/******************************************************************************
 * Copyright (c) 2006, 2010 VMware Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Apache License v2.0 which accompanies this distribution. 
 * The Eclipse Public License is available at 
 * http://www.eclipse.org/legal/epl-v10.html and the Apache License v2.0
 * is available at http://www.opensource.org/licenses/apache2.0.php.
 * You may elect to redistribute this code under either of these licenses. 
 * 
 * Contributors:
 *   VMware Inc.
 *****************************************************************************/

package org.eclipse.gemini.blueprint.context.support;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.xml.DefaultDocumentLoader;
import org.springframework.beans.factory.xml.DocumentLoader;

/**
 * Specialized {@link DocumentLoader} that allows blueprint configurations without a schema location to be properly
 * validated.
 * 
 * @author Costin Leau
 */
class BlueprintDocumentLoader extends DefaultDocumentLoader {

	static final String JAXP_SCHEMA_SOURCE = "http://java.sun.com/xml/jaxp/properties/schemaSource";
	static final String BLUEPRINT_SCHEMA = "http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd";

	/** logger */
	private static final Log log = LogFactory.getLog(BlueprintDocumentLoader.class);

	@Override
	protected DocumentBuilderFactory createDocumentBuilderFactory(int validationMode, boolean namespaceAware)
			throws ParserConfigurationException {
		DocumentBuilderFactory factory = super.createDocumentBuilderFactory(validationMode, namespaceAware);
		try {
			factory.setAttribute(JAXP_SCHEMA_SOURCE, BLUEPRINT_SCHEMA);
		} catch (IllegalArgumentException ex) {
			log.warn("Cannot work with attribute " + JAXP_SCHEMA_SOURCE
					+ " - configurations w/o a schema locations will likely fail to validate", ex);
		}

		return factory;
	}
}