/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
 * (c) 2001 - 2013 OpenPlans
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */
package org.geoserver.cluster.impl.handlers.catalog;

import com.thoughtworks.xstream.XStream;
import org.geoserver.catalog.Catalog;
import org.geoserver.catalog.CatalogInfo;
import org.geoserver.catalog.event.CatalogEvent;
import org.geoserver.catalog.event.CatalogModifyEvent;
import org.geoserver.catalog.event.impl.CatalogModifyEventImpl;
import org.geoserver.catalog.impl.CatalogImpl;
import org.geoserver.cluster.JMSEventHandler;
import org.geoserver.cluster.JMSEventHandlerSPI;

import javax.jms.JMSException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;

/**
 * Abstract class which use Xstream as message serializer/de-serializer.
 * We extend this class to implementing synchronize method.
 * 
 * @author Carlo Cancellieri - carlo.cancellieri@geo-solutions.it
 *
 */
public abstract class JMSCatalogEventHandler extends
		JMSEventHandler<String, CatalogEvent> {
	public JMSCatalogEventHandler(final XStream xstream,
			Class<JMSEventHandlerSPI<String, CatalogEvent>> clazz) {
		super(xstream,clazz);
		// omit not serializable fields
		omitFields();
	}

	/**
	 * omit not serializable fields
	 * @see {@link XStream}
	 */
	private void omitFields() {
		// omit not serializable fields
		xstream.omitField(CatalogImpl.class, "listeners");
		xstream.omitField(CatalogImpl.class, "facade");
		xstream.omitField(CatalogImpl.class, "resourcePool");
		xstream.omitField(CatalogImpl.class, "resourceLoader");
	}

	@Override
	public String serialize(CatalogEvent  event) throws Exception {
		return xstream.toXML(removeCatalogProperties(event));
	}

	@Override
	public CatalogEvent deserialize(String s) throws Exception {
		
		final Object source= xstream.fromXML(s);
		if (source instanceof CatalogEvent) {
			final CatalogEvent ev = (CatalogEvent) source;
			if (LOGGER.isLoggable(Level.FINE)) {
				final CatalogInfo info = ev.getSource();
				LOGGER.fine("Incoming message event of type CatalogEvent: "
						+ info.getId());
			}
			return ev;
		} else {
			throw new JMSException("Unable to deserialize the following object:\n"+s);
		}

	}

	/**
	 * Make sure that properties of type catalog are not serialized
	 * for catalog modified events.
	 */
	private CatalogEvent removeCatalogProperties(CatalogEvent event) {
		if (!(event instanceof CatalogModifyEvent)) {
			// not a modify event so nothing to do
			return event;
		}
		CatalogModifyEvent modifyEvent = (CatalogModifyEvent) event;
		// index all the properties that are not of catalog type
		List<Integer> indexes = new ArrayList<>();
		int totalProperties = modifyEvent.getPropertyNames().size();
		for (int i = 0; i < totalProperties; i++) {
			// we only need to check the new values
			Object value = modifyEvent.getNewValues().get(i);
			if (!(value instanceof Catalog)) {
				// not a property of type catalog
				indexes.add(i);
			}
		}
		// let's see if we need to do anything
		if (indexes.size() == totalProperties) {
			// no properties of type catalog, we can use the original event
			return event;
		}
		// well we need to create a new modify event and ignore the properties of catalog type
		List<String> properties = new ArrayList<>();
		List<Object> oldValues = new ArrayList<>();
		List<Object> newValues = new ArrayList<>();
		for (int index : indexes) {
			// add all the properties that are not of catalog type
			properties.add(modifyEvent.getPropertyNames().get(index));
			oldValues.add(modifyEvent.getOldValues().get(index));
			newValues.add(modifyEvent.getNewValues().get(index));
		}
		// crete the new event
		CatalogModifyEventImpl newEvent = new CatalogModifyEventImpl();
		newEvent.setPropertyNames(properties);
		newEvent.setOldValues(oldValues);
		newEvent.setNewValues(newValues);
		newEvent.setSource(modifyEvent.getSource());
		return newEvent;
	}
}