/BlogEngine/DotNetSlave.BusinessLogic/Ping/Manager.cs

namespace BlogEngine.Core.Ping

{

    using System;

    using System.Collections.Generic;

    using System.Linq;

    using System.Text.RegularExpressions;



    /// <summary>

    /// Manages to send out trackbacks and then pingbacks if trackbacks aren't supported by the linked site.

    /// </summary>

    public static class Manager

    {

        #region Constants and Fields



        /// <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);



        // 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);



        /// <summary>

        ///     Regex used to find all hyperlinks.

        /// </summary>

        private static readonly Regex UrlsRegex = new Regex(

            @"<a.*?href=[""'](?<url>.*?)[""'].*?>(?<name>.*?)</a>", RegexOptions.IgnoreCase | RegexOptions.Compiled);



        #endregion



        #region Public Methods



        /// <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>

        /// <param name="item">

        /// The publishable item.

        /// </param>

        /// <param name="itemUrl">

        /// The item Url.

        /// </param>

        public static void Send(IPublishable item, Uri itemUrl)

        {

            foreach (var url in GetUrlsFromContent(item.Content))

            {

                var trackbackSent = false;



                if (BlogSettings.Instance.EnableTrackBackSend)

                {

                    // ignoreRemoteDownloadSettings should be set to true

                    // for backwards compatibilty with Utils.DownloadWebPage.

                    var remoteFile = new RemoteFile(url, true);

                    var pageContent = remoteFile.GetFileAsString(); // ReadFromWeb(url);

                    var trackbackUrl = GetTrackBackUrlFromPage(pageContent);



                    if (trackbackUrl != null)

                    {

                        var message = new TrackbackMessage(item, trackbackUrl, itemUrl);

                        trackbackSent = Trackback.Send(message);

                    }

                }



                if (!trackbackSent && BlogSettings.Instance.EnablePingBackSend)

                {

                    Pingback.Send(itemUrl, url);

                }

            }

        }



        #endregion



        #region Methods



        /// <summary>

        /// Examines the web page source code to retrieve the trackback link from the RDF.

        /// </summary>

        /// <param name="input">The input.</param>

        /// <returns>The trackback Uri</returns>

        private static Uri GetTrackBackUrlFromPage(string input)

        {

            var url = TrackbackLinkRegex.Match(input).Groups[1].ToString().Trim();

            Uri uri;



            return Uri.TryCreate(url, UriKind.Absolute, out uri) ? uri : null;

        }



        /// <summary>

        /// Gets all the URLs from the specified string.

        /// </summary>

        /// <param name="content">The content.</param>

        /// <returns>A list of Uri</returns>

        private static IEnumerable<Uri> GetUrlsFromContent(string content)

        {

            var urlsList = new List<Uri>();

            foreach (var url in

                UrlsRegex.Matches(content).Cast<Match>().Select(myMatch => myMatch.Groups["url"].ToString().Trim()))

            {

                Uri uri;

                if (Uri.TryCreate(url, UriKind.Absolute, out uri))

                {

                    urlsList.Add(uri);

                }

            }



            return urlsList;

        }



        #endregion

    }

}