private async Task <List <Hashtable> > DecipherFormats(
List <Hashtable> formats,
string videoHtmlPage)
{
var decodedFormats = new List <Hashtable>();
var cipheredFormats = new List <Hashtable>();
Parallel.ForEach(formats, format =>
{
if (format.ContainsKey("signatureCipher"))
{
var signatureCipher = format["signatureCipher"] as string;
signatureCipher?.Split('&')
.Select(pair => pair.Split('='))
.ToList()
.ForEach(keyAndValue => format.Add(keyAndValue[0], keyAndValue[1]));
}
var undecodedUrl = format["url"] as string;
if (undecodedUrl != null)
{
format["url"] = HttpUtility.UrlDecode(undecodedUrl);
}
var url = format["url"] as string ?? String.Empty;
if (url.Contains("signature") ||
(!format.ContainsKey("s") &&
(url.Contains("&sig=") || url.Contains("&lsig="))
)
)
{
decodedFormats.Add(format);
return;
}
cipheredFormats.Add(format);
});
if (cipheredFormats.Count != 0)
{
var baseJsUrl = ExtractBaseJsUrl(videoHtmlPage);
// TODO add exception handling
// wrapped within a Lazy to prevent multiple invocations
var signatureDecoderFunc = SignatureDecoderCache.GetOrAdd(baseJsUrl, new Lazy <Task <SignatureDecoder> >(() => SignatureDecoderExtractor.ExtractDecoder(baseJsUrl)));
var signatureDecoder = await signatureDecoderFunc.Value;
var uncipheredFormats = cipheredFormats.Select(format =>
{
format["url"] = (format["url"] as string)
+ "&sig="
+ signatureDecoder.Decode(format["s"] as string ?? String.Empty);
return(format);
});
decodedFormats.AddRange(uncipheredFormats);
}
return(decodedFormats);
}
public StreamingDataDecoder(IYoutubeApiConfig youtubeApiConfig)
{
YoutubeApiConfig = youtubeApiConfig;
SignatureDecoderExtractor = new SignatureDecoderExtractor(youtubeApiConfig.Client);
SignatureDecoderCache = new ConcurrentDictionary <string, Lazy <Task <SignatureDecoder> > >();
}