// Kepr's browser islands (§18). Every page is complete without this file; it only adds the
// ticker's pace, the drifting timeline, copy buttons, the inline panels, history's scrolling,
// line-range highlighting, the Atlas panel, picker, filter and file viewer, the signed-in
// editor, the phone nav menu, and the profile's glow.

// Kepr 2's save kinds (canvas.js), first match wins: each dot's colour and strength.
const KINDS = [
	[/\b(release|version|bump|tag)\b/i, "accent", 1],
	[/\b(fix|bug|patch|issue|crash|error|regress|revert)\b/i, "accent-dim", 0.8],
	[/\b(add|new|implement|feat|introduce|wire|support)\b/i, "accent", 1],
	[
		/\b(refactor|restructure|reorganize|extract|move|rename|split|cleanup|clean up)\b/i,
		"text",
		0.85,
	],
	[/\b(perf|optim|speed|fast|slow|cache|memory|alloc)\b/i, "accent", 0.9],
	[/\b(test|spec|coverage|assert)\b/i, "text-secondary", 0.74],
	[/\b(doc|readme|comment|example|guide)\b/i, "text-secondary", 0.7],
	[/\b(polish|style|format|lint|whitespace|typo|wording|copy)\b/i, "text-secondary", 0.66],
	[/\b(chore|deps|update|upgrade|build|ci|config)\b/i, "text-secondary", 0.62],
];
// Kepr 2's timeline (canvas.js keprThread): the saves on a strip that drifts slowly and loops.
// Hovering pauses it and shows the save, dragging scrubs, a click opens the save. Under reduced
// motion it moves only when dragged.
function timeline() {
	const svg = document.querySelector("svg.timeline");
	if (!svg) return;
	const css = getComputedStyle(document.documentElement);
	const saves = [...svg.querySelectorAll(".dot")]
		.map((dot) => {
			const [id, message, meta] = (dot.querySelector("title")?.textContent ?? "").split("\n");
			const [, color, alpha] = KINDS.find(([kind]) => kind.test(message)) ?? [
				null,
				"text-secondary",
				0.8,
			];
			const fill = css.getPropertyValue(`--${color}`).trim();
			return { href: dot.getAttribute("href"), id, message, meta, fill, alpha, t: +dot.dataset.t };
		})
		.sort((a, b) => a.t - b.t);
	if (saves.length === 0) return;
	const canvas = document.createElement("canvas");
	canvas.className = "timeline-canvas";
	canvas.setAttribute("role", "img");
	canvas.setAttribute("aria-label", svg.getAttribute("aria-label"));
	svg.replaceWith(canvas);
	const ctx = canvas.getContext("2d");
	const tip = document.createElement("div");
	tip.className = "timeline-tip";
	tip.hidden = true;
	document.body.append(tip);
	const reduce = matchMedia("(prefers-reduced-motion: reduce)");
	let [width, height, strip, radius, offset] = [0, 0, 0, 0, 0];
	// Laid out by time, a repo's bursts sat between long empty stretches the drift crawled
	// through. Each dot instead sits after the one before by the gap between them, on a log scale
	// and capped, so a busy day stays tight and a quiet month reads as a pause, not a wait.
	const spacing = (seconds) => radius + 8 + Math.min(96, 12 * Math.log2(1 + seconds / 3600));
	const resize = () => {
		width = canvas.parentElement.getBoundingClientRect().width;
		// Kepr 2's band was tall to hold two lanes; with one line, only room for the dots and label.
		height = 64;
		canvas.width = Math.round(width * devicePixelRatio);
		canvas.height = Math.round(height * devicePixelRatio);
		canvas.style.width = `${width}px`;
		canvas.style.height = `${height}px`;
		ctx.setTransform(devicePixelRatio, 0, 0, devicePixelRatio, 0, 0);
		radius = 5;
		let x = 0;
		saves.forEach((save, i) => {
			if (i > 0) x += spacing(save.t - saves[i - 1].t);
			save.x = x;
		});
		// The seam is one more capped pause, or the rest of the view when the saves are few.
		strip = Math.max(x + spacing(Number.POSITIVE_INFINITY), width);
		offset = x - width * 0.82;
	};
	// Every visible copy of each x on the looping strip.
	const onScreen = (x, margin) => {
		const shift = ((offset % strip) + strip) % strip;
		const copies = [];
		for (let sx = x - shift - strip; sx < width + margin; sx += strip) {
			if (sx > -margin) copies.push(sx);
		}
		return copies;
	};
	const hit = (event) => {
		const box = canvas.getBoundingClientRect();
		const [mx, my] = [event.clientX - box.left, event.clientY - box.top];
		if (Math.abs(my - height / 2) > radius + 7) return null;
		return (
			saves.find((save) => onScreen(save.x, 0).some((x) => Math.abs(mx - x) < radius + 7)) ?? null
		);
	};
	let [hovered, drag, dragFrom, downX, lastX, velocity, resumeAt, lastFrame] = [
		null,
		null,
		0,
		0,
		0,
		0,
		0,
		0,
	];
	const hover = (save, event) => {
		if (save !== hovered) {
			hovered = save;
			tip.hidden = save === null;
			if (save)
				tip.replaceChildren(
					line("tip-id", save.id),
					line("tip-msg", save.message),
					line("tip-meta", save.meta),
				);
		}
		if (save) {
			const left = event.clientX + 14;
			tip.style.left = `${left + 340 > innerWidth ? Math.max(8, event.clientX - 354) : left}px`;
			tip.style.top = `${event.clientY - 10}px`;
		}
		canvas.style.cursor = save ? "pointer" : drag === null ? "grab" : "grabbing";
	};
	const draw = (time) => {
		const dt = lastFrame ? Math.min((time - lastFrame) / 1000, 0.1) : 0;
		lastFrame = time;
		if (drag === null && hovered === null) {
			if (Math.abs(velocity) > 0.5) {
				offset -= velocity;
				velocity *= 0.92;
			} else if (!reduce.matches && time >= resumeAt) offset += 20 * dt;
		}
		const y = height / 2;
		ctx.clearRect(0, 0, width, height);
		ctx.lineWidth = 1;
		ctx.globalAlpha = 0.7;
		ctx.strokeStyle = css.getPropertyValue("--text-muted");
		ctx.setLineDash([4, 4]);
		ctx.beginPath();
		ctx.moveTo(0, y);
		ctx.lineTo(width, y);
		ctx.stroke();
		ctx.setLineDash([]);
		ctx.font = '10px "Martian Mono", monospace';
		ctx.textAlign = "center";
		for (const save of saves) {
			for (const x of onScreen(save.x, 10)) {
				ctx.globalAlpha = hovered === null ? save.alpha : hovered === save ? 1 : save.alpha * 0.6;
				ctx.fillStyle = save.fill;
				ctx.beginPath();
				ctx.arc(x, y, radius, 0, Math.PI * 2);
				ctx.fill();
				if (hovered === save) {
					ctx.fillStyle = css.getPropertyValue("--accent");
					ctx.fillText(save.id.slice(0, 6), x, y - radius - 6);
				}
			}
		}
		ctx.globalAlpha = 1;
		requestAnimationFrame(draw);
	};
	canvas.addEventListener("pointerdown", (event) => {
		[drag, dragFrom, downX, lastX, velocity] = [
			event.clientX,
			offset,
			event.clientX,
			event.clientX,
			0,
		];
		canvas.setPointerCapture(event.pointerId);
	});
	canvas.addEventListener("pointermove", (event) => {
		if (drag !== null) {
			offset = dragFrom - (event.clientX - drag);
			velocity = velocity * 0.6 + (event.clientX - lastX) * 0.4;
			lastX = event.clientX;
		}
		if (event.pointerType === "mouse") hover(hit(event), event);
	});
	const release = () => {
		drag = null;
		resumeAt = performance.now() + 900;
	};
	canvas.addEventListener("pointerup", (event) => {
		release();
		const save = Math.abs(event.clientX - downX) > 4 ? null : hit(event);
		if (save) location.href = save.href;
	});
	canvas.addEventListener("pointercancel", release);
	canvas.addEventListener("pointerleave", (event) => {
		if (drag === null) hover(null, event);
	});
	addEventListener("resize", resize);
	resize();
	requestAnimationFrame(draw);
}

function line(className, text) {
	const div = document.createElement("div");
	div.className = className;
	div.textContent = text ?? "";
	return div;
}

function copyButtons(root) {
	for (const button of root.querySelectorAll("button[data-copy]")) {
		const label = button.textContent;
		button.hidden = false;
		button.addEventListener("click", async () => {
			await navigator.clipboard.writeText(button.dataset.copy);
			button.textContent = "copied";
			button.classList.add("copied");
			setTimeout(() => {
				button.textContent = label;
				button.classList.remove("copied");
			}, 1400);
		});
	}
}

// A Kepr page's <main>, its links made absolute so they point where they did on their own page
// (after any redirect). An error page's <main> comes back too, so a refused form shows why; null if
// nothing came back, and the caller then goes to the page itself.
async function fetchMain(url, init) {
	try {
		const response = await fetch(url, init);
		const page = new DOMParser().parseFromString(await response.text(), "text/html");
		const main = page.querySelector("main");
		for (const link of main?.querySelectorAll("a[href]:not([href^='#'])") ?? []) {
			link.href = new URL(link.getAttribute("href"), response.url || url).href;
		}
		return main;
	} catch {
		return null;
	}
}

// A click the browser should handle itself: a new tab or window, or a download.
function modified(event) {
	return event.button !== 0 || event.metaKey || event.ctrlKey || event.shiftKey || event.altKey;
}

// §21.9's panels open inline under the tabs, as Kepr 2's did: the panel page without its heading.
// The panel's own pages (an issue, the report form) and its forms stay inside it; a link elsewhere,
// or to a file (a download), navigates. The open tab takes the panel back to its first page, and
// closes it from there.
function panels() {
	const host = document.querySelector(".repo-panel");
	if (!host) return;
	let open = null;
	let shown = "";
	const load = async (url, init) => {
		shown = url;
		const main = await fetchMain(url, init);
		if (shown !== url) return;
		if (!main) {
			location.href = url;
			return;
		}
		main.querySelector(".breadcrumb")?.remove();
		main.querySelector(".file-page-title")?.remove();
		host.replaceChildren(...main.childNodes);
		copyButtons(host);
		host.hidden = false;
	};
	const inside = (url) => {
		const base = new URL(open.href).pathname;
		const { pathname } = new URL(url);
		return (pathname === base || pathname.startsWith(`${base}/`)) && !/\.[^/]*$/.test(pathname);
	};
	for (const tab of document.querySelectorAll(".repo-tab[data-panel]")) {
		tab.addEventListener("click", (event) => {
			if (modified(event)) return;
			event.preventDefault();
			if (open === tab && shown !== tab.href) {
				load(tab.href);
				return;
			}
			open?.classList.remove("active");
			if (open === tab) {
				open = null;
				shown = "";
				host.hidden = true;
				return;
			}
			open = tab;
			tab.classList.add("active");
			load(tab.href);
		});
	}
	host.addEventListener("click", (event) => {
		const link = event.target.closest("a[href]");
		if (!link || !open || modified(event) || link.hasAttribute("download")) return;
		if (!inside(link.href)) return;
		event.preventDefault();
		load(link.href);
	});
	host.addEventListener("submit", (event) => {
		const form = event.target;
		if (!open || !inside(form.action)) return;
		event.preventDefault();
		const method = form.method.toUpperCase();
		const data = new FormData(form);
		if (method === "GET") load(`${form.action}?${new URLSearchParams(data)}`);
		else load(form.action, { method, body: data });
	});
}

// History and the Atlas's save picker hold one page of saves; scrolling to the end of either
// brings in the next page's rows. The pager is for pages without JavaScript.
function saveLists() {
	for (const list of document.querySelectorAll(".save-list")) {
		const observer = new IntersectionObserver(
			async ([entry]) => {
				const older = list.querySelector(".pager-older");
				if (!entry?.isIntersecting || !older) return;
				observer.disconnect();
				const main = await fetchMain(older.href);
				const next = main?.querySelector(`.save-list[data-list="${list.dataset.list}"]`);
				if (!next) return;
				next.querySelector(".pager a:not(.pager-older)")?.remove();
				list.querySelector(".pager").replaceWith(...next.childNodes);
				watch();
			},
			{ root: list },
		);
		const watch = () => {
			const older = list.querySelector(".pager-older");
			if (older) observer.observe(older);
		};
		watch();
	}
}

// `#L42` works through CSS :target alone; a range `#L42-L50` needs marking line by line.
function lineRanges() {
	const code = document.querySelector(".code");
	if (!code) return;
	let anchor = null;
	const mark = () => {
		for (const marked of code.querySelectorAll(".line.hl")) marked.classList.remove("hl");
		const match = /^#L(\d+)(?:-L(\d+))?$/.exec(location.hash);
		if (!match) return;
		const from = Number(match[1]);
		const to = Number(match[2] ?? match[1]);
		anchor = from;
		for (let n = Math.min(from, to); n <= Math.max(from, to); n++) {
			document.getElementById(`L${n}`)?.classList.add("hl");
		}
		document.getElementById(`L${Math.min(from, to)}`)?.scrollIntoView({ block: "center" });
	};
	code.addEventListener("click", (event) => {
		const link = event.target.closest(".ln");
		if (!link || !event.shiftKey || anchor === null) return;
		event.preventDefault();
		const n = Number(link.textContent);
		history.replaceState(null, "", `#L${Math.min(anchor, n)}-L${Math.max(anchor, n)}`);
		mark();
	});
	window.addEventListener("hashchange", mark);
	mark();
}

// The Atlas (§21.5): each row's detail panel waits in the <template> after it; the filter narrows
// by filename; which folders are open is remembered per repo in this browser.
function atlas() {
	const root = document.querySelector(".atlas");
	const filter = document.querySelector(".atlas-filter");
	if (!root || !filter) return;
	const panel = root.querySelector(".atlas-panel");
	const folders = [...root.querySelectorAll(".atlas-folder")];
	const files = [...root.querySelectorAll(".atlas-file")];
	// Its height is the closed tree's, fixed before any folder opens; opening one scrolls within.
	root.style.height = `${root.offsetHeight}px`;
	root.style.overflowY = "hidden";
	const key = `kepr:atlas:${root.dataset.repo}`;
	const opened = new Set(remembered(key));
	// `?open=<folder>` from a file page's breadcrumb unfolds that folder, without remembering it.
	const unfold = new URLSearchParams(location.search).get("open");
	const onPath = (path) => unfold !== null && `${unfold}/`.startsWith(`${path}/`);
	for (const folder of folders) {
		folder.open = opened.has(folder.dataset.path) || onPath(folder.dataset.path);
		folder.addEventListener("toggle", () => {
			if (filter.value.trim()) return;
			if (folder.open) opened.add(folder.dataset.path);
			else opened.delete(folder.dataset.path);
			remember(key, [...opened]);
		});
	}
	let selected = null;
	const show = (row) => {
		selected?.classList.remove("selected");
		selected = row;
		row.classList.add("selected");
		panel.replaceChildren(row.nextElementSibling.content.cloneNode(true));
	};
	for (const row of root.querySelectorAll(".atlas-row")) {
		row.addEventListener("pointerenter", (event) => {
			if (event.pointerType === "mouse") show(row);
		});
		row.addEventListener("focus", () => show(row));
	}
	// A map link in a panel jumps to its row, opening the folders above it.
	const jump = (path) => {
		const row = path.endsWith("/")
			? folders.find((folder) => `${folder.dataset.path}/` === path)?.firstElementChild
			: files.find((file) => file.dataset.path === path);
		if (!row) return false;
		for (const folder of folders) folder.open ||= path.startsWith(`${folder.dataset.path}/`);
		show(row);
		row.scrollIntoView({ block: "nearest" });
		return true;
	};
	panel.addEventListener("click", (event) => {
		const link = event.target.closest("a.atlas-jump");
		if (link && !modified(event) && jump(link.dataset.path)) event.preventDefault();
	});
	const viewer = fileViewer(root, jump);
	for (const file of files) {
		file.addEventListener("click", (event) => {
			if (modified(event)) return;
			event.preventDefault();
			viewer(file);
		});
	}
	const target = folders.find((folder) => folder.dataset.path === unfold)?.firstElementChild;
	if (target) {
		show(target);
		target.scrollIntoView({ block: "center" });
	}
	filter.addEventListener("input", () => {
		const query = filter.value.trim().toLowerCase();
		for (const file of files) file.hidden = query !== "" && !file.dataset.name.includes(query);
		for (const folder of folders) {
			folder.hidden = query !== "" && !folder.querySelector(".atlas-file:not([hidden])");
			folder.open = query !== "" || opened.has(folder.dataset.path);
		}
	});
	// One button opens every folder, or, when they all are, closes them all.
	const fold = document.querySelector(".atlas-fold-btn");
	const label = () => {
		fold.textContent = folders.every((folder) => folder.open) ? "collapse all" : "expand all";
	};
	fold.addEventListener("click", () => {
		const open = !folders.every((folder) => folder.open);
		for (const folder of folders) folder.open = open;
		label();
	});
	for (const folder of folders) folder.addEventListener("toggle", label);
	label();
	fold.hidden = folders.length === 0;
	// The filter waits behind a search button, and folds back into it when left empty.
	const search = document.querySelector(".atlas-search-btn");
	search.addEventListener("click", () => {
		search.hidden = true;
		filter.hidden = false;
		filter.focus();
	});
	filter.addEventListener("blur", () => {
		if (filter.value.trim() !== "") return;
		filter.hidden = true;
		search.hidden = false;
	});
	search.hidden = false;
	panel.hidden = false;
}

// Kepr 2's Atlas picker: saves filtered as you type; a click outside or Escape closes it.
function atlasPicker() {
	const picker = document.querySelector(".atlas-picker");
	if (!picker) return;
	const filter = picker.querySelector(".atlas-picker-filter");
	const rows = [...picker.querySelectorAll(".atlas-picker-row")];
	filter.addEventListener("input", () => {
		const query = filter.value.trim().toLowerCase();
		for (const row of rows) row.hidden = query !== "" && !row.dataset.q.includes(query);
	});
	picker.addEventListener("toggle", () => {
		if (picker.open) filter.focus();
	});
	document.addEventListener("click", (event) => {
		if (!picker.contains(event.target)) picker.open = false;
	});
	picker.addEventListener("keydown", (event) => {
		if (event.key === "Escape") picker.open = false;
	});
	filter.hidden = false;
}

// Files open in a viewer over the page, as in Kepr 2's Atlas: the file page's content with the
// row's detail panel beside it, and controls for text size, wrapping, raw, download and the
// neighbouring files. Escape closes it; the arrow keys step through the files.
function fileViewer(root, jump) {
	let [row, size, wrap] = [null, 12, false];
	const overlay = element("div", "fv-overlay");
	overlay.tabIndex = -1;
	overlay.setAttribute("role", "dialog");
	overlay.setAttribute("aria-modal", "true");
	const close = () => {
		overlay.remove();
		row?.focus();
		row = null;
	};
	const step = (by) => {
		const rows = [...root.querySelectorAll(".atlas-file")].filter((file) => !file.hidden);
		const next = rows[rows.indexOf(row) + by];
		if (next) open(next);
	};
	const restyle = () => {
		overlay.style.setProperty("--fv-size", `${size}px`);
		overlay.classList.toggle("fv-wrap", wrap);
	};
	const open = async (file, url = file.href) => {
		row = file;
		const rows = [...root.querySelectorAll(".atlas-file")].filter((each) => !each.hidden);
		const index = rows.indexOf(file);
		const detail = file.nextElementSibling.content.cloneNode(true);
		const name = detail.querySelector(".atlas-info-name").textContent;
		const path = detail.querySelector(".atlas-info-path").textContent;
		const raw = new URL(file.href);
		raw.pathname = raw.pathname.replace(/^(\/[^/]+)\/files\//, "$1/raw/");
		const button = (text, action, className = "fv-ctrl-btn") => {
			const b = element("button", className, text);
			b.type = "button";
			b.addEventListener("click", action);
			return b;
		};
		const link = (text, download) => {
			const a = element("a", "fv-ctrl-btn", text);
			a.href = raw.href;
			if (download) a.download = name;
			return a;
		};
		const source = element("div", "fv-source", "loading…");
		const panel = element("aside", "fv-detail");
		panel.append(detail);
		const header = element("div", "fv-header");
		const title = element("div", "fv-title");
		title.append(element("span", "fv-name", name), element("span", "fv-path mono", path));
		const controls = element("div", "fv-controls mono");
		controls.append(
			button("A−", () => {
				size = Math.max(9, size - 1);
				restyle();
			}),
			button("A+", () => {
				size = Math.min(20, size + 1);
				restyle();
			}),
			button("⇌ wrap", (event) => {
				wrap = !wrap;
				event.currentTarget.classList.toggle("active", wrap);
				restyle();
			}),
			link("raw", false),
			link("download", true),
		);
		controls.children[2].classList.toggle("active", wrap);
		const nav = element("div", "fv-nav mono");
		const back = button("←", () => step(-1), "fv-ctrl-btn");
		const forward = button("→", () => step(1), "fv-ctrl-btn");
		back.disabled = index <= 0;
		forward.disabled = index >= rows.length - 1;
		nav.append(back, element("span", "fv-pos", `${index + 1}/${rows.length}`), forward);
		header.append(button("×", close, "fv-close"), title, controls, nav);
		const body = element("div", "fv-body");
		body.append(source, panel);
		overlay.replaceChildren(header, body);
		restyle();
		if (!overlay.isConnected) document.body.append(overlay);
		overlay.focus();
		const main = await fetchMain(url);
		if (row !== file) return;
		if (!main) {
			location.href = url;
			return;
		}
		for (const heading of main.querySelectorAll(".breadcrumb, .file-page-title")) heading.remove();
		main.querySelector(".file-meta:not(:last-child)")?.remove();
		source.replaceChildren(...main.childNodes);
	};
	overlay.addEventListener("keydown", (event) => {
		if (event.key === "Escape") close();
		else if (event.key === "ArrowLeft" || event.key === "ArrowRight") {
			event.preventDefault();
			step(event.key === "ArrowLeft" ? -1 : 1);
		}
	});
	// A map link beside the code opens that file here; a folder closes the viewer on its row.
	overlay.addEventListener("click", (event) => {
		const link = event.target.closest(".fv-detail a.atlas-jump");
		if (!link || modified(event)) return;
		const path = link.dataset.path;
		const file = [...root.querySelectorAll(".atlas-file")].find((f) => f.dataset.path === path);
		event.preventDefault();
		if (file) open(file);
		else {
			close();
			jump(path);
		}
	});
	// The Markdown view's rendered/source toggle points at the file page: switch in place.
	overlay.addEventListener("click", (event) => {
		const link = event.target.closest(".fv-source a[href]");
		if (!link || !row || modified(event)) return;
		if (new URL(link.href).pathname !== new URL(row.href).pathname) return;
		event.preventDefault();
		open(row, link.href);
	});
	return open;
}

async function navbarLogin() {
	const link = document.querySelector('.nav-links a[href^="/sign-in"]');
	if (!link || !/(^|;\s*)kepr_editor=1(?:;|$)/.test(document.cookie)) return;
	try {
		const response = await fetch("/admin", { cache: "no-store" });
		if (!response.ok) return;
		const doc = new DOMParser().parseFromString(await response.text(), "text/html");
		const token = doc.querySelector('form[action="/admin/sign-out"] input[name="form"]');
		if (!token) return;
		const form = element("form", "nav-logout");
		form.method = "post";
		form.action = "/admin/sign-out";
		const button = element("button", "", "log out");
		button.type = "submit";
		form.append(token, button);
		form.addEventListener("submit", async (event) => {
			event.preventDefault();
			button.disabled = true;
			try {
				const result = await fetch(form.action, { method: "POST", body: new FormData(form) });
				if (!result.ok) throw new Error("Log out failed. Reload and try again.");
				location.href = "/";
			} catch (error) {
				button.disabled = false;
				button.textContent = "try log out again";
				console.error(error);
			}
		});
		const admin = element("a", "", "admin");
		admin.href = "/admin";
		link.replaceWith(admin, form);
	} catch (error) {
		console.error("Could not check navbar sign-in state", error);
	}
}

// On a phone the nav links fold behind a menu button (2026-10-01). The button only exists with
// JavaScript, so without it the links stay in the bar; the CSS hides them only on `.nav--menu`.
function navMenu() {
	const nav = document.querySelector("body > nav");
	const links = nav?.querySelector(".nav-links");
	if (!links) return;
	links.id = "nav-links";
	const button = element("button", "nav-toggle");
	button.type = "button";
	button.setAttribute("aria-label", "menu");
	button.setAttribute("aria-controls", "nav-links");
	button.setAttribute("aria-expanded", "false");
	button.append(element("span", ""), element("span", ""), element("span", ""));
	const open = () => nav.classList.contains("nav--open");
	const set = (opened) => {
		nav.classList.toggle("nav--open", opened);
		button.setAttribute("aria-expanded", String(opened));
	};
	button.addEventListener("click", () => set(!open()));
	document.addEventListener("click", (event) => {
		if (open() && !nav.contains(event.target)) set(false);
	});
	document.addEventListener("keydown", (event) => {
		if (event.key !== "Escape" || !open()) return;
		set(false);
		button.focus();
	});
	nav.classList.add("nav--menu");
	// Before the links, so tabbing from the open button reaches them next.
	links.before(button);
}

function element(tag, className, text) {
	const node = document.createElement(tag);
	node.className = className;
	if (text !== undefined) node.textContent = text;
	return node;
}

// Signed in, a repo page's description and details are edited in place: Markdown with a toolbar
// and a preview as the page will show it, pictures and videos picked, dropped or pasted in, and
// the one under the caret sized and placed from a row of controls. The page's HTML is the same
// for everyone; only this cookie, which says nothing but "signed in here", brings the controls.
async function repoEditor() {
	const head = document.querySelector(".repo-head");
	if (!head || !/(^|;\s*)kepr_editor=1/.test(document.cookie)) return;
	const base = `/admin/repos/${location.pathname.split("/")[1]}`;
	const response = await fetch(`${base}/text`).catch(() => null);
	if (!response?.ok) return;
	const texts = await response.json();
	const details = document.querySelector(".repo-details");
	const places = [
		["description", head.querySelector(".repo-desc"), head.querySelector(".repo-desc")],
		["details", details, details.querySelector(".repo-details-body")],
	];
	for (const [field, section, body] of places) {
		section.hidden = false;
		if (field === "description") {
			section.tabIndex = 0;
			section.setAttribute("role", "button");
			section.setAttribute("aria-label", "edit repository description");
			section.classList.add("repo-desc-editable");
			if (!section.textContent.trim()) section.textContent = "add a description";
			const activate = (event) => {
				if (event.target.closest(".editor") || body.querySelector(".editor")) return;
				event.preventDefault();
				editText(base, texts.form, field, body, texts[field]);
			};
			section.addEventListener("click", activate);
			section.addEventListener("keydown", (event) => {
				if (event.target === section && (event.key === "Enter" || event.key === " "))
					activate(event);
			});
			continue;
		}
		const button = element("button", "edit-btn mono", "edit");
		button.type = "button";
		(section.querySelector(".repo-details-head") ?? section).append(button);
		button.addEventListener("click", (event) => {
			event.preventDefault();
			if (!body.querySelector(".editor")) editText(base, texts.form, field, body, texts[field]);
		});
	}
}

const MEDIA_MARKDOWN = /!\[([^\]]*)\]\(([^)\s]+)(?:\s+"([^"]*)")?\)/g;
const MEDIA_TYPES = "image/png,image/jpeg,image/gif,image/webp,video/mp4,video/webm";

function editText(base, form, field, body, text) {
	const kept = [...body.childNodes];
	if (field === "description") {
		body.removeAttribute("role");
		body.removeAttribute("tabindex");
		body.removeAttribute("aria-label");
	}
	const input = element("textarea", "editor-input mono");
	input.value = text;
	input.rows = field === "details" ? 16 : 3;
	const preview = element("div", `editor-preview${field === "details" ? " markdown" : ""}`);
	const media = element("div", "editor-media mono");
	const status = element("span", "editor-status");
	const post = (path, fields) => {
		const data = new FormData();
		data.append("form", form);
		for (const [name, value] of Object.entries(fields)) data.append(name, value);
		return fetch(`${base}/${path}`, { method: "POST", body: data });
	};
	let timer = null;
	const changed = () => {
		inspect();
		clearTimeout(timer);
		timer = setTimeout(async () => {
			const answer = await post("preview", { field, value: input.value }).catch(() => null);
			if (!answer?.ok) return;
			// Kepr's own Markdown rendering, raw HTML off: the same markup the page will carry.
			preview.innerHTML = input.value.trim() ? await answer.text() : "";
			preview.dataset.empty = input.value.trim() ? "" : "the README's words show here";
		}, 250);
	};
	const wrap = (before, after = before, fallback = "text") => {
		const [from, to] = [input.selectionStart, input.selectionEnd];
		const chosen = input.value.slice(from, to) || fallback;
		input.setRangeText(before + chosen + after, from, to);
		input.setSelectionRange(from + before.length, from + before.length + chosen.length);
		input.focus();
		changed();
	};
	const prefix = (mark) => {
		const start = input.value.lastIndexOf("\n", input.selectionStart - 1) + 1;
		input.setRangeText(mark, start, start, "end");
		input.focus();
		changed();
	};
	const upload = async (file) => {
		status.textContent = `uploading ${file.name}…`;
		const answer = await post("media", { file }).catch(() => null);
		if (!answer?.ok) {
			status.textContent = answer ? await answer.text() : "upload failed";
			return;
		}
		const { url } = await answer.json();
		const alt = file.name.replace(/\.[^.]+$/, "").replace(/[[\]]/g, "");
		input.setRangeText(
			`\n![${alt}](${url} "width=100 center")\n`,
			input.selectionStart,
			input.selectionEnd,
			"end",
		);
		status.textContent = "";
		input.focus();
		changed();
	};
	const picker = element("input", "");
	picker.type = "file";
	picker.accept = MEDIA_TYPES;
	picker.hidden = true;
	picker.addEventListener("change", () => {
		for (const file of picker.files) upload(file);
		picker.value = "";
	});
	// The picture or video under the caret, with its options, as `![alt](url "options")`.
	const underCaret = () =>
		[...input.value.matchAll(MEDIA_MARKDOWN)].find(
			(m) => input.selectionStart >= m.index && input.selectionStart <= m.index + m[0].length,
		);
	function inspect() {
		const found = field === "details" ? underCaret() : undefined;
		media.hidden = !found;
		if (!found) return;
		const words = (found[3] ?? "").split(/\s+/).filter(Boolean);
		const width = words.find((word) => word.startsWith("width="))?.slice(6) ?? "100";
		const align = words.find((word) => /^(left|center|right)$/.test(word)) ?? "center";
		const loop = words.includes("loop");
		const video = /\.(mp4|webm)$/i.test(found[2]);
		const set = (next) => {
			const options = [`width=${next.width}`, next.align, next.loop && "loop"].filter(Boolean);
			const markdown = `![${found[1]}](${found[2]} "${options.join(" ")}")`;
			const caret = input.selectionStart;
			input.setRangeText(markdown, found.index, found.index + found[0].length);
			input.setSelectionRange(caret, caret);
			changed();
		};
		const choice = (label, active, action) => {
			const b = element("button", `fv-ctrl-btn${active ? " active" : ""}`, label);
			b.type = "button";
			b.addEventListener("click", action);
			return b;
		};
		media.replaceChildren(
			element("span", "editor-label", video ? "video" : "picture"),
			...["25", "33", "50", "66", "75", "100"].map((w) =>
				choice(`${w}%`, w === width, () => set({ width: w, align, loop })),
			),
			...["left", "center", "right"].map((a) =>
				choice(a, a === align, () => set({ width, align: a, loop })),
			),
			...(video ? [choice("loop like a GIF", loop, () => set({ width, align, loop: !loop }))] : []),
		);
	}
	const save = async (value) => {
		status.textContent = "saving…";
		const answer = await post("text", { field, value }).catch(() => null);
		if (answer?.ok) location.reload();
		else status.textContent = answer ? await answer.text() : "not saved: offline?";
	};
	const cancel = () => {
		body.replaceChildren(...kept);
		if (field === "description") {
			body.tabIndex = 0;
			body.setAttribute("role", "button");
			body.setAttribute("aria-label", "edit repository description");
			body.focus();
		}
	};
	const tool = (label, title, action) => {
		const b = element("button", "fv-ctrl-btn", label);
		b.type = "button";
		b.title = title;
		b.addEventListener("click", action);
		return b;
	};
	const toolbar = element("div", "editor-toolbar mono");
	toolbar.append(
		tool("B", "bold (⌘B)", () => wrap("**")),
		tool("I", "italic (⌘I)", () => wrap("_")),
		tool("link", "link (⌘K)", () => wrap("[", "](https://)")),
		tool("code", "code", () => wrap("`")),
	);
	if (field === "details") {
		toolbar.append(
			tool("heading", "heading", () => prefix("## ")),
			tool("list", "list", () => prefix("- ")),
			tool("quote", "quote", () => prefix("> ")),
			tool("picture or video", "add a picture, GIF or video (or drop or paste one)", () =>
				picker.click(),
			),
			picker,
		);
		input.addEventListener("dragover", (event) => event.preventDefault());
		input.addEventListener("drop", (event) => {
			if (event.dataTransfer.files.length === 0) return;
			event.preventDefault();
			for (const file of event.dataTransfer.files) upload(file);
		});
		input.addEventListener("paste", (event) => {
			const files = [...event.clipboardData.files];
			if (files.length === 0) return;
			event.preventDefault();
			for (const file of files) upload(file);
		});
	}
	input.addEventListener("input", changed);
	for (const name of ["click", "keyup"]) input.addEventListener(name, inspect);
	input.addEventListener("keydown", (event) => {
		const command = event.metaKey || event.ctrlKey;
		if (event.key === "Escape") cancel();
		else if (command && event.key === "Enter") save(input.value);
		else if (command && event.key === "b") wrap("**");
		else if (command && event.key === "i") wrap("_");
		else if (command && event.key === "k") wrap("[", "](https://)");
		else return;
		event.preventDefault();
	});
	const actions = element("div", "editor-actions mono");
	actions.append(
		tool("save", "save (⌘↵)", () => save(input.value)),
		tool("cancel", "cancel (esc)", cancel),
		tool("use the README", "clear your words and show the README's again", () => save("")),
		status,
	);
	const panes = element("div", "editor-panes");
	panes.append(input, preview);
	const editor = element("div", `editor editor-${field}`);
	editor.append(toolbar, panes, media, actions);
	body.replaceChildren(editor);
	input.focus();
	changed();
}

// Storage can be missing, refused (private windows, blocked windows) or hold anything; only a
// list of folder paths is trusted, and otherwise the tree starts closed.
function remembered(key) {
	try {
		const value = JSON.parse(localStorage.getItem(key) ?? "[]");
		return Array.isArray(value) && value.every((path) => typeof path === "string") ? value : [];
	} catch {
		return [];
	}
}

function remember(key, value) {
	try {
		localStorage.setItem(key, JSON.stringify(value));
	} catch {}
}

// The profile's hex backdrop already breathes in CSS; this lights a few columns at a time, as
// Kepr 2's canvas did. Nothing moves under reduced motion, including when it is switched on later.
function hexGlow() {
	const columns = document.querySelectorAll(".hex-col");
	if (columns.length === 0) return;
	const reduce = matchMedia("(prefers-reduced-motion: reduce)");
	let timer = null;
	const update = () => {
		clearInterval(timer);
		for (const column of columns) column.classList.remove("glow");
		if (reduce.matches) return;
		timer = setInterval(() => {
			const column = columns[Math.floor(Math.random() * columns.length)];
			if (document.querySelectorAll(".hex-col.glow").length >= 3) return;
			column.classList.add("glow");
			setTimeout(() => column.classList.remove("glow"), 3200);
		}, 1500);
	};
	reduce.addEventListener("change", update);
	update();
}

// A CSS duration cannot follow a track's width, so the pace would depend on the messages; set it
// here so each row slides at its own --speed in px/s, as Kepr 2's canvas did.
function tickerPace() {
	for (const track of document.querySelectorAll(".ticker-track")) {
		const speed = Number(getComputedStyle(track).getPropertyValue("--speed"));
		if (speed > 0) track.style.animationDuration = `${track.scrollWidth / 2 / speed}s`;
	}
}

// Widths are only final once Martian Mono has loaded.
document.fonts.ready.then(tickerPace);
timeline();
copyButtons(document);
panels();
saveLists();
atlasPicker();
repoEditor();
navbarLogin();
navMenu();
lineRanges();
atlas();
hexGlow();