/// <summary>
/// This method is looking for a books, adds books to the main page if they are not contains in the database,
/// deletes books if they don't exist on the user's device. It helps to hold actual data.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="args">An object that contains the event data.</param>
private async void OnClickSearchBooksButton(object sender, EventArgs args)
{
IFiler filer = DependencyService.Get <IFiler>();
IEnumerable <string> pathsOfFoundFiles = await filer.GetFilesPathsAsync(FileExtension.EPUB).ConfigureAwait(false);
List <EpubBook> epubBooks = new List <EpubBook>();
foreach (var path in pathsOfFoundFiles)
{
EpubBook book = await EpubReader.EpubReader.ReadBookAsync(path).ConfigureAwait(false);
epubBooks.Add(book);
}
List <string> pathsOfExistingFiles = this.bookEntities.Select(entity => entity.FilePath).ToList();
// Try to read not all book information.
// I need to read only a necessary information e.g. Title, Author, Cover.
foreach (EpubBook epubBook in epubBooks)
{
// If the book entity does not exist.
// Add a new book info to the main page.
if (pathsOfExistingFiles.Contains(epubBook.FilePath) == false)
{
BookEntity bookEntity = new BookEntity
{
Id = Guid.NewGuid().ToNonDashedString(),
Title = epubBook.Title,
Author = epubBook.Author,
// It should be changed.
// An image might be missed.
Cover = epubBook.Content.Images.FirstOrDefault().Value.Content,
FilePath = epubBook.FilePath
};
SettingsEntity settingsEntity = new SettingsEntity
{
BookId = bookEntity.Id,
LastPage = 1,
FontSize = 14
};
SQLiteResult result = this.bookRepository.Add(bookEntity);
SQLiteResult settingsInsertResult = this.settingsRepository.Add(settingsEntity);
// 0 is SQLITE_OK
// But returns 1 and entity is successfully saved into database.
//if (bookInsertStatusCode == 1)
//{
this.bookEntities.Add(bookEntity);
BookInfoViewModel model = bookEntity.ToBookInfoModelMapper();
this.books.Add(model);
//}
}
}
// Delete book info models and book entities which do not exist yet.
foreach (var pathOfExistingFile in pathsOfExistingFiles)
{
if (pathsOfFoundFiles.Contains(pathOfExistingFile) == false)
{
// Delete entity.
BookEntity deletedBookEntity = this.bookEntities.FirstOrDefault(e => e.FilePath == pathOfExistingFile);
this.bookRepository.DeleteById(deletedBookEntity.Id);
this.bookEntities.Remove(deletedBookEntity);
// Delete book info view model.
BookInfoViewModel deletedBookInfoViewModel = this.books.FirstOrDefault(m => m.FilePath == pathOfExistingFile);
this.books.Remove(deletedBookInfoViewModel);
}
}
Xamarin.Forms.Device.BeginInvokeOnMainThread(() => this.UpdateBookLibrary(this.books));
}