/**
    * Copyright 2005-2012 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.kim.impl.group;
  
  import org.apache.commons.collections.ListUtils;
  import org.apache.commons.lang.StringUtils;
  import org.kuali.rice.kew.api.KewApiServiceLocator;
  import org.kuali.rice.kew.api.KewApiConstants;
  import org.kuali.rice.kim.api.group.GroupService;
  import org.kuali.rice.kim.api.services.KimApiServiceLocator;
  import org.kuali.rice.krad.service.BusinessObjectService;
  import org.kuali.rice.krad.service.KRADServiceLocator;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Concrete Implementation of {@link GroupInternalService}
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   *
   */
  public class GroupInternalServiceImpl implements GroupInternalService {
      protected BusinessObjectService getBusinessObjectService() {
      	return KRADServiceLocator.getBusinessObjectService();
      }
  
  
      public GroupService getGroupService(){
      	return KimApiServiceLocator.getGroupService();
      }
  
      @Override
      public GroupBo saveWorkgroup(GroupBo group) {
      	GroupService ims = getGroupService();
          List<String> oldIds = Collections.emptyList();
      	if (StringUtils.isNotEmpty(group.getId())) {
              oldIds = ims.getMemberPrincipalIds(group.getId());
          }
          group = (GroupBo)getBusinessObjectService().save( group );
          List<String> newIds = ims.getMemberPrincipalIds(group.getId());
          updateForWorkgroupChange(group.getId(), oldIds, newIds);
          return group;
      }
  
      @Override
      public void updateForWorkgroupChange(String groupId,
      		List<String> oldPrincipalIds, List<String> newPrincipalIds) {
          MembersDiff membersDiff = getMembersDiff(oldPrincipalIds, newPrincipalIds);
          for (String removedPrincipalId : membersDiff.getRemovedPrincipalIds()) {
          	updateForUserRemovedFromGroup(removedPrincipalId, groupId);
          }
          for (String addedPrincipalId : membersDiff.getAddedPrincipalIds()) {
          	updateForUserAddedToGroup(addedPrincipalId, groupId);
          }
      }
  
      @Override
      public void updateForUserAddedToGroup(String principalId, String groupId) {
          // first verify that the user is still a member of the workgroup
      	if(getGroupService().isMemberOfGroup(principalId, groupId))
      	{
      	    KewApiServiceLocator.getGroupMembershipChangeQueue()
      	        .notifyMembershipChange(KewApiConstants.GroupMembershipChangeOperations.ADDED, groupId, principalId);
      	}
      }
  
      @Override
      public void updateForUserRemovedFromGroup(String principalId, String groupId) {
          // first verify that the user is no longer a member of the workgroup
      	if(!getGroupService().isMemberOfGroup(principalId, groupId))
      	{
              KewApiServiceLocator.getGroupMembershipChangeQueue()
                  .notifyMembershipChange(KewApiConstants.GroupMembershipChangeOperations.REMOVED, groupId, principalId);
      	}
  
      }
  
      private MembersDiff getMembersDiff(List<String> oldMemberPrincipalIds, List<String> newMemberPrincipalIds) {
  
      	// ListUtils does not check the null case.  Which can happen when adding a new group
      	// so, if they're null make them empty lists.
      	if(oldMemberPrincipalIds == null) oldMemberPrincipalIds = new ArrayList<String>();
     	if(newMemberPrincipalIds == null) newMemberPrincipalIds = new ArrayList<String>();
 
         Set<String> addedPrincipalIds = new HashSet<String>(ListUtils.subtract(newMemberPrincipalIds, oldMemberPrincipalIds));
         Set<String> removedPrincipalIds = new HashSet<String>(ListUtils.subtract(oldMemberPrincipalIds, newMemberPrincipalIds));
         return new MembersDiff(addedPrincipalIds, removedPrincipalIds);
     }
 
     private class MembersDiff {
         private final Set<String> addedPrincipalIds;
 
         private final Set<String> removedPrincipalIds;
 
         public MembersDiff(Set<String> addedPrincipalIds, Set<String>removedPrincipalIds) {
             this.addedPrincipalIds = addedPrincipalIds;
             this.removedPrincipalIds = removedPrincipalIds;
         }
 
         public Set<String> getAddedPrincipalIds() {
             return addedPrincipalIds;
         }
 
         public Set<String> getRemovedPrincipalIds() {
             return removedPrincipalIds;
         }
     }
 
 }