/// <summary>
/// Fetches a resource
/// </summary>
/// <param name="uri">The URI.</param>
/// <param name="options">The options.</param>
/// <param name="isContinuedPage">if set to <c>true</c> [is continued page].</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns></returns>
/// <exception cref="ReadException">
/// </exception>
private async Task<Response> Request(Uri uri, ReadOptions options, Response previousResponse, CancellationToken cancellationToken)
{
// URI already fetched
if (previousResponse != null && _currentPages.Contains(uri.OriginalString))
{
return previousResponse;
}
_currentPages.Add(uri.OriginalString);
HttpResponseMessage response = null;
TranscodingResult transcodingResult;
Encoding encoding;
using (HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, uri))
{
// make async request
try
{
response = await _httpClient.SendAsync(request, cancellationToken);
}
catch (HttpRequestException exc)
{
throw new ReadException(exc.Message);
}
// validate HTTP response
if (response.StatusCode != HttpStatusCode.OK)
{
string exceptionString = String.Format("Request error: {0} ({1})", response.ReasonPhrase, (int)response.StatusCode);
throw new ReadException(exceptionString);
}
}
// read response
Stream responseStream = await response.Content.ReadAsStreamAsync();
string charset = response.Content.Headers.ContentType?.CharSet;
// handle deep links
if (options.UseDeepLinks)
{
_transcoder.AnchorHrefTranformer = ReverseDeepLinks;
}
else
{
_transcoder.AnchorHrefTranformer = null;
}
// readability
try
{
// charset found in HTTP headers
encoding = _encoder.GetEncodingFromString(charset);
// transcode content
transcodingResult = ExtractReadableInformation(uri, responseStream, options, encoding);
// get encoding found in HTML
Encoding encodingFromHTML = _encoder.GetEncodingFromString(transcodingResult.Charset);
// extract again if encoding didn't match or failed to retrieve
if ((encoding != null && String.IsNullOrEmpty(charset))
||
(options.PreferHTMLEncoding && !String.Equals(charset, transcodingResult.Charset, StringComparison.OrdinalIgnoreCase)))
{
transcodingResult = ExtractReadableInformation(uri, responseStream, options, encodingFromHTML);
encoding = encodingFromHTML;
}
}
catch (Exception exc)
{
throw new ReadException(exc.Message);
}
finally
{
response.Dispose();
responseStream.Dispose();
}
Response newResponse = new Response()
{
TranscodingResult = transcodingResult,
PageCount = 1,
Encoding = encoding
};
// in same special cases their are multiple pages, which are only comments or do not contain new content.
// if this is the case we will break here and return the first page only.
if (previousResponse != null && previousResponse.TranscodingResult.ExtractedContent.Contains(transcodingResult.ExtractedContent))
{
previousResponse.TranscodingResult.NextPageUrl = null;
return previousResponse;
}
// multiple pages are available
try
{
if (options.MultipageDownload && transcodingResult.NextPageUrl != null && (previousResponse == null || (previousResponse != null && previousResponse.PageCount < _options.MultipageLimit)))
{
return await Request(new Uri(transcodingResult.NextPageUrl), new ReadOptions()
{
PrettyPrint = options.PrettyPrint,
UseDeepLinks = options.UseDeepLinks,
MultipageDownload = true
}, previousResponse != null ? MergeResponses(previousResponse, newResponse) : newResponse, cancellationToken);
}
// this is not the first page
if (previousResponse != null)
{
return MergeResponses(previousResponse, newResponse);
}
}
// silently fail when next pages fail to download
catch { }
return newResponse;
}
/// <summary>
/// Extracts the readable information.
/// </summary>
/// <param name="uri">The URI.</param>
/// <param name="textStream">The text stream.</param>
/// <param name="options">The options.</param>
/// <param name="encoding">The encoding.</param>
/// <returns></returns>
protected TranscodingResult ExtractReadableInformation(
Uri uri,
Stream textStream,
ReadOptions options,
Encoding encoding = null)
{
// response stream to text
textStream.Position = 0;
StreamReader streamReader = new StreamReader(textStream, encoding ?? Encoding.UTF8);
_rawHTML = streamReader.ReadToEnd();
// set properties for processing
TranscodingInput transcodingInput = new TranscodingInput(_rawHTML)
{
Url = uri.ToString(),
DomSerializationParams = new DomSerializationParams()
{
BodyOnly = !options.HasHeaderTags,
NoHeadline = !options.HasHeadline,
PrettyPrint = options.PrettyPrint,
DontIncludeContentTypeMetaElement = true,
DontIncludeMobileSpecificMetaElements = true,
DontIncludeDocTypeMetaElement = false,
DontIncludeGeneratorMetaElement = true,
ReplaceImagesWithPlaceholders = options.ReplaceImagesWithPlaceholders
}
};
// process/transcode HTML
return _transcoder.Transcode(transcodingInput);
}
/// <summary>
/// Fetches a resource
/// </summary>
/// <param name="uri">The URI.</param>
/// <param name="options">The options.</param>
/// <param name="isContinuedPage">if set to <c>true</c> [is continued page].</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns></returns>
/// <exception cref="ReadException">
/// </exception>
private async Task <Response> Request(Uri uri, ReadOptions options, Response previousResponse, CancellationToken cancellationToken)
{
// URI already fetched
if (previousResponse != null && _currentPages.Contains(uri.OriginalString))
{
return(previousResponse);
}
_currentPages.Add(uri.OriginalString);
HttpResponseMessage response = null;
TranscodingResult transcodingResult;
Encoding encoding;
using (HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, uri))
{
// make async request
try
{
response = await _httpClient.SendAsync(request, cancellationToken);
}
catch (HttpRequestException exc)
{
throw new ReadException(exc.Message);
}
// validate HTTP response
if (response.StatusCode != HttpStatusCode.OK)
{
string exceptionString = String.Format("Request error: {0} ({1})", response.ReasonPhrase, (int)response.StatusCode);
throw new ReadException(exceptionString);
}
}
// read response
Stream responseStream = await response.Content.ReadAsStreamAsync();
string charset = response.Content.Headers.ContentType.CharSet;
// handle deep links
if (options.UseDeepLinks)
{
_transcoder.AnchorHrefTranformer = ReverseDeepLinks;
}
else
{
_transcoder.AnchorHrefTranformer = null;
}
// readability
try
{
// charset found in HTTP headers
encoding = _encoder.GetEncodingFromString(charset);
// transcode content
transcodingResult = ExtractReadableInformation(uri, responseStream, options, encoding);
// get encoding found in HTML
Encoding encodingFromHTML = _encoder.GetEncodingFromString(transcodingResult.Charset);
// extract again if encoding didn't match or failed to retrieve
if ((encoding != null && String.IsNullOrEmpty(charset))
||
(options.PreferHTMLEncoding && !String.Equals(charset, transcodingResult.Charset, StringComparison.OrdinalIgnoreCase)))
{
transcodingResult = ExtractReadableInformation(uri, responseStream, options, encodingFromHTML);
encoding = encodingFromHTML;
}
}
catch (Exception exc)
{
throw new ReadException(exc.Message);
}
finally
{
response.Dispose();
responseStream.Dispose();
}
Response newResponse = new Response()
{
TranscodingResult = transcodingResult,
PageCount = 1,
Encoding = encoding
};
// in same special cases their are multiple pages, which are only comments or do not contain new content.
// if this is the case we will break here and return the first page only.
if (previousResponse != null && previousResponse.TranscodingResult.ExtractedContent.Contains(transcodingResult.ExtractedContent))
{
previousResponse.TranscodingResult.NextPageUrl = null;
return(previousResponse);
}
// multiple pages are available
try
{
if (options.MultipageDownload && transcodingResult.NextPageUrl != null && (previousResponse == null || (previousResponse != null && previousResponse.PageCount < _options.MultipageLimit)))
{
return(await Request(new Uri(transcodingResult.NextPageUrl), new ReadOptions()
{
PrettyPrint = options.PrettyPrint,
UseDeepLinks = options.UseDeepLinks,
MultipageDownload = true
}, previousResponse != null?MergeResponses(previousResponse, newResponse) : newResponse, cancellationToken));
}
// this is not the first page
if (previousResponse != null)
{
return(MergeResponses(previousResponse, newResponse));
}
}
// silently fail when next pages fail to download
catch { }
return(newResponse);
}
/// <summary>
/// Reads article content from the given URI.
/// </summary>
/// <param name="uri">An URI to extract the content from.</param>
/// <param name="options">The transform options.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>
/// An article with extracted content and meta information.
/// </returns>
/// <exception cref="ReadException"></exception>
/// <exception cref="InvalidOperationException"></exception>
/// <exception cref="OperationCanceledException"></exception>
public async Task<Article> Read(Uri uri, ReadOptions options = null, CancellationToken cancellationToken = default(CancellationToken))
{
_currentPages = new List<string>();
Response response;
string uriString = uri.OriginalString;
if (options == null)
{
options = ReadOptions.CreateDefault();
}
// replace domain when URI is marked as faulty
foreach (string faultyUri in _redirectFaultyMobileURIs.Keys)
{
if (uriString.Contains(faultyUri))
{
uri = new Uri(uriString.Replace(faultyUri, _redirectFaultyMobileURIs[faultyUri]));
}
}
// make async request
response = await Request(uri, options, null, cancellationToken);
// get images from article
int id = 1;
IEnumerable<ArticleImage> images = response.TranscodingResult.Images
.Select(image =>
{
Uri imageUri = null;
Uri.TryCreate(image.GetAttributeValue("src", null), UriKind.Absolute, out imageUri);
return new ArticleImage()
{
ID = (id++).ToString(),
Uri = imageUri,
Title = image.GetAttributeValue("title", null),
AlternativeText = image.GetAttributeValue("alt", null)
};
});
//.GroupBy(image => image.Uri)
//.Select(g => g.First())
//.Where(image => image.Uri != null);
// get word count and plain text
string plainContent;
int wordCount = 0;
try
{
plainContent = HtmlUtilities.ConvertToPlainText(response.TranscodingResult.ExtractedContent);
wordCount = HtmlUtilities.CountWords(plainContent);
}
catch
{
plainContent = null;
}
// create article
return new Article()
{
Title = response.TranscodingResult.ExtractedTitle,
Description = response.TranscodingResult.ExtractedDescription,
Content = response.TranscodingResult.ExtractedContent,
ContentExtracted = response.TranscodingResult.ContentExtracted ? wordCount > 0 : false,
Raw = _rawHTML,
PlainContent = plainContent,
WordCount = wordCount,
PageCount = response.PageCount,
FrontImage = response.TranscodingResult.ExtractedImage,
Images = images,
Favicon = response.TranscodingResult.ExtractedFavicon,
NextPage = response.TranscodingResult.NextPageUrl != null ? new Uri(response.TranscodingResult.NextPageUrl, UriKind.Absolute) : null,
Encoding = response.Encoding
};
}
/// <summary>
/// Reads article content from the given URI.
/// </summary>
/// <param name="uri">An URI to extract the content from.</param>
/// <param name="options">The transform options.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>
/// An article with extracted content and meta information.
/// </returns>
/// <exception cref="ReadException"></exception>
/// <exception cref="InvalidOperationException"></exception>
/// <exception cref="OperationCanceledException"></exception>
public async Task <Article> Read(Uri uri, ReadOptions options = null, CancellationToken cancellationToken = default(CancellationToken))
{
_currentPages = new List <string>();
Response response;
string uriString = uri.OriginalString;
if (options == null)
{
options = ReadOptions.CreateDefault();
}
// replace domain when URI is marked as faulty
foreach (string faultyUri in _redirectFaultyMobileURIs.Keys)
{
if (uriString.Contains(faultyUri))
{
uri = new Uri(uriString.Replace(faultyUri, _redirectFaultyMobileURIs[faultyUri]));
}
}
// make async request
response = await Request(uri, options, null, cancellationToken);
// get images from article
int id = 1;
IEnumerable <ArticleImage> images = response.TranscodingResult.Images
.Select(image =>
{
Uri imageUri = null;
Uri.TryCreate(image.GetAttributeValue("src", null), UriKind.Absolute, out imageUri);
return(new ArticleImage()
{
ID = (id++).ToString(),
Uri = imageUri,
Title = image.GetAttributeValue("title", null),
AlternativeText = image.GetAttributeValue("alt", null)
});
});
//.GroupBy(image => image.Uri)
//.Select(g => g.First())
//.Where(image => image.Uri != null);
// get word count and plain text
string plainContent;
int wordCount = 0;
try
{
plainContent = HtmlUtilities.ConvertToPlainText(response.TranscodingResult.ExtractedContent);
wordCount = HtmlUtilities.CountWords(plainContent);
}
catch
{
plainContent = null;
}
// create article
return(new Article()
{
Title = response.TranscodingResult.ExtractedTitle,
Description = response.TranscodingResult.ExtractedDescription,
Content = response.TranscodingResult.ExtractedContent,
ContentExtracted = response.TranscodingResult.ContentExtracted ? wordCount > 0 : false,
Raw = _rawHTML,
PlainContent = plainContent,
WordCount = wordCount,
PageCount = response.PageCount,
FrontImage = response.TranscodingResult.ExtractedImage,
Images = images,
Favicon = response.TranscodingResult.ExtractedFavicon,
NextPage = response.TranscodingResult.NextPageUrl != null ? new Uri(response.TranscodingResult.NextPageUrl, UriKind.Absolute) : null,
Encoding = response.Encoding
});
}
