/*

  * Copyright (c) 2003-2011, Simon Brown

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are met:

  *

  *   - Redistributions of source code must retain the above copyright

  *     notice, this list of conditions and the following disclaimer.

  *

  *   - Redistributions in binary form must reproduce the above copyright

  *     notice, this list of conditions and the following disclaimer in

  *     the documentation and/or other materials provided with the

  *     distribution.

  *

  *   - Neither the name of Pebble nor the names of its contributors may

  *     be used to endorse or promote products derived from this software

  *     without specific prior written permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

  * POSSIBILITY OF SUCH DAMAGE.

  */

 package net.sourceforge.pebble.decorator;

 import java.util.HashSet;

 import java.util.List;

 import java.util.Set;

 import net.sourceforge.pebble.PluginProperties;

 import net.sourceforge.pebble.api.decorator.ContentDecoratorContext;

 import net.sourceforge.pebble.domain.Blog;

 import net.sourceforge.pebble.domain.BlogEntry;

 import net.sourceforge.pebble.domain.Tag;

 import net.sourceforge.pebble.util.I18n;

 import net.sourceforge.pebble.util.StringUtils;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 /**

  * Adds related posts to the current post. The posts are selected by matching

  * tags of the current post to the tags of other posts in the blog. One related

  * post per tag.

  * 

  * Each blog entry can have up to six related posts or none.

  * 

  * @author Alexander Zagniotov

  */

 public class RelatedPostsDecorator extends ContentDecoratorSupport {

   private static final Log log = LogFactory.getLog(RelatedPostsDecorator.class);

   /** the name of the max number of posts property */

   public static final String MAX_POSTS = "RelatedPostsDecorator.maxPosts";

   /**

    * Decorates the specified blog entry.

    * 

    * @param context

    *          the context in which the decoration is running

    * @param blogEntry

    *          the blog entry to be decorated

    */

   public void decorate(ContentDecoratorContext context, BlogEntry blogEntry) {

     PluginProperties props = blogEntry.getBlog().getPluginProperties();

     int maxPosts = StringUtils.MAX_NUM_OF_POSTS;

     if (props.hasProperty(RelatedPostsDecorator.MAX_POSTS)) {

       try {

         maxPosts = Integer.parseInt(props.getProperty(MAX_POSTS));

       }

       catch (NumberFormatException nfe) {

         log.error(nfe.getMessage());

         // do nothing, the value has already been defaulted

       }

     }

     Blog blog = blogEntry.getBlog();

     String body = blogEntry.getBody();

     if (body != null && body.trim().length() > 0) {

       StringBuffer buf = new StringBuffer();

       buf.append(body);

       buf.append("<p><b>" + I18n.getMessage(blog, "common.relatedPosts") + "</b><br />");

       // tags of the current entry

       List<Tag> currentEntryTags = blogEntry.getAllTags();

       // all blog entries of the current blog

       List<BlogEntry> allBlogEntries = (List<BlogEntry>) blog.getBlogEntries();

       // temporary holder for accumulated unique related posts.

       // using hash set assures that we wont have same related post twice for

       // different tags.

       Set<BlogEntry> relatedEntries = new HashSet<BlogEntry>();

       for (BlogEntry entry : allBlogEntries) {

         // don't add current entry as a related post of it self, skip it

         if (entry.getTitle().equals(blogEntry.getTitle()))

           continue;

         // loop through each of the current entry tags, and try to find related

         // post by matching current tag to the posts tags

         for (Tag currentTag : currentEntryTags) {

           if (entry.hasTag(currentTag.getName())) {

             // if we successfully selected related post - create hyperlink for

             // it

             // TODO: Missing escaping -- XSS vulnerabilities here :(

             if (relatedEntries.add(entry))

               buf.append("<a href=\"" + entry.getPermalink() + "\" rel=\"bookmark\" title=\"" + entry.getTitle()

                   + "\">" + entry.getTitle() + "</a><br />");

           }

         }

         // do not allow more than default amount of posts or

         // amount set through the RelatedPostsDecorator.maxPosts property

         if (relatedEntries.size() == maxPosts) {

           break;

         }

       }

       if (relatedEntries.size() == 0)

         buf.append("<i>" + I18n.getMessage(blog, "common.noRelatedPosts") + "</i>");

       buf.append("</p><br />");

       blogEntry.setBody(buf.toString());

     }

   }

 }