public IActionResult AddGuestOnCheckin(string FullName, string Gender, string IdCard, int bookingid)
        {
            if (!GuestDAO.CheckIsExistGuestByIdCard(IdCard))
            {
                var guestid = GuestDAO.InsertGuest(new Guest()
                {
                    FullName     = FullName,
                    Gender       = Gender,
                    IDCardNumber = IdCard
                });

                var stay = StayDAO.InsertStay(new Stay()
                {
                    GuestID   = guestid,
                    BookingID = bookingid,
                    FromDate  = DateTime.Now,
                    ToDate    = null
                });

                return(Json(stay));
            }
            else
            {
                var guestid = GuestDAO.GetGuestByIdCardNumber(IdCard).GuestID;
                if (!StayDAO.CheckGuestStaying(guestid))
                {
                    var stay = StayDAO.InsertStay(new Stay()
                    {
                        GuestID   = guestid,
                        BookingID = bookingid,
                        FromDate  = DateTime.Now,
                        ToDate    = null
                    });

                    return(Json(stay));
                }
                else
                {
                    return(Json(null));
                }
            }
        }