<template>
  <view class="u-wrap">
    <!-- <view class="top-box">
      <view class="switch-box">
        <u-tabs :list="list1" lineWidth="30" lineColor="$uni-bg-color-primary" :activeStyle="{
            color: '#000',
            fontSize: '28rpx',
            transform: 'scale(1.05)',
            marginBottom: '15rpx',
          }" :inactiveStyle="{
            color: '#333',
            fontSize: '30rpx',
            transform: 'scale(1)',
            marginBottom: '15rpx',
          }"></u-tabs>
      </view>
      <view class="search-box">
        <u--input  v-model='search' prefixIcon="search" prefixIconStyle="font-size: 22px;color: #909399" class="search-ipt" placeholder="请输入内容" border="surround" clearable></u--input>
        <button class="btn" @click="handlerSearchBtn">搜索</button>
      </view>
    </view> -->

    <view class="u-menu-wrap">
      <scroll-view scroll-y scroll-with-animation class="u-tab-view menu-scroll-view" :scroll-top="scrollTop"
        :scroll-into-view="itemId">
        <view v-for="(item,index) in tabbar" :key="index" class="u-tab-item"
          :class="[current == index ? 'u-tab-item-active' : '']" @tap.stop="swichMenu(index)">
          <text class="u-line-1">{{item.name}}</text>
        </view>
      </scroll-view>


      <scroll-view :scroll-top="scrollRightTop" scroll-y scroll-with-animation class="right-box" @scroll="rightScroll">
        <view class="page-view">
          <view class="class-item" :id="'item' + index" v-for="(item , index) in tabbar" :key="index">
            <view class="item-title">
              <text>{{item.name}}</text>
            </view>
            <view class="item-box" v-for="itm of item.foods" :key="idx">
              <view class="item-l">
                <img class="l-img" src="@/static/QR57a.jpg" alt="">
              </view>
              <view class="item-r">
                <p class='p1'>yizhiyang的鲜花{{itm.name}}11111111111111</p>
                <p class='p2'>月售100</p>
                <p class='p2'>库存90</p>
                <p class='p3'>￥100起</p>
              </view>
            </view>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>
  export default {
    data() {
      return {
        scrollTop: 0, //tab标题的滚动条位置
        oldScrollTop: 0, // tab标题的滚动条旧位置
        current: 0, // 预设当前项的值
        menuHeight: 0, // 左边菜单的高度
        menuItemHeight: 0, // 左边菜单item的高度
        itemId: '', // 栏目右边scroll-view用于滚动的id
        arr: [], // 储存距离顶部高度的数组
        scrollRightTop: 0, // 右边栏目scroll-view的滚动条高度
        timer: null, // 定时器
        tabbar: [{
            "name": "蔬菜水果",
            "foods": [{
                "cat": 383,
                "name": "蔬菜",
                "icon": "http://nq348.com/uploads/category/20220315/1aeed6fa43b54cd68cce0c4883160f91.png",
                "key": "蔬菜"
              },
              {
                "cat": 384,
                "name": "食用菌",
                "icon": "http://nq348.com/uploads/category/20220418/09839c618b35b510d50151f9a17793ee.png",
                "key": "食用菌"
              },
              {
                "cat": 385,
                "name": "水果",
                "icon": "http://nq348.com/uploads/category/20220418/5294ad2fc7effc9629cbfdb8baf41773.png",
                "key": "水果"
              }
            ]
          },
          {
            "name": "畜禽养殖",
            "foods": [{
                "cat": 388,
                "name": "禽类",
                "icon": "http://nq348.com/uploads/category/20220418/da31895fc5a9aacf93fea6f27f08afd7.png",
                "key": "禽类"
              },
              {
                "cat": 389,
                "name": "畜类",
                "icon": "http://nq348.com/uploads/category/20220418/6352081e3f3b36f9360a933676e9452c.png",
                "key": "畜类"
              },
              {
                "cat": 391,
                "name": "蛋类",
                "icon": "http://nq348.com/uploads/category/20220418/d2e7ab4224679c0c796ba3ddd8a68e2f.png",
                "key": "蛋类"
              },
              {
                "cat": 390,
                "name": "水产",
                "icon": "http://nq348.com/uploads/category/20220418/52a1f1baa7617ef4d4e1a4b344b2fce7.png",
                "key": "水产"
              }
            ]
          },

          {
            "name": "粮油副食",
            "foods": [{
                "cat": 393,
                "name": "米面粮油",
                "icon": "http://nq348.com/uploads/category/20220418/1bb32e319ecf5aa352b7fe26fc265004.png",
                "key": "米面粮油"
              },
              {
                "cat": 394,
                "name": "坚果干果",
                "icon": "http://nq348.com/uploads/category/20220418/6ded13eae4a3b113b5225ca8b99bbfdd.png",
                "key": "坚果干果"
              },
              {
                "cat": 395,
                "name": "加工食品",
                "icon": "http://nq348.com/uploads/category/20220418/1e1c10838799de5834aa77f0f9eb8f40.png",
                "key": "加工食品"
              },
              {
                "cat": 396,
                "name": "茶烟酒",
                "icon": "http://nq348.com/uploads/category/20220418/c43cd994e49023c7efdf2b18b1bca30b.png",
                "key": "茶烟酒"
              }
            ]
          },
          {
            "name": "花卉苗木",
            "foods": [{
                "cat": 398,
                "name": "鲜花盆景",
                "icon": "http://nq348.com/uploads/category/20220418/b21c44045daaa8b8d148981ba9efc2e0.png",
                "key": "鲜花盆景"
              },
              {
                "cat": 399,
                "name": "果树苗",
                "icon": "http://nq348.com/uploads/category/20220418/63ee2b902ff0f4d638d8a5ad770f7641.png",
                "key": "果树苗"
              },
              {
                "cat": 400,
                "name": "蔬瓜种子",
                "icon": "http://nq348.com/uploads/category/20220418/2df521877616ee44fd01aae0434a5815.png",
                "key": "蔬瓜种子"
              },
              {
                "cat": 401,
                "name": "经济作物",
                "icon": "http://nq348.com/uploads/category/20220418/f85be72a98694befd889f30de45a1d64.png",
                "key": "经济作物"
              }
            ]
          },
          {
            "name": "中草药材",
            "foods": [{
                "cat": 403,
                "name": "全草类",
                "icon": "http://nq348.com/uploads/category/20220418/01812c1a83f5db7eafbf3bdae927f134.png",
                "key": "全草类"
              },
              {
                "cat": 405,
                "name": "根茎皮叶花",
                "icon": "http://nq348.com/uploads/category/20220418/dca8dcc814401474d4f19ae7394cc209.png",
                "key": "根茎皮叶花"
              },
              {
                "cat": 406,
                "name": "滋补品类",
                "icon": "http://nq348.com/uploads/category/20220418/33b965295811fdd6f5e672e9a3ce34a2.png",
                "key": "滋补品类"
              },
              {
                "cat": 404,
                "name": "果实籽仁类",
                "icon": "http://nq348.com/uploads/category/20220418/1dc8c46c66b4625d458a7f45787ecef9.png",
                "key": "果实籽仁类"
              }
            ]
          },
          {
            "name": "其他",
            "foods": [{
                "cat": 434,
                "name": "包装",
                "icon": "http://nq348.com/uploads/category/20220418/ebdfd326333344825adbe81dbd89e2c9.png",
                "key": "包装"
              },
              {
                "cat": 435,
                "name": "安全溯源",
                "icon": "http://nq348.com/uploads/category/20220418/03230c63f066f46005abf5f576df0ed1.png",
                "key": "安全溯源"
              },
              {
                "cat": 436,
                "name": "农用百货",
                "icon": "http://nq348.com/uploads/category/20220418/93393f2df3264faba86bb449a0c10a79.png",
                "key": "农用百货"
              },
              {
                "cat": 437,
                "name": "仓储物流",
                "icon": "http://nq348.com/uploads/category/20220418/f553505ebabbcb1bf762b288716cf1e7.png",
                "key": "仓储物流"
              }
            ]
          }
        ],
        list1: [{
          name: '在售中',
        }, {
          name: '已下架',
        }],
        search:''
      }
    },
    /**
     * 获取一个目标元素的高度
     * @elClass 元素的类名
     * @dataVal 储存高度的对象
     */
    onReady() {
      this.getMenuItemTop()
    },
    methods: {
      getElRect(elClass, dataVal) {
        new Promise((resolve, reject) => {
          const query = uni.createSelectorQuery().in(this);
          query.select('.' + elClass).fields({
            size: true
          }, res => {
            // 如果节点尚未生成，res值为null，循环调用执行
            if (!res) {
              setTimeout(() => {
                this.getElRect(elClass);
              }, 10);
              return;
            }
            this[dataVal] = res.height;
            resolve();
          }).exec();
        })
      },

      getMenuItemTop() {
        new Promise(resolve => {
          let selectorQuery = uni.createSelectorQuery();
          selectorQuery.selectAll('.class-item').boundingClientRect((rects) => {
            // 如果节点尚未生成，rects值为[](因为用selectAll，所以返回的是数组)，循环调用执行
            if (!rects.length) {
              setTimeout(() => {
                this.getMenuItemTop();
              }, 10);
              return;
            }
            rects.forEach((rect) => {
              // 视情况而定，这里减去rects[0].top，是因为第一项顶部可能不是贴到导航栏(比如有个搜索框的情况)
              // this.arr.push(rect.top - rects[0].top);
              this.arr.push(rect.top)
              resolve();
            })
          }).exec()
        })
      },
      /**
       * 观测元素相交状态
       * 检测右边scroll-view的id为itemxx的元素与right-box的相交状态
       * 如果跟.right-box底部相交，就动态设置左边栏目的活动状态
       */
      async observer() {
        this.tabbar.map((val, index) => {
          let observer = uni.createIntersectionObserver(this);
          observer.relativeTo('.right-box', {
            top: 0
          }).observe('#item' + index, res => {
            if (res.intersectionRatio > 0) {
              let id = res.id.substring(4);
              this.leftMenuStatus(id);
            }
          })
        })
      },
      /**
       * 设置左边菜单的滚动状态
       * @index 传入的 ID
       */
      async leftMenuStatus(index) {
        this.current = index;
        // 如果为0，意味着尚未初始化
        if (this.menuHeight == 0 || this.menuItemHeight == 0) {
          await this.getElRect('menu-scroll-view', 'menuHeight');
          await this.getElRect('u-tab-item', 'menuItemHeight');
        }
        // 将菜单活动item垂直居中
        this.scrollTop = index * this.menuItemHeight + this.menuItemHeight / 2 - this.menuHeight / 2;
      },
      /**
       * 点击左边的栏目切换
       * @index 传入的 ID
       */
      async swichMenu(index) {
        if (this.arr.length == 0) {
          await this.getMenuItemTop();
        }
        if (index == this.current) return;
        this.scrollRightTop = this.oldScrollTop ;
        this.$nextTick(function() {
          this.scrollRightTop = this.arr[index];
          this.current = index ;
          this.leftMenuStatus(index);
        })
      },
      /**
       * 右边菜单滚动
       * 如果不存在height2，意味着数据循环已经到了最后一个，设置左边菜单为最后一项即可
       */
      async rightScroll(e) {
        this.oldScrollTop = e.detail.scrollTop;
        if (this.arr.length == 0) {
          await this.getMenuItemTop();
        }
        if (this.timer) return;
        if (!this.menuHeight) {
          await this.getElRect('menu-scroll-view', 'menuHeight');
        }
        setTimeout(() => { // 节流
          this.timer = null;
          // scrollHeight为右边菜单垂直中点位置
          // let scrollHeight = e.detail.scrollTop + this.menuHeight / 2;
          // scrollHeight为右边菜单头部位置
          let scrollHeight = e.detail.scrollTop + 20;
          for (let i = 0; i < this.arr.length; i++) {
            let height1 = this.arr[i];
            let height2 = this.arr[i + 1];
            if (!height2 || scrollHeight >= height1 && scrollHeight < height2) {
              this.leftMenuStatus(i);
              return;
            }
          }
        }, 10)
      },

      // 搜索按钮
      handlerSearchBtn(){
        console.log('search',this.search);
      }
    }

  }
</script>

<style lang="scss" scoped>
  .top-box {
    padding: 0 0 20rpx;
    width: 100%;
    .switch-box {
      width: 100%;
    }

    .search-box {
      display: flex;
      justify-content: space-around;
      width: 90% ;
      margin: 20rpx auto 0;
      .btn{
        width: 160rpx;
        height: 80rpx;
        background-color: #5992BB;
        color: #fff;
        text-align: center;
        line-height: 80rpx;
        font-size:26rpx;
        border-radius: 20rpx;
        margin-left: 20rpx;
      }
    }
  }

  .u-wrap {
    /* #ifdef H5 */
    height: calc(100vh - var(--window-top));
    /* #endif */
    display: flex;
    flex-direction: column;
    height: 100vh;
  }

  .u-search-box {
    padding: 18rpx 30rpx;
  }

  .u-menu-wrap {
    flex: 1;
    display: flex;
    overflow: hidden;
  }

  .u-tab-view {
    width: 200rpx;
    background-color: #f6f6f6;
  }

  .u-tab-item {
    height: 110rpx;
    background: #f6f6f6;
    box-sizing: border-box;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 26rpx;
    color: #444;
    font-weight: 400;
    line-height: 1;
    padding: 16rpx 0;
  }

  .u-tab-item-active {
    position: relative;
    color: #5F96BE;
    font-size: 30rpx;
    font-weight: 500;
    background: #FFF;
  }

  .u-tab-item-active::before {
    content: "";
    position: absolute;
    border-left: 4px solid #5F96BE;
    height: 52rpx;
    left: 0;
    top: 29rpx;
  }

  .u-tab-view {
    height: 100%;
  }

  .right-box {
    background-color: rgb(250, 250, 250);
  }

  .page-view {
    padding: 16rpx;
  }

  .class-item {
    margin-bottom: 30rpx;
    background-color: #fff;
    padding: 16rpx;
    border-radius: 8rpx;
  }

  .item-title {
    font-size: 26rpx;
    text-align: center;
    color: #5F96BE;
    margin-bottom: 20rpx;
  }

  .item-box {
    display: flex;
    margin-bottom: 10rpx;

    .item-l {
      border: 2rpx solid #EEF0F0;
      border-radius: 20rpx;
      margin-right: 20rpx;

      .l-img {
        width: 140rpx;
        height: 130rpx;
        border-radius: 20rpx;
      }
    }

    .item-r {
      .p1 {
        width: 350rpx;
        font-size: 28rpx;
        color: #000;
        margin-bottom: 5rpx;
        overflow-x: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
      }

      .p2 {
        font-size: 24rpx;
        color: #A4A5AD;
      }

      .p3 {
        font-size: 26rpx;
        color: #D6534D;
      }
    }
  }

  ::v-deep .u-input--radius.data-v-fdbb9fe6, .u-input--square.data-v-fdbb9fe6{
    background-color: #F7F7F7 !important;
    padding: 40rpx;
    border-radius: 50rpx;
  }
</style>
