using System;

using System.Collections.Generic;

using System.Linq;

​

public class Book

{

    public string ToRead = "To Read";

    public string Reading = "Reading";

    public string Finished = "Finished";

​

    public string Title { get; set; }

    public string Author { get; set; }

    public int Pages { get; set; }

    public string Publisher { get; set; }

    public string ReadingStatus { get; set; }

    public DateTime? StartedReadingAt { get; private set; }

    public DateTime? FinishedReadingAt { get; private set; }

​

    public Book(string title, string author, int pages, string publisher)

    {

        Title = title;

        Author = author;

        Pages = pages;

        Publisher = publisher;

        ReadingStatus = ToRead;

    }

​

    public void StartReading()

    {

        ReadingStatus = Reading;

        StartedReadingAt = DateTime.Now;

    }

​

    public void FinishReading()

    {

        ReadingStatus = Finished;

        FinishedReadingAt = DateTime.Now;

    }

}

​

public class BookRepository

{

    public List<Book> Books = new();

​

    public void Add(Book book)

    {

        Books.Add(book);

    }

​

    public Book GetByTitle(string title)

    {

        return Books.FirstOrDefault(b => b.Title == title);

    }

​

    public List<Book> GetAll()

    {

        return Books;

    }

}

​

public class BookService

{

    public void AddBook(string title, string author, int pages, string publisher)

    {

        Book book = new Book(title, author, pages, publisher);

        BookRepository bookRepository = new BookRepository();

        bookRepository.Add(book);

    }

​

    public void UpdateBook(string title, string author, int pages,

    string publisher, bool isReading, bool isFinishedReading)

    {

        BookRepository bookRepository = new BookRepository();

        Book book = bookRepository.GetByTitle(title);

        book.Author = author;

        book.Pages = pages;

        book.Publisher = publisher;

        if (isReading)

        {

            book.StartReading();

        }

        if (isFinishedReading)

        {

            book.FinishReading();

        }

        else

        {

            book.ReadingStatus = book.ToRead;

        }

    }

​

    public List<Book> GetAllBooks()

    {

        BookRepository bookRepository = new BookRepository();

        return bookRepository.GetAll();

    }

}

​