// web/src/lib/reviewStar.ts

export type ReviewEventType = "send_message" | "review_topic" | "review_all";

export type ReviewStarState = {
  lastActiveDay: string;      // YYYY-MM-DD (local)
  todayCount: number;         // today's valid review actions count
  streakDays: number;         // consecutive active days
  totalDaysActive: number;    // total active days
};

function dayKeyLocal(d = new Date()) {
  const yyyy = d.getFullYear();
  const mm = String(d.getMonth() + 1).padStart(2, "0");
  const dd = String(d.getDate()).padStart(2, "0");
  return `${yyyy}-${mm}-${dd}`;
}

function yesterdayKeyLocal() {
  return dayKeyLocal(new Date(Date.now() - 86400000));
}

export function loadReviewStar(key: string): ReviewStarState | null {
  try {
    const raw = localStorage.getItem(key);
    if (!raw) return null;
    return JSON.parse(raw) as ReviewStarState;
  } catch {
    return null;
  }
}

export function saveReviewStar(key: string, state: ReviewStarState) {
  localStorage.setItem(key, JSON.stringify(state));
}

/**
 * Called when user enters Review section (or on workspace switch while in Review):
 * If day changed, reset today's count to 0 (i.e., dim star until there's real review activity).
 */
export function normalizeToday(key: string): ReviewStarState | null {
  const cur = loadReviewStar(key);
  if (!cur) return null;

  const today = dayKeyLocal();
  if (cur.lastActiveDay === today) return cur;

  const next: ReviewStarState = { ...cur, todayCount: 0 };
  saveReviewStar(key, next);
  return next;
}

/**
 * Mark a valid review activity.
 * - Same day: increment todayCount
 * - New day: todayCount=1, streak updates, totalDaysActive increments
 */
export function markReviewActive(key: string, _event: ReviewEventType): ReviewStarState {
  const today = dayKeyLocal();
  const prev = loadReviewStar(key);

  if (!prev) {
    const next: ReviewStarState = {
      lastActiveDay: today,
      todayCount: 1,
      streakDays: 1,
      totalDaysActive: 1,
    };
    saveReviewStar(key, next);
    return next;
  }

  if (prev.lastActiveDay === today) {
    const next: ReviewStarState = { ...prev, todayCount: prev.todayCount + 1 };
    saveReviewStar(key, next);
    return next;
  }

  const y = yesterdayKeyLocal();
  const streak = prev.lastActiveDay === y ? prev.streakDays + 1 : 1;

  const next: ReviewStarState = {
    ...prev,
    lastActiveDay: today,
    todayCount: 1,
    streakDays: streak,
    totalDaysActive: (prev.totalDaysActive ?? 0) + 1,
  };
  saveReviewStar(key, next);
  return next;
}

/**
 * UI mapping: opacity/energy
 * - 0 activity today => dim
 * - 1 activity => medium
 * - 2+ => bright
 * - streak >= 3 => max
 */
export function starOpacity(state: ReviewStarState | null) {
  if (!state) return 0.15;
  if (state.todayCount <= 0) return 0.15;
  if (state.todayCount === 1) return 0.55;
  if (state.streakDays >= 3) return 1.0;
  return 0.85;
}

export function energyPct(state: ReviewStarState | null) {
  return Math.round(starOpacity(state) * 100);
}