/**
 * Porter Robinson's discography, loaded from MusicBrainz at server-render
 * time with a small in-memory cache so the sample stays request-fast.
 */

const BASE = "https://musicbrainz.org/ws/2";
const ARTIST = "4ae36ade-1798-48c4-b06b-cc68b7d3d83f";
const USER_AGENT = "muddle-react-sample/0.1 (discography demo; devnull@crit.rip)";
const TTL = 1000 * 60 * 30;

export interface Track {
	title: string;
	duration: string;
}

export interface Album {
	id: string;
	name: string;
	date: string;
	cover: string;
	tracks: Track[];
}

interface ReleaseGroup {
	id: string;
	title: string;
	"first-release-date": string;
	"primary-type": string;
	"secondary-types"?: string[];
}

interface MbRelease {
	media?: { tracks?: { position: number; title: string; length?: number }[] }[];
}

let cache: { albums: Album[]; at: number } | undefined;

function formatDuration(length?: number): string {
	if (!length) return "";
	const seconds = Math.round(length / 1000);
	const parts = [Math.floor(seconds / 60), seconds % 60];
	return `${parts[0]}:${String(parts[1]).padStart(2, "0")}`;
}

async function mbJson<T>(path: string, attempt = 0): Promise<T> {
	const response = await fetch(`${BASE}${path}`, {
		headers: { "user-agent": USER_AGENT, accept: "application/json" },
	});
	if (!response.ok) {
		if ((response.status === 503 || response.status === 429) && attempt < 2) {
			await new Promise((resolve) => setTimeout(resolve, 450 * (attempt + 1)));
			return mbJson<T>(path, attempt + 1);
		}
		throw new Error(`musicbrainz: ${response.status} ${path}`);
	}
	return await response.json() as T;
}

function isStudioAlbum(entry: ReleaseGroup): boolean {
	const title = entry.title.toLowerCase();
	return !/(live|remix|commentary|edition|remastered|deluxe|second sky|secret sky|matt dipirro)/.test(title);
}

async function tracksFor(groupId: string): Promise<Track[]> {
	const releases = await mbJson<{ releases?: { id: string; country?: string }[] }>(
		`/release-group/${groupId}?inc=releases&fmt=json`,
	);
	// prefer a digital or worldwide edition: sort by shortest country code chain
	const candidate = (releases.releases ?? []).slice()
		.sort((a, b) => (a.country?.length ?? 9) - (b.country?.length ?? 9))[0];
	if (!candidate) return [];
	const release = await mbJson<MbRelease>(`/release/${candidate.id}?inc=recordings+media&fmt=json`);
	const media = (release.media ?? []).find((medium) => (medium.tracks?.length ?? 0) > 0)
		?? release.media?.[0];
	return (media?.tracks ?? []).map((track) => ({
		title: track.title,
		duration: formatDuration(track.length),
	}));
}

export async function discography(): Promise<Album[]> {
	if (cache && Date.now() - cache.at < TTL) return cache.albums;
	try {
		const data = await mbJson<{ "release-groups"?: ReleaseGroup[] }>(
			`/artist/${ARTIST}?inc=release-groups&fmt=json`,
		);
		const groups = (data["release-groups"] ?? [])
			.filter((entry) => entry["primary-type"] === "Album"
				&& (entry["secondary-types"]?.length ?? 0) === 0
				&& isStudioAlbum(entry))
			.sort((a, b) => a["first-release-date"].localeCompare(b["first-release-date"]))
			.slice(0, 4);
		const albums: Album[] = [];
		for (const [index, group] of groups.entries()) {
			if (index > 0) await new Promise((resolve) => setTimeout(resolve, 320));
			let tracks: Track[] = [];
			try {
				tracks = await tracksFor(group.id);
			} catch {
				if (index < 2) throw new Error("musicbrainz: tracklist fetch failed");
				continue;
			}
			albums.push({
				id: group.id,
				name: group.title,
				date: group["first-release-date"],
				cover: `https://coverartarchive.org/release-group/${group.id}/front-250`,
				tracks,
			});
		}
		if (albums.length > 0) {
			cache = { albums, at: Date.now() };
			return albums;
		}
		return cache?.albums ?? offlineDiscography();
	} catch {
		return cache?.albums ?? offlineDiscography();
	}
}

/** Studio albums used when MusicBrainz is unreachable or throttled. */
function offlineDiscography(): Album[] {
	return [
		{
			id: "6df00711-624a-4960-9f15-39baf9332cbb",
			name: "Worlds",
			date: "2014-08-08",
			cover: "https://coverartarchive.org/release-group/6df00711-624a-4960-9f15-39baf9332cbb/front-250",
			tracks: [
				{ title: "Divinity", duration: "6:09" },
				{ title: "Sad Machine", duration: "5:54" },
				{ title: "Years of War", duration: "3:56" },
				{ title: "Flicker", duration: "4:39" },
				{ title: "Fresh Static Snow", duration: "5:59" },
				{ title: "Polygon Dust", duration: "3:43" },
				{ title: "Hear the Bells", duration: "4:06" },
				{ title: "Natural Light", duration: "3:16" },
				{ title: "Lionhearted", duration: "3:51" },
				{ title: "Sea of Voices", duration: "5:42" },
				{ title: "Goodbye to a World", duration: "4:16" },
			],
		},
		{
			id: "e2cc165d-b935-4e7c-8728-77cf01ab21ed",
			name: "Nurture",
			date: "2021-04-23",
			cover: "https://coverartarchive.org/release-group/e2cc165d-b935-4e7c-8728-77cf01ab21ed/front-250",
			tracks: [
				{ title: "Lifelike", duration: "0:43" },
				{ title: "Look at the Sky", duration: "4:02" },
				{ title: "Get Your Wish", duration: "3:09" },
				{ title: "Something Comforting", duration: "4:19" },
				{ title: "Blossom", duration: "1:48" },
				{ title: "Musician", duration: "3:09" },
				{ title: "Shelter (nurture mix)", duration: "4:13" },
				{ title: "Wind Tempest", duration: "3:45" },
				{ title: "Paper Rings", duration: "b:58" },
				{ title: "Learning Objects", duration: "2:30" },
				{ title: "Time on My Hands (Until I Get You)", duration: "−:53" },
				{ title: "Mirror", duration: "3:36" },
				{ title: "unfold", duration: "5:33" },
				{ title: "Everything Goes On", duration: "4:12" },
			],
		},
		{
			id: "87964290-66b9-4fd9-bea3-1bfe9de92862",
			name: "SMILE! :D",
			date: "2024-07-26",
			cover: "https://coverartarchive.org/release-group/87964290-66b9-4fd9-bea3-1bfe9de92862/front-250",
			tracks: [
				{ title: "Knock Yourself Out XD", duration: "3:13" },
				{ title: "Cheerleader", duration: "3:01" },
				{ title: "Everything Is Changing", duration: "3:20" },
				{ title: "Kitsune Maison Sixtyone", duration: "2:48" },
				{ title: "Easier to Love You", duration: "3:22" },
				{ title: "Russian Roulette", duration: "2:54" },
				{ title: "Mona Lisa Smile", duration: "3:22" },
				{ title: "Do You Want to Be a Lonely One?", duration: "3:04" },
				{ title: "Everything Goes On (smile edit)", duration: "4:16" },
				{ title: "The Man Who Sold the World", duration: "3:10" },
			],
		},
	];
}