/// <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>
/// 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;
}
/// <summary>
/// Saves the favorites feed (the first feed of the feeds list) to local storage.
/// </summary>
public static async Task SaveFavoritesAsync(this FeedViewModel favorites)
{
var file = await ApplicationData.Current.LocalFolder
.CreateFileAsync("favorites.dat", CreationCollisionOption.ReplaceExisting);
byte[] array = Serializer.Serialize(favorites);
await FileIO.WriteBytesAsync(file, array);
}
/// <summary>
/// Retrieves feed data from the server and updates the appropriate FeedViewModel properties.
/// </summary>
private static async Task <bool> TryGetFeedAsync(FeedViewModel feedViewModel, CancellationToken?cancellationToken = null)
{
try
{
var feed = await new SyndicationClient().RetrieveFeedAsync(feedViewModel.Link);
if (cancellationToken.HasValue && cancellationToken.Value.IsCancellationRequested)
{
return(false);
}
feedViewModel.LastSyncDateTime = DateTime.Now;
feedViewModel.Name = String.IsNullOrEmpty(feedViewModel.Name) ? feed.Title.Text : feedViewModel.Name;
feedViewModel.Description = feed.Subtitle?.Text ?? feed.Title.Text;
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);
}
});
feedViewModel.IsInError = false;
feedViewModel.ErrorMessage = null;
return(true);
}
catch (Exception)
{
if (!cancellationToken.HasValue || !cancellationToken.Value.IsCancellationRequested)
{
feedViewModel.IsInError = true;
feedViewModel.ErrorMessage = feedViewModel.Articles.Count == 0 ? BAD_URL_MESSAGE : NO_REFRESH_MESSAGE;
}
return(false);
}
}
/// <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;
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);
}
});
}
catch (Exception)
{
feedViewModel.IsInError = true;
feedViewModel.ErrorMessage = "Hmm... Are you sure this is an RSS URL?";
}
feedViewModel.IsLoading = false;
}
/// <summary>
/// Attempts to update the feed with new data from the server.
/// </summary>
public static async Task RefreshAsync(this FeedViewModel feedViewModel, CancellationToken?cancellationToken = null)
{
if (feedViewModel.Link.Host == "localhost" ||
(feedViewModel.Link.Scheme != "http" && feedViewModel.Link.Scheme != "https"))
{
return;
}
feedViewModel.IsLoading = true;
int numberOfAttempts = 5;
bool success = false;
do
{
success = await TryGetFeedAsync(feedViewModel, cancellationToken);
}while (!success && numberOfAttempts-- > 0 &&
(!cancellationToken.HasValue || !cancellationToken.Value.IsCancellationRequested));
feedViewModel.IsLoading = false;
}
/// <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 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)
{
var feedVM = new FeedViewModel {
Name = feed[0], Link = new Uri(feed[1])
};
feeds.Add(feedVM);
var withoutAwait = feedVM.RefreshAsync();
}
}
return(feeds);
}
