/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2011, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.metamodel.source.annotations.xml.mocker;

import java.io.InputStream;
import java.net.URL;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

import org.jboss.logging.Logger;
import org.xml.sax.SAXException;

import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.internal.jaxb.JaxbRoot;
import org.hibernate.internal.jaxb.Origin;
import org.hibernate.service.classloading.spi.ClassLoaderService;

/**
 * @author Hardy Ferentschik
 */
public class XmlHelper {
    private static final CoreMessageLogger LOG = Logger.getMessageLogger( CoreMessageLogger.class, XmlHelper.class.getName() );

    private XmlHelper() {
    }

    public static <T> JaxbRoot<T> unmarshallXml(String fileName, String schemaName, Class<T> clazz, ClassLoaderService classLoaderService)
            throws JAXBException {
        Schema schema = getMappingSchema( schemaName, classLoaderService );
        InputStream in = classLoaderService.locateResourceStream( fileName );
        JAXBContext jc = JAXBContext.newInstance( clazz );
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        unmarshaller.setSchema( schema );
        StreamSource stream = new StreamSource( in );
        JAXBElement<T> elem = unmarshaller.unmarshal( stream, clazz );
        Origin origin = new Origin( null, fileName );
        return new JaxbRoot<T>( elem.getValue(), origin );
    }

    private static Schema getMappingSchema(String schemaVersion, ClassLoaderService classLoaderService) {
        URL schemaUrl = classLoaderService.locateResource( schemaVersion );
        SchemaFactory sf = SchemaFactory.newInstance( javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI );
        Schema schema = null;
        try {
            schema = sf.newSchema( schemaUrl );
        }
        catch ( SAXException e ) {
            LOG.debugf( "Unable to create schema for %s: %s", schemaVersion, e.getMessage() );
        }
        return schema;
    }
}