const DEFAULTS = () => ({ liked: {}, hfLiked: {}, saved: {}, seen: [], round: null });

export class Store {
  constructor({ key = "bsr:v1", backend } = {}) {
    this.key = key;
    this.backend = backend || globalThis.localStorage;
    this.data = this._read();
  }

  _read() {
    try {
      const raw = this.backend?.getItem(this.key);
      if (!raw) return DEFAULTS();
      return { ...DEFAULTS(), ...JSON.parse(raw) };
    } catch {
      return DEFAULTS();
    }
  }

  _write() {
    try {
      this.backend?.setItem(this.key, JSON.stringify(this.data));
    } catch {
      /* storage full / blocked — ignore */
    }
  }

  // saves
  isSaved(id) { return !!this.data.saved[id]; }
  toggleSaved(id) {
    if (this.data.saved[id]) { delete this.data.saved[id]; this._write(); return false; }
    this.data.saved[id] = Date.now(); this._write(); return true;
  }
  savedIds() {
    return Object.keys(this.data.saved).sort((a, b) => this.data.saved[b] - this.data.saved[a]);
  }

  // local-like fallback
  isLocalLiked(id) { return !!this.data.liked[id]; }
  setLocalLiked(id, on) {
    if (on) this.data.liked[id] = Date.now(); else delete this.data.liked[id];
    this._write();
  }

  // confirmed real HF like (this session/device)
  isHfLiked(id) { return !!this.data.hfLiked[id]; }
  setHfLiked(id, on) {
    if (on) this.data.hfLiked[id] = true; else delete this.data.hfLiked[id];
    this._write();
  }

  // any like (real or local) — for button fill state
  isLiked(id) { return this.isHfLiked(id) || this.isLocalLiked(id); }

  // seen / progress
  markSeen(id) {
    if (!this.data.seen.includes(id)) { this.data.seen.push(id); this._write(); }
  }

  // resume round
  saveRound(round) { this.data.round = round; this._write(); }
  loadRound() { return this.data.round; }
}