/**
 * 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 org.apache.xml.security.keys.content.x509;

import java.security.MessageDigest;
import java.security.cert.X509Certificate;

import org.apache.xml.security.algorithms.JCEMapper;
import org.apache.xml.security.exceptions.XMLSecurityException;
import org.apache.xml.security.utils.Constants;
import org.apache.xml.security.utils.Signature11ElementProxy;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * Provides content model support for the <code>dsig11:X509Digest</code> element.
 * 
 * @author Brent Putman (putmanb@georgetown.edu)
 */
public class XMLX509Digest extends Signature11ElementProxy implements XMLX509DataContent {

    /**
     * Constructor XMLX509Digest
     *
     * @param element
     * @param BaseURI
     * @throws XMLSecurityException
     */
    public XMLX509Digest(Element element, String BaseURI) throws XMLSecurityException {
        super(element, BaseURI);
    }
    
    /**
     * Constructor XMLX509Digest
     *
     * @param doc
     * @param digestBytes
     * @param algorithmURI
     */
    public XMLX509Digest(Document doc, byte[] digestBytes, String algorithmURI) {
        super(doc);
        this.addBase64Text(digestBytes);
        setLocalAttribute(Constants._ATT_ALGORITHM, algorithmURI);
    }

    /**
     * Constructor XMLX509Digest
     *
     * @param doc
     * @param x509certificate
     * @param algorithmURI
     * @throws XMLSecurityException
     */
    public XMLX509Digest(Document doc, X509Certificate x509certificate, String algorithmURI) throws XMLSecurityException {
        super(doc);
        this.addBase64Text(getDigestBytesFromCert(x509certificate, algorithmURI));
        setLocalAttribute(Constants._ATT_ALGORITHM, algorithmURI);
    }
    
    /**
     * Method getAlgorithmAttr
     *
     * @return the Algorithm attribute
     */
    public Attr getAlgorithmAttr() {
        return getElement().getAttributeNodeNS(null, Constants._ATT_ALGORITHM);
    }

    /**
     * Method getAlgorithm
     *
     * @return Algorithm string
     */
    public String getAlgorithm() {
        return this.getAlgorithmAttr().getNodeValue();
    }

    /**
     * Method getDigestBytes
     *
     * @return the digestbytes
     * @throws XMLSecurityException
     */
    public byte[] getDigestBytes() throws XMLSecurityException {
        return this.getBytesFromTextChild();
    }

    /**
     * Method getDigestBytesFromCert
     *
     * @param cert
     * @param algorithmURI
     * @return digest bytes from the given certificate
     *
     * @throws XMLSecurityException
     */
    public static byte[] getDigestBytesFromCert(X509Certificate cert, String algorithmURI) throws XMLSecurityException {
        String jcaDigestAlgorithm = JCEMapper.translateURItoJCEID(algorithmURI);
        if (jcaDigestAlgorithm == null) {
                Object exArgs[] = { algorithmURI };
                throw new XMLSecurityException("XMLX509Digest.UnknownDigestAlgorithm", exArgs);
        }
        
        try {
                        MessageDigest md = MessageDigest.getInstance(jcaDigestAlgorithm);
                        return md.digest(cert.getEncoded());
                } catch (Exception e) {
                Object exArgs[] = { jcaDigestAlgorithm };
                        throw new XMLSecurityException("XMLX509Digest.FailedDigest", exArgs);
                }
        
    }

    /** @inheritDoc */
    public String getBaseLocalName() {
        return Constants._TAG_X509DIGEST;
    }
}
