public static async Task <ISyndicationFeedReader> GetSyndicationFeedReader(IUriEntity uriEntity)
{
if (ReferenceEquals(uriEntity, null) || string.IsNullOrWhiteSpace(uriEntity.Uri))
{
throw new ArgumentException(nameof(uriEntity));
}
var syndicationFeedType = await GetSyndicationFeedType(uriEntity);
switch (syndicationFeedType)
{
case SyndicationFeedType.Rss:
return(new RssFeedReader(XmlReader.Create(uriEntity.Uri, new XmlReaderSettings {
Async = true
})));
case SyndicationFeedType.Atom:
return(new AtomFeedReader(XmlReader.Create(uriEntity.Uri, new XmlReaderSettings {
Async = true
})));
default:
throw new UriFormatException(nameof(uriEntity));
}
}
public async Task <List <News> > GetNews(IUriEntity uriEntity)
{
if (string.IsNullOrWhiteSpace(uriEntity.Uri))
{
return(null);
}
var items = new HashSet <ISyndicationItem>();
try
{
var feedReader = await SyndicationFactory.GetSyndicationFeedReader(uriEntity);
while (await feedReader.Read())
{
switch (feedReader.ElementType)
{
case SyndicationElementType.Item:
var item = await feedReader.ReadItem();
items.Add(item);
break;
}
}
}
catch (Exception exception)
{
_logger.LogError($"Something went wrong: {exception.InnerException?.Message ?? exception.Message}");
}
return(items.Select(i => i.GetNews()).ToList());
}
public static bool UriEquals(this IUriEntity entity, object obj)
{
if (!(obj is IUriEntity uriEntity))
{
return(false);
}
if (ReferenceEquals(entity, uriEntity))
{
return(true);
}
if (entity.Uri.Length != uriEntity.Uri.Length)
{
return(false);
}
return(entity.Uri == uriEntity.Uri);
}
public static int GetUriHashCode(this IUriEntity entity)
{
if (string.IsNullOrWhiteSpace(entity.Uri))
{
return(0);
}
var bytes = Encoding.Unicode.GetBytes(entity.Uri);
var sum = 0;
foreach (var @byte in bytes)
{
for (var i = 0; i < 8; i++)
{
sum += (@byte >> i) & 1;
}
}
return(sum);
}
private static async Task <SyndicationFeedType> GetSyndicationFeedType(IUriEntity uriEntity)
{
if (ReferenceEquals(uriEntity, null) || string.IsNullOrWhiteSpace(uriEntity.Uri))
{
throw new ArgumentException(nameof(uriEntity));
}
using (var xmlReader = XmlReader.Create(uriEntity.Uri, new XmlReaderSettings {
Async = true
}))
{
for (var i = 0; i < 2; i++)
{
if (await xmlReader.ReadAsync() && xmlReader.IsStartElement() && !xmlReader.IsEmptyElement)
{
if (xmlReader.HasAttributes)
{
for (var j = 0; j < xmlReader.AttributeCount; j++)
{
var result = GetSyndicationFeedTypeFromAttribute(xmlReader.GetAttribute(j));
if (result != SyndicationFeedType.None)
{
return(result);
}
}
}
else
{
var result = GetSyndicationFeedTypeFromElement(xmlReader.Name);
if (result != SyndicationFeedType.None)
{
return(result);
}
}
}
}
}
throw new ArgumentException(nameof(uriEntity));
}