/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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
 *
 *      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.apache.camel.component.jpa;

import java.util.Iterator;

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

import org.apache.camel.Exchange;
import org.apache.camel.Expression;
import org.apache.camel.impl.DefaultProducer;
import org.apache.camel.util.ObjectHelper;
import org.springframework.orm.jpa.JpaCallback;

/**
 * @version $Revision: 787911 $
 */
public class JpaProducer extends DefaultProducer {
    private final TransactionStrategy template;
    private final JpaEndpoint endpoint;
    private final Expression expression;

    public JpaProducer(JpaEndpoint endpoint, Expression expression) {
        super(endpoint);
        this.endpoint = endpoint;
        this.expression = expression;
        this.template = endpoint.createTransactionStrategy();
    }

    public void process(Exchange exchange) {
        exchange.getIn().setHeader(JpaConstants.JPA_TEMPLATE, endpoint.getTemplate());
        final Object values = expression.evaluate(exchange, Object.class);
        if (values != null) {
            template.execute(new JpaCallback() {
                public Object doInJpa(EntityManager entityManager) throws PersistenceException {
                    Iterator iter = ObjectHelper.createIterator(values);
                    while (iter.hasNext()) {
                        Object value = iter.next();
                        entityManager.merge(value);
                    }
                    if (endpoint.isFlushOnSend()) {
                        entityManager.flush();
                    }
                    return null;
                }
            });
        }
        exchange.getIn().removeHeader(JpaConstants.JPA_TEMPLATE);
    }
}
