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using System.Collections.ObjectModel;
using System.IO.Compression;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Input;
using VersOne.Epub.WpfDemo.Models;
using VersOne.Epub.WpfDemo.Utils;
namespace VersOne.Epub.WpfDemo.ViewModels
{
/// <summary>
/// View model for the <see cref="Views.BookView" />.
/// </summary>
public class BookViewModel : ViewModel
{
private readonly BookModel bookModel;
private bool isLoading;
private ObservableCollection<NavigationItemViewModel> navigation;
private ObservableCollection<HtmlContentFileViewModel> readingOrder;
private ZipArchive currentEpubArchive;
private HtmlContentFileViewModel currentHtmlContentFile;
private HtmlContentFileViewModel previousHtmlContentFile;
private HtmlContentFileViewModel nextHtmlContentFile;
private string currentAnchor;
private Command navigateCommand;
private Command previousCommand;
private Command nextCommand;
/// <summary>
/// Initializes a new instance of the <see cref="BookViewModel" /> class.
/// </summary>
/// <param name="bookId">The unique identifier of the book which should contain the same value as <see cref="Entities.Book.Id" />.</param>
public BookViewModel(int bookId)
{
bookModel = new BookModel();
isLoading = true;
currentEpubArchive = null;
currentHtmlContentFile = null;
previousHtmlContentFile = null;
nextHtmlContentFile = null;
currentAnchor = null;
navigateCommand = null;
previousCommand = null;
nextCommand = null;
bookModel.OpenBookAsync(bookId).ContinueWith(epubBook => BookOpened(epubBook), TaskScheduler.FromCurrentSynchronizationContext());
}
/// <summary>
/// Gets a collection of navigation items which are used to render the navigation tree in the <see cref="Views.BookView" />.
/// </summary>
public ObservableCollection<NavigationItemViewModel> Navigation
{
get
{
return navigation;
}
private set
{
navigation = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets a collection of HTML content files which determine the order in which they are rendered in the <see cref="Views.BookView" />.
/// </summary>
public ObservableCollection<HtmlContentFileViewModel> ReadingOrder
{
get
{
return readingOrder;
}
private set
{
readingOrder = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets a value indicating whether the book is still loading or not.
/// </summary>
public bool IsLoading
{
get
{
return isLoading;
}
private set
{
isLoading = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets or sets the reference to the EPUB book file currently opened in the <see cref="Views.BookView" />.
/// </summary>
public ZipArchive CurrentEpubArchive
{
get
{
return currentEpubArchive;
}
set
{
currentEpubArchive = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets or sets the reference to a view model of the HTML content file from <see cref="CurrentEpubArchive" /> currently rendered in the <see cref="Views.BookView" />.
/// </summary>
public HtmlContentFileViewModel CurrentHtmlContentFile
{
get
{
return currentHtmlContentFile;
}
set
{
currentHtmlContentFile = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets a value indicating whether the button to navigate to the previous content file in the reading order should be visible or not.
/// </summary>
public bool IsPreviousButtonVisible
{
get
{
return previousHtmlContentFile != null;
}
}
/// <summary>
/// Gets a value indicating whether the button to navigate to the next content file in the reading order should be visible or not.
/// </summary>
public bool IsNextButtonVisible
{
get
{
return nextHtmlContentFile != null;
}
}
/// <summary>
/// Gets or sets the name of the anchor in the <see cref="CurrentHtmlContentFile" /> which is used to determine the place
/// where the content should be scrolled to once it is fully loaded.
/// </summary>
public string CurrentAnchor
{
get
{
return currentAnchor;
}
set
{
currentAnchor = value;
NotifyPropertyChanged();
}
}
/// <summary>
/// Gets the command which is executed when the user clicks on a navigation link in the navigation tree in the <see cref="Views.BookView" />.
/// </summary>
public ICommand NavigateCommand
{
get
{
if (navigateCommand == null)
{
navigateCommand = new Command(param => Navigate(param as NavigationItemViewModel));
}
return navigateCommand;
}
}
/// <summary>
/// Gets the command which is executed when the user clicks on the '< PREVIOUS' button in the <see cref="Views.BookView" />.
/// </summary>
public ICommand PreviousCommand
{
get
{
if (previousCommand == null)
{
previousCommand = new Command(NavigateToPreviousItemInReadingOrder);
}
return previousCommand;
}
}
/// <summary>
/// Gets the command which is executed when the user clicks on the 'NEXT >' button in the <see cref="Views.BookView" />.
/// </summary>
public ICommand NextCommand
{
get
{
if (nextCommand == null)
{
nextCommand = new Command(NavigateToNextItemInReadingOrder);
}
return nextCommand;
}
}
private void BookOpened(Task<EpubBook> task)
{
EpubBook epubBook = task.Result;
currentEpubArchive?.Dispose();
CurrentEpubArchive = ZipFile.OpenRead(epubBook.FilePath);
Navigation = new ObservableCollection<NavigationItemViewModel>(bookModel.GetNavigation(epubBook));
ReadingOrder = new ObservableCollection<HtmlContentFileViewModel>(bookModel.GetReadingOrder(epubBook));
if (ReadingOrder.Any())
{
CurrentHtmlContentFile = ReadingOrder[0];
if (ReadingOrder.Count > 1)
{
nextHtmlContentFile = ReadingOrder[1];
}
}
IsLoading = false;
NotifyPropertyChanged(nameof(IsPreviousButtonVisible));
NotifyPropertyChanged(nameof(IsNextButtonVisible));
}
private void Navigate(NavigationItemViewModel navigationItemViewModel)
{
navigationItemViewModel.IsTreeItemExpanded = true;
if (navigationItemViewModel.IsLink)
{
Navigate(ReadingOrder.FirstOrDefault(htmlContentFile => htmlContentFile.HtmlFilePathInEpubArchive == navigationItemViewModel.FilePathInEpubArchive));
CurrentAnchor = navigationItemViewModel.Anchor;
}
}
private void Navigate(HtmlContentFileViewModel targetHtmlContentFileViewModel)
{
if (targetHtmlContentFileViewModel == null)
{
CurrentHtmlContentFile = null;
previousHtmlContentFile = null;
nextHtmlContentFile = null;
}
else if (CurrentHtmlContentFile != targetHtmlContentFileViewModel)
{
CurrentHtmlContentFile = targetHtmlContentFileViewModel;
int currentReadingOrderItemIndex = ReadingOrder.IndexOf(CurrentHtmlContentFile);
if (currentReadingOrderItemIndex != -1)
{
if (currentReadingOrderItemIndex > 0)
{
previousHtmlContentFile = ReadingOrder[currentReadingOrderItemIndex - 1];
}
else
{
previousHtmlContentFile = null;
}
if (currentReadingOrderItemIndex < ReadingOrder.Count - 1)
{
nextHtmlContentFile = ReadingOrder[currentReadingOrderItemIndex + 1];
}
else
{
nextHtmlContentFile = null;
}
}
else
{
previousHtmlContentFile = null;
nextHtmlContentFile = null;
}
}
NotifyPropertyChanged(nameof(IsPreviousButtonVisible));
NotifyPropertyChanged(nameof(IsNextButtonVisible));
}
private void NavigateToPreviousItemInReadingOrder()
{
if (previousHtmlContentFile != null)
{
Navigate(previousHtmlContentFile);
}
}
private void NavigateToNextItemInReadingOrder()
{
if (nextHtmlContentFile != null)
{
Navigate(nextHtmlContentFile);
}
}
}
}
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