/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 2005 The Apache Software Foundation.

 *

 *  Licensed under the Apache License, Version 2.0 (the "License");

 *  you may not use this file except in compliance with the License.

 *  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 *  Unless required by applicable law or agreed to in writing, software

 *  distributed under the License is distributed on an "AS IS" BASIS,

 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 *  See the License for the specific language governing permissions and

 *  limitations under the License.

 *

 */

/*

 */

/*

 * $Id: DOMURIDereferencer.java,v 1.2 2008/07/24 15:20:32 mullan Exp $

 */

package org.jcp.xml.dsig.internal.dom;

import org.w3c.dom.Attr;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import com.sun.org.apache.xml.internal.security.Init;

import com.sun.org.apache.xml.internal.security.utils.IdResolver;

import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolver;

import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;

import javax.xml.crypto.*;

import javax.xml.crypto.dom.*;

import javax.xml.crypto.dsig.*;

/**

 * DOM-based implementation of URIDereferencer.

 *

 * @author Sean Mullan

 */

public class DOMURIDereferencer implements URIDereferencer {

    static final URIDereferencer INSTANCE = new DOMURIDereferencer();

    private DOMURIDereferencer() {

        // need to call com.sun.org.apache.xml.internal.security.Init.init()

        // before calling any apache security code

        Init.init();

    }

    public Data dereference(URIReference uriRef, XMLCryptoContext context)

        throws URIReferenceException {

        if (uriRef == null) {

            throw new NullPointerException("uriRef cannot be null");

        }

        if (context == null) {

            throw new NullPointerException("context cannot be null");

        }

        DOMURIReference domRef = (DOMURIReference) uriRef;

        Attr uriAttr = (Attr) domRef.getHere();

        String uri = uriRef.getURI();

        DOMCryptoContext dcc = (DOMCryptoContext) context;

        // Check if same-document URI and register ID

        if (uri != null && uri.length() != 0 && uri.charAt(0) == '#') {

            String id = uri.substring(1);

            if (id.startsWith("xpointer(id(")) {

                int i1 = id.indexOf('\'');

                int i2 = id.indexOf('\'', i1+1);

                id = id.substring(i1+1, i2);

            }

            // this is a bit of a hack to check for registered

            // IDRefs and manually register them with Apache's IdResolver

            // map which includes builtin schema knowledge of DSig/Enc IDs

            Node referencedElem = dcc.getElementById(id);

            if (referencedElem != null) {

                IdResolver.registerElementById((Element) referencedElem, id);

            }

        }

        try {

            String baseURI = context.getBaseURI();

            ResourceResolver apacheResolver =

                ResourceResolver.getInstance(uriAttr, baseURI);

            XMLSignatureInput in = apacheResolver.resolve(uriAttr, baseURI);

            if (in.isOctetStream()) {

                return new ApacheOctetStreamData(in);

            } else {

                return new ApacheNodeSetData(in);

            }

        } catch (Exception e) {

            throw new URIReferenceException(e);

        }

    }

}