/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * @(#)BASE64EncoderStream.java       1.6 02/03/27

 */

package com.sun.xml.internal.messaging.saaj.packaging.mime.util;

import java.io.*;

/**

 * This class implements a BASE64 Encoder. It is implemented as

 * a FilterOutputStream, so one can just wrap this class around

 * any output stream and write bytes into this filter. The Encoding

 * is done as the bytes are written out.

 *

 * @author John Mani

 * @author Bill Shannon

 */

public class BASE64EncoderStream extends FilterOutputStream {

    private byte[] buffer;      // cache of bytes that are yet to be encoded

    private int bufsize = 0;    // size of the cache

    private int count = 0;      // number of bytes that have been output

    private int bytesPerLine;   // number of bytes per line

    /**

     * Create a BASE64 encoder that encodes the specified input stream

     * @param out        the output stream

     * @param bytesPerLine  number of bytes per line. The encoder inserts

     *                   a CRLF sequence after the specified number of bytes

     */

    public BASE64EncoderStream(OutputStream out, int bytesPerLine) {

        super(out);

        buffer = new byte[3];

        this.bytesPerLine = bytesPerLine;

    }

    /**

     * Create a BASE64 encoder that encodes the specified input stream.

     * Inserts the CRLF sequence after outputting 76 bytes.

     * @param out        the output stream

     */

    public BASE64EncoderStream(OutputStream out) {

        this(out, 76);

    }

    /**

     * Encodes <code>len</code> bytes from the specified

     * <code>byte</code> array starting at offset <code>off</code> to

     * this output stream.

     *

     * @param      b     the data.

     * @param      off   the start offset in the data.

     * @param      len   the number of bytes to write.

     * @exception  IOException  if an I/O error occurs.

     */

    public void write(byte[] b, int off, int len) throws IOException {

        for (int i = 0; i < len; i++)

            write(b[off + i]);

    }

    /**

     * Encodes <code>b.length</code> bytes to this output stream.

     * @param      b   the data to be written.

     * @exception  IOException  if an I/O error occurs.

     */

    public void write(byte[] b) throws IOException {

        write(b, 0, b.length);

    }

    /**

     * Encodes the specified <code>byte</code> to this output stream.

     * @param      c   the <code>byte</code>.

     * @exception  IOException  if an I/O error occurs.

     */

    public void write(int c) throws IOException {

        buffer[bufsize++] = (byte)c;

        if (bufsize == 3) { // Encoding unit = 3 bytes

            encode();

            bufsize = 0;

        }

    }

    /**

     * Flushes this output stream and forces any buffered output bytes

     * to be encoded out to the stream.

     * @exception  IOException  if an I/O error occurs.

     */

    public void flush() throws IOException {

        if (bufsize > 0) { // If there's unencoded characters in the buffer ..

            encode();      // .. encode them

            bufsize = 0;

        }

        out.flush();

    }

    /**

     * Forces any buffered output bytes to be encoded out to the stream

     * and closes this output stream

     */

    public void close() throws IOException {

        flush();

        out.close();

    }

    /** This array maps the characters to their 6 bit values */

    private final static char pem_array[] = {

        'A','B','C','D','E','F','G','H', // 0

        'I','J','K','L','M','N','O','P', // 1

        'Q','R','S','T','U','V','W','X', // 2

        'Y','Z','a','b','c','d','e','f', // 3

        'g','h','i','j','k','l','m','n', // 4

        'o','p','q','r','s','t','u','v', // 5

        'w','x','y','z','0','1','2','3', // 6

        '4','5','6','7','8','9','+','/'  // 7

    };

    private void encode() throws IOException {

        // If writing out this encoded unit will cause overflow,

        // start a new line.

        if (count + 4 > bytesPerLine) {

            out.write('\r');

            out.write('\n');

            count = 0;

        }

        byte a, b, c;

        if (bufsize == 1) {

            a = buffer[0];

            b = 0;

            c = 0;

            out.write(pem_array[(a >>> 2) & 0x3F]);

            out.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);

            out.write('='); // pad character

            out.write('='); // pad character

        } else if (bufsize == 2) {

            a = buffer[0];

            b = buffer[1];

            c = 0;

            out.write(pem_array[(a >>> 2) & 0x3F]);

            out.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);

            out.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);

            out.write('='); // pad character

        } else {

            a = buffer[0];

            b = buffer[1];

            c = buffer[2];

            out.write(pem_array[(a >>> 2) & 0x3F]);

            out.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);

            out.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);

            out.write(pem_array[c & 0x3F]);

        }

        // increment count

        count += 4;

    }

    /**

     * Base64 encode a byte array.  No line breaks are inserted.

     * This method is suitable for short strings, such as those

     * in the IMAP AUTHENTICATE protocol, but not to encode the

     * entire content of a MIME part.

     */

    public static byte[] encode(byte[] inbuf) {

        if (inbuf.length == 0)

            return inbuf;

        byte[] outbuf = new byte[((inbuf.length + 2) / 3) * 4];

        int inpos = 0, outpos = 0;

        int size = inbuf.length;

        while (size > 0) {

            byte a, b, c;

            if (size == 1) {

                a = inbuf[inpos++];

                b = 0;

                c = 0;

                outbuf[outpos++] = (byte)pem_array[(a >>> 2) & 0x3F];

                outbuf[outpos++] =

                        (byte)pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)];

                outbuf[outpos++] = (byte)'=';  // pad character

                outbuf[outpos++] = (byte)'=';  // pad character

            } else if (size == 2) {

                a = inbuf[inpos++];

                b = inbuf[inpos++];

                c = 0;

                outbuf[outpos++] = (byte)pem_array[(a >>> 2) & 0x3F];

                outbuf[outpos++] =

                        (byte)pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)];

                outbuf[outpos++] =

                        (byte)pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)];

                outbuf[outpos++] = (byte)'=';  // pad character

            } else {

                a = inbuf[inpos++];

                b = inbuf[inpos++];

                c = inbuf[inpos++];

                outbuf[outpos++] = (byte)pem_array[(a >>> 2) & 0x3F];

                outbuf[outpos++] =

                        (byte)pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)];

                outbuf[outpos++] =

                        (byte)pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)];

                outbuf[outpos++] = (byte)pem_array[c & 0x3F];

            }

            size -= 3;

        }

        return outbuf;

    }

    /*** begin TEST program

    public static void main(String argv[]) throws Exception {

        FileInputStream infile = new FileInputStream(argv[0]);

        BASE64EncoderStream encoder = new BASE64EncoderStream(System.out);

        int c;

        while ((c = infile.read()) != -1)

            encoder.write(c);

        encoder.close();

    }

    *** end TEST program **/

}