/* 
 * 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 java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.csstudio.sds.ErrorMessagesTracker;
import org.csstudio.sds.model.DisplayModel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Reader for the XML representation of display models.
 * 
 * @author Alexander Will & Sven Wende
 * @version $Revision: 1.1 $
 * 
 */
public final class DisplayModelReader extends ErrorMessagesTracker {
    private static final Logger LOG = LoggerFactory.getLogger(DisplayModelReader.class);

	/**
	 * This class is not intended to be instantiated by clients.
	 */
	public DisplayModelReader() {
	}

	/**
	 * Parse the given <code>InputStream</code> into the given
	 * <code>DisplayModel</code>.
	 * 
	 * @param inputStream
	 *            An <code>InputStream</code> that contains the XML
	 *            representation of a <code>DisplayModel</code>.
	 * @param displayModel
	 *            The <code>DisplayModel</code> that the read model data will
	 *            be appended to.
	 * @param display
	 *            SWT <code>Display</code> that will be used for asynchroneous
	 *            loading.
	 */
	public void readModelFromXml(final InputStream inputStream,
			final DisplayModel displayModel,
			final IDisplayModelLoadListener loadListener) {
		resetErrorMessages();

		try {
			SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
			
			SaxDisplayModelHandler saxDisplayModelHandler = new SaxDisplayModelHandler(
					displayModel, loadListener);
			parser.parse(inputStream, saxDisplayModelHandler);

		} catch (Exception e) {
			trackErrorMessage("Exception: " + e.getMessage()); //$NON-NLS-1$
			LOG.debug(e.toString());
		} finally {
			// Important - close the stream
			closeStream(inputStream);
		}
	}

	private void closeStream(InputStream stream) {
		try {
			stream.close();
		} catch (IOException e) {
			LOG.debug(e.toString());
		}
	}
}