<!-- 由于uview2.x的swiper3D版本默认不显示第一张时会出现BUG，故重新引入uview1.x版本的swiper -->
<template>
	<view class="u-swiper-wrap" :style="{
		borderRadius: `${borderRadius}rpx`
	}">
		<swiper :current="elCurrent" @change="change" @animationfinish="animationfinish" :interval="interval" :circular="circular" :duration="duration" :autoplay="autoplay"
		 :previous-margin="effect3d ? effect3dPreviousMargin + 'rpx' : '0'" :next-margin="effect3d ? effect3dPreviousMargin + 'rpx' : '0'"
		 :style="{
				height: height + 'rpx',
				backgroundColor: bgColor
			}">
			<swiper-item class="u-swiper-item" v-for="(item, index) in list" :key="index">
				<view class="u-list-image-wrap" @tap.stop.prevent="listClick(index)" :class="[uCurrent != index ? 'u-list-scale' : '']" :style="{
						borderRadius: `${borderRadius}rpx`,
						transform: effect3d && uCurrent != index ? 'scaleY(0.9)' : 'scaleY(1)',
						margin: effect3d && uCurrent != index ? '0 20rpx' : 0,
					}">
					<image class="u-swiper-image" :src="item[name] || item" :mode="imgMode"></image>
					<view v-if="title && item.title" class="u-swiper-title u-line-1" :style="[{
							'padding-bottom': titlePaddingBottom
						}, titleStyle]">
						{{ item.title }}
					</view>
				</view>
			</swiper-item>
		</swiper>
		<view class="u-swiper-indicator" :style="{
				top: indicatorPos == 'topLeft' || indicatorPos == 'topCenter' || indicatorPos == 'topRight' ? '12rpx' : 'auto',
				bottom: indicatorPos == 'bottomLeft' || indicatorPos == 'bottomCenter' || indicatorPos == 'bottomRight' ? '12rpx' : 'auto',
				justifyContent: justifyContent,
				padding: `0 ${effect3d ? '74rpx' : '24rpx'}`
			}">
			<block v-if="mode == 'rect'">
				<view class="u-indicator-item-rect" :class="{ 'u-indicator-item-rect-active': index == uCurrent }" v-for="(item, index) in list"
				 :key="index"></view>
			</block>
			<block v-if="mode == 'dot'">
				<view class="u-indicator-item-dot" :class="{ 'u-indicator-item-dot-active': index == uCurrent }" v-for="(item, index) in list"
				 :key="index"></view>
			</block>
			<block v-if="mode == 'round'">
				<view class="u-indicator-item-round" :class="{ 'u-indicator-item-round-active': index == uCurrent }" v-for="(item, index) in list"
				 :key="index"></view>
			</block>
			<block v-if="mode == 'number'">
				<view class="u-indicator-item-number">{{ uCurrent + 1 }}/{{ list.length }}</view>
			</block>
		</view>
	</view>
</template>

<script>

export default {
  name: 'u-swiper1',
  props: {
    // 轮播图的数据,格式如：[{image: 'xxxx', title: 'xxxx'}，{image: 'yyyy', title: 'yyyy'}]，其中title字段可选
    list: {
      type: Array,
      default () {
        return []
      }
    },
    // 是否显示title标题
    title: {
      type: Boolean,
      default: false
    },
    // 用户自定义的指示器的样式
    indicator: {
      type: Object,
      default () {
        return {}
      }
    },
    // 圆角值
    borderRadius: {
      type: [Number, String],
      default: 8
    },
    // 隔多久自动切换
    interval: {
      type: [String, Number],
      default: 3000
    },
    // 指示器的模式，rect|dot|number|round
    mode: {
      type: String,
      default: 'round'
    },
    // list的高度，单位rpx
    height: {
      type: [Number, String],
      default: 250
    },
    // 指示器的位置，topLeft|topCenter|topRight|bottomLeft|bottomCenter|bottomRight
    indicatorPos: {
      type: String,
      default: 'bottomCenter'
    },
    // 是否开启缩放效果
    effect3d: {
      type: Boolean,
      default: false
    },
    // 3D模式的情况下，激活item与前后item之间的距离，单位rpx
    effect3dPreviousMargin: {
      type: [Number, String],
      default: 50
    },
    // 是否自动播放
    autoplay: {
      type: Boolean,
      default: true
    },
    // 自动轮播时间间隔，单位ms
    duration: {
      type: [Number, String],
      default: 500
    },
    // 是否衔接滑动，即到最后一张时接着滑动，是否自动切换到第一张
    circular: {
      type: Boolean,
      default: true
    },
    // 图片的裁剪模式 
    imgMode: {
      type: String,
      default: 'aspectFill'
    },
    // 从list数组中读取的图片的属性名
    name: {
      type: String,
      default: 'image'
    },
    // 背景颜色
    bgColor: {
      type: String,
      default: '#f3f4f6'
    },
    // 初始化时，默认显示第几项
    current: {
      type: [Number, String],
      default: 0
    },
    // 标题的样式，对象形式
    titleStyle: {
      type: Object,
      default() {
        return {}
      }
    }
  },
  watch: {
    // 如果外部的list发生变化，判断长度是否被修改，如果前后长度不一致，重置uCurrent值，避免溢出
    list(nVal, oVal) {
      if(nVal.length !== oVal.length) this.uCurrent = 0
    },
    // 监听外部current的变化，实时修改内部依赖于此测uCurrent值，如果更新了current，而不是更新uCurrent，
    // 就会错乱，因为指示器是依赖于uCurrent的
    current(n) {
      this.uCurrent = n
    }
  },
  data() {
    return {
      uCurrent: this.current // 当前活跃的swiper-item的index
    }
  },
  computed: {
    justifyContent() {
      if (this.indicatorPos == 'topLeft' || this.indicatorPos == 'bottomLeft') return 'flex-start'
      if (this.indicatorPos == 'topCenter' || this.indicatorPos == 'bottomCenter') return 'center'
      if (this.indicatorPos == 'topRight' || this.indicatorPos == 'bottomRight') return 'flex-end'
    },
    titlePaddingBottom() {
      let tmp = 0
      if (this.mode == 'none') return '12rpx'
      if (['bottomLeft', 'bottomCenter', 'bottomRight'].indexOf(this.indicatorPos) >= 0 && this.mode == 'number') {
        tmp = '60rpx'
      } else if (['bottomLeft', 'bottomCenter', 'bottomRight'].indexOf(this.indicatorPos) >= 0 && this.mode != 'number') {
        tmp = '40rpx'
      } else {
        tmp = '12rpx'
      }
      return tmp
    },
    // 因为uni的swiper组件的current参数只接受Number类型，这里做一个转换
    elCurrent() {
      return Number(this.current)
    }
  },
  methods: {
    listClick(index) {
      this.$emit('click', index)
    },
    change(e) {
      let current = e.detail.current
      this.uCurrent = current
      // 发出change事件，表示当前自动切换的index，从0开始
      this.$emit('change', current)
    },
    // 头条小程序不支持animationfinish事件，改由change事件
    // 暂不监听此事件，因为不再给swiper绑定uCurrent属性
    animationfinish(e) {
      // #ifndef MP-TOUTIAO
      // this.uCurrent = e.detail.current;
      // #endif
    }
  }
}
</script>

<style lang="scss" scoped>
	@import "../../libs/css/style.components.scss";
	
	.u-swiper-wrap {
		position: relative;
		overflow: hidden;
		transform: translateY(0);
	}

	.u-swiper-image {
		width: 100%;
		will-change: transform;
		height: 100%;
		/* #ifndef APP-NVUE */
		display: block;
		/* #endif */
		/* #ifdef H5 */
		pointer-events: none;
		/* #endif */
	}

	.u-swiper-indicator {
		padding: 0 24rpx;
		position: absolute;
		@include vue-flex;
		width: 100%;
		z-index: 1;
	}

	.u-indicator-item-rect {
		width: 26rpx;
		height: 8rpx;
		margin: 0 6rpx;
		transition: all 0.5s;
		background-color: rgba(0, 0, 0, 0.3);
	}

	.u-indicator-item-rect-active {
		background-color: rgba(255, 255, 255, 0.8);
	}

	.u-indicator-item-dot {
		width: 14rpx;
		height: 14rpx;
		margin: 0 6rpx;
		border-radius: 20rpx;
		transition: all 0.5s;
		background-color: rgba(0, 0, 0, 0.3);
	}

	.u-indicator-item-dot-active {
		background-color: rgba(255, 255, 255, 0.8);
	}

	.u-indicator-item-round {
		width: 14rpx;
		height: 14rpx;
		margin: 0 6rpx;
		border-radius: 20rpx;
		transition: all 0.5s;
		background-color: rgba(0, 0, 0, 0.3);
	}

	.u-indicator-item-round-active {
		width: 34rpx;
		background-color: rgba(255, 255, 255, 0.8);
	}

	.u-indicator-item-number {
		padding: 6rpx 16rpx;
		line-height: 1;
		background-color: rgba(0, 0, 0, 0.3);
		border-radius: 100rpx;
		font-size: 26rpx;
		color: rgba(255, 255, 255, 0.8);
	}

	.u-list-scale {
		transform-origin: center center;
	}

	.u-list-image-wrap {
		width: 100%;
		height: 100%;
		flex: 1;
		transition: all 0.5s;
		overflow: hidden;
		box-sizing: content-box;
		position: relative;
	}

	.u-swiper-title {
		position: absolute;
		background-color: rgba(0, 0, 0, 0.3);
		bottom: 0;
		left: 0;
		width: 100%;
		font-size: 28rpx;
		padding: 12rpx 24rpx;
		color: rgba(255, 255, 255, 0.9);
	}

	.u-swiper-item {
		@include vue-flex;
		overflow: hidden;
		align-items: center;
	}
</style>
