// Pure gamification rules: ranks/leagues, rating, XP/levels, coins,
// daily rewards, achievements. No side effects, no storage — unit-testable.

import {
  AchievementCategoryDef,
  AchievementCategoryId,
  AchievementDef,
  AchievementMetric,
  AchievementUnlock,
  CardBackDef,
  CardFrontDef,
  LeagueInfo,
  MatchLeague,
  MatchSummary,
  PlayerStats,
  RankTier,
  RankTierId,
  ReactionPackDef,
  RewardResult,
  StickerPackDef,
  TitleDef,
  TitleUnlock,
  UserProfile,
} from "./types";

/* ------------------------------- Ranks ------------------------------- */

export const RANK_TIERS: RankTier[] = [
  { id: "bronze", nameFa: "برنز", nameEn: "Bronze", floor: 0, color: "#cd7f32" },
  { id: "silver", nameFa: "نقره", nameEn: "Silver", floor: 1100, color: "#c0c7d0" },
  { id: "gold", nameFa: "طلا", nameEn: "Gold", floor: 1300, color: "#e6b800" },
  { id: "platinum", nameFa: "پلاتین", nameEn: "Platinum", floor: 1500, color: "#46c2c2" },
  { id: "diamond", nameFa: "الماس", nameEn: "Diamond", floor: 1700, color: "#6aa6ff" },
  { id: "master", nameFa: "استاد", nameEn: "Master", floor: 1900, color: "#c77dff" },
];

const ROMAN = ["", "I", "II", "III"];

export function divisionLabel(division: number | null): string {
  if (division == null) return "";
  return ROMAN[division] ?? "";
}

export function tierById(id: RankTierId): RankTier {
  return RANK_TIERS.find((t) => t.id === id) ?? RANK_TIERS[0];
}

export function getLeagueInfo(rating: number): LeagueInfo {
  const r = Math.max(0, Math.round(rating));
  let idx = 0;
  for (let i = 0; i < RANK_TIERS.length; i++) {
    if (r >= RANK_TIERS[i].floor) idx = i;
  }
  const tier = RANK_TIERS[idx];
  const isLast = idx === RANK_TIERS.length - 1;

  if (isLast) {
    return { tier, division: null, rating: r, nextThreshold: null, progress: 1 };
  }

  const nextTierFloor = RANK_TIERS[idx + 1].floor;
  const band = nextTierFloor - tier.floor;
  const third = band / 3;
  // division 3 (III) is lowest, 1 (I) is highest
  const within = r - tier.floor;
  let division: number;
  let divStart: number;
  let divEnd: number;
  if (within < third) {
    division = 3;
    divStart = tier.floor;
    divEnd = tier.floor + third;
  } else if (within < 2 * third) {
    division = 2;
    divStart = tier.floor + third;
    divEnd = tier.floor + 2 * third;
  } else {
    division = 1;
    divStart = tier.floor + 2 * third;
    divEnd = nextTierFloor;
  }
  const progress = Math.min(1, Math.max(0, (r - divStart) / (divEnd - divStart)));
  return { tier, division, rating: r, nextThreshold: Math.round(divEnd), progress };
}

/* ------------------------------ Rating ------------------------------- */

const K_FACTOR = 32;

/** Elo-style rating delta for a ranked match (0 for casual). */
export function ratingDelta(
  summary: MatchSummary,
  myRating: number,
  oppRating: number
): number {
  if (!summary.ranked) return 0;
  const expected = 1 / (1 + Math.pow(10, (oppRating - myRating) / 400));
  const score = summary.won ? 1 : 0;
  let delta = K_FACTOR * (score - expected);
  if (summary.won && summary.kotFor) delta += 8;
  if (!summary.won && summary.kotAgainst) delta -= 8;
  const rounded = Math.round(delta);
  // never let a win cost rating or a loss gain it
  if (summary.won) return Math.max(1, rounded);
  return Math.min(-1, rounded);
}

/* ------------------------------- Coins ------------------------------- */

export function coinDelta(summary: MatchSummary): number {
  // Free games (vs computer / private friend rooms) never touch coins.
  if (!summary.ranked) return 0;
  // Ranked: win the stake (+kot bonus scaled to the league), lose the stake.
  // Higher leagues stake more, so wins/losses swing bigger.
  const kotBonus = summary.won && summary.kotFor ? Math.round(summary.stake * 0.4) : 0;
  return (summary.won ? summary.stake : -summary.stake) + kotBonus;
}

/* ----------------------------- Leagues ------------------------------- */

/** Ranked-matchmaking coin entry tiers (the stake you win/lose). */
export const MATCH_LEAGUES: MatchLeague[] = [
  { id: "starter", entry: 100, minLevel: 1, color: "#2dd4bf", icon: "🌱", nameFa: "لیگ شروع", nameEn: "Starter", descFa: "ورود ۱۰۰ سکه — مناسب تازه‌کارها", descEn: "100-coin entry — for newcomers" },
  { id: "pro", entry: 500, minLevel: 10, color: "#e6b800", icon: "⚔️", nameFa: "لیگ حرفه‌ای", nameEn: "Pro", descFa: "ورود ۵۰۰ سکه — برد و باخت بزرگ‌تر", descEn: "500-coin entry — bigger swings" },
  { id: "expert", entry: 1000, minLevel: 20, color: "#c77dff", icon: "👑", nameFa: "لیگ استادان", nameEn: "Expert", descFa: "ورود ۱۰۰۰ سکه — برای حرفه‌ای‌ها", descEn: "1000-coin entry — for the best" },
];

export function leagueById(id: string): MatchLeague {
  return MATCH_LEAGUES.find((l) => l.id === id) ?? MATCH_LEAGUES[0];
}

/* ------------------------------- XP ---------------------------------- */

/** XP required to advance from `level` to `level + 1`. */
export function xpNeededForLevel(level: number): number {
  return 100 * level;
}

export function matchXp(summary: MatchSummary): number {
  return (
    40 +
    (summary.won ? 80 : 0) +
    summary.tricksWon * 5 +
    (summary.kotFor ? 30 : 0)
  );
}

export interface LevelProgress {
  level: number;
  xp: number; // xp within the current level
  leveledUp: boolean;
}

export function addXp(level: number, xpInLevel: number, gained: number): LevelProgress {
  let lvl = level;
  let xp = xpInLevel + gained;
  let leveledUp = false;
  while (xp >= xpNeededForLevel(lvl)) {
    xp -= xpNeededForLevel(lvl);
    lvl += 1;
    leveledUp = true;
  }
  return { level: lvl, xp, leveledUp };
}

/* --------------------------- Achievements ---------------------------- */

export const ACHIEVEMENT_CATEGORIES: AchievementCategoryDef[] = [
  { id: "victory", nameFa: "بردها", nameEn: "Victories", icon: "🏆" },
  { id: "kot", nameFa: "کُت", nameEn: "Kot", icon: "🔥" },
  { id: "streak", nameFa: "نوار پیروزی", nameEn: "Streaks", icon: "⚡" },
  { id: "hakem", nameFa: "حاکمیت", nameEn: "Rulership", icon: "👑" },
  { id: "level", nameFa: "سطح", nameEn: "Levels", icon: "⭐" },
  { id: "rank", nameFa: "لیگ", nameEn: "Ranks", icon: "🏅" },
  { id: "veteran", nameFa: "کارنامه", nameEn: "Veterancy", icon: "🎮" },
];

const FA_DIGITS = "۰۱۲۳۴۵۶۷۸۹";
/** Western → Persian digits, for generated achievement names. */
export function faNum(n: number): string {
  return String(n).replace(/\d/g, (d) => FA_DIGITS[+d]);
}

/** Build a tiered family of achievements for one metric (keeps the list DRY). */
function tier(
  category: AchievementCategoryId,
  metric: AchievementMetric,
  prefix: string,
  icon: string,
  goals: number[],
  faName: (g: string) => string,
  enName: (g: number) => string,
  faDesc: (g: string) => string,
  enDesc: (g: number) => string
): AchievementDef[] {
  return goals.map((g) => ({
    id: `${prefix}_${g}`,
    category,
    metric,
    goal: g,
    coinReward: Math.max(100, Math.round((80 + g * 12) / 50) * 50),
    icon,
    nameFa: faName(faNum(g)),
    nameEn: enName(g),
    descFa: faDesc(faNum(g)),
    descEn: enDesc(g),
  }));
}

export const ACHIEVEMENTS: AchievementDef[] = [
  ...tier("victory", "wins", "wins", "🏆",
    [1, 5, 10, 25, 50, 75, 100, 150, 200, 250, 300, 400, 500, 750, 1000, 2000],
    (g) => `${g} برد`, (g) => `${g} Wins`, (g) => `${g} بازی ببرید`, (g) => `Win ${g} games`),
  ...tier("victory", "shutoutWins", "shutout", "🧹", [1, 3, 5, 10, 25, 50, 100],
    (g) => `${g} بار هفت–هیچ`, (g) => `${g}× Sweep`,
    (g) => `${g} بار حریف را ۷–۰ ببرید`, (g) => `Sweep the opponent ${g}×`),
  ...tier("kot", "kotsFor", "kot", "🔥", [1, 3, 5, 10, 25, 50, 75, 100, 150, 200, 300, 500],
    (g) => `${g} کُت`, (g) => `${g} Kots`, (g) => `${g} بار حریف را کُت کنید`, (g) => `Inflict ${g} Kots`),
  ...tier("streak", "bestWinStreak", "streak", "⚡", [2, 3, 5, 7, 10, 15, 20, 25, 30, 40],
    (g) => `${g} برد پیاپی`, (g) => `${g} Win Streak`,
    (g) => `${g} بازی پشت سر هم ببرید`, (g) => `Win ${g} games in a row`),
  ...tier("hakem", "hakemRounds", "hakem", "👑", [7, 25, 50, 100, 250, 500, 1000],
    (g) => `${g} بار حاکم`, (g) => `Hakem ${g}×`,
    (g) => `${g} دست حاکم شوید`, (g) => `Be the hakem in ${g} rounds`),
  ...tier("level", "level", "level", "⭐",
    [5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100],
    (g) => `سطح ${g}`, (g) => `Level ${g}`, (g) => `به سطح ${g} برسید`, (g) => `Reach level ${g}`),
  ...tier("veteran", "games", "games", "🎮", [10, 25, 50, 100, 200, 300, 500, 750, 1000, 2000, 5000],
    (g) => `${g} بازی`, (g) => `${g} Games`, (g) => `${g} بازی انجام دهید`, (g) => `Play ${g} games`),
  ...tier("veteran", "roundsWon", "rounds", "🎴", [25, 100, 250, 500, 1000, 2000, 5000],
    (g) => `${g} دست برده`, (g) => `${g} Rounds Won`, (g) => `${g} دست ببرید`, (g) => `Win ${g} rounds`),
  ...tier("veteran", "tricks", "tricks", "🗂️", [50, 100, 250, 500, 1000, 2500, 5000, 10000],
    (g) => `${g} دست‌برد`, (g) => `${g} Tricks`, (g) => `${g} دست‌برد بگیرید`, (g) => `Win ${g} tricks`),
  ...tier("veteran", "losses", "grit", "🛡️", [10, 50, 100],
    (g) => `${g} باخت`, (g) => `${g} Losses`,
    (g) => `با وجود ${g} باخت ادامه دهید`, (g) => `Persevere through ${g} losses`),
  // ranks (explicit rating floors)
  { id: "reach_silver", category: "rank", ratingFloor: 1100, goal: 1, coinReward: 200, icon: "🥈", nameFa: "لیگ نقره", nameEn: "Reach Silver", descFa: "به لیگ نقره برسید", descEn: "Reach the Silver league" },
  { id: "reach_gold", category: "rank", ratingFloor: 1300, goal: 1, coinReward: 500, icon: "🥇", nameFa: "لیگ طلا", nameEn: "Reach Gold", descFa: "به لیگ طلا برسید", descEn: "Reach the Gold league" },
  { id: "reach_platinum", category: "rank", ratingFloor: 1500, goal: 1, coinReward: 1000, icon: "🛡️", nameFa: "لیگ پلاتین", nameEn: "Reach Platinum", descFa: "به لیگ پلاتین برسید", descEn: "Reach the Platinum league" },
  { id: "reach_diamond", category: "rank", ratingFloor: 1700, goal: 1, coinReward: 2000, icon: "💠", nameFa: "لیگ الماس", nameEn: "Reach Diamond", descFa: "به لیگ الماس برسید", descEn: "Reach the Diamond league" },
  { id: "reach_master", category: "rank", ratingFloor: 1900, goal: 1, coinReward: 4000, icon: "👑", nameFa: "لیگ استاد", nameEn: "Reach Master", descFa: "به لیگ استاد برسید", descEn: "Reach the Master league" },
];

function metricValue(metric: NonNullable<AchievementDef["metric"]>, stats: PlayerStats, level: number): number {
  switch (metric) {
    case "wins": return stats.wins;
    case "losses": return stats.losses;
    case "kotsFor": return stats.kotsFor;
    case "bestWinStreak": return stats.bestWinStreak;
    case "shutoutWins": return stats.shutoutWins ?? 0;
    case "games": return stats.games;
    case "tricks": return stats.tricks;
    case "hakemRounds": return stats.hakemRounds ?? 0;
    case "roundsWon": return stats.roundsWon ?? 0;
    case "level": return level;
  }
}

/** Current raw progress value (0..goal) for an achievement. */
export function achievementProgress(
  def: AchievementDef,
  stats: PlayerStats,
  rating: number,
  level: number
): number {
  if (def.ratingFloor != null) return rating >= def.ratingFloor ? def.goal : 0;
  if (!def.metric) return 0;
  return Math.min(def.goal, metricValue(def.metric, stats, level));
}

export function achievementById(id: string): AchievementDef | undefined {
  return ACHIEVEMENTS.find((a) => a.id === id);
}

/** The sticker pack (if any) that unlocking this achievement grants. */
export function stickerPackForAchievement(achId: string): StickerPackDef | undefined {
  return STICKER_PACKS.find((p) => p.unlockAchievement === achId);
}

/* ------------------------------ Titles ------------------------------- */

export const TITLES: TitleDef[] = [
  { id: "novice", nameFa: "تازه‌کار", nameEn: "Novice", hintFa: "پیش‌فرض", hintEn: "Default" },
  { id: "winner", nameFa: "برنده", nameEn: "Winner", hintFa: "۱۰ برد", hintEn: "10 wins" },
  { id: "expert", nameFa: "خبره", nameEn: "Expert", hintFa: "سطح ۲۵", hintEn: "Level 25" },
  { id: "kot_master", nameFa: "استاد کُت", nameEn: "Kot Master", hintFa: "۲۵ کُت", hintEn: "25 kots" },
  { id: "professional", nameFa: "حرفه‌ای", nameEn: "Professional", hintFa: "۵۰ برد", hintEn: "50 wins" },
  { id: "veteran", nameFa: "کهنه‌کار", nameEn: "Veteran", hintFa: "سطح ۳۰", hintEn: "Level 30" },
  { id: "captain", nameFa: "کاپیتان", nameEn: "Captain", hintFa: "۱۰۰ برد", hintEn: "100 wins" },
  { id: "champion", nameFa: "قهرمان", nameEn: "Champion", hintFa: "لیگ طلا", hintEn: "Gold league" },
  { id: "leader", nameFa: "فرمانده", nameEn: "Leader", hintFa: "۲۵۰ برد", hintEn: "250 wins" },
  { id: "legend", nameFa: "اسطوره", nameEn: "Legend", hintFa: "لیگ استاد", hintEn: "Master league" },
];

export function titleUnlocked(
  id: string,
  stats: PlayerStats,
  rating: number,
  level: number
): boolean {
  switch (id) {
    case "novice":
      return true;
    case "winner":
      return stats.wins >= 10;
    case "expert":
      return level >= 25;
    case "kot_master":
      return stats.kotsFor >= 25;
    case "professional":
      return stats.wins >= 50;
    case "veteran":
      return level >= 30;
    case "captain":
      return stats.wins >= 100;
    case "champion":
      return rating >= tierById("gold").floor;
    case "leader":
      return stats.wins >= 250;
    case "legend":
      return rating >= tierById("master").floor;
    default:
      return false;
  }
}

/* ---------------------------- Card styles ---------------------------- */

// Card BACKS (pattern on the reverse of every card).
export const CARD_BACKS: CardBackDef[] = [
  { id: "classic", nameFa: "کلاسیک", nameEn: "Classic", c1: "#14274f", c2: "#0a142e", accent: "#d4af37", price: 0, default: true },
  { id: "sapphire", nameFa: "یاقوت کبود", nameEn: "Sapphire", c1: "#0b3a82", c2: "#06173a", accent: "#6aa6ff", price: 800 },
  { id: "emerald", nameFa: "زمرد", nameEn: "Emerald", c1: "#0d6b5e", c2: "#062420", accent: "#2dd4bf", price: 1000 },
  { id: "ruby", nameFa: "یاقوت", nameEn: "Ruby", c1: "#7f1d2e", c2: "#2b0a12", accent: "#ff7a90", price: 0, unlockRating: 1300 }, // earned
  { id: "royal", nameFa: "سلطنتی", nameEn: "Royal", c1: "#4a1d7f", c2: "#1a0a2e", accent: "#c77dff", price: 0, unlockWins: 50 }, // earned
];

// Card FRONTS (the face background/border behind the suit + rank).
export const CARD_FRONTS: CardFrontDef[] = [
  { id: "classic", nameFa: "کلاسیک", nameEn: "Classic", bg1: "#fffdf7", bg2: "#f3ead2", border: "rgba(0,0,0,0.12)", price: 0, default: true },
  { id: "ivory", nameFa: "عاج", nameEn: "Ivory", bg1: "#ffffff", bg2: "#eef2f8", border: "#c9ccd6", price: 600 },
  { id: "rosegold", nameFa: "رزگلد", nameEn: "Rose Gold", bg1: "#fff1ee", bg2: "#f6d9cf", border: "#d98a72", price: 900 },
  { id: "parchment", nameFa: "پوست‌نوشت", nameEn: "Parchment", bg1: "#fbf2d8", bg2: "#efd9a3", border: "#caa84a", price: 0, unlockRating: 1300 }, // earned
  { id: "mint", nameFa: "نعنایی", nameEn: "Mint", bg1: "#f0fff8", bg2: "#d3f3e3", border: "#57c79a", price: 0, unlockWins: 50 }, // earned
];

export function cardBackById(id: string): CardBackDef {
  return CARD_BACKS.find((c) => c.id === id) ?? CARD_BACKS[0];
}
export function cardFrontById(id: string): CardFrontDef {
  return CARD_FRONTS.find((c) => c.id === id) ?? CARD_FRONTS[0];
}

function ownedCosmeticIds(
  defs: { id: string; price: number; default?: boolean; unlockRating?: number; unlockWins?: number }[],
  profile: UserProfile,
  purchased: string[]
): string[] {
  const ids = new Set<string>();
  for (const d of defs) {
    const earned =
      (d.unlockRating != null && profile.rating >= d.unlockRating) ||
      (d.unlockWins != null && profile.stats.wins >= d.unlockWins);
    if (d.default || earned || purchased.includes(d.id)) ids.add(d.id);
  }
  return [...ids];
}

export function ownedCardBackIds(profile: UserProfile): string[] {
  return ownedCosmeticIds(CARD_BACKS, profile, profile.ownedCardBacks ?? []);
}
export function ownedCardFrontIds(profile: UserProfile): string[] {
  return ownedCosmeticIds(CARD_FRONTS, profile, profile.ownedCardFronts ?? []);
}

/* --------------------- Reactions (Sheklak / شکلک) -------------------- */

export const REACTION_PACKS: ReactionPackDef[] = [
  { id: "starter", nameFa: "پایه", nameEn: "Starter", reactions: ["👍", "👏", "😂", "😮"], price: 0, default: true },
  { id: "emotions", nameFa: "احساسات", nameEn: "Emotions", reactions: ["😎", "😭", "🤯", "🥳", "😍"], price: 600 },
  { id: "taunt", nameFa: "طعنه", nameEn: "Taunts", reactions: ["😏", "🤡", "🙄", "😴", "🥱"], price: 900 },
  { id: "champion", nameFa: "قهرمان", nameEn: "Champion", reactions: ["👑", "🏆", "💪", "🔥"], price: 0, unlockRating: 1300 },
  { id: "legend", nameFa: "اسطوره", nameEn: "Legend", reactions: ["💎", "⚡", "🐐", "🎯"], price: 0, unlockWins: 100 },
];

export function reactionPackById(id: string): ReactionPackDef | undefined {
  return REACTION_PACKS.find((p) => p.id === id);
}

/** Which packs the player currently owns (default + earned + purchased). */
export function ownedReactionPackIds(profile: UserProfile): string[] {
  const purchased = profile.ownedReactionPacks ?? [];
  const ids = new Set<string>();
  for (const p of REACTION_PACKS) {
    const earned =
      (p.unlockRating != null && profile.rating >= p.unlockRating) ||
      (p.unlockWins != null && profile.stats.wins >= p.unlockWins);
    if (p.default || earned || purchased.includes(p.id)) ids.add(p.id);
  }
  return [...ids];
}

/** Flattened emoji list the player can send. */
export function ownedReactions(profile: UserProfile): string[] {
  const ids = new Set(ownedReactionPackIds(profile));
  return REACTION_PACKS.filter((p) => ids.has(p.id)).flatMap((p) => p.reactions);
}

/* ------------------------- Sticker packs ----------------------------- */

export const STICKER_PACKS: StickerPackDef[] = [
  { id: "faces", nameFa: "شکلک‌ها", nameEn: "Faces", stickers: ["happy", "sad", "cool", "love", "angry"], price: 0, default: true },
  // Earned by the "Seven–Zip" (7–0 sweep) achievement.
  { id: "hokm", nameFa: "حکم", nameEn: "Hokm", stickers: ["hokm-badge", "kot-stamp", "crown", "ace-spade"], price: 0, unlockAchievement: "shutout_1" },
  // Earned by the "100 Wins" achievement.
  { id: "persian", nameFa: "ایرانی", nameEn: "Persian", stickers: ["chai", "afarin", "rose"], price: 700, unlockAchievement: "wins_100" },
  // Earned by the "25 Kots" achievement.
  { id: "taunt", nameFa: "طعنه", nameEn: "Taunts", stickers: ["clown", "sleep", "weak"], price: 900, unlockAchievement: "kot_25" },
  // Custom packs earned only via achievements.
  { id: "rulership", nameFa: "حاکمیت", nameEn: "Rulership", stickers: ["crown-gold", "seven-zip"], price: 0, unlockAchievement: "hakem_7" },
  { id: "firestorm", nameFa: "آتشین", nameEn: "Firestorm", stickers: ["streak-fire"], price: 0, unlockAchievement: "streak_10" },
];

export function stickerPackById(id: string): StickerPackDef | undefined {
  return STICKER_PACKS.find((p) => p.id === id);
}

export function ownedStickerPackIds(profile: UserProfile): string[] {
  const purchased = profile.ownedStickerPacks ?? [];
  const unlocked = profile.unlocked ?? [];
  const ids = new Set<string>();
  for (const p of STICKER_PACKS) {
    const earned =
      (p.unlockRating != null && profile.rating >= p.unlockRating) ||
      (p.unlockWins != null && profile.stats.wins >= p.unlockWins) ||
      (p.unlockAchievement != null && unlocked.includes(p.unlockAchievement));
    if (p.default || earned || purchased.includes(p.id)) ids.add(p.id);
  }
  return [...ids];
}

/** Flattened sticker-id list the player can send. */
export function ownedStickers(profile: UserProfile): string[] {
  const ids = new Set(ownedStickerPackIds(profile));
  return STICKER_PACKS.filter((p) => ids.has(p.id)).flatMap((p) => p.stickers);
}

/* ---------------------- Apply a match result ------------------------- */

function applyStats(stats: PlayerStats, summary: MatchSummary): PlayerStats {
  const wins = stats.wins + (summary.won ? 1 : 0);
  const losses = stats.losses + (summary.won ? 0 : 1);
  const currentWinStreak = summary.won ? stats.currentWinStreak + 1 : 0;
  return {
    games: stats.games + 1,
    wins,
    losses,
    kotsFor: stats.kotsFor + (summary.kotFor ? 1 : 0),
    kotsAgainst: stats.kotsAgainst + (summary.kotAgainst ? 1 : 0),
    tricks: stats.tricks + summary.tricksWon,
    currentWinStreak,
    bestWinStreak: Math.max(stats.bestWinStreak, currentWinStreak),
    shutoutWins: (stats.shutoutWins ?? 0) + (summary.won && summary.shutout ? 1 : 0),
    hakemRounds: (stats.hakemRounds ?? 0) + (summary.hakemRounds ?? 0),
    roundsWon: (stats.roundsWon ?? 0) + (summary.roundsWon ?? 0),
  };
}

/**
 * Apply a finished match to a profile. Returns a new profile + a RewardResult
 * describing every delta for the post-match UI.
 */
export function applyMatchResult(
  profile: UserProfile,
  summary: MatchSummary,
  oppRating: number
): { profile: UserProfile; reward: RewardResult } {
  const ratingBefore = profile.rating;
  const coinsBefore = profile.coins;
  const levelBefore = profile.level;

  const rDelta = ratingDelta(summary, profile.rating, oppRating);
  const ratingAfter = Math.max(0, ratingBefore + rDelta);

  const cDelta = coinDelta(summary);
  const xpGain = matchXp(summary);
  const lvl = addXp(profile.level, profile.xp, xpGain);

  const stats = applyStats(profile.stats, summary);

  // Evaluate achievements against the new state.
  const achievements = { ...profile.achievements };
  const unlocked = [...profile.unlocked];
  const newAchievements: AchievementUnlock[] = [];
  let achievementCoins = 0;
  for (const def of ACHIEVEMENTS) {
    const prog = achievementProgress(def, stats, ratingAfter, lvl.level);
    achievements[def.id] = prog;
    if (prog >= def.goal && !unlocked.includes(def.id)) {
      unlocked.push(def.id);
      achievementCoins += def.coinReward;
      newAchievements.push({
        id: def.id,
        nameFa: def.nameFa,
        nameEn: def.nameEn,
        icon: def.icon,
        coinReward: def.coinReward,
      });
    }
  }

  const coinsAfter = Math.max(0, coinsBefore + cDelta + achievementCoins);

  // Titles unlocked by the new state.
  const ownedTitles = [...(profile.ownedTitles ?? [])];
  const newTitles: TitleUnlock[] = [];
  for (const tdef of TITLES) {
    if (
      titleUnlocked(tdef.id, stats, ratingAfter, lvl.level) &&
      !ownedTitles.includes(tdef.id)
    ) {
      ownedTitles.push(tdef.id);
      newTitles.push({ id: tdef.id, nameFa: tdef.nameFa, nameEn: tdef.nameEn });
    }
  }

  const leagueBefore = getLeagueInfo(ratingBefore);
  const leagueAfter = getLeagueInfo(ratingAfter);
  const tierIndex = (id: RankTierId) => RANK_TIERS.findIndex((t) => t.id === id);
  const rankValue = (l: LeagueInfo) =>
    tierIndex(l.tier.id) * 10 - (l.division ?? 0);
  const promoted = rankValue(leagueAfter) > rankValue(leagueBefore);
  const demoted = rankValue(leagueAfter) < rankValue(leagueBefore);

  const newProfile: UserProfile = {
    ...profile,
    rating: ratingAfter,
    coins: coinsAfter,
    level: lvl.level,
    xp: lvl.xp,
    stats,
    achievements,
    unlocked,
    ownedTitles,
  };

  const reward: RewardResult = {
    ratingBefore,
    ratingAfter,
    ratingDelta: ratingAfter - ratingBefore,
    coinsBefore,
    coinsAfter,
    coinsDelta: coinsAfter - coinsBefore,
    xpGained: xpGain,
    levelBefore,
    levelAfter: lvl.level,
    leveledUp: lvl.level > levelBefore,
    newAchievements,
    newTitles,
    promoted,
    demoted,
  };

  return { profile: newProfile, reward };
}

/* --------------------------- Daily reward ---------------------------- */

export const DAILY_REWARDS = [100, 150, 200, 300, 400, 500, 1000];

export function dailyRewardFor(day: number): number {
  return DAILY_REWARDS[Math.min(day, DAILY_REWARDS.length) - 1] ?? 100;
}