station-master/test/server/lobby.test.ts

/**
 * The lobby (`src/server/lobby.ts`) — pure logic, no sockets, no filesystem, exercised directly.
 */

import { describe, it } from 'node:test';
import assert from 'node:assert/strict';

import type { GameConfig } from '../../src/engine/state.ts';
import {
  createLobby,
  freshGameCode,
  joinLobby,
  playerCountAllowed,
  reassignHost,
  setBotSeat,
  startLobby,
} from '../../src/server/lobby.ts';

const competitive: GameConfig = {
  mode: 'competitive',
  days: 5,
  minCombinedRevenue: 0,
  maxCollisionsPerDay: 0,
  maxCollisionsTotal: 0,
  pvpCardsAllowed: false,
  optionalRules: {
    reducedVisibility: false,
    sisterTrains: false,
    employeeRotation: false,
    emergencyToolbox: false,
  },
};
const solitaire: GameConfig = { ...competitive, mode: 'solitaire' };

describe('creating and joining', () => {
  it('seats the host at 0 and lays out the whole table at once', () => {
    const { lobby, session } = createLobby(competitive, 'Alice', 'RAIL-0001', 3);
    assert.equal(session.player, 0);
    assert.equal(lobby.hostToken, session.token);
    // The table is its full size immediately — the empty chairs exist and are waiting, rather
    // than being appended as people arrive.
    assert.equal(lobby.seats.length, 3);
    assert.deepEqual(lobby.seats[0], { kind: 'human', token: session.token, displayName: 'Alice' });
    assert.deepEqual(lobby.seats.slice(1), [null, null]);
    assert.deepEqual(lobby.joinOrder, [session.token]);
  });

  it('fills the next empty seat, in order', () => {
    const { lobby: l1, session: s1 } = createLobby(competitive, 'Alice', 'RAIL-0001', 4);
    const j2 = joinLobby(l1, 'Bob');
    assert.ok(j2.ok);
    if (!j2.ok) return;
    assert.equal(j2.session.player, 1);
    const j3 = joinLobby(j2.lobby, 'Carol');
    assert.ok(j3.ok);
    if (!j3.ok) return;
    assert.equal(j3.session.player, 2);
    assert.deepEqual(j3.lobby.joinOrder, [s1.token, j2.session.token, j3.session.token]);
  });

  it('refuses a join once every chair is taken', () => {
    let lobby = createLobby(competitive, 'Alice', 'RAIL-0001', 4).lobby;
    for (const name of ['Bob', 'Carol', 'Dave']) {
      const r = joinLobby(lobby, name);
      assert.ok(r.ok);
      if (r.ok) lobby = r.lobby;
    }
    const fifth = joinLobby(lobby, 'Eve');
    assert.deepEqual(fifth, { ok: false, code: 'LOBBY_FULL' });
  });

  it('refuses a 2nd join to a one-chair table', () => {
    const { lobby } = createLobby(solitaire, 'Alice', 'RAIL-0002', 1);
    const second = joinLobby(lobby, 'Bob');
    assert.deepEqual(second, { ok: false, code: 'LOBBY_FULL' });
  });

  it('rejoins into a seat an earlier player vacated, not past the end', () => {
    // Joining always fills the FIRST empty seat, so a bot-seat cleared back to empty (setBotSeat)
    // is exactly as joinable as one nobody ever filled.
    let lobby = createLobby(competitive, 'Alice', 'RAIL-0003', 3).lobby;
    lobby = setBotSeat(lobby, 1, true);
    lobby = setBotSeat(lobby, 1, false);
    const r = joinLobby(lobby, 'Bob');
    assert.ok(r.ok);
    if (!r.ok) return;
    assert.equal(r.session.player, 1, 'should take the reopened chair 1');
    assert.equal(r.lobby.seats.length, 3, 'joining must never resize the table');
    assert.equal(r.lobby.seats[2], null);
  });

  it('never grows the table, whoever asks', () => {
    // The old model appended a seat for anyone who turned up, which is how a lobby could end up
    // holding more chairs than the host ever asked for.
    const { lobby } = createLobby(competitive, 'Alice', 'RAIL-0013', 2);
    const bob = joinLobby(lobby, 'Bob');
    assert.ok(bob.ok);
    if (!bob.ok) return;
    assert.equal(bob.lobby.seats.length, 2);
    assert.deepEqual(joinLobby(bob.lobby, 'Carol'), { ok: false, code: 'LOBBY_FULL' });
  });
});

describe('bot seats', () => {
  it('fills only an empty seat, and clears only a bot seat', () => {
    const { lobby: l0 } = createLobby(competitive, 'Alice', 'RAIL-0004', 2);
    const withBot = setBotSeat(l0, 1, true);
    assert.deepEqual(withBot.seats[1], { kind: 'bot' });

    // Filling an already-bot seat again is a no-op, not a crash.
    const stillBot = setBotSeat(withBot, 1, true);
    assert.deepEqual(stillBot.seats[1], { kind: 'bot' });

    // Clearing seat 0 (a human) does nothing — a host is removed by leaving, not overwritten.
    const untouched = setBotSeat(withBot, 0, false);
    assert.deepEqual(untouched.seats[0], l0.seats[0]);

    const cleared = setBotSeat(withBot, 1, false);
    assert.equal(cleared.seats[1], null);
  });

  it('refuses a chair that is not at the table, instead of padding one in', () => {
    // Padding is what used to put a hole in the seats array: dropping a bot into chair 3 of a
    // 2-chair table grew it to 4 with a null at 2, and Start then refused for reasons the host
    // had no way to see.
    const { lobby } = createLobby(competitive, 'Alice', 'RAIL-0014', 2);
    assert.equal(setBotSeat(lobby, 3, true), lobby);
    assert.equal(setBotSeat(lobby, 2, true), lobby);
    assert.equal(lobby.seats.length, 2);
  });
});

describe('host transfer', () => {
  it('passes to the earliest-joined remaining human seat when the host departs', () => {
    let lobby = createLobby(competitive, 'Alice', 'RAIL-0005', 2).lobby;
    const hostToken = lobby.hostToken;
    const j2 = joinLobby(lobby, 'Bob');
    assert.ok(j2.ok);
    if (!j2.ok) return;
    lobby = j2.lobby;
    // Alice's own seat is cleared (simulating her leaving the table entirely, not just dropping
    // her connection) so the transfer target is unambiguous in this test.
    lobby = { ...lobby, seats: [null, lobby.seats[1]!] };
    const after = reassignHost(lobby, hostToken);
    assert.equal(after.hostToken, j2.session.token);
  });

  it('does nothing when the departing token is not the host', () => {
    const { lobby } = createLobby(competitive, 'Alice', 'RAIL-0006', 2);
    const after = reassignHost(lobby, 'not-a-real-token');
    assert.equal(after, lobby);
  });

  it('leaves hostToken alone when no other human seat exists', () => {
    const { lobby, session } = createLobby(competitive, 'Alice', 'RAIL-0007', 2);
    const after = reassignHost(lobby, session.token);
    assert.equal(after.hostToken, session.token);
  });
});

describe('starting', () => {
  it('refuses a non-host caller', () => {
    const { lobby } = createLobby(competitive, 'Alice', 'RAIL-0008', 2);
    joinLobby(lobby, 'Bob');
    assert.deepEqual(startLobby(lobby, 'someone-elses-token'), { ok: false, code: 'NOT_HOST' });
  });

  it('refuses to start while a chair is still empty', () => {
    const lobby = createLobby(competitive, 'Alice', 'RAIL-0009', 3).lobby;
    const j2 = joinLobby(lobby, 'Bob');
    assert.ok(j2.ok);
    if (!j2.ok) return;
    assert.deepEqual(startLobby(j2.lobby, j2.lobby.hostToken), { ok: false, code: 'BAD_PLAYER_COUNT' });
  });

  it('refuses a solo human at a table sized for more', () => {
    const { lobby } = createLobby(competitive, 'Alice', 'RAIL-0010', 2);
    assert.deepEqual(startLobby(lobby, lobby.hostToken), { ok: false, code: 'BAD_PLAYER_COUNT' });
  });

  it('starts a full 2-player lobby, naming bots "Bot" and humans by their display name', () => {
    let lobby = createLobby(competitive, 'Alice', 'RAIL-0011', 2).lobby;
    lobby = setBotSeat(lobby, 1, true);
    const r = startLobby(lobby, lobby.hostToken);
    assert.deepEqual(r, { ok: true, playerNames: ['Alice', 'Bot'], botSeats: [1] });
  });

  it('starts a solitaire lobby of exactly 1', () => {
    const { lobby } = createLobby(solitaire, 'Alice', 'RAIL-0012', 1);
    const r = startLobby(lobby, lobby.hostToken);
    assert.deepEqual(r, { ok: true, playerNames: ['Alice'], botSeats: [] });
  });

  it('seat index is player index, with no compaction to shift it', () => {
    // The seats array is never resized or squeezed, so the chair a player joined into is the
    // player index the game gives them — which is what every PlayerSession already recorded at
    // join time, and what /api/stream and /api/intent route by.
    let lobby = createLobby(competitive, 'Alice', 'RAIL-0015', 4).lobby;
    const bob = joinLobby(lobby, 'Bob');
    assert.ok(bob.ok);
    if (!bob.ok) return;
    lobby = setBotSeat(setBotSeat(bob.lobby, 2, true), 3, true);
    const r = startLobby(lobby, lobby.hostToken);
    assert.deepEqual(r, { ok: true, playerNames: ['Alice', 'Bob', 'Bot', 'Bot'], botSeats: [2, 3] });
    assert.equal(bob.session.player, 1, "Bob's stored player index still names his chair");
  });
});

describe('playerCountAllowed', () => {
  it('solitaire is exactly 1', () => {
    assert.equal(playerCountAllowed('solitaire', 1), true);
    assert.equal(playerCountAllowed('solitaire', 0), false);
    assert.equal(playerCountAllowed('solitaire', 2), false);
  });

  it('competitive and coop are 2-4', () => {
    for (const mode of ['competitive', 'coop'] as const) {
      assert.equal(playerCountAllowed(mode, 1), false);
      assert.equal(playerCountAllowed(mode, 2), true);
      assert.equal(playerCountAllowed(mode, 4), true);
      assert.equal(playerCountAllowed(mode, 5), false);
    }
  });
});

describe('game codes', () => {
  it('skips codes the caller marks taken', () => {
    let calls = 0;
    const code = freshGameCode((c) => {
      calls++;
      return calls < 3; // taken twice, free on the third
    });
    assert.equal(typeof code, 'string');
    assert.equal(calls, 3);
  });

  it('is speakable — a word, a dash, four digits', () => {
    const code = freshGameCode(() => false);
    assert.match(code, /^[A-Z]+-\d{4}$/);
  });
});