/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * licenses this file to you 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 the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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.apereo.portal.portlet.rendering.worker;

import javax.persistence.EntityManager;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.orm.jpa.EntityManagerFactoryUtils;
import org.springframework.orm.jpa.EntityManagerHolder;
import org.springframework.orm.jpa.JpaAccessor;
import org.springframework.orm.jpa.JpaInterceptor;
import org.springframework.transaction.support.TransactionSynchronizationManager;

/**
 * Opens and closes an {@link EntityManager} around the execution of a portlet, participates in an
 * existing {@link EntityManager} if one already exists.
 *
 * @see JpaInterceptor
 */
public class JpaPortletExecutionInterceptor extends JpaAccessor
        implements IPortletExecutionInterceptor {
    private static final String IS_NEW = JpaPortletExecutionInterceptor.class.getName() + ".IS_NEW";
    private static final String ENTITY_MANAGER_FACTORY =
            JpaPortletExecutionInterceptor.class.getName() + ".ENTITY_MANAGER_FACTORY";

    @Override
    public void preExecution(
            HttpServletRequest request,
            HttpServletResponse response,
            IPortletExecutionContext context) {
        // Determine current EntityManager: either the transactional one
        // managed by the factory or a temporary one for the given invocation.
        EntityManager em = getTransactionalEntityManager();
        boolean isNewEm = false;
        if (em == null) {
            logger.debug("Creating new EntityManager for JpaInterceptor invocation");
            em = createEntityManager();
            isNewEm = true;
            TransactionSynchronizationManager.bindResource(
                    getEntityManagerFactory(), new EntityManagerHolder(em));

            //For new EM store as attribute so it can be closed
            context.setExecutionAttribute(ENTITY_MANAGER_FACTORY, em);
        }

        context.setExecutionAttribute(IS_NEW, isNewEm);
    }

    @Override
    public void postExecution(
            HttpServletRequest request,
            HttpServletResponse response,
            IPortletExecutionContext context,
            Exception e) {
        boolean isNewEm = (Boolean) context.getExecutionAttribute(IS_NEW);
        if (isNewEm) {
            TransactionSynchronizationManager.unbindResource(getEntityManagerFactory());
            EntityManager em =
                    (EntityManager) context.getExecutionAttribute(ENTITY_MANAGER_FACTORY);
            EntityManagerFactoryUtils.closeEntityManager(em);
        }
    }

    /* (non-Javadoc)
     * @see org.apereo.portal.portlet.rendering.worker.IPortletExecutionInterceptor#preSubmit(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, org.apereo.portal.portlet.rendering.worker.IPortletExecutionContext)
     */
    @Override
    public void preSubmit(
            HttpServletRequest request,
            HttpServletResponse response,
            IPortletExecutionContext context) {
        //noop
    }
}