public static string GetBooksByCategory(BookShopContext context, string input)
        {
            string[] categories = input.ToLower().Split(" ", StringSplitOptions.RemoveEmptyEntries);

            List<string> books = context.Books
                .Where(x => x.BookCategories.Any(x => categories.Contains(x.Category.Name.ToLower())))
                .Select(x => x.Title)
                .OrderBy(x => x)
                .ToList();

            return string.Join(Environment.NewLine, books);

        }