<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>
    /**
     * swiper 轮播图
     * @description 该组件一般用于导航轮播,广告展示等场景,可开箱即用
     * @tutorial https://www.uviewui.com/components/swiper.html
     * @property {Array} list 轮播图数据,见官网"基本使用"说明
     * @property {Boolean} title 是否显示标题文字,需要配合list参数,见官网说明(默认false)
     * @property {String} mode 指示器模式,见官网说明(默认round)
     * @property {String Number} height 轮播图组件高度,单位rpx(默认250)
     * @property {String} indicator-pos 指示器的位置(默认bottomCenter)
     * @property {Boolean} effect3d 是否开启3D效果(默认false)
     * @property {Boolean} autoplay 是否自动播放(默认true)
     * @property {String Number} interval 自动轮播时间间隔,单位ms(默认2500)
     * @property {Boolean} circular 是否衔接播放,见官网说明(默认true)
     * @property {String} bg-color 背景颜色(默认#f3f4f6)
     * @property {String Number} border-radius 轮播图圆角值,单位rpx(默认8)
     * @property {Object} title-style 自定义标题样式
     * @property {String Number} effect3d-previous-margin mode = true模式的情况下,激活项与前后项之间的距离,单位rpx(默认50)
     * @property {String} img-mode 图片的裁剪模式,详见image组件裁剪模式(默认aspectFill)
     * @event {Function} click 点击轮播图时触发
     * @example <u-swiper :list="list" mode="dot" indicator-pos="bottomRight"></u-swiper>
     */
    export default {
        name: "u-swiper",
        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>