/BlogEngine/DotNetSlave.BusinessLogic/Web/HttpHandlers/Sioc.cs

namespace BlogEngine.Core.Web.HttpHandlers

{

    using System;

    using System.Collections.Generic;

    using System.IO;

    using System.Linq;

    using System.Security.Cryptography;

    using System.Text;

    using System.Text.RegularExpressions;

    using System.Web;

    using System.Web.Security;

    using System.Xml;



    /// <summary>

    /// Based on John Dyer's (http://johndyer.name/) extension.

    /// </summary>

    public class Sioc : IHttpHandler

    {

        #region Constants and Fields



        /// <summary>

        ///     The xml namespaces.

        /// </summary>

        private static Dictionary<string, string> xmlNamespaces;



        #endregion



        #region Properties



        /// <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>

        ///     Gets SupportedNamespaces.

        /// </summary>

        private static Dictionary<string, string> SupportedNamespaces

        {

            get

            {

                return xmlNamespaces ??

                       (xmlNamespaces =

                        new Dictionary<string, string>

                            {

                                { "foaf", "http://xmlns.com/foaf/0.1/" },

                                { "rss", "http://purl.org/rss/1.0/" },

                                { "admin", "http://webns.net/mvcb/" },

                                { "dc", "http://purl.org/dc/elements/1.1/" },

                                { "dcterms", "http://purl.org/dc/terms/" },

                                { "rdfs", "http://www.w3.org/2000/01/rdf-schema#" },

                                { "rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#" },

                                { "content", "http://purl.org/rss/1.0/modules/content" },

                                { "sioc", "http://rdfs.org/sioc/ns#" }

                            });

            }

        }



        #endregion



        #region Implemented Interfaces



        #region IHttpHandler



        /// <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";

            var siocType = context.Request["sioc_type"] + string.Empty;

            var siocId = context.Request["sioc_id"] + string.Empty;



            switch (siocType)

            {

                default:



                    // case "site":

                    var list = Post.Posts.ConvertAll(ConvertToIPublishable);

                    var max = Math.Min(BlogSettings.Instance.PostsPerFeed, list.Count);

                    list = list.GetRange(0, max);

                    WriteSite(context.Response.OutputStream, list);

                    break;



                case "post":

                    Guid postId;

                    if (siocId.TryParse(out postId))

                    {

                        var post = Post.GetPost(postId);

                        if (post != null)

                        {

                            WritePub(context.Response.OutputStream, post);

                        }

                    }



                    break;



                case "comment":

                    Guid commentId;

                    if (siocId.TryParse(out commentId))

                    {

                        // TODO: is it possible to get a single comment?

                        var 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



        #endregion



        #region Methods



        /// <summary>

        /// Calculates the SHA1.

        /// </summary>

        /// <param name="text">

        /// The text string.

        /// </param>

        /// <param name="enc">

        /// The encoding.

        /// </param>

        /// <returns>

        /// The hash string.

        /// </returns>

        private static string CalculateSha1(string text, Encoding enc)

        {

            var buffer = enc.GetBytes(text);

            var cryptoTransformSha1 = new SHA1CryptoServiceProvider();

            var hash = BitConverter.ToString(cryptoTransformSha1.ComputeHash(buffer)).Replace("-", string.Empty);



            return hash.ToLower();

        }



        /// <summary>

        /// Closes the writer.

        /// </summary>

        /// <param name="xmlWriter">

        /// The XML writer.

        /// </param>

        private static void CloseWriter(XmlWriter xmlWriter)

        {

            xmlWriter.WriteEndElement(); // rdf:RDF

            xmlWriter.WriteEndDocument();

            xmlWriter.Close();

        }



        /// <summary>

        /// Converts to publishable interface.

        /// </summary>

        /// <param name="item">

        /// The publishable item.

        /// </param>

        /// <returns>

        /// The publishable interface.

        /// </returns>

        private static IPublishable ConvertToIPublishable(IPublishable item)

        {

            return item;

        }



        /// <summary>

        /// Gets the blog author URL.

        /// </summary>

        /// <param name="username">

        /// The username.

        /// </param>

        /// <returns>

        /// Blog author url.

        /// </returns>

        private static string GetBlogAuthorUrl(string username)

        {

            return string.Format("{0}author/{1}.aspx", Utils.AbsoluteWebRoot, HttpUtility.UrlEncode(username));

        }



        /// <summary>

        /// Gets the comment.

        /// </summary>

        /// <param name="commentId">

        /// The comment id.

        /// </param>

        /// <returns>

        /// The comment.

        /// </returns>

        private static Comment GetComment(Guid commentId)

        {

            var posts = Post.Posts;

            return posts.SelectMany(post => post.Comments).FirstOrDefault(comm => comm.Id == commentId);

        }



        /// <summary>

        /// Gets the sioc author URL.

        /// </summary>

        /// <param name="username">

        /// The username.

        /// </param>

        /// <returns>

        /// The SIOC Author Url.

        /// </returns>

        private static string GetSiocAuthorUrl(string username)

        {

            return string.Format(

                "{0}sioc.axd?sioc_type=user&sioc_id={1}", Utils.AbsoluteWebRoot, HttpUtility.UrlEncode(username));

        }



        /// <summary>

        /// Gets the sioc authors URL.

        /// </summary>

        /// <returns>

        /// The SIOC Author Url.

        /// </returns>

        private static string GetSiocAuthorsUrl()

        {

            return string.Format("{0}sioc.axd?sioc_type=site#authors", Utils.AbsoluteWebRoot);

        }



        /// <summary>

        /// Gets the sioc blog URL.

        /// </summary>

        /// <returns>

        /// The SIOC Blog Url.

        /// </returns>

        private static string GetSiocBlogUrl()

        {

            return string.Format("{0}sioc.axd?sioc_type=site#webblog", Utils.AbsoluteWebRoot);

        }



        /// <summary>

        /// Gets the sioc comment URL.

        /// </summary>

        /// <param name="id">

        /// The comment id.

        /// </param>

        /// <returns>

        /// The SIOC Comment Url.

        /// </returns>

        private static string GetSiocCommentUrl(string id)

        {

            return string.Format("{0}sioc.axd?sioc_type=comment&sioc_id={1}", Utils.AbsoluteWebRoot, id);

        }



        /// <summary>

        /// Gets the sioc post URL.

        /// </summary>

        /// <param name="id">

        /// The SIOC post id.

        /// </param>

        /// <returns>

        /// The SIOC Post Url.

        /// </returns>

        private static string GetSiocPostUrl(string id)

        {

            return string.Format("{0}sioc.axd?sioc_type=post&sioc_id={1}", Utils.AbsoluteWebRoot, id);

        }



        /*

                /// <summary>

                /// Gets the sioc site URL.

                /// </summary>

                /// <returns>

                /// The SIOC Site Url.

                /// </returns>

                private static string GetSiocSiteUrl()

                {

                    return string.Format("{0}sioc.axd?sioc_type=site", Utils.AbsoluteWebRoot);

                }

        */



        /// <summary>

        /// Gets the writer.

        /// </summary>

        /// <param name="stream">

        /// The stream.

        /// </param>

        /// <returns>

        /// The Xml Writer.

        /// </returns>

        private static XmlWriter GetWriter(Stream stream)

        {

            var settings = new XmlWriterSettings { Encoding = Encoding.UTF8, Indent = true };

            var 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 (var prefix in SupportedNamespaces.Keys)

            {

                xmlWriter.WriteAttributeString("xmlns", prefix, null, SupportedNamespaces[prefix]);

            }



            return xmlWriter;

        }



        /// <summary>

        /// Writes the author.

        /// </summary>

        /// <param name="stream">

        /// The stream.

        /// </param>

        /// <param name="authorName">

        /// Name of the author.

        /// </param>

        private static void WriteAuthor(Stream stream, string authorName)

        {

            var xmlWriter = GetWriter(stream);



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



            var user = Membership.GetUser(authorName);

            var 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.Private && ap.FirstName != String.Empty)

            {

                xmlWriter.WriteElementString("foaf", "firstName", null, ap.FirstName);

            }



            if (ap != null && !ap.Private && ap.LastName != String.Empty)

            {

                xmlWriter.WriteElementString("foaf", "surname", null, ap.LastName);

            }



            xmlWriter.WriteElementString(

                "foaf", "mbox_sha1sum", null, (user != null) ? CalculateSha1(user.Email, Encoding.UTF8) : string.Empty);

            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);

        }



        /// <summary>

        /// Writes the foaf document.

        /// </summary>

        /// <param name="xmlWriter">

        /// The XML writer.

        /// </param>

        /// <param name="siocType">

        /// Type of the sioc.

        /// </param>

        /// <param name="url">

        /// The URL string.

        /// </param>

        private static void WriteFoafDocument(XmlWriter xmlWriter, string siocType, string url)

        {

            var title = string.Format("SIOC {0} profile for \"{1}\"", siocType, BlogSettings.Instance.Name);

            const 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, string.Format("BlogEngine.NET{0}", BlogSettings.Instance.Version()));



            xmlWriter.WriteEndElement(); // foaf:Document

        }



        /// <summary>

        /// Writes the forum.

        /// </summary>

        /// <param name="xmlWriter">

        /// The xml writer.

        /// </param>

        /// <param name="list">

        /// The enumerable of publishable interface.

        /// </param>

        private static void WriteForum(XmlWriter xmlWriter, IEnumerable<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 (var 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

        }



        /// <summary>

        /// Writes an IPublishable to a stream.

        /// </summary>

        /// <param name="stream">

        /// The stream.

        /// </param>

        /// <param name="pub">

        /// The publishable interface.

        /// </param>

        private static void WritePub(Stream stream, IPublishable pub)

        {

            var 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);

        }



        /// <summary>

        /// Writes SIOC post.

        /// </summary>

        /// <param name="xmlWriter">

        /// The xml writer.

        /// </param>

        /// <param name="pub">

        /// The publishable interface.

        /// </param>

        private static 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)

            {

                var user = Membership.GetUser(pub.Author);

                xmlWriter.WriteElementString(

                    "foaf", 

                    "mbox_sha1sum", 

                    null, 

                    (user != null) ? CalculateSha1(user.Email, Encoding.UTF8) : string.Empty);

            }

            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 (var 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 (var tag in ((Post)pub).Tags)

                {

                    xmlWriter.WriteStartElement("sioc", "topic", null);

                    xmlWriter.WriteAttributeString("rdfs", "label", null, tag);

                    xmlWriter.WriteAttributeString("rdf", "resource", null, Utils.AbsoluteWebRoot + "?tag=/" + tag);

                    xmlWriter.WriteEndElement(); // sioc:topic

                }



                // COMMENTS

                foreach (var 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

                var linkMatches = Regex.Matches(pub.Content, @"<a[^(href)]?href=""([^""]+)""[^>]?>([^<]+)</a>");

                var linkPairs = new List<string>();



                foreach (Match linkMatch in linkMatches)

                {

                    var url = linkMatch.Groups[1].Value;

                    var text = linkMatch.Groups[2].Value;



                    if (url.IndexOf(Utils.AbsoluteWebRoot.ToString()) == 0)

                    {

                        continue;

                    }



                    var pair = url + "|" + text;

                    if (linkPairs.Contains(pair))

                    {

                        continue;

                    }



                    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

        }



        /// <summary>

        /// Writes sioc site.

        /// </summary>

        /// <param name="xmlWriter">

        /// The xml writer.

        /// </param>

        private static 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

        }



        /// <summary>

        /// Writes site.

        /// </summary>

        /// <param name="stream">

        /// The stream.

        /// </param>

        /// <param name="list">

        /// The enumerable of IPublishable.

        /// </param>

        private static void WriteSite(Stream stream, IEnumerable<IPublishable> list)

        {

            var xmlWriter = GetWriter(stream);



            WriteUserGroup(xmlWriter);

            WriteFoafDocument(xmlWriter, "site", Utils.AbsoluteWebRoot.ToString());

            WriteSiocSite(xmlWriter);

            WriteForum(xmlWriter, list);



            CloseWriter(xmlWriter);

        }



        /// <summary>

        /// Writes the user group.

        /// </summary>

        /// <param name="xmlWriter">

        /// The XML writer.

        /// </param>

        private static 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;

            var 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

        }



        #endregion

    }

}