/*
 * Copyright 2005-2010 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.wamblee.wicket.page;

import java.util.logging.Level;
import java.util.logging.Logger;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceException;
import javax.persistence.TransactionRequiredException;

import org.apache.wicket.markup.html.WebPage;

/**
 * Behavior to flush the entity manager after rendering of the page.
 * 
 * @author Erik Brakkee
 * 
 */
public abstract class FlushEntityManagerBehavior extends AbstractPageBehavior {

    private static final Logger LOGGER = Logger
        .getLogger(FlushEntityManagerBehavior.class.getName());

    /**
     * Constructs the behavior.
     * 
     * @param aEntityManager
     *            Contextual reference to an entitymanager.
     */
    public FlushEntityManagerBehavior() {
        // Empty.
    }

    @Override
    public void onAfterRender(WebPage aPage) {
        EntityManager entityManager = getEntityManager();
        try {
            if (entityManager.isOpen()) {
                entityManager.flush();
            }
        } catch (TransactionRequiredException e) {
            throw e;
        } catch (PersistenceException e) {
            throw e;
        } catch (Exception e) {
            LOGGER.log(Level.WARNING, "Could not flush entitymanager", e);
        }
    }

    /**
     * Gets the entity mmanager to flush.
     * 
     * @return Entity manager.
     */
    public abstract EntityManager getEntityManager();

}