/* 
 * Copyright (c) 2006 Stiftung Deutsches Elektronen-Synchroton, 
 * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY.
 *
 * THIS SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "../AS IS" BASIS. 
 * WITHOUT WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED 
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE AND 
 * NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR 
 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. SHOULD THE SOFTWARE PROVE DEFECTIVE 
 * IN ANY RESPECT, THE USER ASSUMES THE COST OF ANY NECESSARY SERVICING, REPAIR OR 
 * CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. 
 * NO USE OF ANY SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS DISCLAIMER.
 * DESY HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, 
 * OR MODIFICATIONS.
 * THE FULL LICENSE SPECIFYING FOR THE SOFTWARE THE REDISTRIBUTION, MODIFICATION, 
 * USAGE AND OTHER RIGHTS AND OBLIGATIONS IS INCLUDED WITH THE DISTRIBUTION OF THIS 
 * PROJECT IN THE FILE LICENSE.HTML. IF THE LICENSE IS NOT INCLUDED YOU MAY FIND A COPY 
 * AT HTTP://WWW.DESY.DE/LEGAL/LICENSE.HTM
 */
package org.csstudio.sds.internal.persistence;

import org.csstudio.platform.model.pvs.IProcessVariableAddress;
import org.csstudio.platform.model.pvs.ProcessVariableAdressFactory;
import org.jdom.Element;

/**
 * Persistence handler for the property type <code>sds.pv</code>.
 * 
 * @author Kai Meyer
 * 
 */
public final class ProcessVariablePropertyPersistenceHandler extends
		AbstractPropertyPersistenceHandler {

	/**
	 * XML tag name <code>ProcessVariable</code>.
	 */
	public static final String XML_ELEMENT_PROCESSVARIABLE = "processvariable"; //$NON-NLS-1$
	
	/**
	 * XML tag name <code>value</code>.
	 */
	public static final String XML_ATTRIBUTE_VALUE = "value";

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void writeProperty(final Element domElement,
			final Object propertyValue) {
		IProcessVariableAddress pv = (IProcessVariableAddress) propertyValue;
		Element pvElement = new Element(XML_ELEMENT_PROCESSVARIABLE);
		if (pv==null) {
			pvElement.setAttribute(XML_ATTRIBUTE_VALUE, ""); //$NON-NLS-1$
		} else {
			pvElement.setAttribute(XML_ATTRIBUTE_VALUE, pv.getFullName()); 
		}
		domElement.addContent(pvElement);
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public Object readProperty(final Element domElement) {
		Element pvElement = domElement.getChild(XML_ELEMENT_PROCESSVARIABLE);
		String value = pvElement.getAttributeValue(XML_ATTRIBUTE_VALUE);
		if (value==null || value.trim().length()==0) {
			return null;
		} else {
			IProcessVariableAddress processVariable = ProcessVariableAdressFactory.getInstance().createProcessVariableAdress(value);
			return processVariable;
		}
	}
}