001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.codec.binary;
019
020import static org.apache.commons.codec.binary.BaseNCodec.EOF;
021
022import java.io.FilterOutputStream;
023import java.io.IOException;
024import java.io.OutputStream;
025
026import org.apache.commons.codec.binary.BaseNCodec.Context;
027
028/**
029 * Abstract superclass for Base-N output streams.
030 *
031 * @since 1.5
032 * @version $Id: BaseNCodecOutputStream.java 1544347 2013-11-21 22:30:31Z ggregory $
033 */
034public class BaseNCodecOutputStream extends FilterOutputStream {
035
036    private final boolean doEncode;
037
038    private final BaseNCodec baseNCodec;
039
040    private final byte[] singleByte = new byte[1];
041
042    private final Context context = new Context();
043
044    // TODO should this be protected?
045    public BaseNCodecOutputStream(final OutputStream out, final BaseNCodec basedCodec, final boolean doEncode) {
046        super(out);
047        this.baseNCodec = basedCodec;
048        this.doEncode = doEncode;
049    }
050
051    /**
052     * Writes the specified <code>byte</code> to this output stream.
053     *
054     * @param i
055     *            source byte
056     * @throws IOException
057     *             if an I/O error occurs.
058     */
059    @Override
060    public void write(final int i) throws IOException {
061        singleByte[0] = (byte) i;
062        write(singleByte, 0, 1);
063    }
064
065    /**
066     * Writes <code>len</code> bytes from the specified <code>b</code> array starting at <code>offset</code> to this
067     * output stream.
068     *
069     * @param b
070     *            source byte array
071     * @param offset
072     *            where to start reading the bytes
073     * @param len
074     *            maximum number of bytes to write
075     *
076     * @throws IOException
077     *             if an I/O error occurs.
078     * @throws NullPointerException
079     *             if the byte array parameter is null
080     * @throws IndexOutOfBoundsException
081     *             if offset, len or buffer size are invalid
082     */
083    @Override
084    public void write(final byte b[], final int offset, final int len) throws IOException {
085        if (b == null) {
086            throw new NullPointerException();
087        } else if (offset < 0 || len < 0) {
088            throw new IndexOutOfBoundsException();
089        } else if (offset > b.length || offset + len > b.length) {
090            throw new IndexOutOfBoundsException();
091        } else if (len > 0) {
092            if (doEncode) {
093                baseNCodec.encode(b, offset, len, context);
094            } else {
095                baseNCodec.decode(b, offset, len, context);
096            }
097            flush(false);
098        }
099    }
100
101    /**
102     * Flushes this output stream and forces any buffered output bytes to be written out to the stream. If propagate is
103     * true, the wrapped stream will also be flushed.
104     *
105     * @param propagate
106     *            boolean flag to indicate whether the wrapped OutputStream should also be flushed.
107     * @throws IOException
108     *             if an I/O error occurs.
109     */
110    private void flush(final boolean propagate) throws IOException {
111        final int avail = baseNCodec.available(context);
112        if (avail > 0) {
113            final byte[] buf = new byte[avail];
114            final int c = baseNCodec.readResults(buf, 0, avail, context);
115            if (c > 0) {
116                out.write(buf, 0, c);
117            }
118        }
119        if (propagate) {
120            out.flush();
121        }
122    }
123
124    /**
125     * Flushes this output stream and forces any buffered output bytes to be written out to the stream.
126     *
127     * @throws IOException
128     *             if an I/O error occurs.
129     */
130    @Override
131    public void flush() throws IOException {
132        flush(true);
133    }
134
135    /**
136     * Closes this output stream and releases any system resources associated with the stream.
137     *
138     * @throws IOException
139     *             if an I/O error occurs.
140     */
141    @Override
142    public void close() throws IOException {
143        // Notify encoder of EOF (-1).
144        if (doEncode) {
145            baseNCodec.encode(singleByte, 0, EOF, context);
146        } else {
147            baseNCodec.decode(singleByte, 0, EOF, context);
148        }
149        flush();
150        out.close();
151    }
152
153}