/// <summary>
/// Check Update Articles
/// </summary>
public static async Task UpdateArticles(this FeedViewModel feedViewModel)
{
var feed_old = new ArticleViewModel();
feed_old.Title = feedViewModel.Articles.First().Title;
feedViewModel.Articles.Clear();
var feedFile =
await ApplicationData.Current.LocalFolder.TryGetItemAsync("feeds.dat") as StorageFile ??
await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/feeds.dat"));
if (feedFile != null)
{
var bytes = (await FileIO.ReadBufferAsync(feedFile)).ToArray();
var feedData = Serializer.Deserialize <string[][]>(bytes);
foreach (var feed in feedData)
{
feedViewModel.LinkAsString = feedViewModel.Name == feed[0] ? feed[1] : feedViewModel.LinkAsString;
}
}
await RefreshAsync(feedViewModel);
//
if (!feed_old.Title.Equals(feedViewModel.Articles.First().Title))
{
SendToast(feedViewModel);
}
}
/// <summary>
/// Gets the initial set of feeds, either from local storage or
/// from the app package if there is nothing in local storage.
/// </summary>
public static async Task <List <FeedViewModel> > GetFeedsAsync()
{
var feeds = new List <FeedViewModel>();
var favoritesFile = await ApplicationData.Current.LocalFolder.TryGetItemAsync("favorites.dat") as StorageFile;
if (favoritesFile != null)
{
var buffer = await FileIO.ReadBufferAsync(favoritesFile);
feeds.Add(Serializer.Deserialize <FeedViewModel>(buffer.ToArray()));
}
else
{
var feed = new FeedViewModel
{
Name = "Favorites",
Description = "Articles that you've starred",
Symbol = Symbol.OutlineStar,
Link = new Uri("http://localhost"),
IsFavoritesFeed = true
};
feeds.Add(feed);
}
var feedFile =
await ApplicationData.Current.LocalFolder.TryGetItemAsync("feeds.dat") as StorageFile ??
await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/feeds.dat"));
if (feedFile != null)
{
var bytes = (await FileIO.ReadBufferAsync(feedFile)).ToArray();
var feedData = Serializer.Deserialize <string[][]>(bytes);
foreach (var feed in feedData)
{
feeds.Add(new FeedViewModel {
Name = feed[0], Link = new Uri(feed[1])
});
}
}
return(feeds);
}
/// <summary>
/// Show the toast
/// </summary>
private static void SendToast(this FeedViewModel feedViewModel)
{
ToastTemplateType toastTemplate = ToastTemplateType.ToastImageAndText03;
XmlDocument toastXml = ToastNotificationManager.GetTemplateContent(toastTemplate);
XmlNodeList toastTextElements = toastXml.GetElementsByTagName("text");
toastTextElements[0].AppendChild(toastXml.CreateTextNode(feedViewModel.Name));
toastTextElements[1].AppendChild(toastXml.CreateTextNode("Has a news!"));
XmlNodeList toastImageElements = toastXml.GetElementsByTagName("image");
((XmlElement)toastImageElements[0]).SetAttribute("src", "ms-appx:///Assets/StoreLogo.scale-200.png");
IXmlNode toastNode = toastXml.SelectSingleNode("/toast");
((XmlElement)toastNode).SetAttribute("duration", "long");
// Create the toast and attach event listeners
ToastNotification toast = new ToastNotification(toastXml);
// Show the toast. Be sure to specify the AppUserModelId on your application's shortcut!
ToastNotificationManager.CreateToastNotifier().Show(toast);
}
/// <summary>
/// Retrieves feed data from the server and updates the appropriate FeedViewModel properties.
/// </summary>
public static async Task RefreshAsync(this FeedViewModel feedViewModel)
{
if (feedViewModel.Link.Host == "localhost" ||
(feedViewModel.Link.Scheme != "http" && feedViewModel.Link.Scheme != "https"))
{
return;
}
feedViewModel.IsInError = false;
feedViewModel.ErrorMessage = null;
feedViewModel.IsLoading = true;
feedViewModel.Symbol = Symbol.PostUpdate;
Func <Task <bool> > tryGetFeed = async() =>
{
try
{
var feed = await new SyndicationClient().RetrieveFeedAsync(feedViewModel.Link);
feedViewModel.Name = String.IsNullOrEmpty(feedViewModel.Name) ? feed.Title.Text : feedViewModel.Name;
feedViewModel.Description = feed.Subtitle?.Text ?? String.Empty;
feed.Items.Select(item => new ArticleViewModel
{
Title = item.Title.Text,
Summary = item.Summary == null ? string.Empty :
item.Summary.Text.RegexRemove("\\&.{0,4}\\;").RegexRemove("<.*?>"),
Author = item.Authors.Select(a => a.NodeValue).FirstOrDefault(),
Link = item.ItemUri ?? item.Links.Select(l => l.Uri).FirstOrDefault(),
PublishedDate = item.PublishedDate
})
.ToList().ForEach(article =>
{
var favorites = AppShell.Current.ViewModel.FavoritesFeed;
var existingCopy = favorites.Articles.FirstOrDefault(a => a.Equals(article));
article = existingCopy ?? article;
if (!feedViewModel.Articles.Contains(article))
{
feedViewModel.Articles.Add(article);
}
});
return(true);
}
catch (Exception)
{
if (feedViewModel.Articles.Count == 0)
{
feedViewModel.IsInError = true;
feedViewModel.ErrorMessage = "Hmm... Are you sure this is an RSS URL?";
}
else
{
// TODO display error state that doesn't replace articles that have already been retrieved.
}
return(false);
}
};
int numberOfAttempts = 5;
bool success = false;
do
{
success = await tryGetFeed();
}while (!success && numberOfAttempts-- > 0);
feedViewModel.IsLoading = false;
}