1Using#region Using
  2
  3using System;
  4using System.Collections.Generic;
  5using System.Text;
  6using System.Text.RegularExpressions;
  7using System.Net;
  8
  9#endregion
 10
 11namespace LiveBlog.Core.Ping
 12...{
 13  /**//// <summary>
 14  /// Manages to send out trackbacks and then pingbacks if trackbacks aren't supported by the linked site.
 15  /// </summary>
 16  public static class Manager
 17  ...{
 18    /**//// <summary>
 19    /// Sends the trackback or pingback message.
 20        /// <remarks>
 21        /// It will try to send a trackback message first, and if the refered web page
 22        /// doesn't support trackbacks, a pingback is sent.
 23        /// </remarks>
 24    /// </summary>
 25    public static void Send(IPublishable item)
 26    ...{
 27      foreach (Uri url in GetUrlsFromContent(item.Content))
 28      ...{
 29                if (url.Host == Utils.AbsoluteWebRoot.Host)
 30                    continue;
 31
 32        string pageContent = ReadFromWeb(url);
 33                Uri trackbackUrl = GetTrackBackUrlFromPage(pageContent);
 34                bool isTrackbackSent = false;
 35
 36                if (trackbackUrl != null)
 37                ...{
 38                    TrackbackMessage message = new TrackbackMessage(item, trackbackUrl);
 39                    isTrackbackSent = Trackback.Send(message);                    
 40                }
 41
 42                if (!isTrackbackSent)
 43                ...{
 44                    Pingback.Send(item.AbsoluteLink, url);
 45                }
 46      }
 47    }
 48
 49    "RegEx Methods"#region "RegEx Methods"
 50
 51        /**//// <summary>
 52        /// Regex used to find all hyperlinks.
 53        /// </summary>
 54    private static readonly Regex urlsRegex = new Regex(@"\<a\s+href=""(http://.*?)"".*\>.+\<\/a\>", RegexOptions.IgnoreCase | RegexOptions.Compiled);
 55
 56        /**//// <summary>
 57        /// Regex used to find the trackback link on a remote web page.
 58        /// </summary>
 59    private static readonly Regex trackbackLinkRegex = new Regex("trackback:ping=\"([^\"]+)\"", RegexOptions.IgnoreCase | RegexOptions.Compiled);
 60
 61        /**//// <summary>
 62        /// Gets all the URLs from the specified string.
 63        /// </summary>
 64    private static List<Uri> GetUrlsFromContent(string content)
 65    ...{
 66      List<Uri> urlsList = new List<Uri>();
 67      foreach (Match myMatch in urlsRegex.Matches(content))
 68      ...{
 69        string url = myMatch.Groups[1].ToString().Trim();
 70        Uri uri;
 71        if (Uri.TryCreate(url, UriKind.Absolute, out uri))
 72          urlsList.Add(uri);
 73      }
 74
 75      return urlsList;
 76    }
 77
 78        /**//// <summary>
 79        /// Examines the web page source code to retrieve the trackback link from the RDF.
 80        /// </summary>
 81    private static Uri GetTrackBackUrlFromPage(string input)
 82    ...{
 83      string url = trackbackLinkRegex.Match(input).Groups[1].ToString().Trim();
 84      Uri uri;
 85
 86      if (Uri.TryCreate(url, UriKind.Absolute, out uri))
 87        return uri;
 88      else
 89        return null;
 90    }
 91
 92    #endregion
 93
 94        /**//// <summary>
 95    /// Returns the HTML code of a given URL.
 96    /// </summary>
 97    /// <param name="sourceUrl">The URL you want to extract the html code.</param>
 98    /// <returns></returns>
 99    private static string ReadFromWeb(Uri sourceUrl)
100    ...{
101      string html;
102      using (WebClient client = new WebClient())
103      ...{
104                client.Headers.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)");
105        html = client.DownloadString(sourceUrl);
106      }
107      return html;
108    }
109  }
110}
111