public async Task <IEnumerable <StoryDTO> > GetTopStoriesAsync()
{
var key = GetTopStoriesCacheKey();
if (cacheService.Get(key) is IReadOnlyCollection <StoryDTO> stories)
{
return(stories);
}
var topStoriesIds = await hackerNewsClient.GetTopStoriesAsync(topStoriesSize);
if (topStoriesIds == null || topStoriesIds.Count == 0)
{
return(Enumerable.Empty <StoryDTO>());
}
stories = (await Task.WhenAll(topStoriesIds.Select(o => hackerNewsClient.GetStoryAsync(o)))).ToDto();
if (stories.Count > 0)
{
cacheService.Add(key, stories, cacheTimeInMinutes);
}
return(stories);
}
public async void RefreshTopStories()
{
if (!isUpdating.GetAndSet(true))
{
NotifyOfPropertyChange("IsUpdating");
try
{
var newStories = await hn.GetTopStoriesAsync();
var existingIds = new HashSet <long>(topStories.Select(ts => ts.Id));
var added = false;
// assuming that story IDs are chronologically-ordered
foreach (var story in from ns in newStories
where !existingIds.Contains(ns.Id)
orderby ns.Id ascending
select new TopStoryViewModel(ns, navigationService))
{
added = true;
topStories.Insert(0, story);
}
if (added && existingIds.Count > 0)
{
// need to sort the list
var items = topStories.OrderBy(ts => ts.Id).ToList();
topStories.Clear();
foreach (var ts in items)
{
topStories.Add(ts);
}
}
}
catch (Exception ex)
{
// whoops
Log.Error(ex);
}
finally
{
IsUpdating = false;
}
}
}