<template>
  <div class="slider-headimg">
    <div class="out">
      <div class="inner">
        <div class="img" ref="headimgList" v-for="(item,index) in sliderHeadimgList" :key="index">
          <img :src="item.headImgUrl">
        </div>
      </div>
    </div>
  </div>
</template>
<script>
export default {
  props: {
    sliderHeadimgList: {
      type: Array,
      default: () => []
    }
  },
  data () {
    return {
      timer: null,
      // 定義位置數組
      idArr: ['first', 'second', 'right', 'last']
    }
  },
  mounted () {
    this.init()
  },
  destroyed () {
    if (this.timer) {
      clearInterval(this.timer)
    }
  },
  methods: {
    init () {
    // 初始化圖片位置，根據id不同，初始化樣式
      var img = this.$refs.headimgList
      img[0].id = this.idArr[0]
      img[1].id = this.idArr[1]
      img[3].id = this.idArr[3]
      for (let i = 0; i < (this.sliderHeadimgList.length - 4); i++) {
        this.idArr.splice(3, 0, 'left')
      }
      this.initialize()
      // 定時器圖片輪播
      this.timer = setInterval(this.next, 1000)
    },
    next () {
    // 將位置數組的最后一個元素刪除，并將刪除元素添加到位置數組第一個
      this.idArr.unshift(this.idArr.pop())
      this.initialize()
    },
    // 將位置數組元素作為id賦值給img，達到輪播效果
    initialize () {
      var img = this.$refs.headimgList
      for (var i = 0; i < img.length; i++) {
        img[i].id = this.idArr[i]
      }
    }
  }
}
</script>
<style lang="less">
.slider-headimg {
  position: relative;
  display: flex;
  align-items: center;
  width: 200px;
  padding-bottom: 55px;
  margin-right: 10px;
}
.out {
  width: 100%;
  height: 100%;
  position: relative;
  .inner {
    width: 100%;
    .img {
      width: 48px;
      height: 48px;
      position: absolute;
      transition: 0.3s;
      display: flex;
      border-radius: 50%;
      border: 1px solid #fff;
      img {
        width: 100%;
        height: 100%;
        border-radius: 50%;
      }
    }
  }
  //設置id樣式
  #last {
    display: flex;
    transform: translateX(48px);
    z-index: 3;
    opacity: 1;
  }
  #first {
    display: flex;
    transform: translateX(96px);
    z-index: 2;
    opacity: 1;
  }
  #second {
    display: flex;
    transform: translateX(144px);
    z-index: 1;
    opacity: 1;
  }
  #left {
    display: none;
    transform: translateX(-48px);
    z-index: 1;
    opacity: 0;
  }
  #right {
    display: flex;
    transform: translateX(240px);
    z-index: 1;
    opacity: 0;
  }
}
</style>