import "./common.js";
//#region js/about-history.js
function setActiveNav() {
	const pageNav = document.querySelector("[data-nav]")?.getAttribute("data-nav");
	if (!pageNav) return;
	document.querySelectorAll(".site-header__nav a").forEach((link) => {
		const active = link.textContent.trim().startsWith(pageNav);
		link.classList.toggle("is-active", active);
	});
}

function getHeaderOffset() {
	const header = document.querySelector(".site-header");
	const h = header ? header.offsetHeight : 88;
	const isMobile = window.matchMedia("(max-width: 992px)").matches;
	if (isMobile) {
		const years = document.querySelector(".ah-nav__years");
		const yearsH = years ? years.offsetHeight : 60;
		return h + yearsH + 12;
	}
	return h + 24;
}

function clamp(n, min, max) {
	return Math.min(max, Math.max(min, n));
}

function initHistorySpy() {
	const root = document.querySelector("[data-ah-spy]");
	if (!root) return;
	const navItems = Array.from(root.querySelectorAll(".ah-nav__item[data-year]"));
	const blocks = Array.from(root.querySelectorAll(".ah-block[data-year]"));
	const yearsWrap = root.querySelector(".ah-nav__years");
	const rail = root.querySelector(".ah-nav__rail");
	const indicator = root.querySelector(".ah-nav__indicator");
	if (!navItems.length || !blocks.length) return;

	let activeYear = navItems[0].dataset.year;
	let clicking = false;
	let rafId = 0;

	const isMobile = () => window.matchMedia("(max-width: 992px)").matches;

	const syncRailHeight = () => {
		if (!yearsWrap || !rail || isMobile()) return;
		rail.style.height = `${yearsWrap.offsetHeight}px`;
	};

	const setProgress = (progress) => {
		if (!indicator) return;
		indicator.style.transform = `scaleY(${clamp(progress, 0.04, 1)})`;
	};

	const getActiveIndex = () => {
		const offset = getHeaderOffset() + 8;
		let idx = 0;
		for (let i = 0; i < blocks.length; i++) {
			if (blocks[i].getBoundingClientRect().top <= offset) idx = i;
		}
		return idx;
	};

	/**
	 * 进度只跟内容滚动的年份序号插值，不依赖左侧字号布局。
	 * 跨年时 (idx+local)/(n-1) 单调连续，避免「先变短再变长」。
	 */
	const updateProgressFromScroll = () => {
		if (!indicator || !rail || isMobile()) return;
		syncRailHeight();
		const n = navItems.length;
		if (n <= 1) {
			setProgress(1);
			return;
		}
		const offset = getHeaderOffset() + 8;
		const idx = getActiveIndex();
		let local = 1;
		if (blocks[idx + 1]) {
			const curTop = blocks[idx].getBoundingClientRect().top;
			const nextTop = blocks[idx + 1].getBoundingClientRect().top;
			const span = nextTop - curTop;
			local = span > 0 ? clamp((offset - curTop) / span, 0, 1) : 1;
		}
		setProgress((idx + local) / (n - 1));
	};

	const setActive = (year, { scrollNav = true } = {}) => {
		if (!year || year === activeYear) return;
		activeYear = year;
		navItems.forEach((el) => {
			el.classList.toggle("is-active", el.dataset.year === year);
		});
		if (scrollNav && isMobile()) {
			const current = navItems.find((el) => el.dataset.year === year);
			current?.scrollIntoView({
				inline: "center",
				block: "nearest",
				behavior: "smooth"
			});
		}
	};

	const onScroll = () => {
		if (rafId) return;
		rafId = requestAnimationFrame(() => {
			rafId = 0;
			// 点击滚动过程中仍跟手更新进度；仅锁定高亮年份，避免中途抢焦点
			if (!clicking) {
				const idx = getActiveIndex();
				const year = navItems[idx]?.dataset.year;
				if (year) setActive(year);
			}
			updateProgressFromScroll();
		});
	};

	const scrollToYear = (year) => {
		const target = blocks.find((el) => el.dataset.year === year);
		if (!target) return;
		clicking = true;
		setActive(year);
		const top = window.scrollY + target.getBoundingClientRect().top - getHeaderOffset();
		const done = () => {
			clicking = false;
			updateProgressFromScroll();
		};
		if (window.lenis) {
			window.lenis.scrollTo(top, {
				duration: 1,
				onComplete: done
			});
		} else {
			window.scrollTo({
				top,
				behavior: "smooth"
			});
			window.setTimeout(done, 800);
		}
	};

	navItems.forEach((item) => {
		item.addEventListener("click", (event) => {
			event.preventDefault();
			scrollToYear(item.dataset.year);
		});
	});

	if (window.lenis) window.lenis.on("scroll", onScroll);
	else window.addEventListener("scroll", onScroll, { passive: true });

	if (typeof ResizeObserver !== "undefined" && yearsWrap) {
		new ResizeObserver(() => {
			syncRailHeight();
			updateProgressFromScroll();
		}).observe(yearsWrap);
	}

	window.addEventListener("resize", () => {
		syncRailHeight();
		updateProgressFromScroll();
	});

	navItems[0]?.classList.add("is-active");
	syncRailHeight();
	updateProgressFromScroll();

	const hashYear = (location.hash || "").replace(/^#year-/, "");
	if (hashYear && blocks.some((el) => el.dataset.year === hashYear)) {
		requestAnimationFrame(() => scrollToYear(hashYear));
	}
}

setActiveNav();
initHistorySpy();
//#endregion