station-master/src/server/index.ts

/**
 * Process bootstrap — Phase 2 §12 step 8, extended for Phase 3 (§12 steps 14-15) load-on-start and
 * Phase 4 (§12 steps 17-20) to resume every saved game and lobby, not just one.
 *
 * Run with:  node src/server/index.ts
 *
 * Env-configured, no config file — matches how the rest of this project's dev-side tooling reads
 * `process.env` directly (`scripts/build-web.ts`'s `BUILD_DIST_DIR`).
 */

import { readFileSync } from 'node:fs';
import { dirname, join, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';
import { startServer } from './http.ts';
import { gameDir, loadGame, readIndex, readLobby, readSessions } from './persistence.ts';
import { tryResumeSession } from './session.ts';
import type { GameSession } from './session.ts';
import type { Lobby, PlayerSession } from './lobby.ts';

const port = Number(process.env['PORT'] ?? 8081);
const bindAddress = process.env['BIND_ADDRESS'] ?? '0.0.0.0';
const joinSecret = process.env['JOIN_SECRET'];
/**
 * Optional, unlike `JOIN_SECRET`: a server with no administrator is a perfectly good server, and
 * refusing to boot without one would break every existing deployment and every dev run. Unset
 * simply means the admin routes are not there (`http.ts`), which is the safe default — the
 * capability has to be granted, never merely left ungated.
 */
const adminSecret = process.env['ADMIN_SECRET'];
const distDir = resolve(process.env['DIST_DIR'] ?? 'dist');
const dataDir = resolve(process.env['DATA_DIR'] ?? 'data');

if (!joinSecret) {
  console.error('JOIN_SECRET must be set — a server-wide secret, passed out of band (D14).');
  process.exit(1);
}

// `package.json`'s version IS `engineVersion` (§12 step 15) — the same reading `scripts/build-web.ts`'s
// `buildStamp()` already does, just from `src/server/` rather than the repo root script directory.
const root = join(dirname(fileURLToPath(import.meta.url)), '..', '..');
const engineVersion = (JSON.parse(readFileSync(join(root, 'package.json'), 'utf8')) as { version: string }).version;

const initialGames = new Map<string, GameSession>();
const initialLobbies = new Map<string, Lobby>();
const initialSessions = new Map<string, PlayerSession>();

const index = await readIndex(dataDir);
// Said before the loop, not after it: replaying is the reason a restart pauses before the port
// opens, and a log that only reports each game once it is done gives no warning of how much is
// still to come.
const resumable = index.filter((e) => e.status !== 'finished').length;
if (resumable > 0) console.log(`Resuming ${resumable} saved game(s)…`);
for (const entry of index) {
  const sessions = await readSessions(dataDir, entry.gameId);
  for (const s of sessions) initialSessions.set(s.token, s);

  if (entry.status === 'lobby') {
    const lobby = await readLobby(dataDir, entry.gameId);
    if (lobby) initialLobbies.set(entry.gameId, lobby);
    continue;
  }

  const loaded = await loadGame(gameDir(dataDir, entry.gameId));
  if (loaded.found) {
    const resumed = tryResumeSession(loaded.saved);
    if (resumed.ok) {
      initialGames.set(entry.gameId, resumed.session);
      console.log(`Resumed ${entry.gameId} (${entry.gameCode}) — ${loaded.saved.history.length} intents replayed.`);
    } else {
      /**
       * The save does not replay under these rules, which is the only thing that has ever actually
       * mattered — and now the only thing asked. Says which move it choked on, because "some
       * version differs" was never enough to act on: the file is left untouched, so an operator who
       * wants the game back can put the previous version on and finish it.
       */
      const f = resumed.failure;
      console.error(
        `Refusing to resume ${entry.gameId} (${entry.gameCode}): move ${f.stoppedAt + 1} of ${f.of} ` +
          `(${f.intent}) is rejected by the current rules with ${f.code}. Saved under engine ` +
          `version ${loaded.storedVersion}, this server is running ${engineVersion}. The file is ` +
          `left untouched.`,
      );
    }
  }
  // `entry.status === 'finished'` games are not resumed into memory at all — nothing plays them
  // forward, and their files stay on disk for post-game replay (`lobby-and-sessions.md` §6).
}

startServer({
  port,
  bindAddress,
  joinSecret,
  adminSecret,
  distDir,
  dataDir,
  engineVersion,
  initialGames,
  initialLobbies,
  initialSessions,
});
console.log(
  `Station Master multiplayer server on ${bindAddress}:${port}, serving ${distDir} — ` +
    `${initialGames.size} game(s) and ${initialLobbies.size} lobby(ies) resumed.`,
);
if (!adminSecret) {
  console.log('ADMIN_SECRET is unset — the /api/games administration routes are disabled.');
}