<template>
	<!-- #ifdef H5 -->
	<th :rowspan="rowspan" :colspan="colspan" class="uni-table-th" :class="{ 'table--border': border }" :style="{ width: width + 'px', 'text-align': align }">
		<view class="uni-table-th-content" :style="{ 'justify-content': contentAlign }" @click="sort">
			<slot></slot>
			<view v-if="sortable" class="arrow-box">
				<text class="arrow up" :class="{ active: ascending }" @click.stop="ascendingFn"></text>
				<text class="arrow down" :class="{ active: descending }" @click.stop="descendingFn"></text>
			</view>
		</view>
	</th>
	<!-- #endif -->
	<!-- #ifndef H5 -->
	<view class="uni-table-th" :class="{ 'table--border': border }" :style="{ width: width + 'px', 'text-align': align }">
		<slot></slot>
	</view>
	<!-- #endif -->
</template>

<script>
	/**
	 * Th 表头
	 * @description 表格内的表头单元格组件
	 * @tutorial https://ext.dcloud.net.cn/plugin?id=3270
	 * @property {Number} 	width 						单元格宽度
	 * @property {Boolean} 	sortable 					是否启用排序
	 * @property {Number} 	align = [left|center|right]	单元格对齐方式
	 * @value left   	单元格文字左侧对齐
	 * @value center	单元格文字居中
	 * @value right		单元格文字右侧对齐
	 * @event {Function} sort-change 排序触发事件 
	 */

	export default {
		name: 'uniTh',
		options: {
			virtualHost: true
		},
		props: {
			width: {
				type: [String, Number],
				default: ''
			},
			align: {
				type: String,
				default: 'left'
			},
			rowspan: {
				type: [Number, String],
				default: 1
			},
			colspan: {
				type: [Number, String],
				default: 1
			},
			sortable: {
				type: Boolean,
				default: false
			}
		},
		data() {
			return {
				border: false,
				ascending: false,
				descending: false
			}
		},
		computed: {
			contentAlign() {
				let align = 'left'
				switch (this.align) {
					case 'left':
						align = 'flex-start'
						break
					case 'center':
						align = 'center'
						break
					case 'right':
						align = 'flex-end'
						break
				}
				return align
			}
		},
		created() {
			this.root = this.getTable('uniTable')
			this.rootTr = this.getTable('uniTr')
			this.rootTr.minWidthUpdate(this.width ? this.width : 140)
			this.border = this.root.border
			this.root.thChildren.push(this)
		},
		methods: {
			sort() {
				if (!this.sortable) return
				this.clearOther()
				if (!this.ascending && !this.descending) {
					this.ascending = true
					this.$emit('sort-change', {
						order: 'ascending'
					})
					return
				}
				if (this.ascending && !this.descending) {
					this.ascending = false
					this.descending = true
					this.$emit('sort-change', {
						order: 'descending'
					})
					return
				}

				if (!this.ascending && this.descending) {
					this.ascending = false
					this.descending = false
					this.$emit('sort-change', {
						order: null
					})
				}
			},
			ascendingFn() {
				this.clearOther()
				this.ascending = !this.ascending
				this.descending = false
				this.$emit('sort-change', {
					order: this.ascending ? 'ascending' : null
				})
			},
			descendingFn() {
				this.clearOther()
				this.descending = !this.descending
				this.ascending = false
				this.$emit('sort-change', {
					order: this.descending ? 'descending' : null
				})
			},
			clearOther() {
				this.root.thChildren.map(item => {
					if (item !== this) {
						item.ascending = false
						item.descending = false
					}
					return item
				})
			},
			/**
			 * 获取父元素实例
			 */
			getTable(name) {
				let parent = this.$parent
				let parentName = parent.$options.name
				while (parentName !== name) {
					parent = parent.$parent
					if (!parent) return false
					parentName = parent.$options.name
				}
				return parent
			}
		}
	}
</script>

<style scoped>
	.uni-table-th {
		padding: 12px 10px;
		/* #ifndef APP-NVUE */
		display: table-cell;
		box-sizing: border-box;
		/* #endif */
		font-size: 14px;
		font-weight: bold;
		color: #909399;
		border-bottom: 1px #ebeef5 solid;
	}

	.table--border {
		border-right: 1px #ebeef5 solid;
	}

	.uni-table-th-content {
		display: flex;
		align-items: center;
	}

	.arrow {
		display: block;
		position: relative;
		width: 10px;
		height: 8px;
		left: 5px;
		overflow: hidden;
		cursor: pointer;
	}

	.down {
		top: 3px;
	}

	.down ::after {
		content: "";
		width: 8px;
		height: 8px;
		position: absolute;
		left: 2px;
		top: -5px;
		transform: rotate(45deg);
		background-color: #ccc;
	}

	.down.active ::after {
		background-color: #007aff;
	}

	.up ::after {
		content: "";
		width: 8px;
		height: 8px;
		position: absolute;
		left: 2px;
		top: 5px;
		transform: rotate(45deg);
		background-color: #ccc;
	}

	.up.active ::after {
		background-color: #007aff;
	}
</style>