/*

  * 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;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import java.util.Date;

 import java.util.Properties;

 import java.io.InputStream;

 import java.io.IOException;

 import java.net.URL;

 import net.sourceforge.pebble.util.RelativeDate;

 import net.sourceforge.pebble.domain.*;

 import net.sf.ehcache.Element;

 import net.sf.ehcache.Cache;

 import net.sf.ehcache.CacheManager;

 /**

  * A wrapper for a cache used to store blog entries and static pages.

  *

  * @author    Simon Brown

  */

 public class ContentCache {

   private static final ContentCache instance = new ContentCache();

   /** the log used by this class */

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

   private Cache cache;

   private ContentCache() {

     URL url = BlogService.class.getResource("/ehcache.xml");

     CacheManager cacheManager = new CacheManager(url);

     cache = cacheManager.getCache("contentCache");

     // size the cache (number of blogs * max elements in memory configured in the ehcache.xml file)

     // Fix: Previously the number of blogs was calculated through blogManager.getBlogs().getSize() which

     // caused the blog to load and access the Cache that is just now being initialized.

     // This lead to NPE because instance is not yet set to this instance.

     cache.getCacheConfiguration().setMaxElementsInMemory(cache.getCacheConfiguration().getMaxElementsInMemory() * BlogManager.getInstance().getNumberOfBlogs());

   }

   public static ContentCache getInstance() {

     return instance;

   }

   public synchronized void putBlogEntry(BlogEntry blogEntry) {

     Element element = new Element(getCompositeKeyForBlogEntry(blogEntry), blogEntry);

     cache.put(element);

   }

   public synchronized BlogEntry getBlogEntry(Blog blog, String blogEntryId) {

     BlogEntry blogEntry = null;

     Element element = cache.get(getCompositeKeyForBlogEntry(blog, blogEntryId));

     if (element != null) {

       blogEntry = (BlogEntry)element.getValue(); 

     }

     return blogEntry;

   }

   public synchronized void removeBlogEntry(BlogEntry blogEntry) {

     cache.remove(getCompositeKeyForBlogEntry(blogEntry));

   }

   private String getCompositeKeyForBlogEntry(BlogEntry blogEntry) {

     return getCompositeKeyForBlogEntry(blogEntry.getBlog(), blogEntry.getId());

   }

   private String getCompositeKeyForBlogEntry(Blog blog, String blogEntryId) {

     return blog.getId() + "/blogEntry/" + blogEntryId;

   }

   public synchronized void putStaticPage(StaticPage staticPage) {

     Element element = new Element(getCompositeKeyForStaticPage(staticPage), staticPage);

     cache.put(element);

   }

   public synchronized StaticPage getStaticPage(Blog blog, String staticPageId) {

     StaticPage staticPage = null;

     Element element = cache.get(getCompositeKeyForStaticPage(blog, staticPageId));

     if (element != null) {

       staticPage = (StaticPage)element.getValue();

     }

     return staticPage;

   }

   public synchronized void removeStaticPage(StaticPage staticPage) {

     cache.remove(getCompositeKeyForStaticPage(staticPage));

   }

   private String getCompositeKeyForStaticPage(StaticPage staticPage) {

     return getCompositeKeyForStaticPage(staticPage.getBlog(), staticPage.getId());

   }

   private String getCompositeKeyForStaticPage(Blog blog, String staticPageId) {

     return blog.getId() + "/staticPage/" + staticPageId;

   }

 }