/**
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of Intalio, Inc.  For written permission,
 *    please contact info@exolab.org.
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Intalio, Inc. Exolab is a registered
 *    trademark of Intalio, Inc.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * INTALIO, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 1999 (C) Intalio, Inc. All Rights Reserved.
 *
 * $Id: DTDResolver.java,v 1.4 2005/05/06 00:41:00 rjoachim Exp $
 */


package org.exolab.castor.util;


import java.net.URL;
import java.net.MalformedURLException;
import java.io.IOException;
import org.xml.sax.SAXException;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.exolab.castor.net.util.URIUtils;


/**
 * Entity resolver for various DTD/schema. Holds information and
 * performs resolving on a variety of DTD and schema, both those
 * defined by Castor and those used by Castor and cached by it.
 * <p>
 * The following DTD and XML schema are supported:
 * <ul>
 * <li>Castor mapping DTD/Schema
 * <li>Castor JDO configuration DTD/Schema
 * <li>XML Schema DTDs
 * </ul>
 * <p>
 * Thie resolver can resolve both public and system identifiers,
 * and will return an input stream into a cached resource in the
 * Castor JAR.
 * <p>
 * This resolver can be used as wrapper to another entity resolver.
 * For example, if a resolver is used for external entities in the
 * mapping file, construct a new resolver using the {@link
 * #DTDResolver(EntityResolver)} constructor.
 * <p>
 *
 * @author <a href="mailto:arkin@intalio.com">Assaf Arkin</a>
 * @version $Revision: 1.4 $ $Date: 2005/05/06 00:41:00 $
 */
public class DTDResolver
    implements EntityResolver
{


    /**
     * Holds information about a given DTD of XML Schema.
     */
    static class DTDInfo
    {

        /**
         * The public identifier. Null if unknown.
         */
        final String publicId;

        /**
         * The system identifier.  Null if unknown.
         */
        final String systemId;

        /**
         * The resource name, if a copy of the document is available.
         */
        final String resource;

        /**
         * The namespace URI. Null if unknown.
         */
        final String namespace;

        /**
         * The default namespace prefix.
         */
        final String prefix;

        DTDInfo( String publicId, String systemId, String namespace, String prefix, String resource )
        {
            this.publicId = publicId;
            this.systemId = systemId;
            this.resource = resource;
            this.namespace = namespace;
            this.prefix = prefix;
        }

    }


    /**
     * Defines information about a variety of DTDs, both those
     * defined by Castor and those defined elsewhere and cached
     * by Castor.
     */
    private final DTDInfo[] _dtdInfo = new DTDInfo[] {
        // Information for Mapping DTD and schema
        new DTDInfo( "-//EXOLAB/Castor Mapping DTD Version 1.0//EN",
                     "http://castor.exolab.org/mapping.dtd",
                     "castor.exolab.org", "castor",
                     "/org/exolab/castor/mapping/mapping.dtd" ),
        new DTDInfo( "-//EXOLAB/Castor Mapping Schema Version 1.0//EN",
                     "http://castor.exolab.org/mapping.xsd",
                     "castor.exolab.org", "castor",
                     "/org/exolab/castor/mapping/mapping.xsd" ),
        // Information for JDO configuration DTD and schema
        new DTDInfo( "-//EXOLAB/Castor JDO Configuration DTD Version 1.0//EN",
                     "http://castor.exolab.org/jdo-conf.dtd",
                     "castor.exolab.org", "castor",
                     "/org/exolab/castor/jdo/conf/jdo-conf.dtd" ),
        new DTDInfo( "-//EXOLAB/Castor JDO Configuration Schema Version 1.0//EN",
                     "http://castor.exolab.org/jdo-conf.xsd",
                     "castor.exolab.org", "castor",
                     "/org/exolab/castor/jdo/conf/jdo-conf.xsd" ),
        // Resolving for XML Schema DTDs
        new DTDInfo( "-//W3C//DTD XMLSCHEMA 19991216//EN",
                     "http://www.w3.org/TR/2000/WD-xmlschema-1-20000225/structures.dtd",
                     null, null, "/org/exolab/castor/util/resources/structures.dtd" ),
        new DTDInfo( null, "http://www.w3.org/TR/2000/WD-xmlschema-2-20000225/datatypes.dtd",
                     null, null, "/org/exolab/castor/util/resources/datatypes.dtd" ),
        new DTDInfo( null, "http://www.w3.org/TR/2000/WD-xmlschema-1-20000225/structures.xsd",
                     null, null, "/org/exolab/castor/util/resources/structures.xsd" ),

    };


    /**
     * The wrapped resolver.
     */
    private EntityResolver _resolver;


    /**
     * Base URL, if known.
     */
    private URL            _baseUrl;


    /**
     * Constructs a new DTD resolver. This resolver wraps another
     * resolver and will delegate all resolving not related to the
     * Castor mapping files to that resolver. The wrapper resolver
     * will typically be used for entities appearing in the actual
     * mapping file.
     */
    public DTDResolver( EntityResolver resolver )
    {
        _resolver = resolver;
    }


    /**
     * Constructs a new DTD resolver.
     */
    public DTDResolver()
    {
    }


    public void setBaseURL( URL baseUrl )
    {
        _baseUrl = baseUrl;
        
//        //-- make sure we have a document base and not
//        //-- a full URL to an actual file
//        if (baseUrl != null) {
//            String urlString = baseUrl.toExternalForm();
//            String docBase = URIUtils.getDocumentBase(urlString);
//            if (urlString.equals(docBase)) {
//                _baseUrl = baseUrl;
//            }
//            else if ((docBase != null) && (docBase.length() > 0)) {
//                try {
//                    _baseUrl = new URL(docBase);
//                }
//                catch(MalformedURLException mue) {
//                    // TODO: bubble up exception instead of
//                    // rethrowing
//                    String error = "Malformed URL: " + docBase;
//                    throw new IllegalStateException(error);
//                }
//            }
//            else {
//                _baseUrl = null;
//            }
//        }
    }


    public URL getBaseURL( )
    {
        return _baseUrl;
    }


    public InputSource resolveEntity( String publicId, String systemId )
        throws IOException, SAXException
    {
        int         i;
        InputSource source = null;

        // First, resolve all the DTD/schema.
        for ( i = 0 ; i < _dtdInfo.length ; ++i ) {
            if  ( publicId != null && publicId.equals( _dtdInfo[ i ].publicId ) )
            {
                source =  new InputSource( getClass().getResourceAsStream( _dtdInfo[ i ].resource ) );
                source.setPublicId(publicId);
                return source;
            }
            if  ( systemId != null && systemId.equals( _dtdInfo[ i ].systemId ) )
            {
                source =  new InputSource( getClass().getResourceAsStream( _dtdInfo[ i ].resource ) );
                source.setSystemId(systemId);
                return source;
            }
        }

        // If a resolver was specified, use it.
        if ( _resolver != null ) {
            source = _resolver.resolveEntity( publicId, systemId );
            if ( source != null )
                return source;
        }


        // Can't resolve public id, but might be able to resolve relative
        // system id, since we have a base URI.
        if ( systemId != null && _baseUrl != null ) {
            URL url;

            try {
                url = new URL( _baseUrl, systemId );
                source = new InputSource( url.openStream() );
                source.setSystemId(systemId);
                return source;
            } catch ( MalformedURLException except ) {
                try {
                    String absURL = URIUtils.resolveAsString(systemId, _baseUrl.toString());
                    url = new URL( absURL );
                    source = new InputSource( url.openStream() );
                    source.setSystemId(systemId);
                    return source;
                 } catch ( MalformedURLException ex2 ) { }
            }
            catch ( java.io.FileNotFoundException fnfe) {
                try {
                    String absURL = URIUtils.resolveAsString(systemId, _baseUrl.toString());
                    url = new URL( absURL );
                    source = new InputSource( url.openStream() );
                    source.setSystemId(systemId);
                    return source;
                 } catch ( MalformedURLException ex2 ) { }
            }
            return null;
        }

        // No resolving.
        return null;
    }


}
