const STORAGE_KEY = 'stb:visited-pots';
const MAX_ENTRIES = 20;

export interface VisitedPot {
  slug: string;
  name: string;
  currency: string;
  visitedAt: number;
}

type StorageLike = Pick<Storage, 'getItem' | 'setItem'>;

export function readVisitedPots(storage: StorageLike): VisitedPot[] {
  const raw = storage.getItem(STORAGE_KEY);
  if (!raw) return [];

  try {
    const parsed = JSON.parse(raw);
    if (!Array.isArray(parsed)) return [];
    return parsed.filter(
      (item): item is VisitedPot =>
        typeof item?.slug === 'string' &&
        item.slug.trim() !== '' &&
        typeof item?.name === 'string' &&
        typeof item?.currency === 'string' &&
        typeof item?.visitedAt === 'number',
    );
  } catch {
    return [];
  }
}

export function recordVisitedPot(
  storage: StorageLike,
  pot: Omit<VisitedPot, 'visitedAt'>,
): VisitedPot[] {
  const rest = readVisitedPots(storage).filter((p) => p.slug !== pot.slug);
  const updated = [{ ...pot, visitedAt: Date.now() }, ...rest]
    .sort((a, b) => b.visitedAt - a.visitedAt)
    .slice(0, MAX_ENTRIES);

  storage.setItem(STORAGE_KEY, JSON.stringify(updated));
  return updated;
}