/BlogEngine/BlogEngine.NET/App_Code/Extensions/BreakPost.cs

#region using



using System;

using System.Linq;

using System.Text.RegularExpressions;

using System.Web;



using BlogEngine.Core;

using BlogEngine.Core.Web.Controls;

using BlogEngine.Core.Web.Extensions;

using Resources;



#endregion



/// <summary>

/// Breaks a post where [more] is found in the body and adds a link to full post.

/// </summary>

[Extension(

    "Breaks a post where [more] is found in the body and adds a link to full post",

    "1.4",

    "BlogEngine.NET",

    1010)]

public class BreakPost

{

    #region Constants and Fields



    /// <summary>

    /// The closed tag regex.

    /// </summary>

    private static readonly Regex ClosedTagRegex = new Regex(

        @"</([A-Z][A-Z0-9]*?)\b[^>]*>", RegexOptions.IgnoreCase | RegexOptions.Compiled);



    /// <summary>

    /// The opening tag regex.

    /// </summary>

    private static readonly Regex OpeningTagRegex = new Regex(

        @"<([A-Z][A-Z0-9]*?)\b[^>/]*>", RegexOptions.IgnoreCase | RegexOptions.Compiled);



    #endregion



    #region Constructors and Destructors



    /// <summary>

    /// Initializes static members of the <see cref="BreakPost"/> class. 

    ///     Hooks up an event handler to the Post.Serving event.

    /// </summary>

    static BreakPost()

    {

        Post.Serving += PostServing;

    }



    #endregion



    #region Methods



    /// <summary>

    /// Replaces the [more] string with a hyperlink to the full post.

    /// </summary>

    /// <param name="sender">

    /// The sender.

    /// </param>

    /// <param name="e">

    /// The event arguments.

    /// </param>

    private static void AddMoreLink(object sender, ServingEventArgs e)

    {

        var post = (Post)sender;

        var index = e.Body.IndexOf("[more]");

        var link = string.Format("<a class=\"more\" href=\"{0}#continue\">{1}...</a>", post.RelativeLink, labels.more);

        var newBody = e.Body.Substring(0, index);



        // Need to close any open HTML tags in NewBody where the matching close tags have been truncated.

        var closingTagsToAppend = string.Empty;

        var openingTagsCollection = OpeningTagRegex.Matches(newBody);



        if (openingTagsCollection.Count > 0)

        {

            // Copy the opening tags in MatchCollection to a generic list.

            var openingTags = openingTagsCollection.Cast<Match>().Where(openTag => openTag.Groups.Count == 2).Select(

                openTag => openTag.Groups[1].Value).ToList();



            var closingTagsCollection = ClosedTagRegex.Matches(newBody);



            // Iterate through closed tags and remove the first matching open tag from the openingTags list.

            foreach (var indexToRemove in from Match closedTag in closingTagsCollection

                                          where closedTag.Groups.Count == 2

                                          select openingTags.FindIndex(

                                              openTag =>

                                              openTag.Equals(

                                                  closedTag.Groups[1].Value, StringComparison.InvariantCultureIgnoreCase))

                                          into indexToRemove

                                          where indexToRemove != -1

                                          select indexToRemove)

            {

                openingTags.RemoveAt(indexToRemove);

            }



            // A closing tag needs to be created for any remaining tags in the openingTags list.

            if (openingTags.Count > 0)

            {

                // Reverse the order of the tags so tags opened later are closed first.

                openingTags.Reverse();

                closingTagsToAppend = string.Format("</{0}>", string.Join("></", openingTags.ToArray()));

            }

        }



        e.Body = newBody + link + closingTagsToAppend;

    }



    /// <summary>

    /// Handles the Serving event of the Post control.

    /// Handles the Post.Serving event to take care of the [more] keyword.

    /// </summary>

    /// <param name="sender">The source of the event.</param>

    /// <param name="e">The <see cref="BlogEngine.Core.ServingEventArgs"/> instance containing the event data.</param>

    private static void PostServing(object sender, ServingEventArgs e)

    {

        if (!ExtensionManager.ExtensionEnabled("BreakPost"))

            return;



        if (!e.Body.Contains("[more]"))

            return;



        switch (e.Location)

        {

            case ServingLocation.PostList:

                AddMoreLink(sender, e);

                break;

            case ServingLocation.SinglePost:

                PrepareFullPost(e);

                break;

            case ServingLocation.Feed:

                e.Body = e.Body.Replace("[more]", string.Empty);

                break;

        }

    }



    /// <summary>

    /// Replaces the [more] string on the full post page.

    /// </summary>

    /// <param name="e">

    /// The event arguments.

    /// </param>

    private static void PrepareFullPost(ServingEventArgs e)

    {

        var request = HttpContext.Current.Request;

        e.Body = request.UrlReferrer == null || request.UrlReferrer.Host != request.Url.Host

                     ? e.Body.Replace("[more]", string.Empty)

                     : e.Body.Replace("[more]", "<span id=\"continue\"></span>");

    }



    #endregion

}