/**
 * tosu (https://github.com/tosuapp/tosu) reads the osu! tourney client's
 * memory and serves it over a websocket. We need each spectated player's
 * live score, how far through the map they are, and the team names of the
 * room being spectated (to confirm the right room was selected).
 */

export interface TosuClientScore {
	osuId: number;
	name: string;
	score: number;
	/** Percent. */
	accuracy: number;
	combo: number;
	failed: boolean;
}

export interface TosuFrame {
	/** 1 idle, 2 waiting for clients, 3 playing, 4 results (tosu's ipcState). */
	ipcState: number | null;
	beatmapId: number | null;
	/** 0–1 through the map. */
	progress: number | null;
	/** Team names osu!tourney parsed from the spectated room's name; empty when none. */
	teams: { left: string; right: string };
	clients: TosuClientScore[];
}

/** Picks what Vash needs out of one tosu v2 message. Returns null outside tourney mode. */
export function parseTosu(message: unknown): TosuFrame | null {
	const root = message as {
		tourney?: {
			ipcState?: number;
			team?: { left?: string; right?: string };
			clients?: {
				user?: { id?: number; name?: string };
				play?: {
					playerName?: string;
					score?: number;
					accuracy?: number;
					failed?: boolean;
					combo?: { current?: number };
				};
			}[];
		};
		beatmap?: { id?: number; time?: { live?: number; firstObject?: number; lastObject?: number } };
	};
	if (!root?.tourney || !Array.isArray(root.tourney.clients)) return null;
	const time = root.beatmap?.time;
	const span =
		time && time.lastObject != null && time.firstObject != null
			? time.lastObject - time.firstObject
			: 0;
	return {
		ipcState: root.tourney.ipcState ?? null,
		beatmapId: root.beatmap?.id ?? null,
		progress:
			span > 0 && time?.live != null
				? Math.max(0, Math.min(1, (time.live - time.firstObject!) / span))
				: null,
		teams: {
			left: String(root.tourney.team?.left ?? '').trim(),
			right: String(root.tourney.team?.right ?? '').trim()
		},
		clients: root.tourney.clients
			.filter(
				(client) =>
					(client.user?.id ?? 0) > 0 || client.user?.name?.trim() || client.play?.playerName?.trim()
			)
			.map((client) => ({
				osuId: client.user?.id ?? 0,
				name: client.user?.name?.trim() || client.play?.playerName?.trim() || '',
				score: client.play?.score ?? 0,
				accuracy: client.play?.accuracy ?? 0,
				combo: client.play?.combo?.current ?? 0,
				failed: client.play?.failed ?? false
			}))
	};
}

/** Keeps a websocket to tosu open and remembers its latest tourney frame. */
export class TosuFeed {
	latest: TosuFrame | null = null;
	latestAt = 0;
	connected = false;
	private socket: WebSocket | null = null;
	private attempts = 0;
	private stopped = false;
	private timer: ReturnType<typeof setTimeout> | null = null;

	constructor(
		private url: string,
		private onFrame: (frame: TosuFrame) => void,
		private log: (...parts: unknown[]) => void = () => {}
	) {}

	start() {
		this.stopped = false;
		this.connect();
	}

	private connect() {
		if (this.stopped) return;
		const socket = new WebSocket(this.url);
		this.socket = socket;
		socket.onopen = () => {
			this.attempts = 0;
			this.connected = true;
			this.log('tosu connected');
		};
		socket.onmessage = (event) => {
			let frame: TosuFrame | null;
			try {
				frame = parseTosu(JSON.parse(String(event.data)));
			} catch {
				return;
			}
			if (!frame) return;
			this.latest = frame;
			this.latestAt = Date.now();
			this.onFrame(frame);
		};
		socket.onclose = () => {
			if (this.socket !== socket) return;
			if (this.connected) this.log('tosu disconnected');
			this.connected = false;
			this.socket = null;
			if (this.stopped) return;
			// tosu often starts after us; keep trying quietly.
			const wait = Math.min(15_000, 1000 * 2 ** this.attempts++);
			if (this.attempts === 4)
				this.log(`tosu is not answering at ${this.url}; live scores start when it does.`);
			this.timer = setTimeout(() => this.connect(), wait);
		};
	}

	/** The latest frame if it is recent enough to trust. */
	fresh(maxAgeMs = 5000) {
		return this.connected && Date.now() - this.latestAt <= maxAgeMs ? this.latest : null;
	}

	stop() {
		this.stopped = true;
		if (this.timer) clearTimeout(this.timer);
		const socket = this.socket;
		this.socket = null;
		this.connected = false;
		socket?.close();
	}
}