public async Task <IActionResult> Add(Reservation reservation)
        {
            using var client = new ApiClient();
            User user;

            client.Token = Request.Cookies["token"];
            user         = await client.GetUserAsync();

            if (user == null)
            {
                return(RedirectToAction("Login", "Authentication"));
            }

            reservation.UserId = user.Id;
            var result = await client.AddReservationAsync(reservation);

            if (result != null)
            {
                return(RedirectToAction("Details", new { id = result.Id }));
            }

            return(RedirectToAction("Details", "Reservations", new { id = reservation.AdvertisementId }));
        }