/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 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 Lesser General Public License for more details.
 *
 * Copyright (c) 2006 - 2009 Object Refinery Ltd, Pentaho Corporation and Contributors.  All rights reserved.
 */

package org.pentaho.reporting.libraries.xmlns.parser;

/**
 * Provides encoding of raw bytes to base64-encoded characters, and decoding of
 * base64 characters to raw bytes. date: 06 August 1998 modified: 14 February
 * 2000 modified: 22 September 2000
 *
 * @author Kevin Kelley (kelley@ruralnet.net)
 * @version 1.3
 */
public class Base64
{
  /**
   * Private constructor prevents object creation.
   */
  private Base64()
  {
  }

  /**
   * returns an array of base64-encoded characters to represent the passed
   * data array.
   *
   * @param data the array of bytes to encode
   * @return base64-coded character array.
   */
  public static char[] encode(final byte[] data)
  {
    final char[] out = new char[((data.length + 2) / 3) * 4];

    //
    // 3 bytes encode to 4 chars.  Output is always an even
    // multiple of 4 characters.
    //
    for (int i = 0, index = 0; i < data.length; i += 3, index += 4)
    {

      int val = (0xFF & data[i]);
      val <<= 8;
      boolean trip = false;
      if ((i + 1) < data.length)
      {
        val |= (0xFF & data[i + 1]);
        trip = true;
      }
      val <<= 8;
      boolean quad = false;
      if ((i + 2) < data.length)
      {
        val |= (0xFF & data[i + 2]);
        quad = true;
      }
      out[index + 3] = Base64.ALPHABET[(quad ? (val & 0x3F) : 64)];
      val >>= 6;
      out[index + 2] = Base64.ALPHABET[(trip ? (val & 0x3F) : 64)];
      val >>= 6;
      out[index + 1] = Base64.ALPHABET[val & 0x3F];
      val >>= 6;
      out[index] = Base64.ALPHABET[val & 0x3F];
    }
    return out;
  }

  /**
   * Decodes a BASE-64 encoded stream to recover the original data. White
   * space before and after will be trimmed away, but no other manipulation of
   * the input will be performed.
   * <p/>
   * As of version 1.2 this method will properly handle input containing junk
   * characters (newlines and the like) rather than throwing an error. It does
   * this by pre-parsing the input and generating from that a count of VALID
   * input characters.
   *
   * @param data the character data.
   * @return The decoded data.
   */
  public static byte[] decode(final char[] data)
  {
    // as our input could contain non-BASE64 data (newlines,
    // whitespace of any sort, whatever) we must first adjust
    // our count of USABLE data so that...
    // (a) we don't misallocate the output array, and
    // (b) think that we miscalculated our data length
    //     just because of extraneous throw-away junk

    int tempLen = data.length;
    for (int ix = 0; ix < data.length; ix++)
    {
      if ((data[ix] > 255) || Base64.CODES[data[ix]] < 0)
      {
        --tempLen; // ignore non-valid chars and padding
      }
    }
    // calculate required length:
    //  -- 3 bytes for every 4 valid base64 chars
    //  -- plus 2 bytes if there are 3 extra base64 chars,
    //     or plus 1 byte if there are 2 extra.

    int len = (tempLen / 4) * 3;
    if ((tempLen % 4) == 3)
    {
      len += 2;
    }
    if ((tempLen % 4) == 2)
    {
      len += 1;
    }

    final byte[] out = new byte[len];


    int shift = 0; // # of excess bits stored in accum
    int accum = 0; // excess bits
    int index = 0;

    // we now go through the entire array (NOT using the 'tempLen' value)
    for (int ix = 0; ix < data.length; ix++)
    {
      final int value = (data[ix] > 255) ? -1 : Base64.CODES[data[ix]];

      if (value >= 0)
      { // skip over non-code
        accum <<= 6; // bits shift up by 6 each time thru
        shift += 6; // loop, with new bits being put in
        accum |= value; // at the bottom.
        if (shift >= 8)
        { // whenever there are 8 or more shifted in,
          shift -= 8; // write them out (from the top, leaving any
          out[index] = // excess at the bottom for next iteration.
              (byte) ((accum >> shift) & 0xff);
          index += 1;
        }
      }
      // we will also have skipped processing a padding null byte ('=') here;
      // these are used ONLY for padding to an even length and do not legally
      // occur as encoded data. for this reason we can ignore the fact that
      // no index++ operation occurs in that special case: the out[] array is
      // initialized to all-zero bytes to start with and that works to our
      // advantage in this combination.
    }

    // if there is STILL something wrong we just have to throw up now!
    if (index != out.length)
    {
      throw new Error("Miscalculated data length (wrote "
          + index + " instead of " + out.length + ')');
    }

    return out;
  }


  //
  // code characters for values 0..63
  //
  private static final char[] ALPHABET =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=".toCharArray();

  //
  // lookup table for converting base64 characters to value in range 0..63
  //
  private static final byte[] CODES = new byte[256];

  static
  {
    for (int i = 0; i < 256; i++)
    {
      Base64.CODES[i] = -1;
    }
    for (int i = 'A'; i <= 'Z'; i++)
    {
      Base64.CODES[i] = (byte) (i - 'A');
    }
    for (int i = 'a'; i <= 'z'; i++)
    {
      Base64.CODES[i] = (byte) (26 + i - 'a');
    }
    for (int i = '0'; i <= '9'; i++)
    {
      Base64.CODES[i] = (byte) (52 + i - '0');
    }
    Base64.CODES['+'] = 62;
    Base64.CODES['/'] = 63;
  }

//
//
//    ///////////////////////////////////////////////////
//    // remainder (main method and helper functions) is
//    // for testing purposes only, feel free to clip it.
//    ///////////////////////////////////////////////////
//
//    /**
//     * Entry point.
//     *
//     * @param args  the command line arguments.
//     */
//    public static void main(final String[] args) {
//        boolean decode = false;
//
//        if (args.length == 0) {
//            System.out.println("usage:  java Base64 [-d[ecode]] filename");
//            System.exit(0);
//        }
//        for (int i = 0; i < args.length; i++) {
//            if ("-decode".equalsIgnoreCase(args[i])) {
//                decode = true;
//            }
//            else if ("-d".equalsIgnoreCase(args[i])) {
//                decode = true;
//            }
//        }
//
//        final String filename = args[args.length - 1];
//        final File file = new File(filename);
//        if (!file.exists()) {
//            System.out.println("Error:  file '" + filename + "' doesn't exist!");
//            System.exit(0);
//        }
//
//        if (decode) {
//            final char[] encoded = org.pentaho.reporting.libraries.xmls.parser.Base64.readChars(file);
//            final byte[] decoded = org.pentaho.reporting.libraries.xmls.parser.Base64.decode(encoded);
//            org.pentaho.reporting.libraries.xmls.parser.Base64.writeBytes(file, decoded);
//        }
//        else {
//            final byte[] decoded = org.pentaho.reporting.libraries.xmls.parser.Base64.readBytes(file);
//            final char[] encoded = org.pentaho.reporting.libraries.xmls.parser.Base64.encode(decoded);
//            org.pentaho.reporting.libraries.xmls.parser.Base64.writeChars(file, encoded);
//        }
//    }
//
//    private static byte[] readBytes(final File file) {
//        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
//        try {
//            final InputStream fis = new FileInputStream(file);
//            final InputStream is = new BufferedInputStream(fis);
//
//            int count;
//            final byte[] buf = new byte[16384];
//            while ((count = is.read(buf)) != -1) {
//                if (count > 0) {
//                    baos.write(buf, 0, count);
//                }
//            }
//            is.close();
//        }
//        catch (Exception e) {
//            e.printStackTrace();
//        }
//
//        return baos.toByteArray();
//    }
//
//    private static char[] readChars(final File file) {
//        final CharArrayWriter caw = new CharArrayWriter();
//        try {
//            final Reader fr = new FileReader(file);
//            final Reader in = new BufferedReader(fr);
//            int count;
//            final char[] buf = new char[16384];
//            while ((count = in.read(buf)) != -1) {
//                if (count > 0) {
//                    caw.write(buf, 0, count);
//                }
//            }
//            in.close();
//        }
//        catch (Exception e) {
//            e.printStackTrace();
//        }
//
//        return caw.toCharArray();
//    }
//
//    private static void writeBytes(final File file, final byte[] data) {
//        try {
//            final OutputStream fos = new FileOutputStream(file);
//            final OutputStream os = new BufferedOutputStream(fos);
//            os.write(data);
//            os.close();
//        }
//        catch (Exception e) {
//            e.printStackTrace();
//        }
//    }
//
//    private static void writeChars(final File file, final char[] data) {
//        try {
//            final Writer fos = new FileWriter(file);
//            final Writer os = new BufferedWriter(fos);
//            os.write(data);
//            os.close();
//        }
//        catch (Exception e) {
//            e.printStackTrace();
//        }
//    }
//    ///////////////////////////////////////////////////
//    // end of test code.
//    ///////////////////////////////////////////////////
//
}