ProjectLib/ProjectLibrary/Forms/FBook.cs

using ProjectLibrary.Entities;
using ProjectLibrary.Entities.Enums;
using ProjectLibrary.Repositores;
using ProjectLibrary.Repositories;

namespace ProjectLibrary.Forms
{
    public partial class FBook : Form
    {
        private readonly IBookRepository _bookRepository;
        private int? _bookId;

        public int Id
        {
            set
            {
                try
                {
                    var book = _bookRepository.ReadBookById(value);
                    if (book == null)
                    {
                        throw new InvalidOperationException("Книга не найдена.");
                    }

                    txtAuthor.Text = book.Author;
                    txtName.Text = book.Name;
                    cmbType.SelectedItem = book.Type;
                    comboBoxLibrary.SelectedItem = book.LibraryID;
                    _bookId = value;
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "Ошибка при загрузке данных", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }

        public FBook(IBookRepository bookRepository, ILibraryRepository libraryRepository)
        {
            InitializeComponent();
            _bookRepository = bookRepository ?? throw new ArgumentNullException(nameof(bookRepository));
            comboBoxLibrary.DataSource = libraryRepository.ReadLibraries();
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            try
            {
                if (string.IsNullOrWhiteSpace(txtAuthor.Text) || string.IsNullOrWhiteSpace(txtName.Text) || comboBoxLibrary.SelectedItem == null)
                {
                    throw new Exception("Имеются незаполненные поля.");
                }

                var book = Book.CreateEntity(
                    _bookId ?? 0,
                    txtAuthor.Text,
                    txtName.Text,
                    (BookType)cmbType.SelectedValue,
                    Convert.ToInt32(comboBoxLibrary.SelectedItem)
                );

                if (_bookId.HasValue)
                {
                    _bookRepository.UpdateBook(book);
                }
                else
                {
                    _bookRepository.CreateBook(book);
                }

                Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Ошибка при сохранении данных", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void ButtonCancel_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}