions: this.pageSizeOptions,
        pageSize: this.pageSize,
        defaultCurrent: this.defaultCurrent,
        onChange: this.onPagerChange,
        onShowSizeChange: this.onPagerSizeChange
      }
    }
  },
  watch: {
    'selectedRows': function (selectedRows) {
      this.needTotalList = this.needTotalList.map(item => {
        return {
          ...item,
          total: selectedRows.reduce((sum, val) => {
            return sum + val[item.dataIndex]
          }, 0)
        }
      })
    }
  }
}
</script>

<style scoped>
.alert {
  margin-bottom: 16px;
}
</style>