Sioc.cs :  » Bloggers » BlogEngine.NET » BlogEngine.Core » Web » HttpHandlers » C# / CSharp Open Source

#region Using

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.Xml;
using System.Web;
using System.Web.Security;
using System.IO;
using System.Security;
using System.Security.Cryptography;

#endregion

namespace BlogEngine.Core.Web.HttpHandlers{
  /// <summary>
  /// Based on John Dyer's (http://johndyer.name/) extension.
  /// </summary>
  public class Sioc : IHttpHandler
  {

    #region IHttpHandler Members

    /// <summary>
    /// Gets a value indicating whether another request can use the <see cref="T:System.Web.IHttpHandler"></see> instance.
    /// </summary>
    /// <value></value>
    /// <returns>true if the <see cref="T:System.Web.IHttpHandler"></see> instance is reusable; otherwise, false.</returns>
    public bool IsReusable
    {
      get { return false; }
    }

    /// <summary>
    /// Enables processing of HTTP Web requests by a custom HttpHandler that implements the <see cref="T:System.Web.IHttpHandler"></see> interface.
    /// </summary>
    /// <param name="context">An <see cref="T:System.Web.HttpContext"></see> object that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) used to service HTTP requests.</param>
    public void ProcessRequest(HttpContext context)
    {
      context.Response.ContentType = "text/xml";
      string siocType = context.Request["sioc_type"] + string.Empty;
      string siocID = context.Request["sioc_id"] + string.Empty;

      switch (siocType)
      {
        default:
        case "site":
          List<IPublishable> list = Post.Posts.ConvertAll(new Converter<Post, IPublishable>(ConvertToIPublishable));
          int max = Math.Min(BlogSettings.Instance.PostsPerFeed, list.Count);
          list = list.GetRange(0, max);
          WriteSite(context.Response.OutputStream, list);
          break;

        case "post":
          Guid postID = Guid.Empty;
          try
          {
            postID = new Guid(siocID);
          }
          catch { }

          if (postID != Guid.Empty)
          {
            Post post = Post.GetPost(postID);
            if (post != null)
            {
              WritePub(context.Response.OutputStream, post);
            }
          }
          break;

        case "comment":
          Guid commentID = Guid.Empty;
          try
          {
            commentID = new Guid(siocID);
          }
          catch { }

          if (commentID != Guid.Empty)
          {
            // TODO: is it possible to get a single comment?
            Comment comment = GetComment(commentID);

            if (comment != null)
            {
              WritePub(context.Response.OutputStream, comment);
            }
          }
          break;

        case "user":
          WriteAuthor(context.Response.OutputStream, siocID);
          break;
        /*
        case "post":
          generator.WriteSite(context.Response.OutputStream);
          break;
        */
      }
    }

    #endregion

    #region Urls

    private static string GetSiocSiteUrl()
    {
      return Utils.AbsoluteWebRoot.ToString() + "sioc.axd?sioc_type=site";
    }

    private static string GetSiocAuthorsUrl()
    {
      return Utils.AbsoluteWebRoot.ToString() + "sioc.axd?sioc_type=site#authors";
    }

    private static string GetSiocBlogUrl()
    {
      return Utils.AbsoluteWebRoot.ToString() + "sioc.axd?sioc_type=site#webblog";
    }

    private static string GetSiocPostUrl(string id)
    {
      return Utils.AbsoluteWebRoot.ToString() + "sioc.axd?sioc_type=post&sioc_id=" + id;
    }

    private static string GetSiocAuthorUrl(string username)
    {
      return Utils.AbsoluteWebRoot.ToString() + "sioc.axd?sioc_type=user&sioc_id=" + System.Web.HttpUtility.UrlEncode(username);
    }

    private static string GetBlogAuthorUrl(string username)
    {
      return Utils.AbsoluteWebRoot.ToString() + "author/" + System.Web.HttpUtility.UrlEncode(username) + ".aspx";
    }

    private string GetSiocCommentUrl(string id)
    {
      return Utils.AbsoluteWebRoot.ToString() + "sioc.axd?sioc_type=comment&sioc_id=" + id;
    }

    #endregion

    #region Write XML

    private static Dictionary<string, string> xmlNamespaces;
    private static Dictionary<string, string> SupportedNamespaces
    {
      get
      {
        if (xmlNamespaces == null)
        {
          xmlNamespaces = new Dictionary<string, string>();

          xmlNamespaces.Add("foaf", "http://xmlns.com/foaf/0.1/");
          xmlNamespaces.Add("rss", "http://purl.org/rss/1.0/");
          xmlNamespaces.Add("admin", "http://webns.net/mvcb/");
          xmlNamespaces.Add("dc", "http://purl.org/dc/elements/1.1/");
          xmlNamespaces.Add("dcterms", "http://purl.org/dc/terms/");
          xmlNamespaces.Add("rdfs", "http://www.w3.org/2000/01/rdf-schema#");
          xmlNamespaces.Add("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
          xmlNamespaces.Add("content", "http://purl.org/rss/1.0/modules/content");
          xmlNamespaces.Add("sioc", "http://rdfs.org/sioc/ns#");
        }

        return xmlNamespaces;
      }
    }

    private XmlWriter GetWriter(Stream stream)
    {
      XmlWriterSettings settings = new XmlWriterSettings();
      settings.Encoding = Encoding.UTF8;
      settings.Indent = true;
      XmlWriter xmlWriter = XmlWriter.Create(stream, settings);

      xmlWriter.WriteStartDocument();
      xmlWriter.WriteStartElement("rdf", "RDF", "http://www.w3.org/1999/02/22-rdf-syntax-ns#"); //"http://xmlns.com/foaf/0.1/");

      foreach (string prefix in SupportedNamespaces.Keys)
      {
        xmlWriter.WriteAttributeString("xmlns", prefix, null, SupportedNamespaces[prefix]);
      }

      return xmlWriter;
    }

    private void CloseWriter(XmlWriter xmlWriter)
    {
      xmlWriter.WriteEndElement(); // rdf:RDF
      xmlWriter.WriteEndDocument();
      xmlWriter.Close();
    }

    private void WriteSite(Stream stream, List<IPublishable> list)
    {
      XmlWriter xmlWriter = GetWriter(stream);

      WriteUserGroup(xmlWriter);
      WriteFoafDocument(xmlWriter, "site", Utils.AbsoluteWebRoot.ToString());
      WriteSiocSite(xmlWriter);
      WriteForum(xmlWriter, list);

      CloseWriter(xmlWriter);
    }

    private void WriteUserGroup(XmlWriter xmlWriter)
    {
      xmlWriter.WriteStartElement("sioc", "Usergroup", null);

      xmlWriter.WriteAttributeString("rdf", "about", null, GetSiocAuthorsUrl());
      xmlWriter.WriteElementString("dc", "title", null, "Authors at \"" + BlogSettings.Instance.Name + "\"");

      int count = 0;
      MembershipUserCollection members = Membership.Provider.GetAllUsers(0, 999, out count);

      foreach (MembershipUser user in members)
      {
        xmlWriter.WriteStartElement("sioc", "has_member", null);
        xmlWriter.WriteStartElement("sioc", "User", null);
        xmlWriter.WriteAttributeString("rdf", "about", null, GetBlogAuthorUrl(user.UserName));
        xmlWriter.WriteAttributeString("rdfs", "label", null, user.UserName);

        xmlWriter.WriteStartElement("sioc", "see_also", null);
        xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocAuthorUrl(user.UserName));
        xmlWriter.WriteEndElement(); //sioc:see_also

        xmlWriter.WriteEndElement(); //sioc:User
        xmlWriter.WriteEndElement(); //sioc:has_member
      }

      xmlWriter.WriteEndElement(); //foaf:Document
    }

    private void WriteFoafDocument(XmlWriter xmlWriter, string siocType, string url)
    {
      string title = "SIOC " + siocType + " profile for \"" + BlogSettings.Instance.Name + "\"";
      string description = "A SIOC profile describes the structure and contents of a weblog in a machine readable form. For more information please refer to http://sioc-project.org/.";

      xmlWriter.WriteStartElement("foaf", "Document", null);
      xmlWriter.WriteAttributeString("rdf", "about", null, Utils.AbsoluteWebRoot.ToString());

      xmlWriter.WriteElementString("dc", "title", null, title);
      xmlWriter.WriteElementString("dc", "description", null, description);
      xmlWriter.WriteElementString("foaf", "primaryTopic", null, url);
      xmlWriter.WriteElementString("admin", "generatorAgent", null, "BlogEngine.NET" + BlogSettings.Instance.Version());

      xmlWriter.WriteEndElement(); //foaf:Document
    }

    private void WriteSiocSite(XmlWriter xmlWriter)
    {
      xmlWriter.WriteStartElement("sioc", "Site", null);
      xmlWriter.WriteAttributeString("rdf", "about", null, Utils.AbsoluteWebRoot.ToString());

      xmlWriter.WriteElementString("dc", "title", null, BlogSettings.Instance.Name);
      xmlWriter.WriteElementString("dc", "description", null, BlogSettings.Instance.Description);
      xmlWriter.WriteElementString("sioc", "link", null, Utils.AbsoluteWebRoot.ToString());
      xmlWriter.WriteElementString("sioc", "host_of", null, GetSiocBlogUrl());
      xmlWriter.WriteElementString("sioc", "has_group", null, GetSiocAuthorsUrl());

      xmlWriter.WriteEndElement(); //sioc:Site
    }

    private void WriteForum(XmlWriter xmlWriter, List<IPublishable> list)
    {
      xmlWriter.WriteStartElement("sioc", "Forum", null);

      xmlWriter.WriteAttributeString("rdf", "about", null, GetSiocBlogUrl());
      xmlWriter.WriteElementString("sioc", "name", null, BlogSettings.Instance.Name);
      xmlWriter.WriteStartElement("sioc", "link", null);
      xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocBlogUrl());
      xmlWriter.WriteEndElement();

      foreach (IPublishable pub in list)
      {
        xmlWriter.WriteStartElement("sioc", "container_of", null);
        xmlWriter.WriteStartElement("sioc", "Post", null);
        xmlWriter.WriteAttributeString("rdf", "about", null, pub.AbsoluteLink.ToString());
        xmlWriter.WriteAttributeString("dc", "title", null, pub.Title);

        xmlWriter.WriteStartElement("rdfs", "seeAlso", null);
        xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocPostUrl(pub.Id.ToString()));
        xmlWriter.WriteEndElement(); //sioc:Post

        xmlWriter.WriteEndElement(); //sioc:Post
        xmlWriter.WriteEndElement(); //sioc:Forum
      }

      xmlWriter.WriteEndElement(); //sioc:Forum
    }

    private void WritePub(Stream stream, IPublishable pub)
    {
      XmlWriter xmlWriter = GetWriter(stream);

      if (pub is Post)
        WriteFoafDocument(xmlWriter, "post", pub.AbsoluteLink.ToString());
      else
        WriteFoafDocument(xmlWriter, "comment", pub.AbsoluteLink.ToString());

      WriteSiocPost(xmlWriter, pub);
      CloseWriter(xmlWriter);
    }

    private void WriteSiocPost(XmlWriter xmlWriter, IPublishable pub)
    {
      xmlWriter.WriteStartElement("sioc", "Post", null);
      xmlWriter.WriteAttributeString("rdf", "about", null, pub.AbsoluteLink.ToString());

      xmlWriter.WriteStartElement("sioc", "link", null);
      xmlWriter.WriteAttributeString("rdf", "resource", null, pub.AbsoluteLink.ToString());
      xmlWriter.WriteEndElement(); //sioc:link

      xmlWriter.WriteStartElement("sioc", "has_container", null);
      xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocBlogUrl());
      xmlWriter.WriteEndElement(); //sioc:has_container

      xmlWriter.WriteElementString("dc", "title", null, pub.Title);

      // SIOC:USER
      if (pub is Post)
      {
        xmlWriter.WriteStartElement("sioc", "has_creator", null);
        xmlWriter.WriteStartElement("sioc", "User", null);
        xmlWriter.WriteAttributeString("rdf", "about", null, GetBlogAuthorUrl(pub.Author));
        xmlWriter.WriteStartElement("rdfs", "seeAlso", null);
        xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocAuthorUrl(pub.Author));
        xmlWriter.WriteEndElement(); //rdf:about
        xmlWriter.WriteEndElement(); //sioc:User
        xmlWriter.WriteEndElement(); //sioc:has_creator
      }

      // FOAF:maker
      xmlWriter.WriteStartElement("foaf", "maker", null);
      xmlWriter.WriteStartElement("foaf", "Person", null);
      if (pub is Post)
        xmlWriter.WriteAttributeString("rdf", "about", null, GetBlogAuthorUrl(pub.Author));

      xmlWriter.WriteAttributeString("foaf", "name", null, pub.Author);

      if (pub is Post)
      {
        MembershipUser user = Membership.GetUser(pub.Author);
        xmlWriter.WriteElementString("foaf", "mbox_sha1sum", null, (user != null) ? CalculateSHA1(user.Email, Encoding.UTF8) : "");
      }
      else
      {
        xmlWriter.WriteElementString("foaf", "mbox_sha1sum", null, CalculateSHA1(((Comment)pub).Email, Encoding.UTF8));
      }

      xmlWriter.WriteStartElement("foaf", "homepage", null);
      if (pub is Post)
        xmlWriter.WriteAttributeString("rdf", "resource", null, Utils.AbsoluteWebRoot.ToString());
      else
        xmlWriter.WriteAttributeString("rdf", "resource", null, "TODO:");
      xmlWriter.WriteEndElement(); //foaf:homepage

      if (pub is Post)
      {
        xmlWriter.WriteStartElement("rdfs", "seeAlso", null);
        xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocAuthorUrl(pub.Author));
        xmlWriter.WriteEndElement(); //rdfs:seeAlso
      }

      xmlWriter.WriteEndElement(); //foaf:Person
      xmlWriter.WriteEndElement(); //foaf:maker

      // CONTENT
      //xmlWriter.WriteElementString("dcterms", "created", null, DpUtility.ToW3cDateTime(pub.DateCreated));
      xmlWriter.WriteElementString("sioc", "content", null, Utils.StripHtml(pub.Content));
      xmlWriter.WriteElementString("content", "encoded", null, pub.Content);

      // TOPICS
      if (pub is Post)
      {
        // categories
        foreach (Category category in ((Post)pub).Categories)
        {
          xmlWriter.WriteStartElement("sioc", "topic", null);
          xmlWriter.WriteAttributeString("rdfs", "label", null, category.Title);
          xmlWriter.WriteAttributeString("rdf", "resource", null, category.AbsoluteLink.ToString());
          xmlWriter.WriteEndElement(); //sioc:topic
        }

        // tags are also supposed to be treated as sioc:topic 
        foreach (string tag in ((Post)pub).Tags)
        {
          xmlWriter.WriteStartElement("sioc", "topic", null);
          xmlWriter.WriteAttributeString("rdfs", "label", null, tag);
          xmlWriter.WriteAttributeString("rdf", "resource", null, Utils.AbsoluteWebRoot.ToString() + "?tag=/" + tag);
          xmlWriter.WriteEndElement(); //sioc:topic
        }

        // COMMENTS
        foreach (Comment comment in ((Post)pub).ApprovedComments)
        {
          xmlWriter.WriteStartElement("sioc", "has_reply", null);
          xmlWriter.WriteStartElement("sioc", "Post", null);
          xmlWriter.WriteAttributeString("rdf", "about", null, comment.AbsoluteLink.ToString());

          xmlWriter.WriteStartElement("rdfs", "seeAlso", null);
          xmlWriter.WriteAttributeString("rdf", "resource", null, GetSiocCommentUrl(comment.Id.ToString()));
          xmlWriter.WriteEndElement(); //rdfs:seeAlso

          xmlWriter.WriteEndElement(); //sioc:Post
          xmlWriter.WriteEndElement(); //sioc:has_reply
        }

        // TODO: LINKS
        MatchCollection linkMatches = Regex.Matches(pub.Content, @"<a[^(href)]?href=""([^""]+)""[^>]?>([^<]+)</a>");
        List<string> linkPairs = new List<string>();

        foreach (Match linkMatch in linkMatches)
        {
          string url = linkMatch.Groups[1].Value;
          string text = linkMatch.Groups[2].Value;

          if (url.IndexOf(Utils.AbsoluteWebRoot.ToString()) != 0)
          {
            string pair = url + "|" + text;
            if (!linkPairs.Contains(pair))
            {
              xmlWriter.WriteStartElement("sioc", "links_to", null);
              xmlWriter.WriteAttributeString("rdf", "resource", null, url);
              xmlWriter.WriteAttributeString("rdfs", "label", null, text);
              xmlWriter.WriteEndElement(); //sioc:links_to

              linkPairs.Add(pair);
            }
          }
        }
      }

      xmlWriter.WriteEndElement(); //sioc:Post
    }

    private void WriteAuthor(Stream stream, string authorName)
    {
      XmlWriter xmlWriter = GetWriter(stream);

      WriteFoafDocument(xmlWriter, "user", GetSiocAuthorUrl(authorName));

      MembershipUser user = Membership.GetUser(authorName);
            AuthorProfile ap = AuthorProfile.GetProfile(authorName);
      // FOAF:Person
      xmlWriter.WriteStartElement("foaf", "Person", null);
      xmlWriter.WriteAttributeString("rdf", "about", null, GetSiocAuthorUrl(authorName));

      xmlWriter.WriteElementString("foaf", "Name", null, authorName);
            if (ap != null && !ap.IsPrivate && ap.FirstName != String.Empty)
                xmlWriter.WriteElementString("foaf", "firstName", null,ap.FirstName);
            if (ap != null && !ap.IsPrivate && ap.LastName != String.Empty)
                xmlWriter.WriteElementString("foaf", "surname", null, ap.LastName);
            xmlWriter.WriteElementString("foaf", "mbox_sha1sum", null, (user != null) ? CalculateSHA1(user.Email, Encoding.UTF8) : "");
      xmlWriter.WriteStartElement("foaf", "homepage", null);
      xmlWriter.WriteAttributeString("rdf", "resource", null, Utils.AbsoluteWebRoot.ToString());
      xmlWriter.WriteEndElement(); //foaf:homepage 

      xmlWriter.WriteStartElement("foaf", "holdsAccount", null);
      xmlWriter.WriteAttributeString("rdf", "resource", null, GetBlogAuthorUrl(authorName));
      xmlWriter.WriteEndElement(); //foaf:holdsAccount  

      xmlWriter.WriteEndElement(); //foaf:Person

      //SIOC:User
      xmlWriter.WriteStartElement("sioc", "User", null);
      xmlWriter.WriteAttributeString("rdf", "about", null, GetBlogAuthorUrl(authorName));
      xmlWriter.WriteElementString("foaf", "accountName", null, authorName);
      xmlWriter.WriteElementString("sioc", "name", null, authorName);
      //xmlWriter.WriteElementString("dcterms", "created", null, "TODO:" + authorName);

      xmlWriter.WriteEndElement(); //sioc:User

      CloseWriter(xmlWriter);
    }

    #endregion

    #region Helper methods

    private static IPublishable ConvertToIPublishable(IPublishable item)
    {
      return item;
    }

    private Comment GetComment(Guid commentID)
    {
      List<Post> posts = Post.Posts;
      foreach (Post post in posts)
      {

        foreach (Comment comm in post.Comments)
        {
          if (comm.Id == commentID)
          {
            return comm;
          }
        }

      }
      return null;
    }

    private static string CalculateSHA1(string text, Encoding enc)
    {
      byte[] buffer = enc.GetBytes(text);
      SHA1CryptoServiceProvider cryptoTransformSHA1 =
      new SHA1CryptoServiceProvider();
      string hash = BitConverter.ToString(
        cryptoTransformSHA1.ComputeHash(buffer)).Replace("-", "");

      return hash.ToLower();
    }

    #endregion

  }
}