LINQ für die Suche

using System;
using System.Collections.Generic;

namespace LibrarySystem
{
    class Program
    {
        public static void Main(string[] args)
        {
            // Bibliotheksnamen lesen
            string libraryName = Console.ReadLine();
            
            // Eine Library-Instanz mit dem Bibliotheksnamen erstellen
            Library library = new Library(libraryName);
            
            // Anzahl der Bücher lesen
            int numBooks = Convert.ToInt32(Console.ReadLine());
            
            // Bücher lesen und hinzufügen
            for (int i = 0; i < numBooks; i++)
            {
                string bookInput = Console.ReadLine();
                string[] bookParts = bookInput.Split('|');
                string bookId = bookParts[0];
                string bookTitle = bookParts[1];
                string bookAuthor = bookParts[2];
                
                Book book = new Book(bookId, bookTitle, bookAuthor);
                library.AddBook(book);
            }
            
            // Anzahl der Ausleihvorgänge lesen, um den Anfangszustand festzulegen
            int numBorrows = Convert.ToInt32(Console.ReadLine());
            
            // Ausleihvorgänge verarbeiten (nur Buch-IDs)
            for (int i = 0; i < numBorrows; i++)
            {
                string bookId = Console.ReadLine();
                Book book = library.GetBookById(bookId);
                if (book != null)
                {
                    book.IsAvailable = false;
                }
            }
            
            // Suchbefehl lesen
            string searchCommand = Console.ReadLine();
            
            // Suchbefehl verarbeiten
            List<Book> results = new List<Book>();
            
            if (searchCommand == "available")
            {
                results = library.GetAvailableBooks();
            }
            else if (searchCommand == "borrowed")
            {
                results = library.GetBorrowedBooks();
            }
            else if (searchCommand.Contains("|"))
            {
                string[] parts = searchCommand.Split('|');
                string searchType = parts[0];
                string searchValue = parts[1];
                
                if (searchType == "title")
                {
                    results = library.SearchByTitle(searchValue);
                }
                else if (searchType == "author")
                {
                    results = library.GetBooksByAuthor(searchValue);
                }
            }
            
            // Ergebnisse ausgeben
            if (results.Count == 0)
            {
                Console.WriteLine("No books found");
            }
            else
            {
                foreach (Book book in results)
                {
                    Console.WriteLine($"{book.Title} by {book.Author}");
                }
            }
        }
    }
}