public IList <Card> EditCard(IList <PendingCard> pendingCards, int userId) { if (pendingCards == null || !pendingCards.Any()) { throw new ArgumentNullException("Invalid cards"); } if (IsAnAdmin(userId)) { var oldCardDeleted = RemoveCorrespondingOldCard(pendingCards); if (oldCardDeleted) { var cardsEdited = AddNewCardsToCatalog(pendingCards); _catalogRepository.DeletePendingCard(pendingCards); return(cardsEdited); } } return(null); }