<template>
 <div class="chart"></div>
</template>

<script>
import { merge } from 'lodash';
import echart from 'echarts';
import { BASIC_OPTION } from './default_option';
import { COLOR_ARRAY } from '../color';
import ResizeListener from 'element-resize-detector';

export default {
 name: 'ChartPie',
 props: {
  seriesData: {
   type: Array,
   required: true,
   default: () => []
  },
  extraOption: {
   type: Object,
   default: () => ({})
  }
 },
 data() {
  return {
   chart: null
  };
 },
 watch: {
  seriesData: {
   deep: true,
   handler() {
    this.updateChartView();
   }
  }
 },
 mounted() {
  this.chart = echart.init(this.$el);
  this.updateChartView();
  window.addEventListener('resize', this.handleWindowResize);
  this.addChartResizeListener();
 },
 beforeDestroy() {
  window.removeEventListener('resize', this.handleWindowResize);
 },
 methods: {
  /**
   * 將業(yè)務(wù)數(shù)據(jù)加入到基礎(chǔ)樣式配置中
   * @returns {Object} 完整的echart配置
   */
  assembleDataToOption() {
   const formatter = name => {
    const total = this.seriesData.reduce((acc, cur) => acc + cur.value, 0);
    const data = this.seriesData.find(item => item.name === name) || {};
    const percent = data.value
     ? `${Math.round((data.value / total) * 100)}%`
     : '0%';

    return `{a|${name}}{b|${percent}}`;
   };

   return merge(
    {},
    BASIC_OPTION,
    { color: COLOR_ARRAY },
    {
     legend: { formatter },
     series: [{ data: this.seriesData }]
    },
    this.extraOption
   );
  },

  /**
   * 對(duì)chart元素尺寸進(jìn)行監(jiān)聽，當(dāng)發(fā)生變化時(shí)同步更新echart視圖
   */
  addChartResizeListener() {
   const instance = ResizeListener({
    strategy: 'scroll',
    callOnAdd: true
   });

   instance.listenTo(this.$el, () => {
    if (!this.chart) return;
    this.chart.resize();
   });
  },

  /**
   * 更新echart視圖
   */
  updateChartView() {
   if (!this.chart) return;

   const fullOption = this.assembleDataToOption();
   this.chart.setOption(fullOption, true);
  },

  /**
   * 當(dāng)窗口縮放時(shí)，echart動(dòng)態(tài)調(diào)整自身大小
   */
  handleWindowResize() {
   if (!this.chart) return;
   this.chart.resize();
  }
 }
};
</script>

<style lang="less" scoped>
.chart {
 width: 100%;
 height: 100%;
}
</style>

<template>
 <van-empty v-if="isSeriesEmpty" />
 <chart-pie v-else v-bind="$props" />
</template>

<script>
import { isEmpty } from 'lodash';
import ChartPie from './echart_pie.vue';

export default {
 name: 'EchartPie',
 components: { ChartPie },
 props: ChartPie.props,
 computed: {
  isSeriesEmpty() {
   return (
    isEmpty(this.seriesData) || this.seriesData.every(item => !item.value)
   );
  }
 }
};
</script>

<template>
<div class="echart-pie-wrap">
 <echart-pie :series-data="dataList" :extra-option="extraOption" />
</div>
</template>

<script>
import EchartPie from '@/components/echarts/echart_pie';

export default{
 components: { EchartPie },
 data() {
  return {
   dataList: [
    {
     name: "西瓜",
     value: 20
    },
    {
     name: "橘子",
     value: 13
    },
    {
     name: "楊桃",
     value: 33
    }
   ],
   extraOption: {
     color: [ '#fe883a', '#2d90d1','#f75981', '#90e2a9']
   }
  }
 }
}

</script>

<style lang="less" scoped>
.echart-wrapper {
 width: 300px;
 height: 300px;
 margin: 10px auto;
}
</style>