<template>
	<view class="u-subsection" :style="[subsectionStyle]">
		<view
			class="u-item u-line-1"
			:style="[itemStyle(index)]"
			@tap="click(index)"
			:class="[noBorderRight(index), 'u-item-' + index]"
			v-for="(item, index) in listInfo"
			:key="index"
		>
			<view :style="[textStyle(index)]" class="u-item-text u-line-1">{{ item.name }}</view>
		</view>
		<view class="u-item-bg" :style="[itemBarStyle]"></view>
	</view>
</template>

<script>
export default {
	props: {
		// tab的数据
		list: {
			type: Array,
			default() {
				return [];
			}
		},
		// 当前活动的tab的index
		current: {
			type: [Number, String],
			default: 0
		},
		// 激活的颜色
		activeColor: {
			type: String,
			default: '#303133'
		},
		// 模式选择，mode=button为按钮形式，mode=subsection时为分段模式
		mode: {
			type: String,
			default: 'button'
		},
		// 字体大小，单位rpx
		fontSize: {
			type: [Number, String],
			default: 28
		},
		// 是否开启动画效果
		animation: {
			type: Boolean,
			default: true
		},
		// 组件的高度，单位rpx
		height: {
			type: [Number, String],
			default: 70
		},
		// 激活tab的字体是否加粗
		bold: {
			type: Boolean,
			default: true
		},
		// mode=button时，组件背景颜色
		bgColor: {
			type: String,
			default: '#eeeeef'
		},
		// mode = button时，滑块背景颜色
		buttonColor: {
			type: String,
			default: '#ffffff'
		},
		// 在切换分段器的时候，是否让设备震一下
		vibrateShort: {
			type: Boolean,
			default: false
		}
	},
	data() {
		return {
			listInfo: [],
			itemBgStyle: {
				width: 0,
				left: 0,
				backgroundColor: '#ffffff',
				height: '100%',
				transition: ''
			},
			currentIndex: this.current,
			buttonPadding: 3, // mode = button 时，组件的内边距
			borderRadius: 5, // 圆角值
			firstTimeVibrateShort: true // 组件初始化时，会触发current变化，此时不应震动
		};
	},
	watch: {
		current: {
			immediate: true,
			handler(nVal) {
				this.currentIndex = nVal;
				this.changeSectionStatus(nVal);
			}
		}
	},
	created() {
		// 将list的数据，传入listInfo数组，因为不能修改props传递的list值
		// 可以接受直接数组形式，或者数组元素为对象的形式，如：['简介', '评论'],或者[{name: '简介'}, {name: '评论'}]
		this.listInfo = this.list.map((val, index) => {
			if (typeof val != 'object') {
				let obj = {
					width: 0,
					name: val
				};
				return obj;
			} else {
				val.width = 0;
				return val;
			}
		});
	},
	computed: {
		// 设置mode=subsection时，滑块特有的样式
		noBorderRight() {
			return index => {
				if (this.mode != 'subsection') return;
				let classs = '';
				// 不显示右边的边框
				if (index < this.list.length - 1) classs += ' u-none-border-right';
				// 显示整个组件的左右边圆角
				if (index == 0) classs += ' u-item-first';
				if (index == this.list.length - 1) classs += ' u-item-last';
				return classs;
			};
		},
		// 文字的样式
		textStyle() {
			return index => {
				let style = {};
				// 设置字体颜色
				if (this.mode == 'subsection') {
					if (index == this.currentIndex) {
						style.color = '#ffffff';
					} else {
						style.color = this.activeColor;
					}
				} else {
					if (index == this.currentIndex) {
						style.color = this.activeColor;
					} else {
						style.color = this.inactiveColor;
					}
				}
				// 字体加粗
				if (index == this.currentIndex && this.bold) style.fontWeight = 'bold';
				// 文字大小
				style.fontSize = this.fontSize + 'rpx';
				return style;
			};
		},
		// 每个分段器item的样式
		itemStyle() {
			return index => {
				let style = {};
				if (this.mode == 'subsection') {
					// 设置border的样式
					style.borderColor = this.activeColor;
					style.borderWidth = '1px';
					style.borderStyle = 'solid';
				}
				return style;
			};
		},
		// mode=button时，外层view的样式
		subsectionStyle() {
			let style = {};
			style.height = uni.upx2px(this.height) + 'px';
			if (this.mode == 'button') {
				style.backgroundColor = this.bgColor;
				style.padding = `${this.buttonPadding}px`;
				style.borderRadius = `${this.borderRadius}px`;
			}
			return style;
		},
		// 滑块的样式
		itemBarStyle() {
			let style = {};
			style.backgroundColor = this.activeColor;
			style.zIndex = 1;
			if (this.mode == 'button') {
				style.backgroundColor = this.buttonColor;
				style.borderRadius = `${this.borderRadius}px`;
				style.bottom = `${this.buttonPadding}px`;
				style.height = uni.upx2px(this.height) - this.buttonPadding * 2 + 'px';
				style.zIndex = 0;
			}
			return Object.assign(this.itemBgStyle, style);
		}
	},
	mounted() {
		setTimeout(() => {
			this.getTabsInfo();
		}, 10);
	},
	methods: {
		// 改变滑块的样式
		changeSectionStatus(nVal) {
			if (this.mode == 'subsection') {
				// 根据滑块在最左边和最右边时，显示左边和右边的圆角
				if (nVal == this.list.length - 1) {
					this.itemBgStyle.borderRadius = `0 ${this.buttonPadding}px ${this.buttonPadding}px 0`;
				}
				if (nVal == 0) {
					this.itemBgStyle.borderRadius = `${this.buttonPadding}px 0 0 ${this.buttonPadding}px`;
				}
				if (nVal > 0 && nVal < this.list.length - 1) {
					this.itemBgStyle.borderRadius = '0';
				}
			}
			// 更新滑块的位置
			setTimeout(() => {
				this.itemBgLeft();
			}, 10);
			if (this.vibrateShort && !this.firstTimeVibrateShort) {
				// 使手机产生短促震动，微信小程序有效，APP(HX 2.6.8)和H5无效
				// #ifndef H5
				uni.vibrateShort();
				// #endif
			}
			// 第一次过后，设置firstTimeVibrateShort为false，让其下一次可以震动(如果允许震动的话)
			this.firstTimeVibrateShort = false;
		},
		click(index) {
			// 不允许点击当前激活选项
			if (index == this.currentIndex) return;
			this.currentIndex = index;
			this.changeSectionStatus(index);
			this.$emit('change', Number(index));
		},
		// 获取各个tab的节点信息
		getTabsInfo() {
			let view = uni.createSelectorQuery().in(this);
			for (let i = 0; i < this.list.length; i++) {
				view.select('.u-item-' + i).boundingClientRect();
			}
			view.exec(res => {
				if (!res.length) {
					setTimeout(() => {
						this.getTabsInfo();
						return;
					}, 10);
				}
				// 将分段器每个item的宽度，放入listInfo数组
				res.map((val, index) => {
					this.listInfo[index].width = val.width;
				});
				// 初始化滑块的宽度
				if (this.mode == 'subsection') {
					this.itemBgStyle.width = this.listInfo[0].width + 'px';
				} else if (this.mode == 'button') {
					this.itemBgStyle.width = this.listInfo[0].width + 'px';
				}
				// 初始化滑块的位置
				this.itemBgLeft();
			});
		},
		itemBgLeft() {
			// 根据是否开启动画效果，
			if (this.animation) {
				this.itemBgStyle.transition = 'all 0.35s';
			} else {
				this.itemBgStyle.transition = 'all 0s';
			}
			let left = 0;
			// 计算当前活跃item到组件左边的距离
			this.listInfo.map((val, index) => {
				if (index < this.currentIndex) left += val.width;
			});
			// 根据mode不同模式，计算滑块需要移动的距离
			if (this.mode == 'subsection') {
				this.itemBgStyle.left = left + 'px';
			} else if (this.mode == 'button') {
				this.itemBgStyle.left = left + this.buttonPadding + 'px';
			}
		}
	}
};
</script>

<style lang="scss" scoped>
.u-subsection {
	display: flex;
	align-items: center;
	overflow: hidden;
	position: relative;
}

.u-item {
	flex: 1;
	text-align: center;
	font-size: 26rpx;
	height: 100%;
	display: flex;
	align-items: center;
	justify-content: center;
	color: $u-main-color;
	display: inline-flex;
	padding: 0 6rpx;
}

.u-item-bg {
	background-color: $u-type-primary;
	position: absolute;
	z-index: -1;
}

.u-none-border-right {
	border-right: none !important;
}

.u-item-first {
	border-top-left-radius: 8rpx;
	border-bottom-left-radius: 8rpx;
}

.u-item-last {
	border-top-right-radius: 8rpx;
	border-bottom-right-radius: 8rpx;
}

.u-item-text {
	transition: all 0.35s;
	color: $u-main-color;
	display: flex;
	align-items: center;
	position: relative;
	z-index: 99;
}
</style>
