private int GetEquipmentFreeId() { var addIds = equipmentRepository.GetAllIds(); if (addIds.Count == 0) { return(0); } addIds.Sort(); var lastId = addIds.Last(); if (addIds.Count != lastId) { for (var i = 0; i < lastId; i++) { if (addIds.Contains(i)) { continue; } return(i); } } return(lastId + 1); }