Manager.cs :  » Bloggers » BlogEngine.NET » BlogEngine.Core » Ping » C# / CSharp Open Source

#region Using

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.Net;

#endregion

namespace BlogEngine.Core.Ping{
  /// <summary>
  /// Manages to send out trackbacks and then pingbacks if trackbacks aren't supported by the linked site.
  /// </summary>
  public static class Manager
  {
    /// <summary>
    /// Sends the trackback or pingback message.
    /// <remarks>
    /// It will try to send a trackback message first, and if the refered web page
    /// doesn't support trackbacks, a pingback is sent.
    /// </remarks>
    /// </summary>
    public static void Send(IPublishable item, Uri itemUrl)
    {
      foreach (Uri url in GetUrlsFromContent(item.Content))
      {
                bool isTrackbackSent = false;

                if (BlogSettings.Instance.EnableTrackBackSend)
                { 
            string pageContent = Utils.DownloadWebPage(url);// ReadFromWeb(url);
            Uri trackbackUrl = GetTrackBackUrlFromPage(pageContent);

            if (trackbackUrl != null)
            {
              TrackbackMessage message = new TrackbackMessage(item, trackbackUrl, itemUrl);
              isTrackbackSent = Trackback.Send(message);
            }
                }

                if (!isTrackbackSent && BlogSettings.Instance.EnablePingBackSend)
        {
          Pingback.Send(itemUrl, url);
        }
      }
    }

    #region "RegEx Methods"

    /// <summary>
    /// Regex used to find all hyperlinks.
    /// </summary>
    //private static readonly Regex urlsRegex = new Regex(@"\<a\s+href=""(http://.*?)"".*\>.+\<\/a\>", RegexOptions.IgnoreCase | RegexOptions.Compiled);
    //private static readonly Regex urlsRegex = new Regex(@"<a[^(href)]?href=""([^""]+)""[^>]?>([^<]+)</a>", RegexOptions.IgnoreCase | RegexOptions.Compiled);
        private static readonly Regex urlsRegex = new System.Text.RegularExpressions.Regex(@"<a.*?href=[""'](?<url>.*?)[""'].*?>(?<name>.*?)</a>", RegexOptions.IgnoreCase | RegexOptions.Compiled);

    /// <summary>
    /// Regex used to find the trackback link on a remote web page.
    /// </summary>
    private static readonly Regex trackbackLinkRegex = new Regex("trackback:ping=\"([^\"]+)\"", RegexOptions.IgnoreCase | RegexOptions.Compiled);

    /// <summary>
    /// Gets all the URLs from the specified string.
    /// </summary>
    private static List<Uri> GetUrlsFromContent(string content)
    {
      List<Uri> urlsList = new List<Uri>();
      foreach (Match myMatch in urlsRegex.Matches(content))
      {
                string url = myMatch.Groups["url"].ToString().Trim();
        Uri uri;
        if (Uri.TryCreate(url, UriKind.Absolute, out uri))
          urlsList.Add(uri);
      }

      return urlsList;
    }

    /// <summary>
    /// Examines the web page source code to retrieve the trackback link from the RDF.
    /// </summary>
    private static Uri GetTrackBackUrlFromPage(string input)
    {
      string url = trackbackLinkRegex.Match(input).Groups[1].ToString().Trim();
      Uri uri;

      if (Uri.TryCreate(url, UriKind.Absolute, out uri))
        return uri;
      else
        return null;
    }

    #endregion

    /// <summary>
    /// Returns the HTML code of a given URL.
    /// </summary>
    /// <param name="sourceUrl">The URL you want to extract the html code.</param>
    /// <returns></returns>
    private static string ReadFromWeb(Uri sourceUrl)
    {
      string html;
      using (WebClient client = new WebClient())
      {
        client.Headers.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)");
        html = client.DownloadString(sourceUrl);
      }
      return html;
    }
  }
}