/**********************************************************************************
 * $URL: https://source.sakaiproject.org/svn/db/trunk/db-impl/ext/src/java/org/sakaiproject/springframework/orm/hibernate/SakaiCacheProvider.java $
 * $Id: SakaiCacheProvider.java 34143 2007-08-20 14:16:23Z ian@caret.cam.ac.uk $
 ***********************************************************************************
 *
 * Copyright (c) 2003, 2004, 2005, 2006, 2007 The Sakai Foundation.
 *
 * Licensed under the Educational Community License, Version 1.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/ecl1.php
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 **********************************************************************************/

package org.sakaiproject.springframework.orm.hibernate;

import java.util.Properties;

import net.sf.ehcache.CacheManager;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.cache.Cache;
import org.hibernate.cache.CacheException;
import org.hibernate.cache.CacheProvider;
import org.hibernate.cache.EhCache;
import org.hibernate.cache.Timestamper;
import org.sakaiproject.component.cover.ComponentManager;

/**
 * @author ieb
 * @author azeckoski - fixed naming issues and now gets caches from the configuration as well
 */
public class SakaiCacheProvider implements CacheProvider {

   private static final Log log = LogFactory.getLog(SakaiCacheProvider.class);
   private static final String DEFAULT = "org.sakaiproject.springframework.orm.hibernate.L2Cache";
   private static final String CACHE_MANAGER = "org.sakaiproject.memory.api.MemoryService.cacheManager";

   public Cache buildCache(final String cacheName, Properties properties) throws CacheException {
      try {
         net.sf.ehcache.Cache cache = null;
         // try to get a bean which defines this cache first
         try {
            cache = (net.sf.ehcache.Cache) ComponentManager.get(cacheName);
         } catch (ClassCastException e) {
            log.warn("Illegal class type (must be net.sf.ehcache.Cache) for cache bean: " + cacheName);
         }

         // try to get cache directly from ehcache next
         if (cache == null) {
            try {
               CacheManager cacheManager = (CacheManager) ComponentManager.get(CACHE_MANAGER);
               if (cacheManager != null && cacheManager.cacheExists(cacheName)) {
                  cache = cacheManager.getCache(cacheName);
                  log.info("Loaded cache from cache manager: " + cacheName);
               }
            } catch (ClassCastException e) {
               log.warn("Illegal class type (must be net.sf.ehcache.CacheManager) for cache manager bean: " + CACHE_MANAGER);
            }
         }

         // load up the default cache bean next
         if (cache == null) {
            cache = (net.sf.ehcache.Cache) ComponentManager.get(DEFAULT);
            if (cache != null) {
               log.info("Loaded Default Cache bean ("+DEFAULT+") for " + cacheName);
            }
         }

         // finally just get a default cache from the cache manager
         if (cache == null) {
            // this will throw exceptions if it fails at this point
            CacheManager cacheManager = (CacheManager) ComponentManager.get(CACHE_MANAGER);
            cache = cacheManager.getCache(cacheName);
            log.info("Loaded default cache from cache manager: " + cacheName);
         }

         return new EhCache(cache) {
            @Override
            public void destroy() throws CacheException {
               log.debug("Closing Cache, leaving cleanup to the context: " + cacheName);
            }
         };
      } catch (Exception e) {
         log.error("Failed to build Cache: " + cacheName, e);
         throw new CacheException("Failed to build Cache: " + cacheName, e);
      }
   }

   public boolean isMinimalPutsEnabledByDefault() {
      return false;
   }

   public long nextTimestamp() {
      return Timestamper.next();
   }

   public void start(Properties arg0) throws CacheException {
      log.info("Starting Hibernate Cache Cache ++++++++++++++++++++++++++++++++ ");
   }

   public void stop() {
      log.info("Stopping Hibernate Cache Cache ------------------------------- ");
      // leave spring to perform the shutdown
   }

}