/*
 * RHQ Management Platform
 * Copyright (C) 2005-2008 Red Hat, Inc.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation version 2 of the License.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed 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.
 */

package org.rhq.core.db.ant;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;

/**
 * Class to Base64 encode strings.
 */
public class Base64 {
    private static final char[] S_BASE64CHAR = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
        'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
        'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
        '6', '7', '8', '9', '+', '/' };
    private static final char S_BASE64PAD = '=';
    private static final byte[] S_DECODETABLE = new byte[128];

    static {
        for (int i = 0; i < S_DECODETABLE.length; i++) {
            S_DECODETABLE[i] = Byte.MAX_VALUE; // 127
        }

        for (int i = 0; i < S_BASE64CHAR.length; i++) // 0 to 63
        {
            S_DECODETABLE[S_BASE64CHAR[i]] = (byte) i;
        }
    }

    private static int decode0(char[] ibuf, byte[] obuf, int wp) {
        int outlen = 3;
        if (ibuf[3] == S_BASE64PAD) {
            outlen = 2;
        }

        if (ibuf[2] == S_BASE64PAD) {
            outlen = 1;
        }

        int b0 = S_DECODETABLE[ibuf[0]];
        int b1 = S_DECODETABLE[ibuf[1]];
        int b2 = S_DECODETABLE[ibuf[2]];
        int b3 = S_DECODETABLE[ibuf[3]];
        switch (outlen) {
        case 1: {
            obuf[wp] = (byte) (((b0 << 2) & 0xfc) | ((b1 >> 4) & 0x3));
            return 1;
        }

        case 2: {
            obuf[wp++] = (byte) (((b0 << 2) & 0xfc) | ((b1 >> 4) & 0x3));
            obuf[wp] = (byte) (((b1 << 4) & 0xf0) | ((b2 >> 2) & 0xf));
            return 2;
        }

        case 3: {
            obuf[wp++] = (byte) (((b0 << 2) & 0xfc) | ((b1 >> 4) & 0x3));
            obuf[wp++] = (byte) (((b1 << 4) & 0xf0) | ((b2 >> 2) & 0xf));
            obuf[wp] = (byte) (((b2 << 6) & 0xc0) | (b3 & 0x3f));
            return 3;
        }

        default: {
            throw new RuntimeException("Internal Errror");
        }
        }
    }

    /**
     */
    public static byte[] decode(char[] data, int off, int len) {
        char[] ibuf = new char[4];
        int ibufcount = 0;
        byte[] obuf = new byte[(len / 4 * 3) + 3];
        int obufcount = 0;
        for (int i = off; i < (off + len); i++) {
            char ch = data[i];
            if ((ch == S_BASE64PAD) || ((ch < S_DECODETABLE.length) && (S_DECODETABLE[ch] != Byte.MAX_VALUE))) {
                ibuf[ibufcount++] = ch;
                if (ibufcount == ibuf.length) {
                    ibufcount = 0;
                    obufcount += decode0(ibuf, obuf, obufcount);
                }
            }
        }

        if (obufcount == obuf.length) {
            return obuf;
        }

        byte[] ret = new byte[obufcount];
        System.arraycopy(obuf, 0, ret, 0, obufcount);
        return ret;
    }

    /**
     */
    public static byte[] decode(String data) {
        char[] ibuf = new char[4];
        int ibufcount = 0;
        byte[] obuf = new byte[(data.length() / 4 * 3) + 3];
        int obufcount = 0;
        for (int i = 0; i < data.length(); i++) {
            char ch = data.charAt(i);
            if ((ch == S_BASE64PAD) || ((ch < S_DECODETABLE.length) && (S_DECODETABLE[ch] != Byte.MAX_VALUE))) {
                ibuf[ibufcount++] = ch;
                if (ibufcount == ibuf.length) {
                    ibufcount = 0;
                    obufcount += decode0(ibuf, obuf, obufcount);
                }
            }
        }

        if (obufcount == obuf.length) {
            return obuf;
        }

        byte[] ret = new byte[obufcount];
        System.arraycopy(obuf, 0, ret, 0, obufcount);
        return ret;
    }

    /**
     */
    public static void decode(char[] data, int off, int len, OutputStream ostream) throws IOException {
        char[] ibuf = new char[4];
        int ibufcount = 0;
        byte[] obuf = new byte[3];
        for (int i = off; i < (off + len); i++) {
            char ch = data[i];
            if ((ch == S_BASE64PAD) || ((ch < S_DECODETABLE.length) && (S_DECODETABLE[ch] != Byte.MAX_VALUE))) {
                ibuf[ibufcount++] = ch;
                if (ibufcount == ibuf.length) {
                    ibufcount = 0;
                    int obufcount = decode0(ibuf, obuf, 0);
                    ostream.write(obuf, 0, obufcount);
                }
            }
        }
    }

    /**
     */
    public static void decode(String data, OutputStream ostream) throws IOException {
        char[] ibuf = new char[4];
        int ibufcount = 0;
        byte[] obuf = new byte[3];
        for (int i = 0; i < data.length(); i++) {
            char ch = data.charAt(i);
            if ((ch == S_BASE64PAD) || ((ch < S_DECODETABLE.length) && (S_DECODETABLE[ch] != Byte.MAX_VALUE))) {
                ibuf[ibufcount++] = ch;
                if (ibufcount == ibuf.length) {
                    ibufcount = 0;
                    int obufcount = decode0(ibuf, obuf, 0);
                    ostream.write(obuf, 0, obufcount);
                }
            }
        }
    }

    /**
     * Returns base64 representation of specified byte array.
     */
    public static String encode(byte[] data) {
        return encode(data, 0, data.length);
    }

    /**
     * Returns base64 representation of specified byte array.
     */
    public static String encode(byte[] data, int off, int len) {
        if (len <= 0) {
            return "";
        }

        char[] out = new char[(len / 3 * 4) + 4];
        int rindex = off;
        int windex = 0;
        int rest = len - off;
        while (rest >= 3) {
            int i = ((data[rindex] & 0xff) << 16) + ((data[rindex + 1] & 0xff) << 8) + (data[rindex + 2] & 0xff);
            out[windex++] = S_BASE64CHAR[i >> 18];
            out[windex++] = S_BASE64CHAR[(i >> 12) & 0x3f];
            out[windex++] = S_BASE64CHAR[(i >> 6) & 0x3f];
            out[windex++] = S_BASE64CHAR[i & 0x3f];
            rindex += 3;
            rest -= 3;
        }

        if (rest == 1) {
            int i = data[rindex] & 0xff;
            out[windex++] = S_BASE64CHAR[i >> 2];
            out[windex++] = S_BASE64CHAR[(i << 4) & 0x3f];
            out[windex++] = S_BASE64PAD;
            out[windex++] = S_BASE64PAD;
        } else if (rest == 2) {
            int i = ((data[rindex] & 0xff) << 8) + (data[rindex + 1] & 0xff);
            out[windex++] = S_BASE64CHAR[i >> 10];
            out[windex++] = S_BASE64CHAR[(i >> 4) & 0x3f];
            out[windex++] = S_BASE64CHAR[(i << 2) & 0x3f];
            out[windex++] = S_BASE64PAD;
        }

        return new String(out, 0, windex);
    }

    /**
     * Outputs base64 representation of the specified byte array to a byte stream.
     */
    public static void encode(byte[] data, int off, int len, OutputStream ostream) throws IOException {
        if (len <= 0) {
            return;
        }

        byte[] out = new byte[4];
        int rindex = off;
        int rest = len - off;
        while (rest >= 3) {
            int i = ((data[rindex] & 0xff) << 16) + ((data[rindex + 1] & 0xff) << 8) + (data[rindex + 2] & 0xff);
            out[0] = (byte) S_BASE64CHAR[i >> 18];
            out[1] = (byte) S_BASE64CHAR[(i >> 12) & 0x3f];
            out[2] = (byte) S_BASE64CHAR[(i >> 6) & 0x3f];
            out[3] = (byte) S_BASE64CHAR[i & 0x3f];
            ostream.write(out, 0, 4);
            rindex += 3;
            rest -= 3;
        }

        if (rest == 1) {
            int i = data[rindex] & 0xff;
            out[0] = (byte) S_BASE64CHAR[i >> 2];
            out[1] = (byte) S_BASE64CHAR[(i << 4) & 0x3f];
            out[2] = (byte) S_BASE64PAD;
            out[3] = (byte) S_BASE64PAD;
            ostream.write(out, 0, 4);
        } else if (rest == 2) {
            int i = ((data[rindex] & 0xff) << 8) + (data[rindex + 1] & 0xff);
            out[0] = (byte) S_BASE64CHAR[i >> 10];
            out[1] = (byte) S_BASE64CHAR[(i >> 4) & 0x3f];
            out[2] = (byte) S_BASE64CHAR[(i << 2) & 0x3f];
            out[3] = (byte) S_BASE64PAD;
            ostream.write(out, 0, 4);
        }
    }

    /**
     * Outputs base64 representation of the specified byte array to a character stream.
     */
    public static void encode(byte[] data, int off, int len, Writer writer) throws IOException {
        if (len <= 0) {
            return;
        }

        char[] out = new char[4];
        int rindex = off;
        int rest = len - off;
        int output = 0;
        while (rest >= 3) {
            int i = ((data[rindex] & 0xff) << 16) + ((data[rindex + 1] & 0xff) << 8) + (data[rindex + 2] & 0xff);
            out[0] = S_BASE64CHAR[i >> 18];
            out[1] = S_BASE64CHAR[(i >> 12) & 0x3f];
            out[2] = S_BASE64CHAR[(i >> 6) & 0x3f];
            out[3] = S_BASE64CHAR[i & 0x3f];
            writer.write(out, 0, 4);
            rindex += 3;
            rest -= 3;
            output += 4;
            if ((output % 76) == 0) {
                writer.write("\n");
            }
        }

        if (rest == 1) {
            int i = data[rindex] & 0xff;
            out[0] = S_BASE64CHAR[i >> 2];
            out[1] = S_BASE64CHAR[(i << 4) & 0x3f];
            out[2] = S_BASE64PAD;
            out[3] = S_BASE64PAD;
            writer.write(out, 0, 4);
        } else if (rest == 2) {
            int i = ((data[rindex] & 0xff) << 8) + (data[rindex + 1] & 0xff);
            out[0] = S_BASE64CHAR[i >> 10];
            out[1] = S_BASE64CHAR[(i >> 4) & 0x3f];
            out[2] = S_BASE64CHAR[(i << 2) & 0x3f];
            out[3] = S_BASE64PAD;
            writer.write(out, 0, 4);
        }
    }
}