/**
 * 라스베가스 규칙 계산 (docs/games/las-vegas.md §3–§5, §8). Pure helpers shared by the definition,
 * the view and the tests. State-mutating helpers work on a state `apply` has already cloned.
 */
import { z } from 'zod';
import type { PlayerId } from '@bg/engine';

// ---------------------------------------------------------------- options & actions

const lit = <T extends number | null>(...vals: T[]) =>
  z.union(vals.map((v) => z.literal(v)) as unknown as [z.ZodLiteral<T>, z.ZodLiteral<T>, ...z.ZodLiteral<T>[]]);

export const lasVegasOptionsSchema = z.object({
  rounds: lit(3, 4, 5)
    .default(4)
    .meta({ title: '라운드 수', labels: { 3: '3라운드(짧게)', 4: '4라운드(기본)', 5: '5라운드' } }),
  neutralDice: z
    .enum(['auto', 'on', 'off'])
    .default('auto')
    .meta({
      title: '중립(흰) 주사위',
      labels: { auto: '자동(2명일 때만, 1인당 4개)', on: '켜기(2명 4개, 3~4명 2개씩)', off: '끄기' },
    }),
  hideMoney: z.boolean().default(true).meta({ title: '다른 사람이 받은 지폐 금액 숨기기(장 수만 공개)' }),
  turnSeconds: lit(20, 30, 60, null)
    .default(30)
    .meta({ title: '굴리기·놓기 제한 시간', labels: { 20: '20초', 30: '30초', 60: '60초', null: '무제한' } }),
});
export type LasVegasOptions = z.infer<typeof lasVegasOptionsSchema>;

export const lasVegasActionSchema = z.discriminatedUnion('type', [
  z.object({ type: z.literal('ROLL') }),
  z.object({ type: z.literal('PLACE'), value: z.number().int().min(1).max(6) }),
  z.object({ type: z.literal('CONCEDE') }),
]);
export type LasVegasClientAction = z.infer<typeof lasVegasActionSchema>;
/** Client actions plus the system-only timer action (not in the schema, docs/09 §2). */
export type LasVegasAction = LasVegasClientAction | { type: 'TIMEOUT' };

// ---------------------------------------------------------------- components

export type Note = number;
export const HOUSE = 'house' as const;
export type Owner = PlayerId | typeof HOUSE;
export type CasinoValue = 1 | 2 | 3 | 4 | 5 | 6;

/** Bill denominations → count (§3): 54 bills, 250 in total. */
export const NOTE_COUNTS: Record<Note, number> = { 1: 6, 2: 8, 3: 8, 4: 6, 5: 6, 6: 5, 7: 5, 8: 5, 9: 5 };
export const ALL_NOTES: Note[] = Object.entries(NOTE_COUNTS).flatMap(([v, n]) => Array<Note>(n).fill(Number(v)));
export const OWN_DICE = 8;
export const MIN_CASINO_SUM = 5;
export const CASINO_VALUES: CasinoValue[] = [1, 2, 3, 4, 5, 6];
/** Consecutive automatic actions before a player is shown as "자리 비움" (§8.5). */
export const AWAY_AFTER = 3;
/** Deadline for away players (keeps the game moving). */
export const AWAY_MS = 5000;

export interface Casino {
  value: CasinoValue;
  /** Descending. */
  notes: Note[];
  dice: Partial<Record<Owner, number>>;
}

export interface Payout {
  casino: number;
  removedTies: Owner[];
  awards: { owner: Owner; note: Note }[];
  returned: Note[];
}

export interface RoundResult {
  round: number;
  payouts: Payout[];
}

export interface LasVegasState {
  options: LasVegasOptions;
  seats: PlayerId[];
  round: number;
  /** This round's first player (seat index). */
  startSeat: number;
  /** Seat index of the player to act. */
  current: number;
  phase: 'roll' | 'place' | 'finished';
  /** Hidden draw pile, index 0 = top. */
  pile: Note[];
  casinos: Casino[];
  /** Dice still in hand. */
  hand: Record<PlayerId, { own: number; neutral: number }>;
  lastRoll: { own: number[]; neutral: number[] } | null;
  money: Record<PlayerId, Note[]>;
  roundResults: RoundResult[];
  /** Neutral dice each player gets per round (0 = variant off). */
  neutralPer: number;
  /** Neutral dice the round's first player rolls straight onto the casinos (3 players + variant). */
  houseExtra: number;
  /** Last round-start house roll (3 players + variant). */
  houseRoll: { round: number; player: PlayerId; values: number[] } | null;
  lastPlace: { player: PlayerId; value: number; own: number; neutral: number; auto: boolean } | null;
  conceded: PlayerId[];
  timeouts: Record<PlayerId, number>;
  rollSeq: number;
  turnSeq: number;
  deadlineAt: number | null;
}

// ---------------------------------------------------------------- setup helpers

/** Neutral dice per player for a player count; null = not allowed (5 players + `on`). */
export function neutralPerFor(option: LasVegasOptions['neutralDice'], players: number): number | null {
  if (option === 'off') return 0;
  if (option === 'auto') return players === 2 ? 4 : 0;
  if (players === 2) return 4;
  if (players <= 4) return 2;
  return null;
}

/** Leftover neutral dice the first player rolls each round (only 3 players: 8 − 3×2 = 2). */
export const houseExtraFor = (neutralPer: number, players: number): number => (neutralPer > 0 && players === 3 ? 2 : 0);

/** Deals bills from the top of the pile until each casino holds ≥ 5 (§4.2). Casinos are emptied first. */
export function refillCasinos(s: Pick<LasVegasState, 'pile' | 'casinos'>): void {
  for (const c of s.casinos) {
    c.notes = [];
    c.dice = {};
    let sum = 0;
    while (sum < MIN_CASINO_SUM && s.pile.length > 0) {
      const n = s.pile.shift()!;
      c.notes.push(n);
      sum += n;
    }
    c.notes.sort((a, b) => b - a);
  }
}

// ---------------------------------------------------------------- settlement

/**
 * One casino's payout (§5 정산): owners with equal counts are all removed (the house included), the rest
 * take bills in descending order. Bills the house wins and bills nobody wins are returned.
 * `order` fixes the listing order of tied owners (seat order, house last).
 */
export function settleCasino(notes: Note[], dice: Partial<Record<Owner, number>>, order: Owner[]): Payout & { ranked: Owner[] } {
  const owners = order.filter((o) => (dice[o] ?? 0) > 0);
  const byCount = new Map<number, Owner[]>();
  for (const o of owners) byCount.set(dice[o]!, [...(byCount.get(dice[o]!) ?? []), o]);
  const removedTies = owners.filter((o) => byCount.get(dice[o]!)!.length > 1);
  const ranked = owners.filter((o) => !removedTies.includes(o)).sort((a, b) => dice[b]! - dice[a]!);
  const sorted = [...notes].sort((a, b) => b - a);
  const awards: Payout['awards'] = [];
  ranked.forEach((o, i) => {
    if (i < sorted.length) awards.push({ owner: o, note: sorted[i]! });
  });
  const returned = [...awards.filter((a) => a.owner === HOUSE).map((a) => a.note), ...sorted.slice(ranked.length)].sort((a, b) => b - a);
  return { casino: 0, removedTies, awards, returned, ranked };
}

export const ownerOrder = (s: Pick<LasVegasState, 'seats'>): Owner[] => [...s.seats, HOUSE];

/** What placing `own` + `neutral` dice on casino `value` would mean for `player` right now (§9 미리 보기). */
export function placementPreview(
  s: Pick<LasVegasState, 'seats' | 'casinos'>,
  player: PlayerId,
  value: number,
  own: number,
  neutral: number,
): { standing: 'first' | 'award' | 'tie' | 'none'; note: Note | null; count: number } {
  const c = s.casinos[value - 1]!;
  const dice = { ...c.dice };
  if (own > 0) dice[player] = (dice[player] ?? 0) + own;
  if (neutral > 0) dice[HOUSE] = (dice[HOUSE] ?? 0) + neutral;
  const count = dice[player] ?? 0;
  if (count === 0) return { standing: 'none', note: null, count };
  const out = settleCasino(c.notes, dice, ownerOrder(s));
  if (out.removedTies.includes(player)) return { standing: 'tie', note: null, count };
  const idx = out.ranked.indexOf(player);
  const note = out.awards.find((a) => a.owner === player)?.note ?? null;
  return { standing: note === null ? 'none' : idx === 0 ? 'first' : 'award', note, count };
}

/** Deterministic timeout choice (§8.5): most dice, then the casino's best bill, then the smaller number. */
export function autoPlaceValue(s: Pick<LasVegasState, 'casinos'>, roll: { own: number[]; neutral: number[] }): number {
  let best = 0;
  let bestKey: [number, number] = [-1, -1];
  for (const v of CASINO_VALUES) {
    const n = roll.own.filter((d) => d === v).length + roll.neutral.filter((d) => d === v).length;
    if (n === 0) continue;
    const key: [number, number] = [n, s.casinos[v - 1]!.notes[0] ?? 0];
    if (key[0] > bestKey[0] || (key[0] === bestKey[0] && key[1] > bestKey[1])) {
      best = v;
      bestKey = key;
    }
  }
  return best;
}

export const sum = (notes: Note[]): number => notes.reduce((a, b) => a + b, 0);
export const diceLeft = (s: Pick<LasVegasState, 'hand'>, p: PlayerId): number => (s.hand[p] ? s.hand[p]!.own + s.hand[p]!.neutral : 0);