/*

  * Copyright 2005-2007 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.opensource.org/licenses/ecl2.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.kuali.rice.kns.util;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.Iterator;

 import java.util.List;

 import org.apache.log4j.Logger;

 import org.kuali.rice.kns.bo.PersistableBusinessObject;

 import org.springframework.orm.ObjectRetrievalFailureException;

 /**

  * Helper object to deal with persisting collections.

  */

 public class OjbCollectionHelper {

         private static final Logger LOG = Logger.getLogger(OjbCollectionHelper.class);

     /**

      * OJB RemovalAwareLists do not survive through the response/request lifecycle. This method is a work-around to forcibly remove

      * business objects that are found in Collections stored in the database but not in memory.

      * 

      * @param orig

      * @param id

      * @param template

      */

     public void processCollections(OjbCollectionAware template, PersistableBusinessObject orig, PersistableBusinessObject copy) {

         if (copy == null) {

             return;

         }

         List originalCollections = orig.buildListOfDeletionAwareLists();

         if (originalCollections != null && !originalCollections.isEmpty()) {

             /*

              * Prior to being saved, the version in the database will not yet reflect any deleted collections. So, a freshly

              * retrieved version will contain objects that need to be removed:

              */

             try {

                 List copyCollections = copy.buildListOfDeletionAwareLists();

                 int size = originalCollections.size();

                 if (copyCollections.size() != size) {

                     throw new RuntimeException("size mismatch while attempting to process list of Collections to manage");

                 }

                 for (int i = 0; i < size; i++) {

                     Collection origSource = (Collection) originalCollections.get(i);

                     Collection copySource = (Collection) copyCollections.get(i);

                     List list = findUnwantedElements(copySource, origSource);

                     cleanse(template, origSource, list);

                 }

             }

             catch (ObjectRetrievalFailureException orfe) {

                 // object wasn't found, must be pre-save

             }

         }

     }

     /**

      * OJB RemovalAwareLists do not survive through the response/request lifecycle. This method is a work-around to forcibly remove

      * business objects that are found in Collections stored in the database but not in memory.

      * 

      * @param orig

      * @param id

      * @param template

      */

     public void processCollections2(OjbCollectionAware template, PersistableBusinessObject orig, PersistableBusinessObject copy) {

         // if copy is null this is the first time we are saving the object, don't have to worry about updating collections

         if (copy == null) {

             return;

         }

         List originalCollections = orig.buildListOfDeletionAwareLists();

         if (originalCollections != null && !originalCollections.isEmpty()) {

             /*

              * Prior to being saved, the version in the database will not yet reflect any deleted collections. So, a freshly

              * retrieved version will contain objects that need to be removed:

              */

             try {

                 List copyCollections = copy.buildListOfDeletionAwareLists();

                 int size = originalCollections.size();

                 if (copyCollections.size() != size) {

                     throw new RuntimeException("size mismatch while attempting to process list of Collections to manage");

                 }

                 for (int i = 0; i < size; i++) {

                     Collection origSource = (Collection) originalCollections.get(i);

                     Collection copySource = (Collection) copyCollections.get(i);

                     List list = findUnwantedElements(copySource, origSource);

                     cleanse(template, origSource, list);

                 }

             }

             catch (ObjectRetrievalFailureException orfe) {

                 // object wasn't found, must be pre-save

             }

         }

     }

     /**

      * This method deletes unwanted objects from the database as well as from the given input List

      * 

      * @param origSource - list containing unwanted business objects

      * @param unwantedItems - business objects to be permanently removed

      * @param template

      */

     private void cleanse(OjbCollectionAware template, Collection origSource, List unwantedItems) {

         if (unwantedItems.size() > 0) {

             Iterator iter = unwantedItems.iterator();

             while (iter.hasNext()) {

                     Object obj = iter.next();

                     if ( LOG.isDebugEnabled() ) {

                             LOG.debug( "cleansing " + obj);

                     }

                 template.getPersistenceBrokerTemplate().delete(obj);

             }

         }

     }

     /**

      * This method identifies items in the first List that are not contained in the second List. It is similar to the (optional)

      * java.util.List retainAll method.

      * 

      * @param fromList

      * @param controlList

      * @return true iff one or more items were removed

      */

     private List findUnwantedElements(Collection fromList, Collection controlList) {

         List toRemove = new ArrayList();

         Iterator iter = fromList.iterator();

         while (iter.hasNext()) {

             PersistableBusinessObject line = (PersistableBusinessObject) iter.next();

             if (!ObjectUtils.collectionContainsObjectWithIdentitcalKey(controlList, line)) {

                 toRemove.add(line);

             }

         }

         return toRemove;

     }

 }