public ActionResult Delete(int bookId)
        {
            var book = bookService.FindBookById(bookId);

            genreBookLinksService.DeleteGenreBookLink(book.GenreId, book.Id);
            genreAuthorLinksService.DeleteGenreAuthorLink(book.GenreId, book.AuthorId);
            authorBookLinksService.DeleteAuthorBookLink(book.AuthorId, book.Id);

            var reviewsList = reviewService.GetAllReviewsByBookId(bookId);

            foreach (var review in reviewsList)
            {
                reviewService.DeleteReview(review);
            }

            bookService.DeleteBook(book);

            return(RedirectToAction("Index"));
        }
        public ActionResult Delete(int authorId)
        {
            var author = authorService.GetAuthorById(authorId);

            var genresList = genreAuthorLinkService.GetAllGenresByAuthorId(author.Id);

            foreach (var genre in genresList)
            {
                genreAuthorLinkService.DeleteGenreAuthorLink(genre.Id, author.Id);
            }

            var bookList = authorBookLinksService.GetBooksByAuthorId(authorId);

            foreach (var book in bookList)
            {
                authorBookLinksService.DeleteAuthorBookLink(author.Id, book.Id);
            }

            authorService.DeleteAuthor(author);

            return(RedirectToAction("Index"));
        }