/*
    * Copyright 2002-2012 the original author or authors.
    *
    * Licensed under the Apache 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.apache.org/licenses/LICENSE-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.springframework.orm.hibernate3;
  
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.hibernate.FlushMode;
  import org.hibernate.Session;
  import org.hibernate.Transaction;
  
  import org.springframework.transaction.support.ResourceHolderSupport;
  import org.springframework.util.Assert;
  
  /**
   * Session holder, wrapping a Hibernate Session and a Hibernate Transaction.
   * HibernateTransactionManager binds instances of this class to the thread,
   * for a given SessionFactory.
   *
   * <p>Note: This is an SPI class, not intended to be used by applications.
   *
   * @author Juergen Hoeller
   * @since 1.2
   * @see HibernateTransactionManager
   * @see SessionFactoryUtils
   */
  public class SessionHolder extends ResourceHolderSupport {
  
  	private static final Object DEFAULT_KEY = new Object();
  
  	/**
  	 * This Map needs to be concurrent because there might be multi-threaded
  	 * access in the case of JTA with remote transaction propagation.
  	 */
  	private final Map<Object, Session> sessionMap = new ConcurrentHashMap<Object, Session>(1);
  
  	private Transaction transaction;
  
  	private FlushMode previousFlushMode;
  
  
  	public SessionHolder(Session session) {
  		addSession(session);
  	}
  
  	public SessionHolder(Object key, Session session) {
  		addSession(key, session);
  	}
  
  
  	public Session getSession() {
  		return getSession(DEFAULT_KEY);
  	}
  
  	public Session getSession(Object key) {
  		return this.sessionMap.get(key);
  	}
  
  	public Session getValidatedSession() {
  		return getValidatedSession(DEFAULT_KEY);
  	}
  
  	public Session getValidatedSession(Object key) {
  		Session session = this.sessionMap.get(key);
  		// Check for dangling Session that's around but already closed.
  		// Effectively an assertion: that should never happen in practice.
  		// We'll seamlessly remove the Session here, to not let it cause
  		// any side effects.
  		if (session != null && !session.isOpen()) {
  			this.sessionMap.remove(key);
  			session = null;
  		}
  		return session;
  	}
  
  	public Session getAnySession() {
  		if (!this.sessionMap.isEmpty()) {
  			return this.sessionMap.values().iterator().next();
  		}
  		return null;
  	}
  
  	public void addSession(Session session) {
  		addSession(DEFAULT_KEY, session);
  	}
 
 	public void addSession(Object key, Session session) {
 		Assert.notNull(key, "Key must not be null");
 		Assert.notNull(session, "Session must not be null");
 		this.sessionMap.put(key, session);
 	}
 
 	public Session removeSession(Object key) {
 		return this.sessionMap.remove(key);
 	}
 
 	public boolean containsSession(Session session) {
 		return this.sessionMap.containsValue(session);
 	}
 
 	public boolean isEmpty() {
 		return this.sessionMap.isEmpty();
 	}
 
 	public boolean doesNotHoldNonDefaultSession() {
 		return this.sessionMap.isEmpty() ||
 				(this.sessionMap.size() == 1 && this.sessionMap.containsKey(DEFAULT_KEY));
 	}
 
 
 	public void setTransaction(Transaction transaction) {
 		this.transaction = transaction;
 	}
 
 	public Transaction getTransaction() {
 		return this.transaction;
 	}
 
 	public void setPreviousFlushMode(FlushMode previousFlushMode) {
 		this.previousFlushMode = previousFlushMode;
 	}
 
 	public FlushMode getPreviousFlushMode() {
 		return this.previousFlushMode;
 	}
 
 
 	@Override
 	public void clear() {
 		super.clear();
 		this.transaction = null;
 		this.previousFlushMode = null;
 	}
 
 }