/**
    * Copyright 2005-2011 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.krad.util;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  import org.apache.log4j.Logger;
  import org.kuali.rice.krad.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<Collection<PersistableBusinessObject>> 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<Collection<PersistableBusinessObject>> 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<PersistableBusinessObject> origSource = originalCollections.get(i);
                      Collection<PersistableBusinessObject> copySource = copyCollections.get(i);
                      List<PersistableBusinessObject> 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<Collection<PersistableBusinessObject>> 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<Collection<PersistableBusinessObject>> 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<PersistableBusinessObject> origSource = originalCollections.get(i);
                     Collection<PersistableBusinessObject> copySource = copyCollections.get(i);
                     List<PersistableBusinessObject> 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<PersistableBusinessObject> origSource, List<PersistableBusinessObject> unwantedItems) {
         if (unwantedItems.size() > 0) {
         	for (PersistableBusinessObject unwantedItem : unwantedItems) {
             	if ( LOG.isDebugEnabled() ) {
             		LOG.debug( "cleansing " + unwantedItem);
             	}
                 template.getPersistenceBrokerTemplate().delete(unwantedItem);
             }
         }
 
     }
 
     /**
      * 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<PersistableBusinessObject> findUnwantedElements(Collection<PersistableBusinessObject> fromList, Collection<PersistableBusinessObject> controlList) {
         List<PersistableBusinessObject> toRemove = new ArrayList<PersistableBusinessObject>();
 
         for (PersistableBusinessObject fromObject : fromList) {
         	if (!ObjectUtils.collectionContainsObjectWithIdentitcalKey(controlList, fromObject)) {
                 toRemove.add(fromObject);
             }
         }
         return toRemove;
     }
 }