/**
    * Copyright 2005-2013 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.kew.documentlink.dao.impl;
  
  import org.kuali.rice.kew.documentlink.DocumentLink;
  import org.kuali.rice.kew.documentlink.dao.DocumentLinkDAO;
  import org.kuali.rice.krad.data.DataObjectService;
  import org.springframework.beans.factory.annotation.Required;
  
  import javax.persistence.EntityManager;
  import javax.persistence.NoResultException;
  import javax.persistence.PersistenceContext;
  import javax.persistence.TypedQuery;
  import java.util.List;
  
  /**
   * A JPA-based implementation of the {@link DocumentLinkDAO}.
   * 
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class DocumentLinkDAOJpa implements DocumentLinkDAO {
  
  	
      @PersistenceContext(unitName = "kew")
      private EntityManager entityManager;
      private DataObjectService dataObjectService;
  
      @Override
  	public void deleteDocumentLink(DocumentLink link) {
          getDataObjectService().delete(link);
          // see if a reverse link exists or not
          DocumentLink reverseLink = getLinkedDocument(link.getDestDocId(), link.getOrgnDocId());
          if (reverseLink != null) {
              getDataObjectService().delete(reverseLink);
          }
  	}
  
      @Override
  	public List<DocumentLink> getLinkedDocumentsByDocId(String docId) {
          TypedQuery<DocumentLink> query =
                  getEntityManager().createNamedQuery("DocumentLink.GetLinkedDocumentsByDocId", DocumentLink.class);
          query.setParameter("orgnDocId",docId);
          return query.getResultList();
  	
  	}
  
      @Override
  	public List<DocumentLink> getOutgoingLinkedDocumentsByDocId(String docId) {
          TypedQuery<DocumentLink> query =
                  getEntityManager().createNamedQuery("DocumentLink.GetOutgoingLinkedDocumentsByDocId", DocumentLink.class);
          query.setParameter("destDocId",docId);
          return query.getResultList();
  	}
  
      @Override
  	public DocumentLink saveDocumentLink(DocumentLink link) {
          link = saveIfNotExists(link);
          // create the 2-way linked pair
          saveIfNotExists(createReverseLink(link));
          getDataObjectService().flush(DocumentLink.class);
          return link;
  	}
  
      protected DocumentLink saveIfNotExists(DocumentLink link) {
          // if an existing link already exists for this, we pretty much just ignore the request to save since it's
          // already there
          DocumentLink existingLink = getLinkedDocument(link.getOrgnDocId(), link.getDestDocId());
          if (existingLink == null) {
              link = getDataObjectService().save(link);
          } else {
              link = existingLink;
          }
          return link;
      }
  
      protected DocumentLink getLinkedDocument(String orgnDocId, String destDocId) {
          TypedQuery<DocumentLink> query =
                  getEntityManager().createNamedQuery("DocumentLink.GetLinkedDocument", DocumentLink.class);
          query.setParameter("orgnDocId", orgnDocId);
          query.setParameter("destDocId", destDocId);
          try {
              return query.getSingleResult();
          } catch (NoResultException e) {
              return null;
          }
      }
 
 
     private DocumentLink createReverseLink(DocumentLink link) {
         DocumentLink reverseLink = new DocumentLink();
         reverseLink.setOrgnDocId(link.getDestDocId());
         reverseLink.setDestDocId(link.getOrgnDocId());
         return reverseLink;
     }
 
 	@Override
 	public DocumentLink getDocumentLink(String documentLinkId) {
 		return getDataObjectService().find(DocumentLink.class,documentLinkId);
 	}
 
 
     public DataObjectService getDataObjectService() {
         return dataObjectService;
     }
 
     @Required
     public void setDataObjectService(DataObjectService dataObjectService) {
         this.dataObjectService = dataObjectService;
     }
 
 
     public EntityManager getEntityManager() {
         return this.entityManager;
     }
 
     public void setEntityManager(EntityManager entityManager) {
         this.entityManager = entityManager;
     }
 	
 }