/**
 * 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.
 */
/*
 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
 */
package org.apache.jcp.xml.dsig.internal;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.MessageDigest;

import org.apache.xml.security.utils.UnsyncByteArrayOutputStream;

/**
 * This class has been modified slightly to use java.security.MessageDigest
 * objects as input, rather than
 * org.apache.xml.security.algorithms.MessageDigestAlgorithm objects.
 * It also optionally caches the input bytes.
 *
 */
public class DigesterOutputStream extends OutputStream {
    private static final org.slf4j.Logger LOG =
        org.slf4j.LoggerFactory.getLogger(DigesterOutputStream.class);

    private final boolean buffer;
    private UnsyncByteArrayOutputStream bos;
    private final MessageDigest md;

    /**
     * Creates a DigesterOutputStream.
     *
     * @param md the MessageDigest
     */
    public DigesterOutputStream(MessageDigest md) {
        this(md, false);
    }

    /**
     * Creates a DigesterOutputStream.
     *
     * @param md the MessageDigest
     * @param buffer if true, caches the input bytes
     */
    public DigesterOutputStream(MessageDigest md, boolean buffer) {
        this.md = md;
        this.buffer = buffer;
        if (buffer) {
            bos = new UnsyncByteArrayOutputStream();
        }
    }

    public void write(int input) {
        if (buffer) {
            bos.write(input);
        }
        md.update((byte)input);
    }

    @Override
    public void write(byte[] input, int offset, int len) {
        if (buffer) {
            bos.write(input, offset, len);
        }
        if (LOG.isDebugEnabled()) {
            LOG.debug("Pre-digested input:");
            StringBuilder sb = new StringBuilder(len);
            for (int i = offset; i < (offset + len); i++) {
                sb.append((char)input[i]);
            }
            LOG.debug(sb.toString());
        }
        md.update(input, offset, len);
    }

    /**
     * @return the digest value
     */
    public byte[] getDigestValue() {
         return md.digest();
    }

    /**
     * @return an input stream containing the cached bytes, or
     *    null if not cached
     */
    public InputStream getInputStream() {
        if (buffer) {
            return new ByteArrayInputStream(bos.toByteArray());
        } else {
            return null;
        }
    }

    @Override
    public void close() throws IOException {
        if (buffer) {
            bos.close();
        }
    }
}
