/**
    * Copyright 2010 The Kuali Foundation Licensed under the
    * Educational Community License, Version 2.0 (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.osedu.org/licenses/ECL-2.0
    *
    * 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.kuali.student.common.util.spring;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import net.sf.ehcache.CacheManager;
  import net.sf.ehcache.Element;
  import net.sf.ehcache.ObjectExistsException;
  
  import org.aopalliance.aop.Advice;
  import org.apache.commons.collections.keyvalue.MultiKey;
  import org.apache.log4j.Logger;
  import org.aspectj.lang.ProceedingJoinPoint;
  
  public class MethodArgsToObjectEhcacheAdvice implements Advice {
  	final Logger LOG = Logger.getLogger(getClass());
  
  	private CacheManager cacheManager;
  	private String cacheName;
  	private boolean enabled;
  
  	/**
  	 * 
  	 */
  	public MethodArgsToObjectEhcacheAdvice() {
  		super();
  	}
  
  	/**
  	 * @param cacheName
  	 */
  	public MethodArgsToObjectEhcacheAdvice(String cacheName) {
  		super();
  		this.cacheName = cacheName;
  	}
  
  	public Object invalidateCache(ProceedingJoinPoint pjp) throws Throwable {
  		Object result = pjp.proceed();
  		if(enabled){
  			if (cacheManager == null) {
  				cacheManager = CacheManager.getInstance();
  				try {
  					cacheManager.addCache(cacheName);
  				} catch (ObjectExistsException e) {
  	
  				}
  			}
  			LOG.info("Invalidating Cache: " + cacheName);
  			cacheManager.getCache(cacheName).removeAll();
  		}
  		return result;
  	}
  
  	public Object getFromCache(ProceedingJoinPoint pjp) throws Throwable {
  		if(!enabled){
  			return pjp.proceed();
  		}
  		
  		if (cacheManager == null) {
  			cacheManager = CacheManager.getInstance();
  			try {
  				cacheManager.addCache(cacheName);
  			} catch (ObjectExistsException e) {
  
  			}
  		}
  		MultiKey cacheKey = getCacheKey(pjp);
  
  		Element cachedResult = cacheManager.getCache(cacheName).get(cacheKey);
  		Object result = null;
  		if (cachedResult == null) {
  			result = pjp.proceed();
  			LOG.info("Storing to Cache: " + cacheName);
  			cacheManager.getCache(cacheName).put(new Element(cacheKey, result));
  		} else {
  			LOG.info("Found in Cache: " + cacheName);
  			result = cachedResult.getValue();
  		}
  
  		return result;
  	}
  	
  	private MultiKey getCacheKey(ProceedingJoinPoint pjp) {
          List<Object> keyList = new ArrayList<Object>();
         keyList.add(pjp.getSignature().getName());
         for(Object arg : pjp.getArgs()){
             if(arg==null){
                 keyList.add("_null_");
             }else{
                 keyList.add(arg.toString());
             }
         }
         return new MultiKey(keyList.toArray());
     }
 
 	/**
 	 * @return the cacheName
 	 */
 	public String getCacheName() {
 		return cacheName;
 	}
 
 	/**
 	 * @param cacheName
 	 *            the cacheName to set
 	 */
 	public void setCacheName(String cacheName) {
 		this.cacheName = cacheName;
 	}
 
 	public void setCacheManager(CacheManager cacheManager) {
 		this.cacheManager = cacheManager;
 	}
 
 	public boolean isEnabled() {
 		return enabled;
 	}
 
 	public void setEnabled(boolean enabled) {
 		this.enabled = enabled;
 	}
 
 }