/*
 * 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.servicemix.wsn.jms;

import java.io.StringWriter;

import javax.jms.Connection;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.Topic;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;

import org.apache.activemq.advisory.ConsumerEvent;
import org.apache.activemq.advisory.ConsumerEventSource;
import org.apache.activemq.advisory.ConsumerListener;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.servicemix.wsn.AbstractPublisher;
import org.apache.servicemix.wsn.jaxws.InvalidTopicExpressionFault;
import org.apache.servicemix.wsn.jaxws.PublisherRegistrationFailedFault;
import org.apache.servicemix.wsn.jaxws.PublisherRegistrationRejectedFault;
import org.apache.servicemix.wsn.jaxws.ResourceNotDestroyedFault;
import org.apache.servicemix.wsn.jaxws.ResourceUnknownFault;
import org.apache.servicemix.wsn.jaxws.TopicNotSupportedFault;
import org.oasis_open.docs.wsn.b_2.InvalidTopicExpressionFaultType;
import org.oasis_open.docs.wsn.b_2.NotificationMessageHolderType;
import org.oasis_open.docs.wsn.b_2.Notify;
import org.oasis_open.docs.wsn.br_2.PublisherRegistrationFailedFaultType;
import org.oasis_open.docs.wsn.br_2.RegisterPublisher;
import org.oasis_open.docs.wsn.br_2.ResourceNotDestroyedFaultType;

public abstract class JmsPublisher extends AbstractPublisher implements ConsumerListener {

    private static Log log = LogFactory.getLog(JmsPublisher.class);

    private Connection connection;

    private JmsTopicExpressionConverter topicConverter;

    private JAXBContext jaxbContext;

    private Topic jmsTopic;

    private ConsumerEventSource advisory;

    private Object subscription;

    public JmsPublisher(String name) {
        super(name);
        topicConverter = new JmsTopicExpressionConverter();
        try {
            jaxbContext = JAXBContext.newInstance(Notify.class);
        } catch (JAXBException e) {
            throw new RuntimeException("Unable to create JAXB context", e);
        }
    }

    public Connection getConnection() {
        return connection;
    }

    public void setConnection(Connection connection) {
        this.connection = connection;
    }

    @Override
    public void notify(NotificationMessageHolderType messageHolder) {
        Session session = null;
        try {
            Topic topic = topicConverter.toActiveMQTopic(messageHolder.getTopic());
            session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
            MessageProducer producer = session.createProducer(topic);
            Notify notify = new Notify();
            notify.getNotificationMessage().add(messageHolder);
            StringWriter writer = new StringWriter();
            jaxbContext.createMarshaller().marshal(notify, writer);
            Message message = session.createTextMessage(writer.toString());
            producer.send(message);
        } catch (JMSException e) {
            log.warn("Error dispatching message", e);
        } catch (JAXBException e) {
            log.warn("Error dispatching message", e);
        } catch (InvalidTopicException e) {
            log.warn("Error dispatching message", e);
        } finally {
            if (session != null) {
                try {
                    session.close();
                } catch (JMSException e) {
                    log.debug("Error closing session", e);
                }
            }
        }
    }

    @Override
    protected void validatePublisher(RegisterPublisher registerPublisherRequest) throws InvalidTopicExpressionFault,
            PublisherRegistrationFailedFault, PublisherRegistrationRejectedFault, ResourceUnknownFault,
            TopicNotSupportedFault {
        super.validatePublisher(registerPublisherRequest);
        try {
            jmsTopic = topicConverter.toActiveMQTopic(topic);
        } catch (InvalidTopicException e) {
            InvalidTopicExpressionFaultType fault = new InvalidTopicExpressionFaultType();
            throw new InvalidTopicExpressionFault(e.getMessage(), fault);
        }
    }

    @Override
    protected void start() throws PublisherRegistrationFailedFault {
        if (demand) {
            try {
                advisory = new ConsumerEventSource(connection, jmsTopic);
                advisory.setConsumerListener(this);
                advisory.start();
            } catch (Exception e) {
                PublisherRegistrationFailedFaultType fault = new PublisherRegistrationFailedFaultType();
                throw new PublisherRegistrationFailedFault("Error starting demand-based publisher", fault, e);
            }
        }
    }

    protected void destroy() throws ResourceNotDestroyedFault {
        try {
            if (advisory != null) {
                advisory.stop();
            }
        } catch (Exception e) {
            ResourceNotDestroyedFaultType fault = new ResourceNotDestroyedFaultType();
            throw new ResourceNotDestroyedFault("Error destroying publisher", fault, e);
        } finally {
            super.destroy();
        }
    }

    public void onConsumerEvent(ConsumerEvent event) {
        if (event.getConsumerCount() > 0) {
            if (subscription == null) {
                // start subscription
                subscription = startSubscription();
            }
        } else {
            if (subscription != null) {
                // destroy subscription
                Object sub = subscription;
                subscription = null;
                destroySubscription(sub);
            }
        }
    }

    protected abstract void destroySubscription(Object sub);

    protected abstract Object startSubscription();

}
