hnefatafl/server/src/tally.ts

// The tally: what the ledgers add up to, for the hall's about panel. Read
// from the files on demand and cached for a minute, so a curious visitor
// costs nothing and a busy hall costs one scan a minute. The counts are
// the kit's; a game may add its own lines through GameSpec.tally.

import type { GameSpec, SeatId } from '../../src/lib/game/spec';
import type { LedgerLine, Store } from './store';

export interface Tally {
	tablesOpened: number;
	gamesBegun: number;
	gamesFinished: number;
	/** Distinct names of people who have taken a seat; a bot's name is not counted. */
	namesSeated: number;
	turnsPlayed: number;
	/** Minutes at the table: gaps under ten minutes between one move and the next, summed. */
	minutesAtTable: number;
	longestGameTurns: number;
	gamesWithBot: number;
	talkLines: number;
	firstGameAt: string | null;
	/** The game's own lines, summed over finished games. */
	byGame: Record<string, number>;
}

const GAP_LIMIT_MS = 10 * 60 * 1000;
const CACHE_MS = 60 * 1000;

export class Tallies<State, Input> {
	private cached: { at: number; tally: Tally } | null = null;

	constructor(
		private game: GameSpec<State, Input>,
		private store: Store
	) {}

	get(): Tally {
		if (this.cached && Date.now() - this.cached.at < CACHE_MS) return this.cached.tally;
		const tally = this.count();
		this.cached = { at: Date.now(), tally };
		return tally;
	}

	private count(): Tally {
		const t: Tally = { tablesOpened: 0, gamesBegun: 0, gamesFinished: 0, namesSeated: 0, turnsPlayed: 0, minutesAtTable: 0, longestGameTurns: 0, gamesWithBot: 0, talkLines: 0, firstGameAt: null, byGame: {} };
		const names = new Set<string>();
		let firstStart = Infinity;
		for (const id of this.store.roomIds()) {
			const lines = this.store.read(id);
			if (lines[0]?.t !== 'room') continue;
			t.tablesOpened += 1;
			const seats: { id: SeatId; name: string; bot: boolean }[] = [];
			let state: State | null = null;
			let turns = 0;
			let lastMoveAt = 0;
			let hasBot = false;
			let over: LedgerLine | null = null;
			for (const line of lines) {
				if (line.t === 'seat') {
					seats.push(line);
					if (line.bot) hasBot = true;
					else names.add(line.name.toLowerCase());
				} else if (line.t === 'unseat') seats.splice(seats.findIndex((s) => s.id === line.id), 1);
				else if (line.t === 'start') {
					t.gamesBegun += 1;
					if (hasBot) t.gamesWithBot += 1;
					if (lines[0].createdAt < firstStart) firstStart = lines[0].createdAt;
					try {
						state = this.game.create(Object.fromEntries(seats.map((s) => [s.id, s.name])), line.seed, line.rules ?? 1, lines[0].options);
					} catch {
						state = null;
					}
				} else if (line.t === 'input') {
					if (lastMoveAt && line.at - lastMoveAt < GAP_LIMIT_MS) t.minutesAtTable += (line.at - lastMoveAt) / 60000;
					lastMoveAt = line.at;
				} else if (line.t === 'turn') {
					turns += 1;
					if (lastMoveAt && line.at - lastMoveAt < GAP_LIMIT_MS) t.minutesAtTable += (line.at - lastMoveAt) / 60000;
					lastMoveAt = line.at;
					if (state) {
						try {
							state = this.game.resolve(state, line.inputs as Record<SeatId, Input>);
						} catch {
							state = null;
						}
					}
				} else if (line.t === 'chat') t.talkLines += 1;
				else if (line.t === 'over') over = line;
			}
			t.turnsPlayed += turns;
			if (turns > t.longestGameTurns) t.longestGameTurns = turns;
			if (over) {
				t.gamesFinished += 1;
				if (state && this.game.tally) {
					for (const [k, v] of Object.entries(this.game.tally(state))) t.byGame[k] = (t.byGame[k] ?? 0) + v;
				}
			}
		}
		t.namesSeated = names.size;
		t.minutesAtTable = Math.round(t.minutesAtTable);
		t.firstGameAt = Number.isFinite(firstStart) ? new Date(firstStart).toISOString() : null;
		return t;
	}
}