<template>
	<view class="ssq adffc">
		<view class="box">
			<view class="box-top adfac">
				<view class="box-top-btn qx" @click="handleCancel">取消</view>
				<view class="box-top-title">{{ title }}</view>
				<view class="box-top-btn qd" @click="handleConfirm">确定</view>
			</view>
			<picker-view :value="pickerValue" @change="handlePickerChange" class="picker-view" 
				itemHeight="44px" indicator-style="height: 44px;" mask-style="background-color: transparent;">
				<!-- 省份列 -->
				<picker-view-column>
					<view class="picker-item" :class="{ 'selected-item': pickerValue[0] === index }" v-for="(province, index) in provinces" :key="province.id">
						{{ province.name }}
					</view>
				</picker-view-column>
				<!-- 城市列 -->
				<picker-view-column>
					<view class="picker-item" :class="{ 'selected-item': pickerValue[1] === index }" v-for="(city, index) in cities" :key="city.id">
						{{ city.name }}
					</view>
				</picker-view-column>
				<!-- 区县列 -->
				<picker-view-column>
					<view class="picker-item" :class="{ 'selected-item': pickerValue[2] === index }" v-for="(area, index) in areas" :key="area.id">
						{{ area.name }}
					</view>
				</picker-view-column>
			</picker-view>
		</view>
	</view>
</template>

<script>
export default {
	props: {
		title: {
			typeof: String,
			default: '所属地区'
		}
	},
	data() {
		return {
			provinces: [],
			cities: [],
			areas: [],
			pickerValue: [0, 0, 0]
		};
	},
	computed: {
		selectedProvince: function () {
			return this.provinces[this.pickerValue[0]] || {};
		},
		selectedCity: function () {
			return this.cities[this.pickerValue[1]] || {};
		},
		selectedArea: function () {
			return this.areas[this.pickerValue[2]] || {};
		}
	},
	mounted() {
		this.getProvinceCityAreaData();
	},
	methods: {
		getProvinceCityAreaData() {
			this.$api.get('/sys/region/tree').then(({ data: res }) => {
				if (res.code !== 0) return this.$showToast(res.msg);
				this.provinces = this.arrayToTreeOptimized(res.data);
				this.initialize();
			});
		},
		//方法一：递归
		arrayToTree(list, rootPid = '0') {
			const tree = [];

			// 1. 首先找到所有根节点
			list.forEach((item) => {
				if (item.pid === rootPid) {
					// 2. 找到根节点后，递归寻找它的子节点
					const children = this.arrayToTree(list, item.id);
					if (children.length > 0) {
						item.children = children;
					}
					tree.push(item);
				}
			});

			return tree;
		},
		//方法二：Map映射，性能提升
		arrayToTreeOptimized(list, rootPid = '0') {
			const map = new Map();
			const tree = [];

			list.forEach((item) => {
				map.set(item.id, { ...item, children: [] });
			});

			// 2. 再次遍历列表，建立父子关系
			map.forEach((node) => {
				const parent = map.get(node.pid);
				if (parent) {
					// 如果找到父节点，则将当前节点添加到父节点的 children 数组中
					parent.children.push(node);
				} else if (node.pid === rootPid) {
					// 如果没有父节点，并且 pid 是根 pid，则为根节点
					tree.push(node);
				}
			});

			// 清理空 children 数组（可选步骤，如果不需要空数组）
			map.forEach((node) => {
				if (node.children.length === 0) {
					delete node.children;
				}
			});

			return tree;
		},
		handlePickerChange(e) {
			const newPickerValue = e.detail.value;
			const [provinceIndex, cityIndex, areaIndex] = newPickerValue;
			const oldProvinceIndex = this.pickerValue[0];
			const oldCityIndex = this.pickerValue[1];

			if (provinceIndex !== oldProvinceIndex) {
				this.cities = this.provinces[provinceIndex].children;
				this.areas = this.cities[0]?.children || [];
				this.pickerValue = [provinceIndex, 0, 0];
			} else if (cityIndex !== oldCityIndex) {
				// 更新地区列表，并将地区索引重置为0
				this.areas = this.cities[cityIndex]?.children || [];
				this.pickerValue = [provinceIndex, cityIndex, 0];
			} else {
				this.pickerValue = newPickerValue;
			}
		},
		initialize() {
			this.cities = this.provinces[0]?.children || [];
			this.areas = this.cities[0]?.children || [];
		},
		handleCancel() {
			this.$emit('cancel');
		},
		handleConfirm() {
			this.$emit('confirm', {
				provinceId:this.provinces[this.pickerValue[0]].id,
				cityId:this.cities[this.pickerValue[1]].id,
				districtId:this.areas[this.pickerValue[2]].id,
				provinceName:this.provinces[this.pickerValue[0]].name,
				cityName:this.cities[this.pickerValue[1]].name,
				districtName:this.areas[this.pickerValue[2]].name,
			});
		}
	}
};
</script>

<style scoped lang="scss">
.ssq {
	position: fixed;
	left: 0;
	right: 0;
	top: 0;
	bottom: 0;
	background: rgba(0, 0, 0, 0.5);
	justify-content: flex-end;
	z-index: 1001;

	.box {
		background: #ffffff;
		border-radius: 24rpx 24rpx 0 0;
		&-top {
			width: 100%;
			height: 84rpx;
			&-btn {
				width: 120rpx;
				font-size: 30rpx;
				text-align: center;
				line-height: 42rpx;
				&.qx {
					color: #909193;
				}
				&.qd {
					color: #3c9cff;
				}
			}
			&-title {
				flex: 1;
				font-size: 32rpx;
				color: #303133;
				text-align: center;
				line-height: 42rpx;
			}
		}
	}
}

.picker-view {
	width: 100%;
	height: 580rpx;
	margin: 100rpx 0;
}

.picker-item {
	height: 44px;
	line-height: 44px;
	display: flex;
	align-items: center;
	justify-content: center;
	font-size: 30rpx;
	color: #303133;
	transition: all 0.2s;

	&.selected-item {
		font-size: 30rpx;
		font-weight: bold;
		color: #303133;
	}
}
</style>
