package org.geoserver.cluster.hazelcast;

import java.util.logging.Logger;

import org.geoserver.platform.resource.ResourceNotification;
import org.geoserver.platform.resource.ResourceNotificationDispatcher;
import org.geoserver.platform.resource.SimpleResourceNotificationDispatcher;
import org.geotools.util.logging.Logging;
import com.hazelcast.core.ITopic;
import com.hazelcast.core.Message;
import com.hazelcast.core.MessageListener;

/**
 * A {@link ResourceNotificationDispatcher} implementation .
 * <p>
 * A Spring bean of this type shall be configured in the project's {@code applicationContext.xml}
 * spring configuration file in order for {@link ResourceStore} to find it.
 * 
 */
public class HzResourceNotificationDispatcher extends SimpleResourceNotificationDispatcher implements MessageListener<ResourceNotification> {
    
    static final String TOPIC_NAME = "resourceWatcher";
    
    private static final Logger LOGGER = Logging.getLogger(HzResourceNotificationDispatcher.class);
        
    private HzCluster cluster; 
    
    public HzResourceNotificationDispatcher() {
        //lazy loaded cluster
    }
    
    public HzResourceNotificationDispatcher(HzCluster cluster) {
        this.cluster = cluster;
        topic().addMessageListener(this);
    }
     
    private ITopic<ResourceNotification> topic() {   
        if (cluster == null) {
            cluster = HzCluster.getInstanceIfAvailable().orNull();
            if (cluster != null) {
                topic().addMessageListener(this);
            }
        }
        return cluster == null ? null : cluster.getHz().getTopic(TOPIC_NAME);
    }

    @Override
    public void changed(ResourceNotification event) {
        ITopic<ResourceNotification> topic = topic();
        if (topic != null) {
            topic.publish(event);
        } else {
            LOGGER.warning("Failed to publish resource notification, cluster not initialized (yet).");
            super.changed(event); 
        }
    }

    @Override
    public void onMessage(Message<ResourceNotification> msg) {
        LOGGER.info( "Received ResourceNotification from HazelCast: " + 
               msg.getMessageObject());
        
        super.changed(msg.getMessageObject());        
    }
    
}