<template>
  <div ref="videoArea" class="video_area" :style="getAreaStyle()">
    <SerialNumberPosition v-if="isEnable(data.property.sn_display_mode)" :property="data.property" />
    <div ref="videoAreaBox" class="main">
      <ul v-if="'independent' === data.property.view_method" class="view-independent">
        <li v-for="(file, i) in data.file_list" :key="i">
          <VideoPlay
            view-size="small"
            view-method="independent"
            :file-id="file.file_id"
            :cur-video-index="curVideoIndex"
            @changeFile="changeFile"
          />
        </li>
      </ul>
      <div v-else class="view-list">
        <el-carousel
          ref="video_carousel"
          indicator-position="none"
          direction="vertical"
          :autoplay="false"
          :interval="0"
          :style="{ width: elementWidth - 248 - 32 + 'px', height: elementHeight <= 0 ? 139 : elementHeight + 'px' }"
        >
          <el-carousel-item v-for="(file, i) in data.file_list" :key="i">
            <VideoPlay
              view-size="big"
              :file-id="file.file_id"
              :cur-video-index="curVideoIndex"
              @changeFile="changeFile"
            />
          </el-carousel-item>
        </el-carousel>
        <div class="container-box" :style="{ height: elementHeight <= 0 ? 139 : elementHeight + 'px' }">
          <ul
            ref="container"
            class="view-list-bottom"
            :style="{ height: elementHeight + 'px', transform: `translateY(${translateY}px)` }"
          >
            <li v-for="(file, i) in data.file_list" :key="i" @click="handleAudioClick(i)">
              <VideoPlay view-size="small" :file-id="file.file_id" :audio-index="i" :cur-video-index="curVideoIndex" />
            </li>
          </ul>
          <button v-if="viewTopBottomBtn" class="arrow top" @click="scroll(1)">
            <i class="el-icon-arrow-up"></i>
          </button>
          <button v-if="viewTopBottomBtn" class="arrow bottom" @click="scroll(-1)">
            <i class="el-icon-arrow-down"></i>
          </button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
import { getVideoData } from '@/views/book/courseware/data/video';
import PreviewMixin from '../common/PreviewMixin';
import VideoPlay from '../common/VideoPlay.vue';

export default {
  name: 'VideoPreview',
  components: { VideoPlay },
  mixins: [PreviewMixin],
  inject: ['getDragStatus'],
  data() {
    return {
      data: getVideoData(),
      curVideoIndex: 0,
      elementWidth: 0,
      elementHeight: 0,
      viewTopBottomBtn: false,
      fileLen: 0,
      translateY: 0,
      elementID: '',
      videoObserversMap: {},
    };
  },
  watch: {
    data: {
      handler(val) {
        this.fileLen = val.file_list.length;
        if (this.fileLen > 0 && this.data.property.view_method === 'list') {
          const ele = this.$refs.videoAreaBox;
          const sn_position = this.data.property.sn_position;
          // 序号在左和右补齐序号高度，去掉padding(8*2)
          if (sn_position.includes('left') || sn_position.includes('right')) {
            this.elementWidth = ele.clientWidth - 16;
            this.elementHeight = ele.clientHeight + 30;
          } else {
            this.elementWidth = ele.clientWidth;
            this.elementHeight = ele.clientHeight;
          }

          if (ele.clientHeight <= 0) {
            this.elementHeight = this.data.minHeight;
          }

          const mainEle = this.$refs.videoArea;
          // 检查元素是否包含已知的类名
          mainEle.classList.forEach((className) => {
            // 排除已知的类名
            if (className !== 'audio-area') {
              // 打印另一个类名
              this.elementID = className;
            }
          });
        }
      },
      deep: true,
    },
    elementWidth(newWidth) {
      this.elementWidth = newWidth;
    },
    elementHeight(newHeight) {
      this.elementHeight = newHeight;
      this.isViewTopBottomBtn();
    },
  },
  mounted() {
    this.$nextTick(() => {
      const canvasElement = document.querySelector('.canvas');
      if (!canvasElement) return;
      const instanceName = `observer_${this.elementID}`;
      this.videoObserversMap[instanceName] = new ResizeObserver((entries) => {
        if (!this.getDragStatus()) return;
        for (let entry of entries) {
          window.requestAnimationFrame(() => {
            const sn_position = this.data.property.sn_position;
            // 序号在上方和下方减去序号高度，在左右去掉padding(8*2)
            if (sn_position.includes('top') || sn_position.includes('bottom')) {
              this.elementWidth = entry.contentRect.width;
              this.elementHeight = entry.contentRect.height - 30;
            } else {
              this.elementWidth = entry.contentRect.width - 16;
              this.elementHeight = entry.contentRect.height;
            }
          });
        }
      });
      this.videoObserversMap[instanceName].observe(this.$el);
    });
  },
  beforeDestroy() {
    Object.values(this.videoObserversMap).forEach((observer) => {
      observer.disconnect();
    });
  },
  methods: {
    handleAudioClick(index) {
      // 获取 Carousel 实例
      const carousel = this.$refs.video_carousel;
      // 切换到对应索引的文件
      carousel.setActiveItem(index);
      this.curVideoIndex = index;
    },
    changeFile(type) {
      // 获取 Carousel 实例
      const carousel = this.$refs.video_carousel;
      // 切换到对应索引的文件
      if (type === 'prev') {
        carousel.prev();
        this.curVideoIndex += -1;
      } else {
        carousel.next();
        this.curVideoIndex += 1;
      }
      if (this.curVideoIndex >= this.data.file_id_list.length) {
        this.curVideoIndex = 0;
      }
      if (this.curVideoIndex < 0) {
        this.curVideoIndex = this.data.file_id_list.length - 1;
      }
    },
    handleResize() {
      const width = this.$refs.videoAreaBox.clientWidth;
      if (width !== this.elementWidth) {
        this.elementWidth = width;
      }
    },
    // 是否显示上下箭头
    isViewTopBottomBtn() {
      // 计算右侧列表图片高度
      let listHeight = this.fileLen * this.data.min_height + 20 * (this.fileLen - 1);
      if (listHeight > this.elementHeight) {
        this.viewTopBottomBtn = true;
      } else {
        this.viewTopBottomBtn = false;
        this.translateY = 0;
      }
    },
    // 滚动图片列表
    scroll(direction) {
      const minHeight = Number(this.data.min_height);
      const step = minHeight + 20; // 每次滚动的距离
      let _down = (minHeight + 20) * (this.fileLen - 1);
      // 计算滚动后的 translateY 值
      let newY = this.translateY + step * direction;
      // 检查是否超出上下边界
      if (newY > 0) {
        // 滚动到第一张图片时不再向上滚动
        this.translateY = 0;
      } else if (newY < -_down) {
        // 滚动到最后一张图片时不再向下滚动
        this.translateY = -_down;
      } else {
        // 在边界内时执行滚动
        this.translateY = newY;
      }
    },
  },
};
</script>

<style lang="scss" scoped>
.video_area {
  display: grid;
  gap: 6px;
  padding: 8px;

  > .main {
    display: flex;

    > span {
      display: flex;
    }
  }

  .main {
    grid-area: main;
    width: 100%;

    .view-independent {
      display: flex;
      flex-wrap: wrap;
      gap: 20px;
      width: 100%;

      > li {
        width: 248px;
        height: 139px;
      }
    }

    .view-list {
      display: flex;
      column-gap: 32px;

      :deep .el-carousel {
        background-color: #d9d9d9;

        &__container {
          height: 100%;
        }
      }

      .container-box {
        position: relative;
        overflow: hidden;

        .arrow {
          position: absolute;
          z-index: 10;
          width: 100%;
          height: 40px;
          text-align: center;
          background-color: rgba(0, 0, 0, 10%);
          border-radius: 0;
        }

        .arrow:hover {
          background-color: rgba(0, 0, 0, 30%);
        }

        .top {
          top: 0;
        }

        .bottom {
          bottom: 0;
        }

        .view-list-bottom {
          display: flex;
          flex-direction: column;
          row-gap: 20px;

          > li {
            width: 248px;
            height: calc(248px * 9 / 16);
          }
        }
      }
    }
  }
}
</style>
