import { ref, watch, nextTick, getCurrentInstance } from 'vue';
import { onReady } from '@dcloudio/uni-app';
import { generateHazardHistory } from './hazardDetail.js';

/**
 * 隐患详情左右联动滚动（与 HazardDetailPanel 保持一致）
 * - 右侧滚动时，根据 node-section 位置同步左侧 activeIndex
 * - 点击左侧步骤时，右侧 scroll-into-view 定位到对应卡片
 */
export function useHazardDetailScroll(detailSource, loadingSource) {
	const instance = getCurrentInstance();
	const queryScope = instance?.proxy || instance;

	const historyList = ref([]);
	const activeIndex = ref(0);
	const sectionOffsets = ref([0]);
	const contentViewHeight = ref(0);
	const contentScrollIntoView = ref('');
	const stepScrollIntoView = ref('');
	const scrollWithAnimation = ref(true);
	const isProgrammaticScroll = ref(false);
	let measureLayoutTimer = null;

	const measureLayout = () => {
		if (!historyList.value.length) return;

		nextTick(() => {
			const query = uni.createSelectorQuery().in(queryScope);
			query.select('.content-scroll').boundingClientRect();
			query.select('.content-scroll').scrollOffset();
			query.selectAll('.node-section').boundingClientRect();
			query.exec((res) => {
				const containerRect = res?.[0];
				const scrollOffset = res?.[1];
				const sections = res?.[2] || [];
				if (!containerRect || !sections.length) return;

				contentViewHeight.value = containerRect.height || 0;
				const baseScrollTop = scrollOffset?.scrollTop || 0;
				sectionOffsets.value = sections.map(
					(section) => section.top - containerRect.top + baseScrollTop
				);
			});
		});
	};

	const scheduleMeasureLayout = () => {
		clearTimeout(measureLayoutTimer);
		measureLayoutTimer = setTimeout(() => {
			measureLayout();
		}, 80);
	};

	const rebuildHistory = (data) => {
		historyList.value = generateHazardHistory(data);
		activeIndex.value = 0;
		contentScrollIntoView.value = '';
		scheduleMeasureLayout();
		setTimeout(scheduleMeasureLayout, 300);
	};

	const syncActiveIndex = (scrollTop, scrollHeight = 0) => {
		const count = historyList.value.length;
		if (!count) return;

		if (scrollHeight > 0 && contentViewHeight.value > 0) {
			if (scrollTop + contentViewHeight.value >= scrollHeight - 60) {
				if (activeIndex.value !== count - 1) {
					activeIndex.value = count - 1;
				}
				return;
			}
		}

		const offsets = sectionOffsets.value;
		if (!offsets.length) return;

		let idx = 0;
		for (let i = offsets.length - 1; i >= 0; i--) {
			if (scrollTop >= offsets[i] - 80) {
				idx = i;
				break;
			}
		}

		if (idx !== activeIndex.value) {
			activeIndex.value = idx;
		}
	};

	const onContentScroll = (e) => {
		if (isProgrammaticScroll.value) return;
		const { scrollTop = 0, scrollHeight = 0 } = e.detail || {};
		syncActiveIndex(scrollTop, scrollHeight);
		scheduleMeasureLayout();
	};

	const onScrollToLower = () => {
		const count = historyList.value.length;
		if (count > 0 && activeIndex.value !== count - 1) {
			activeIndex.value = count - 1;
		}
	};

	const scrollToNode = (index) => {
		if (index < 0 || index >= historyList.value.length) return;

		isProgrammaticScroll.value = true;
		scrollWithAnimation.value = true;
		activeIndex.value = index;
		contentScrollIntoView.value = 'hazard-node-' + index;

		setTimeout(() => {
			contentScrollIntoView.value = '';
			isProgrammaticScroll.value = false;
			scheduleMeasureLayout();
		}, 350);
	};

	watch(
		() => (typeof loadingSource === 'function' ? loadingSource() : loadingSource?.value),
		(loading) => {
			if (!loading) {
				scheduleMeasureLayout();
				setTimeout(scheduleMeasureLayout, 300);
			}
		}
	);

	watch(
		() => (typeof detailSource === 'function' ? detailSource() : detailSource?.value),
		(val) => rebuildHistory(val),
		{ immediate: true, deep: true }
	);

	watch(activeIndex, (index) => {
		stepScrollIntoView.value = 'hazard-step-' + index;
		setTimeout(() => {
			stepScrollIntoView.value = '';
		}, 300);
	});

	watch(
		() => historyList.value.length,
		() => scheduleMeasureLayout()
	);

	onReady(() => {
		scheduleMeasureLayout();
		setTimeout(scheduleMeasureLayout, 300);
	});

	return {
		historyList,
		activeIndex,
		contentScrollIntoView,
		stepScrollIntoView,
		scrollWithAnimation,
		onContentScroll,
		onScrollToLower,
		scrollToNode,
		scheduleMeasureLayout
	};
}