/*
 * 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.
 *
 */
/*
 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
 */
/*
 * $Id: DOMKeyValue.java 647272 2008-04-11 19:22:21Z mullan $
 */
package org.jcp.xml.dsig.internal.dom;

import javax.xml.crypto.*;
import javax.xml.crypto.dom.DOMCryptoContext;
import javax.xml.crypto.dsig.*;
import javax.xml.crypto.dsig.keyinfo.KeyValue;

import java.security.KeyException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.interfaces.DSAParams;
import java.security.interfaces.DSAPublicKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.DSAPublicKeySpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.security.spec.RSAPublicKeySpec;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * DOM-based implementation of KeyValue.
 *
 * @author Sean Mullan
 */
public final class DOMKeyValue extends DOMStructure implements KeyValue {

    private KeyFactory rsakf, dsakf;
    private PublicKey publicKey;
    private javax.xml.crypto.dom.DOMStructure externalPublicKey;

    // DSAKeyValue CryptoBinaries
    private DOMCryptoBinary p, q, g, y, j, seed, pgen;

    // RSAKeyValue CryptoBinaries
    private DOMCryptoBinary modulus, exponent;

    public DOMKeyValue(PublicKey key)  throws KeyException {
	if (key == null) {
	    throw new NullPointerException("key cannot be null");
	}
	this.publicKey = key;
	if (key instanceof DSAPublicKey) {
	    DSAPublicKey dkey = (DSAPublicKey) key;
	    DSAParams params = dkey.getParams();
	    p = new DOMCryptoBinary(params.getP());
	    q = new DOMCryptoBinary(params.getQ());
	    g = new DOMCryptoBinary(params.getG());
	    y = new DOMCryptoBinary(dkey.getY());
	} else if (key instanceof RSAPublicKey) {
	    RSAPublicKey rkey = (RSAPublicKey) key;
	    exponent = new DOMCryptoBinary(rkey.getPublicExponent());
	    modulus = new DOMCryptoBinary(rkey.getModulus());
	} else {
	    throw new KeyException("unsupported key algorithm: " +
		key.getAlgorithm());
	}
    }

    /**
     * Creates a <code>DOMKeyValue</code> from an element.
     *
     * @param kvElem a KeyValue element
     */
    public DOMKeyValue(Element kvElem) throws MarshalException {
	Element kvtElem = DOMUtils.getFirstChildElement(kvElem);
        if (kvtElem.getLocalName().equals("DSAKeyValue")) {
            publicKey = unmarshalDSAKeyValue(kvtElem);
        } else if (kvtElem.getLocalName().equals("RSAKeyValue")) {
            publicKey = unmarshalRSAKeyValue(kvtElem);
        } else {
	    publicKey = null;
	    externalPublicKey = new javax.xml.crypto.dom.DOMStructure(kvtElem);
	}
    }

    public PublicKey getPublicKey() throws KeyException {
	if (publicKey == null) {
	    throw new KeyException("can't convert KeyValue to PublicKey");
	} else {
            return publicKey;
	}
    }

    public void marshal(Node parent, String dsPrefix, DOMCryptoContext context)
	throws MarshalException {
        Document ownerDoc = DOMUtils.getOwnerDocument(parent);

        // create KeyValue element
        Element kvElem = DOMUtils.createElement
	    (ownerDoc, "KeyValue", XMLSignature.XMLNS, dsPrefix);
        marshalPublicKey(kvElem, ownerDoc, dsPrefix, context);

        parent.appendChild(kvElem);
    }

    private void marshalPublicKey(Node parent, Document doc, String dsPrefix,
	DOMCryptoContext context) throws MarshalException {
        if (publicKey != null) {
            if (publicKey instanceof DSAPublicKey) {
                // create and append DSAKeyValue element
                marshalDSAPublicKey(parent, doc, dsPrefix, context);
            } else if (publicKey instanceof RSAPublicKey) {
                // create and append RSAKeyValue element
                marshalRSAPublicKey(parent, doc, dsPrefix, context);
            } else {
                throw new MarshalException(publicKey.getAlgorithm() +
                    " public key algorithm not supported");
            }
        } else {
	    parent.appendChild(externalPublicKey.getNode());
        }
    }

    private void marshalDSAPublicKey(Node parent, Document doc, 
	String dsPrefix, DOMCryptoContext context) throws MarshalException {
        Element dsaElem = DOMUtils.createElement
	    (doc, "DSAKeyValue", XMLSignature.XMLNS, dsPrefix);
        // parameters J, Seed & PgenCounter are not included
        Element pElem = DOMUtils.createElement
	    (doc, "P", XMLSignature.XMLNS, dsPrefix);
        Element qElem = DOMUtils.createElement
	    (doc, "Q", XMLSignature.XMLNS, dsPrefix);
        Element gElem = DOMUtils.createElement
	    (doc, "G", XMLSignature.XMLNS, dsPrefix);
        Element yElem = DOMUtils.createElement
	    (doc, "Y", XMLSignature.XMLNS, dsPrefix);
        p.marshal(pElem, dsPrefix, context);
        q.marshal(qElem, dsPrefix, context);
        g.marshal(gElem, dsPrefix, context);
        y.marshal(yElem, dsPrefix, context);
        dsaElem.appendChild(pElem);
        dsaElem.appendChild(qElem);
        dsaElem.appendChild(gElem);
        dsaElem.appendChild(yElem);
        parent.appendChild(dsaElem);
    }

    private void marshalRSAPublicKey(Node parent, Document doc, 
	String dsPrefix, DOMCryptoContext context) throws MarshalException {
        Element rsaElem = DOMUtils.createElement
	    (doc, "RSAKeyValue", XMLSignature.XMLNS, dsPrefix);
        Element modulusElem = DOMUtils.createElement
	    (doc, "Modulus", XMLSignature.XMLNS, dsPrefix);
        Element exponentElem = DOMUtils.createElement
	    (doc, "Exponent", XMLSignature.XMLNS, dsPrefix);
	modulus.marshal(modulusElem, dsPrefix, context);
	exponent.marshal(exponentElem, dsPrefix, context);
        rsaElem.appendChild(modulusElem);
        rsaElem.appendChild(exponentElem);
        parent.appendChild(rsaElem);
    }

    private DSAPublicKey unmarshalDSAKeyValue(Element kvtElem) 
	throws MarshalException {
	if (dsakf == null) {
	    try {
	        dsakf = KeyFactory.getInstance("DSA");
	    } catch (NoSuchAlgorithmException e) {
	        throw new RuntimeException("unable to create DSA KeyFactory: " +
		    e.getMessage());
	    }
	}
	Element curElem = DOMUtils.getFirstChildElement(kvtElem);
	// check for P and Q
	if (curElem.getLocalName().equals("P")) {
	    p = new DOMCryptoBinary(curElem.getFirstChild());
	    curElem = DOMUtils.getNextSiblingElement(curElem);
	    q = new DOMCryptoBinary(curElem.getFirstChild());
	    curElem = DOMUtils.getNextSiblingElement(curElem);
	} 
        if (curElem.getLocalName().equals("G")) {
            g = new DOMCryptoBinary(curElem.getFirstChild());
	    curElem = DOMUtils.getNextSiblingElement(curElem);
	}
        y = new DOMCryptoBinary(curElem.getFirstChild());
        curElem = DOMUtils.getNextSiblingElement(curElem);
        if (curElem != null && curElem.getLocalName().equals("J")) {
	    j = new DOMCryptoBinary(curElem.getFirstChild());
	    curElem = DOMUtils.getNextSiblingElement(curElem);
	}
	if (curElem != null) {
	    seed = new DOMCryptoBinary(curElem.getFirstChild());
	    curElem = DOMUtils.getNextSiblingElement(curElem);
	    pgen = new DOMCryptoBinary(curElem.getFirstChild());
	}
	//@@@ do we care about j, pgenCounter or seed?
	DSAPublicKeySpec spec = new DSAPublicKeySpec
	    (y.getBigNum(), p.getBigNum(), q.getBigNum(), g.getBigNum());
        return (DSAPublicKey) generatePublicKey(dsakf, spec);
    }

    private RSAPublicKey unmarshalRSAKeyValue(Element kvtElem) 
	throws MarshalException {
	if (rsakf == null) {
	    try {
	        rsakf = KeyFactory.getInstance("RSA");
	    } catch (NoSuchAlgorithmException e) {
	        throw new RuntimeException("unable to create RSA KeyFactory: " +
		    e.getMessage());
	    }
	}
	Element modulusElem = DOMUtils.getFirstChildElement(kvtElem);
        modulus = new DOMCryptoBinary(modulusElem.getFirstChild());
	Element exponentElem = DOMUtils.getNextSiblingElement(modulusElem);
        exponent = new DOMCryptoBinary(exponentElem.getFirstChild());
        RSAPublicKeySpec spec = new RSAPublicKeySpec
	    (modulus.getBigNum(), exponent.getBigNum());
        return (RSAPublicKey) generatePublicKey(rsakf, spec);
    }

    private PublicKey generatePublicKey(KeyFactory kf, KeySpec keyspec) {
        try {
            return kf.generatePublic(keyspec);
        } catch (InvalidKeySpecException e) {
	    //@@@ should dump exception to log
	    return null;
        }
    }
    
    public boolean equals(Object obj) {
	if (this == obj) {
	    return true;
	}
        if (!(obj instanceof KeyValue)) {
            return false;
        }
	try {
            KeyValue kv = (KeyValue) obj;
            if (publicKey == null ) {
                if (kv.getPublicKey() != null) {
                    return false;
                }
            } else if (!publicKey.equals(kv.getPublicKey())) {
                return false;
            }
	} catch (KeyException ke) {
	    // no practical way to determine if the keys are equal
	    return false;
	}
        
        return true;
    }

    public int hashCode() {
	assert false : "hashCode not designed";
	return 45;
    }
}