/**
 * 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.algorithms;

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;
import java.security.spec.AlgorithmParameterSpec;

import org.apache.xml.security.signature.XMLSignatureException;
import org.w3c.dom.Element;

public abstract class SignatureAlgorithmSpi {

    /**
     * Returns the URI representation of <code>Transformation algorithm</code>
     *
     * @return the URI representation of <code>Transformation algorithm</code>
     */
    protected abstract String engineGetURI();

    /**
     * Proxy method for {@link java.security.Signature#getAlgorithm}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @return the result of the {@link java.security.Signature#getAlgorithm} method
     */
    protected abstract String engineGetJCEAlgorithmString();

    /**
     * Method engineGetJCEProviderName
     *
     * @return the JCE ProviderName
     */
    protected abstract String engineGetJCEProviderName();

    /**
     * Proxy method for {@link java.security.Signature#update(byte[])}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param input
     * @throws XMLSignatureException
     */
    protected abstract void engineUpdate(byte[] input) throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#update(byte[])}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param input
     * @throws XMLSignatureException
     */
    protected abstract void engineUpdate(byte input) throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#update(byte[], int, int)}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param buf
     * @param offset
     * @param len
     * @throws XMLSignatureException
     */
    protected abstract void engineUpdate(byte[] buf, int offset, int len)
        throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#initSign(java.security.PrivateKey)}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param signingKey
     * @throws XMLSignatureException if this method is called on a MAC
     */
    protected abstract void engineInitSign(Key signingKey) throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#initSign(java.security.PrivateKey,
     * java.security.SecureRandom)}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param signingKey
     * @param secureRandom
     * @throws XMLSignatureException if this method is called on a MAC
     */
    protected abstract void engineInitSign(Key signingKey, SecureRandom secureRandom)
        throws XMLSignatureException;

    /**
     * Proxy method for {@link javax.crypto.Mac}
     * which is executed on the internal {@link javax.crypto.Mac#init(Key)} object.
     *
     * @param signingKey
     * @param algorithmParameterSpec
     * @throws XMLSignatureException if this method is called on a Signature
     */
    protected abstract void engineInitSign(
        Key signingKey, AlgorithmParameterSpec algorithmParameterSpec
    ) throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#sign()}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @return the result of the {@link java.security.Signature#sign()} method
     * @throws XMLSignatureException
     */
    protected abstract byte[] engineSign() throws XMLSignatureException;

    /**
     * Method engineInitVerify
     *
     * @param verificationKey
     * @throws XMLSignatureException
     */
    protected abstract void engineInitVerify(Key verificationKey) throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#verify(byte[])}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param signature
     * @return true if the signature is correct
     * @throws XMLSignatureException
     */
    protected abstract boolean engineVerify(byte[] signature) throws XMLSignatureException;

    /**
     * Proxy method for {@link java.security.Signature#setParameter(
     * java.security.spec.AlgorithmParameterSpec)}
     * which is executed on the internal {@link java.security.Signature} object.
     *
     * @param params
     * @throws XMLSignatureException
     */
    protected abstract void engineSetParameter(AlgorithmParameterSpec params)
        throws XMLSignatureException;


    /**
     * Method engineGetContextFromElement
     *
     * @param element
     */
    protected void engineGetContextFromElement(Element element) throws XMLSignatureException {
    }

    protected void engineAddContextToElement(Element element) throws XMLSignatureException {
    }

    /**
     * Method engineSetHMACOutputLength
     *
     * @param HMACOutputLength
     * @throws XMLSignatureException
     */
    protected abstract void engineSetHMACOutputLength(int HMACOutputLength)
        throws XMLSignatureException;

    protected static void engineInitVerify(Key publicKey, Signature signatureAlgorithm) throws XMLSignatureException {
        if (!(publicKey instanceof PublicKey)) {
            String supplied = null;
            if (publicKey != null) {
                supplied = publicKey.getClass().getName();
            }
            String needed = PublicKey.class.getName();
            Object[] exArgs = { supplied, needed };

            throw new XMLSignatureException("algorithms.WrongKeyForThisOperation", exArgs);
        }

        try {
            signatureAlgorithm.initVerify((PublicKey) publicKey);
        } catch (InvalidKeyException ex) {
            throw new XMLSignatureException(ex);
        }
    }

    protected static void engineInitSign(Key privateKey, SecureRandom secureRandom, Signature signatureAlgorithm)
            throws XMLSignatureException {
        if (!(privateKey instanceof PrivateKey)) {
            String supplied = null;
            if (privateKey != null) {
                supplied = privateKey.getClass().getName();
            }
            String needed = PrivateKey.class.getName();
            Object[] exArgs = { supplied, needed };

            throw new XMLSignatureException("algorithms.WrongKeyForThisOperation", exArgs);
        }

        try {
            if (secureRandom == null) {
                signatureAlgorithm.initSign((PrivateKey) privateKey);
            } else {
                signatureAlgorithm.initSign((PrivateKey) privateKey, secureRandom);
            }
        } catch (InvalidKeyException ex) {
            throw new XMLSignatureException(ex);
        }
    }

}
