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
}