two-keys/server/src/engines/story.ts

import { matchesAnswer, type Role } from '@two-keys/shared';
import type { Lock, StoryGame } from '../content/schemas';
import { OK, fail, type ActionResult, type Ctx } from './types';

export const HINT_PENALTY_SECONDS = 120;
export const SUBMIT_COOLDOWN_MS = 2000;
export const NUDGE_AFTER_WRONG = 5;

export interface StoryState {
  /** Index of the open chapter; equals chapters.length once the finale is open. */
  chapter: number;
  awaitingContinue: boolean;
  solved: string[];
  hints: Record<string, number>;
  wrong: Record<string, number>;
  lastSubmit: Record<string, number>;
  finale: {
    proposal: { answers: Record<string, string>; by: Role } | null;
    agreed: boolean;
    attempts: number;
  };
}

export function initStory(): StoryState {
  return {
    chapter: 0,
    awaitingContinue: false,
    solved: [],
    hints: {},
    wrong: {},
    lastSubmit: {},
    finale: { proposal: null, agreed: false, attempts: 0 },
  };
}

const state = (ctx: Ctx) => ctx.room.engine as StoryState;
const atFinale = (game: StoryGame, s: StoryState) => s.chapter >= game.chapters.length;

/** The one lock that can currently be worked on, if any. */
export function openLock(game: StoryGame, s: StoryState): { lock: Lock; finale: boolean } | null {
  if (!atFinale(game, s)) {
    return s.awaitingContinue ? null : { lock: game.chapters[s.chapter].lock, finale: false };
  }
  if (game.finale.type === 'escape' && !s.solved.includes(game.finale.lock.id)) {
    return { lock: game.finale.lock, finale: true };
  }
  return null;
}

export function submitLock(game: StoryGame, ctx: Ctx, lockId: string, value: string): ActionResult {
  const s = state(ctx);
  const open = openLock(game, s);
  if (!open || open.lock.id !== lockId) return fail('lock_closed', "That lock isn't open right now.");

  const last = s.lastSubmit[lockId] ?? 0;
  if (ctx.now - last < SUBMIT_COOLDOWN_MS) {
    return fail('rate_limited', 'Easy! One guess every two seconds.');
  }
  s.lastSubmit[lockId] = ctx.now;

  if (!matchesAnswer(value, open.lock.answers)) {
    s.wrong[lockId] = (s.wrong[lockId] ?? 0) + 1;
    ctx.room.wrongGuesses++;
    return { ok: true, correct: false };
  }

  s.solved.push(lockId);
  if (open.finale) {
    ctx.finish(true, game.finale.successEnding);
  } else {
    ctx.addKey(open.lock.keyName ?? 'Key');
    s.awaitingContinue = true;
  }
  return { ok: true, correct: true };
}

export function requestHint(game: StoryGame, ctx: Ctx, lockId: string): ActionResult {
  const s = state(ctx);
  const open = openLock(game, s);
  if (!open || open.lock.id !== lockId) return fail('lock_closed', "That lock isn't open right now.");
  const tier = s.hints[lockId] ?? 0;
  if (tier >= open.lock.hints.length) return fail('no_more_hints', "That's every hint for this lock.");
  s.hints[lockId] = tier + 1;
  ctx.room.hintsUsed++;
  ctx.addPenalty(HINT_PENALTY_SECONDS);
  ctx.toast('all', `Hint ${tier + 1} revealed (+2:00)`);
  return OK;
}

export function continueChapter(game: StoryGame, ctx: Ctx): ActionResult {
  const s = state(ctx);
  if (!s.awaitingContinue) return fail('not_ready', 'Solve the lock first.');
  s.awaitingContinue = false;
  s.chapter++;
  return OK;
}

function accusation(game: StoryGame, s: StoryState) {
  return atFinale(game, s) && game.finale.type === 'accusation' ? game.finale : null;
}

export function proposeAccusation(
  game: StoryGame,
  ctx: Ctx,
  role: Role,
  answers: Record<string, string>,
): ActionResult {
  const s = state(ctx);
  const finale = accusation(game, s);
  if (!finale) return fail('no_finale', "The finale isn't open yet.");
  const clean: Record<string, string> = {};
  for (const q of finale.questions) {
    const pick = answers[q.id];
    if (!q.options.some((o) => o.id === pick)) return fail('incomplete', 'Answer every question first.');
    clean[q.id] = pick;
  }
  s.finale.proposal = { answers: clean, by: role };
  s.finale.agreed = false;
  return OK;
}

export function agreeAccusation(game: StoryGame, ctx: Ctx, role: Role): ActionResult {
  const s = state(ctx);
  if (!accusation(game, s) || !s.finale.proposal) return fail('no_proposal', 'Nothing to agree to yet.');
  if (s.finale.proposal.by === role) return fail('own_proposal', 'Your partner has to agree, not you.');
  s.finale.agreed = true;
  return OK;
}

export function submitAccusation(game: StoryGame, ctx: Ctx): ActionResult {
  const s = state(ctx);
  const finale = accusation(game, s);
  if (!finale || !s.finale.proposal) return fail('no_proposal', 'Propose an accusation first.');
  if (!s.finale.agreed) return fail('not_agreed', 'You both have to agree before submitting.');

  const { answers } = s.finale.proposal;
  const correct = finale.questions.every((q) => answers[q.id] === q.answer);
  if (correct) {
    ctx.finish(true, finale.successEnding);
    return { ok: true, correct: true };
  }

  s.finale.attempts++;
  s.finale.proposal = null;
  s.finale.agreed = false;
  ctx.room.wrongGuesses++;
  const left = finale.maxAttempts - s.finale.attempts;
  if (left <= 0) {
    ctx.finish(false, finale.failEnding, finale.reveal);
  } else {
    // Deliberately doesn't say which part was wrong.
    ctx.toast('all', `Not quite. ${left} attempt${left === 1 ? '' : 's'} left.`);
  }
  return { ok: true, correct: false };
}