public async Task <ActionResult <Drug> > GetDrugById(int id) { var drug = await _drugRepository.FindById(id); var drugDTO = _mapper.Map <DrugDTO>(drug); // what time is it now? How many days passed? int diffDays = DateTime.Now.Subtract(drug.StartDate).Days; int NoPillsLeft = drug.NoPills - (diffDays * drug.DoseToTake); int DaysLeft = drug.DoseToTake == 0 ? NoPillsLeft:(NoPillsLeft / drug.DoseToTake); DateTime dateToEnd = DateTime.Now.AddDays(DaysLeft); drug.DateToEnd = dateToEnd; if (drug == null) { return(NotFound()); } return(drug); }