/**
 * Copyright (C) 2013 - present by OpenGamma Inc. and the OpenGamma group of companies
 *
 * Please see distribution for license.
 */
package com.opengamma.engine.marketdata.live;

import java.util.Set;

import org.fudgemsg.FudgeContext;
import org.fudgemsg.FudgeMsg;
import org.fudgemsg.FudgeMsgEnvelope;
import org.fudgemsg.mapping.FudgeDeserializer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.Lifecycle;

import com.opengamma.id.ExternalScheme;
import com.opengamma.transport.ByteArrayFudgeMessageReceiver;
import com.opengamma.transport.FudgeMessageReceiver;
import com.opengamma.transport.jms.JmsByteArrayMessageDispatcher;
import com.opengamma.util.jms.JmsConnector;
import com.opengamma.util.jms.JmsTopicContainer;

/**
 * Listens to JMS messages announcing that market data providers have become available and invokes
 * {@link #notificationReceived}.
 */
/* package */ abstract class AvailabilityNotificationListener implements Lifecycle {

  /** Logger */
  private static final Logger s_logger = LoggerFactory.getLogger(LiveDataAvailabilityNotificationListener.class);

  /** For receiving JMS messages. */
  private final JmsTopicContainer _jmsTopicContainer;

  /**
   * @param topic The topic for {@link MarketDataAvailabilityNotification} messages
   * @param jmsConnector For receiving JMS messages
   */
  public AvailabilityNotificationListener(String topic, JmsConnector jmsConnector) {
    ByteArrayFudgeMessageReceiver receiver = new ByteArrayFudgeMessageReceiver(new Receiver());
    JmsByteArrayMessageDispatcher dispatcher = new JmsByteArrayMessageDispatcher(receiver);
    _jmsTopicContainer = jmsConnector.getTopicContainerFactory().create(topic, dispatcher);
  }

  @Override
  public void start() {
    _jmsTopicContainer.start();
  }

  @Override
  public void stop() {
    _jmsTopicContainer.stop();
  }

  @Override
  public boolean isRunning() {
    return _jmsTopicContainer.isRunning();
  }

  /**
   * Invoked when notification is received that a market data provider is available.
   * @param schemes The schemes handled by the newly available provider
   */
  protected abstract void notificationReceived(Set<ExternalScheme> schemes);

  /**
   * Receives {@link MarketDataAvailabilityNotification}s via Fudge and calls {@link LiveDataFactory#resubscribe}
   * on each of its factories.
   */
  private final class Receiver implements FudgeMessageReceiver {

    @Override
    public void messageReceived(FudgeContext fudgeContext, FudgeMsgEnvelope msgEnvelope) {
      FudgeDeserializer deserializer = new FudgeDeserializer(fudgeContext);
      FudgeMsg msg = msgEnvelope.getMessage();
      MarketDataAvailabilityNotification notification =
          deserializer.fudgeMsgToObject(MarketDataAvailabilityNotification.class, msg);
      s_logger.info("Received notification of market data availability: {}", notification);
      Set<ExternalScheme> schemes = notification.getSchemes();
      notificationReceived(schemes);
    }
  }
}