export interface GameStats {
  streak: number;
  lastDate: string;    // ISO date YYYY-MM-DD of last solve
  total: number;
  bestTime: number;    // seconds, 0 = never recorded
  lastTime: number;    // seconds for the most recent solve (0 if none)
  solvedDates: string[]; // history of solved ISO dates (for heatmap)
}

const DEFAULT: GameStats = { streak: 0, lastDate: "", total: 0, bestTime: 0, lastTime: 0, solvedDates: [] };

function storageKey(game: string) { return `stats-${game}`; }

export function loadStats(game: string): GameStats {
  if (typeof window === "undefined") return DEFAULT;
  try {
    const raw = localStorage.getItem(storageKey(game));
    if (!raw) return DEFAULT;
    return { ...DEFAULT, ...JSON.parse(raw) };
  } catch { return DEFAULT; }
}

export function recordSolve(game: string, date: string, secs: number): GameStats {
  const prev = loadStats(game);

  // Compute yesterday ISO using local-date arithmetic (avoids UTC offset bug)
  const [y, m, d] = date.split("-").map(Number);
  const prev2 = new Date(y, m - 1, d - 1);
  const yesterdayISO = `${prev2.getFullYear()}-${String(prev2.getMonth() + 1).padStart(2, "0")}-${String(prev2.getDate()).padStart(2, "0")}`;

  let streak = prev.streak;
  if (prev.lastDate === date) {
    // Already solved today — don't double-count streak
  } else if (prev.lastDate === yesterdayISO) {
    streak += 1;
  } else {
    streak = 1;
  }

  // Build solved dates history (keep last 120 days, no duplicates)
  const prevDates = prev.solvedDates ?? [];
  const solvedDates = prevDates.includes(date) ? prevDates : [...prevDates, date].slice(-120);

  const stats: GameStats = {
    streak,
    lastDate: date,
    total: prev.lastDate === date ? prev.total : prev.total + 1,
    bestTime: prev.bestTime === 0 || secs < prev.bestTime ? secs : prev.bestTime,
    lastTime: secs,
    solvedDates,
  };
  localStorage.setItem(storageKey(game), JSON.stringify(stats));
  return stats;
}

// ── Ritual streak (global: all 5 games solved in a day) ───────────────────────

export interface RitualStats {
  streak: number;   // consecutive days with all 5 solved
  lastDate: string; // last day all 5 were solved
}

const RITUAL_KEY = "stats-ritual";

export function getRitualStreak(): RitualStats {
  if (typeof window === "undefined") return { streak: 0, lastDate: "" };
  try {
    const raw = localStorage.getItem(RITUAL_KEY);
    return raw ? { ...{ streak: 0, lastDate: "" }, ...JSON.parse(raw) } : { streak: 0, lastDate: "" };
  } catch { return { streak: 0, lastDate: "" }; }
}

/** Call this when all 5 games are confirmed solved today. Updates global ritual streak. */
export function updateRitualStreak(date: string): RitualStats {
  if (typeof window === "undefined") return { streak: 0, lastDate: "" };
  const prev = getRitualStreak();
  if (prev.lastDate === date) return prev; // already counted today

  const [y, m, d] = date.split("-").map(Number);
  const yesterday = new Date(y, m - 1, d - 1);
  const yesterdayISO = `${yesterday.getFullYear()}-${String(yesterday.getMonth() + 1).padStart(2, "0")}-${String(yesterday.getDate()).padStart(2, "0")}`;

  const streak = prev.lastDate === yesterdayISO ? prev.streak + 1 : 1;
  const updated: RitualStats = { streak, lastDate: date };
  localStorage.setItem(RITUAL_KEY, JSON.stringify(updated));
  return updated;
}