/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/**

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements. See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership. The ASF licenses this file

 * to you 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.

 */

package com.sun.org.apache.xml.internal.security.transforms.implementations;

import java.io.OutputStream;

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

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

import com.sun.org.apache.xml.internal.security.transforms.Transform;

import com.sun.org.apache.xml.internal.security.transforms.TransformSpi;

import com.sun.org.apache.xml.internal.security.transforms.TransformationException;

import com.sun.org.apache.xml.internal.security.transforms.Transforms;

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

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

import org.w3c.dom.Element;

import org.w3c.dom.Node;

/**

 * Implements the {@code http://www.w3.org/2000/09/xmldsig#enveloped-signature}

 * transform.

 *

 */

public class TransformEnvelopedSignature extends TransformSpi {

    /** Field implementedTransformURI */

    public static final String implementedTransformURI =

        Transforms.TRANSFORM_ENVELOPED_SIGNATURE;

    /**

     * Method engineGetURI

     *

     * {@inheritDoc}

     */

    protected String engineGetURI() {

        return implementedTransformURI;

    }

    /**

     * {@inheritDoc}

     */

    protected XMLSignatureInput enginePerformTransform(

        XMLSignatureInput input, OutputStream os, Transform transformObject

    ) throws TransformationException {

        /**

         * If the actual input is an octet stream, then the application MUST

         * convert the octet stream to an XPath node-set suitable for use by

         * Canonical XML with Comments. (A subsequent application of the

         * REQUIRED Canonical XML algorithm would strip away these comments.)

         *

         * ...

         *

         * The evaluation of this expression includes all of the document's nodes

         * (including comments) in the node-set representing the octet stream.

         */

        Node signatureElement = transformObject.getElement();

        signatureElement = searchSignatureElement(signatureElement);

        input.setExcludeNode(signatureElement);

        input.addNodeFilter(new EnvelopedNodeFilter(signatureElement));

        return input;

    }

    /**

     * @param signatureElement

     * @return the node that is the signature

     * @throws TransformationException

     */

    private static Node searchSignatureElement(Node signatureElement)

        throws TransformationException {

        boolean found = false;

        while (true) {

            if (signatureElement == null

                || signatureElement.getNodeType() == Node.DOCUMENT_NODE) {

                break;

            }

            Element el = (Element) signatureElement;

            if (el.getNamespaceURI().equals(Constants.SignatureSpecNS)

                && el.getLocalName().equals(Constants._TAG_SIGNATURE)) {

                found = true;

                break;

            }

            signatureElement = signatureElement.getParentNode();

        }

        if (!found) {

            throw new TransformationException(

                "transform.envelopedSignatureTransformNotInSignatureElement");

        }

        return signatureElement;

    }

    static class EnvelopedNodeFilter implements NodeFilter {

        Node exclude;

        EnvelopedNodeFilter(Node n) {

            exclude = n;

        }

        public int isNodeIncludeDO(Node n, int level) {

            if (n == exclude) {

                return -1;

            }

            return 1;

        }

        /**

         * @see com.sun.org.apache.xml.internal.security.signature.NodeFilter#isNodeInclude(org.w3c.dom.Node)

         */

        public int isNodeInclude(Node n) {

            if (n == exclude || XMLUtils.isDescendantOrSelf(exclude, n)) {

                return -1;

            }

            return 1;

            //return !XMLUtils.isDescendantOrSelf(exclude, n);

        }

    }

}