/**
    * 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.ui.server.applicationstate.dao.impl;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  import javax.persistence.EntityManager;
  import javax.persistence.PersistenceContext;
  import javax.persistence.Query;
  
  import org.kuali.student.common.dao.impl.AbstractSearchableCrudDaoImpl;
  import org.kuali.student.common.exceptions.AlreadyExistsException;
  import org.kuali.student.common.exceptions.DoesNotExistException;
  import org.kuali.student.common.ui.server.applicationstate.dao.ApplicationStateDao;
  import org.kuali.student.common.ui.server.applicationstate.entity.ApplicationState;
  
  /**
   * This data access class stores the GUI (page, section, widget, etc.) 
   * application states as key value pairs in a database.
   */
  public class ApplicationStateDaoImpl extends AbstractSearchableCrudDaoImpl implements ApplicationStateDao {
  
  	private final static String DEFAULT_USER_ID = "APPLICATION";
  	
  	@PersistenceContext(unitName = "ApplicationState")
  	@Override
  	public void setEm(EntityManager em) {
  		super.setEm(em);
  	}
  
  	/**
  	 * Gets an application states by <code>applicationId</code>, 
  	 * <code>referenceKey</code>, <code>referenceType</code> and 
  	 * <code>userId</code>.
  	 * 
  	 * @param applicationId Application id
  	 * @param referenceKey Reference key
  	 * @param referenceType Reference type
  	 * @param userId User id
  	 * @return An application state
  	 * @throws DoesNotExistException Thrown if application state does not exist
  	 */
  	public ApplicationState getApplicationState(String applicationId, String referenceKey, String referenceType, String userId) throws DoesNotExistException {
  		Query query = em.createNamedQuery("ApplicationState.getApplicationStateByAppRefUserId");
  		query.setParameter("applicationId", applicationId);
  		query.setParameter("referenceKey", referenceKey);
  		query.setParameter("referenceType", referenceType);
  		query.setParameter("userId", userId);
  
  		try {
  			ApplicationState appState = (ApplicationState) query.getSingleResult();
  			return appState;
  		} catch(javax.persistence.NoResultException e) {
  			throw new DoesNotExistException("Application state does not exist");
  		}
  	}
  
  	/**
  	 * Gets an application states by <code>applicationId</code>, 
  	 * <code>referenceKey</code> and <code>referenceType</code>.
  	 * 
  	 * @param applicationId Application id
  	 * @param referenceKey Reference key
  	 * @param referenceType Reference type
  	 * @return A list of application states
  	 * @throws DoesNotExistException Thrown if application state does not exist
  	 */
  	public ApplicationState getApplicationState(String applicationId, String referenceKey, String referenceType) throws DoesNotExistException {
  		return getApplicationState(applicationId, referenceKey, referenceType, DEFAULT_USER_ID);
  	}
  
  	/**
  	 * Creates and returns an application state.
  	 * 
  	 * @param appState Application state
  	 * @return A new application state
  	 * @throws AlreadyExistsException Thrown if application state already exists
  	 */
  	public ApplicationState createApplicationState(ApplicationState appState) throws AlreadyExistsException {
  		if(appState.getUserId() == null) {
  			appState.setUserId(DEFAULT_USER_ID);
  		}
  
  		try {
 			getApplicationState(appState.getApplicationId(), appState.getReferenceKey(), appState.getReferenceType(), appState.getUserId());
 		} catch(DoesNotExistException e) {
 			return super.create(appState);
 		}
 		throw new AlreadyExistsException("Application state already exists");
 	}
 
 	/**
 	 * Creates a collection of application states and returns their ids.
 	 * 
 	 * @param appStateList collection of application states
 	 * @return A list of newly created application state ids
 	 * @throws AlreadyExistsException Thrown if application state already exists
 	 */
 	public List<String> createApplicationState(Collection<ApplicationState> appStates) throws AlreadyExistsException {
 		List<String> newAppStateList = new ArrayList<String>();
 		for(ApplicationState appState : appStates) {
 			ApplicationState newAppState = createApplicationState(appState);
 			newAppStateList.add(newAppState.getId());
 		}
 		return newAppStateList;
 	}
 
 }