/*
 *
 * Copyright (c) 2013 - 2017 Lijun Liao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 *
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * THE AUTHOR LIJUN LIAO. LIJUN LIAO DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the XiPKI software without
 * disclosing the source code of your own applications.
 *
 * For more information, please contact Lijun Liao at this
 * address: lijun.liao@gmail.com
 */

package org.xipki.commons.security;

import java.io.IOException;
import java.io.OutputStream;
import java.security.InvalidKeyException;
import java.security.PrivateKey;
import java.security.Signature;
import java.security.SignatureException;

import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.operator.RuntimeOperatorException;
import org.xipki.commons.common.util.ParamUtil;

/**
 * @author Lijun Liao
 * @since 2.0.0
 */

public class SignatureSigner implements ContentSigner {

    private class SignatureStream extends OutputStream {

        public byte[] getSignature() throws SignatureException {
            return signer.sign();
        }

        @Override
        public void write(final int singleByte) throws IOException {
            try {
                signer.update((byte) singleByte);
            } catch (SignatureException ex) {
                throw new IOException(ex.getMessage(), ex);
            }
        }

        @Override
        public void write(final byte[] bytes) throws IOException {
            try {
                signer.update(bytes);
            } catch (SignatureException ex) {
                throw new IOException(ex.getMessage(), ex);
            }
        }

        @Override
        public void write(final byte[] bytes, final int off, final int len) throws IOException {
            try {
                signer.update(bytes, off, len);
            } catch (SignatureException ex) {
                throw new IOException(ex.getMessage(), ex);
            }
        }

    } // class SignatureStream

    private final AlgorithmIdentifier sigAlgId;

    private final Signature signer;

    private final SignatureStream stream = new SignatureStream();

    private final PrivateKey key;

    public SignatureSigner(final AlgorithmIdentifier sigAlgId, final Signature signer,
            final PrivateKey key) {
        this.sigAlgId = ParamUtil.requireNonNull("sigAlgId", sigAlgId);
        this.signer = ParamUtil.requireNonNull("signer", signer);
        this.key = ParamUtil.requireNonNull("key", key);
    }

    @Override
    public AlgorithmIdentifier getAlgorithmIdentifier() {
        return sigAlgId;
    }

    @Override
    public OutputStream getOutputStream() {
        try {
            signer.initSign(key);
        } catch (InvalidKeyException ex) {
            throw new RuntimeOperatorException("could not initSign", ex);
        }
        return stream;
    }

    @Override
    public byte[] getSignature() {
        try {
            return stream.getSignature();
        } catch (SignatureException ex) {
            throw new RuntimeOperatorException("exception obtaining signature: " + ex.getMessage(),
                    ex);
        }
    }

}