public ICollection <Book> GetAvailableBooksSorted()
{
var allBooks = _readerWriter.GetBooks();
ICollection <Book> availableBooks = new List <Book>();
foreach (Book book in allBooks)
{
foreach (BookCopy bookCopy in book.Copies)
{
if (bookCopy.LastReturnDate != null && !availableBooks.Contains(book))
{
availableBooks.Add(book);
}
}
}
ICollection <Book> sortedAvailableBooks = availableBooks.OrderBy(o => o.Author).ToList();
return(sortedAvailableBooks);
}