/*
 * Jitsi, the OpenSource Java VoIP and Instant Messaging client.
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 *
 * The contents of this file has been copied from the Base64 and Base64Encoder
 * classes of the Bouncy Castle libraries and included the following license.
 *
 * Copyright (c) 2000 - 2006 The Legion Of The Bouncy Castle
 * (http://www.bouncycastle.org)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package net.java.sip.communicator.util;

import java.io.*;

public class Base64
{
    private static final Base64Encoder encoder = new Base64Encoder();

    /**
     * encode the input data producing a base 64 encoded byte array.
     *
     * @param data the byte array to encode
     * @return a byte array containing the base 64 encoded data.
     */
    public static byte[] encode(
            byte[] data)
    {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        try {
            encoder.encode(data, 0, data.length, bOut);
        } catch (IOException e) {
            throw new RuntimeException("exception encoding base64 string: " + e);
        }

        return bOut.toByteArray();
    }

    /**
     * Encode the byte data to base 64 writing it to the given output stream.
     *
     * @param data the byte array to encode
     * @param out the output stream where the result is to be written.
     * @return the number of bytes produced.
     * @throws IOException if the output stream throws one
     */
    public static int encode(byte[] data, OutputStream out)
            throws IOException
    {
        return encoder.encode(data, 0, data.length, out);
    }

    /**
     * Encode the byte data to base 64 writing it to the given output stream.
     *
     * @param data the byte array to encode
     * @param off offset
     * @param length length
     * @param out OutputStream
     * @return the number of bytes produced.
     * @throws IOException
     */
    public static int encode(byte[] data, int off, int length, OutputStream out)
            throws IOException
    {
        return encoder.encode(data, off, length, out);
    }

    /**
     * decode the base 64 encoded input data. It is assumed the input data is valid.
     *
     * @param data the byte array to encode
     * @return a byte array representing the decoded data.
     */
    public static byte[] decode(byte[] data)
    {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        try {
            encoder.decode(data, 0, data.length, bOut);
        } catch (IOException e) {
            throw new RuntimeException("exception decoding base64 string: " + e);
        }
        return bOut.toByteArray();
    }

    /**
     * decode the base 64 encoded String data - whitespace will be ignored.
     *
     * @param data the byte array to encode
     * @return a byte array representing the decoded data.
     */
    public static byte[] decode(String data)
    {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        try {
            encoder.decode(data, bOut);
        } catch (IOException e) {
            throw new RuntimeException("exception decoding base64 string: " + e);
        }
        return bOut.toByteArray();
    }

    /**
     * decode the base 64 encoded String data writing it to the given output stream,
     * whitespace characters will be ignored.
     *
     * @param data the data to decode
     * @param out OutputStream
     * @return the number of bytes produced.
     * @throws IOException if an exception occurs while writing to the specified output stream
     */
    public static int decode(
            String data,
            OutputStream out)
            throws IOException
    {
        return encoder.decode(data, out);
    }

    /**
     * Prevents the initialization of <code>Base64</code> instances.
     */
    private Base64()
    {
    }

    public static class Base64Encoder
    {
        protected final byte[] encodingTable =
                {
                        (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G',
                        (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N',
                        (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U',
                        (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z',
                        (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g',
                        (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n',
                        (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u',
                        (byte) 'v',
                        (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z',
                        (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6',
                        (byte) '7', (byte) '8', (byte) '9',
                        (byte) '+', (byte) '/'
                };

        protected byte padding = (byte) '=';

        /*
         * set up the decoding table.
         */
        protected final byte[] decodingTable = new byte[128];

        protected void initialiseDecodingTable()
        {
            for (int i = 0; i < encodingTable.length; i++) {
                decodingTable[encodingTable[i]] = (byte) i;
            }
        }

        public Base64Encoder()
        {
            initialiseDecodingTable();
        }

        /**
         * encode the input data producing a base 64 output stream.
         *
         * @param data the byte array to encode
         * @param off offset
         * @param length length
         * @param out OutputStream
         * @return the number of bytes produced.
         * @throws IOException if an exception occurs while writing to the stream.
         */
        public int encode(byte[] data, int off, int length, OutputStream out) throws IOException
        {
            int modulus = length % 3;
            int dataLength = (length - modulus);
            int a1, a2, a3;

            for (int i = off; i < off + dataLength; i += 3) {
                a1 = data[i] & 0xff;
                a2 = data[i + 1] & 0xff;
                a3 = data[i + 2] & 0xff;

                out.write(encodingTable[(a1 >>> 2) & 0x3f]);
                out.write(encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f]);
                out.write(encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f]);
                out.write(encodingTable[a3 & 0x3f]);
            }

            /*
             * process the tail end.
             */
            int b1, b2, b3;
            int d1, d2;

            switch (modulus) {
                case 0: /* nothing left to do */
                    break;
                case 1:
                    d1 = data[off + dataLength] & 0xff;
                    b1 = (d1 >>> 2) & 0x3f;
                    b2 = (d1 << 4) & 0x3f;

                    out.write(encodingTable[b1]);
                    out.write(encodingTable[b2]);
                    out.write(padding);
                    out.write(padding);
                    break;
                case 2:
                    d1 = data[off + dataLength] & 0xff;
                    d2 = data[off + dataLength + 1] & 0xff;

                    b1 = (d1 >>> 2) & 0x3f;
                    b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
                    b3 = (d2 << 2) & 0x3f;

                    out.write(encodingTable[b1]);
                    out.write(encodingTable[b2]);
                    out.write(encodingTable[b3]);
                    out.write(padding);
                    break;
            }
            return (dataLength / 3) * 4 + ((modulus == 0) ? 0 : 4);
        }

        private boolean ignore(char c)
        {
            return (c == '\n' || c == '\r' || c == '\t' || c == ' ');
        }

        /**
         * decode the base 64 encoded byte data writing it to the given output
         * stream, whitespace characters will be ignored.
         *
         * @param data the byte array to encode
         * @param off offset
         * @param length length
         * @param out OutputStream
         * @return the number of bytes produced.
         * @throws IOException if an exception occurs while wrinting to the
         * stream.
         */
        public int decode(byte[] data, int off, int length, OutputStream out) throws IOException
        {
            byte b1, b2, b3, b4;
            int outLen = 0;

            int end = off + length;
            while (end > off) {
                if (!ignore((char) data[end - 1])) {
                    break;
                }
                end--;
            }

            int i = off;
            int finish = end - 4;

            i = nextI(data, i, finish);
            while (i < finish) {
                b1 = decodingTable[data[i++]];

                i = nextI(data, i, finish);
                b2 = decodingTable[data[i++]];

                i = nextI(data, i, finish);
                b3 = decodingTable[data[i++]];

                i = nextI(data, i, finish);
                b4 = decodingTable[data[i++]];

                out.write((b1 << 2) | (b2 >> 4));
                out.write((b2 << 4) | (b3 >> 2));
                out.write((b3 << 6) | b4);
                outLen += 3;
                i = nextI(data, i, finish);
            }

            outLen += decodeLastBlock(out, (char) data[end - 4], (char) data[end - 3],
                    (char) data[end - 2], (char) data[end - 1]);

            return outLen;
        }

        private int nextI(byte[] data, int i, int finish)
        {
            while ((i < finish) && ignore((char) data[i])) {
                i++;
            }
            return i;
        }

        /**
         * decode the base 64 encoded String data writing it to the given output
         * stream, whitespace characters will be ignored.
         *
         * @param data the byte array to encode
         * @param out OutputStream
         * @return the number of bytes produced.
         * @throws IOException if an exception occurs while writing to the stream
         */
        public int decode(String data, OutputStream out) throws IOException
        {
            byte b1, b2, b3, b4;
            int length = 0;

            int end = data.length();
            while (end > 0) {
                if (!ignore(data.charAt(end - 1))) {
                    break;
                }
                end--;
            }

            int i = 0;
            int finish = end - 4;

            i = nextI(data, i, finish);
            while (i < finish) {
                b1 = decodingTable[data.charAt(i++)];

                i = nextI(data, i, finish);
                b2 = decodingTable[data.charAt(i++)];

                i = nextI(data, i, finish);
                b3 = decodingTable[data.charAt(i++)];

                i = nextI(data, i, finish);
                b4 = decodingTable[data.charAt(i++)];

                out.write((b1 << 2) | (b2 >> 4));
                out.write((b2 << 4) | (b3 >> 2));
                out.write((b3 << 6) | b4);

                length += 3;
                i = nextI(data, i, finish);
            }

            length += decodeLastBlock(out, data.charAt(end - 4), data.charAt(end - 3),
                    data.charAt(end - 2), data.charAt(end - 1));

            return length;
        }

        private int decodeLastBlock(OutputStream out, char c1, char c2, char c3, char c4) throws IOException
        {
            byte b1, b2, b3, b4;

            if (c3 == padding) {
                b1 = decodingTable[c1];
                b2 = decodingTable[c2];

                out.write((b1 << 2) | (b2 >> 4));

                return 1;
            }
            else if (c4 == padding) {
                b1 = decodingTable[c1];
                b2 = decodingTable[c2];
                b3 = decodingTable[c3];

                out.write((b1 << 2) | (b2 >> 4));
                out.write((b2 << 4) | (b3 >> 2));

                return 2;
            }
            else {
                b1 = decodingTable[c1];
                b2 = decodingTable[c2];
                b3 = decodingTable[c3];
                b4 = decodingTable[c4];

                out.write((b1 << 2) | (b2 >> 4));
                out.write((b2 << 4) | (b3 >> 2));
                out.write((b3 << 6) | b4);

                return 3;
            }
        }

        private int nextI(String data, int i, int finish)
        {
            while ((i < finish) && ignore(data.charAt(i))) {
                i++;
            }
            return i;
        }
    }
}