public PurchaseResponse PurchaseMovie(Customer customer, Movie movie)
        {
            if (customer.MoviePurchases.Select(r => r.MovieId).Contains(movie.Id))
            {
                throw new MovieAlreadyPurchasedException("Movie already purchased.");
            }

            if (!paymentService.Pay(customer, movie))
            {
                InvalidateCustomerCreditCard(customer);

                throw new PaymentFailedException(
                          $"Payment failed for customer {customer.FullName.ToString()}. " +
                          "Please check and update your credit card details."
                          );
            }

            var moviePurchase = MoviePurchase.Create(customer, movie);

            customersRepository.AddMoviePurchase(moviePurchase);

            FinishCurrentRentalIfExists(customer, movie);

            var movieLinkWithDownload = streamingService.GetMovieStreamWithDownload(movie);

            return(new PurchaseResponse(moviePurchase, movieLinkWithDownload));
        }
        public string WatchMovie(Customer customer, Movie movie)
        {
            var currentlyRentedMovie = customer.MovieRentals
                                       .FirstOrDefault(mr => mr.MovieId == movie.Id && mr.EndDate > DateTime.Now);
            var purchasedMovie = customer.MoviePurchases.FirstOrDefault(m => m.MovieId == movie.Id);

            if (currentlyRentedMovie == null && purchasedMovie == null)
            {
                throw new MovieNotAcquiredException("Movie is not acquired. Please rent or purchase movie and try again.");
            }

            if (currentlyRentedMovie != null)
            {
                return(streamingService.GetMovieStream(currentlyRentedMovie.Movie));
            }

            if (purchasedMovie != null)
            {
                return(streamingService.GetMovieStreamWithDownload(purchasedMovie.Movie));
            }

            return(string.Empty);
        }