package com.secspace.lib.common.utils;

public class Base64Coder {

    //The line separator string of the operating system.
    private static final String systemLineSeparator = System.getProperty("line.separator");

    //Mapping table from 6-bit nibbles to Base64 characters.
    private static char[] map1 = new char[64];
    static {
       int i=0;
       for (char c='A'; c<='Z'; c++) map1[i++] = c;
       for (char c='a'; c<='z'; c++) map1[i++] = c;
       for (char c='0'; c<='9'; c++) map1[i++] = c;
       map1[i++] = '+'; map1[i++] = '/'; }

    //Mapping table from Base64 characters to 6-bit nibbles.
    private static byte[] map2 = new byte[128];
    static {
       for (int i=0; i<map2.length; i++) map2[i] = -1;
       for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; }

    /**
    * Encodes a string into Base64 format.
    * No blanks or line breaks are inserted.
    * @param s  A String to be encoded.
    * @return   A String containing the Base64 encoded data.
    */
    public static String encodeString (String s) {
    return new String(encode(s.getBytes())); }

    /**
    * Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters.
    * This method is compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
    * @param in  An array containing the data bytes to be encoded.
    * @return    A String containing the Base64 encoded data, broken into lines.
    */
    public static String encodeLines (byte[] in) {
    return encodeLines(in, 0, in.length, 76, systemLineSeparator); }

    /**
    * Encodes a byte array into Base 64 format and breaks the output into lines.
    * @param in            An array containing the data bytes to be encoded.
    * @param iOff          Offset of the first byte in <code>in</code> to be processed.
    * @param iLen          Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>.
    * @param lineLen       Line length for the output data. Should be a multiple of 4.
    * @param lineSeparator The line separator to be used to separate the output lines.
    * @return              A String containing the Base64 encoded data, broken into lines.
    */
    public static String encodeLines (byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
    int blockLen = (lineLen*3) / 4;
    if (blockLen <= 0) throw new IllegalArgumentException();
    int lines = (iLen+blockLen-1) / blockLen;
    int bufLen = ((iLen+2)/3)*4 + lines*lineSeparator.length();
    StringBuilder buf = new StringBuilder(bufLen);
    int ip = 0;
    while (ip < iLen) {
       int l = Math.min(iLen-ip, blockLen);
       buf.append (encode(in, iOff+ip, l));
       buf.append (lineSeparator);
       ip += l; }
    return buf.toString(); }

    /**
    * Encodes a byte array into Base64 format.
    * No blanks or line breaks are inserted in the output.
    * @param in  An array containing the data bytes to be encoded.
    * @return    A character array containing the Base64 encoded data.
    */
    public static char[] encode (byte[] in) {
    return encode(in, 0, in.length); }

    /**
    * Encodes a byte array into Base64 format.
    * No blanks or line breaks are inserted in the output.
    * @param in    An array containing the data bytes to be encoded.
    * @param iLen  Number of bytes to process in <code>in</code>.
    * @return      A character array containing the Base64 encoded data.
    */
    public static char[] encode (byte[] in, int iLen) {
    return encode(in, 0, iLen); }

    /**
    * Encodes a byte array into Base64 format.
    * No blanks or line breaks are inserted in the output.
    * @param in    An array containing the data bytes to be encoded.
    * @param iOff  Offset of the first byte in <code>in</code> to be processed.
    * @param iLen  Number of bytes to process in <code>in</code>, starting at <code>iOff</code>.
    * @return      A character array containing the Base64 encoded data.
    */
    public static char[] encode (byte[] in, int iOff, int iLen) {
    int oDataLen = (iLen*4+2)/3;       // output length without padding
    int oLen = ((iLen+2)/3)*4;         // output length including padding
    char[] out = new char[oLen];
    int ip = iOff;
    int iEnd = iOff + iLen;
    int op = 0;
    while (ip < iEnd) {
       int i0 = in[ip++] & 0xff;
       int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
       int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
       int o0 = i0 >>> 2;
       int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
       int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
       int o3 = i2 & 0x3F;
       out[op++] = map1[o0];
       out[op++] = map1[o1];
       out[op] = op < oDataLen ? map1[o2] : '='; op++;
       out[op] = op < oDataLen ? map1[o3] : '='; op++; }
    return out; }

    /**
    * Decodes a string from Base64 format.
    * No blanks or line breaks are allowed within the Base64 encoded input data.
    * @param s  A Base64 String to be decoded.
    * @return   A String containing the decoded data.
    * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
    */
    public static String decodeString (String s) {
    return new String(decode(s)); }

    /**
    * Decodes a byte array from Base64 format and ignores line separators, tabs and blanks.
    * CR, LF, Tab and Space characters are ignored in the input data.
    * This method is compatible with <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
    * @param s  A Base64 String to be decoded.
    * @return   An array containing the decoded data bytes.
    * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
    */
    public static byte[] decodeLines (String s) {
    char[] buf = new char[s.length()];
    int p = 0;
    for (int ip = 0; ip < s.length(); ip++) {
       char c = s.charAt(ip);
       if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
          buf[p++] = c; }
    return decode(buf, 0, p); }

    /**
    * Decodes a byte array from Base64 format.
    * No blanks or line breaks are allowed within the Base64 encoded input data.
    * @param s  A Base64 String to be decoded.
    * @return   An array containing the decoded data bytes.
    * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
    */
    public static byte[] decode (String s) {
    return decode(s.toCharArray()); }

    /**
    * Decodes a byte array from Base64 format.
    * No blanks or line breaks are allowed within the Base64 encoded input data.
    * @param in  A character array containing the Base64 encoded data.
    * @return    An array containing the decoded data bytes.
    * @throws    IllegalArgumentException If the input is not valid Base64 encoded data.
    */
    public static byte[] decode (char[] in) {
    return decode(in, 0, in.length); }

    /**
    * Decodes a byte array from Base64 format.
    * No blanks or line breaks are allowed within the Base64 encoded input data.
    * @param in    A character array containing the Base64 encoded data.
    * @param iOff  Offset of the first character in <code>in</code> to be processed.
    * @param iLen  Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
    * @return      An array containing the decoded data bytes.
    * @throws      IllegalArgumentException If the input is not valid Base64 encoded data.
    */
    public static byte[] decode (char[] in, int iOff, int iLen) {
    if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
    while (iLen > 0 && in[iOff+iLen-1] == '=') iLen--;
    int oLen = (iLen*3) / 4;
    byte[] out = new byte[oLen];
    int ip = iOff;
    int iEnd = iOff + iLen;
    int op = 0;
    while (ip < iEnd) {
       int i0 = in[ip++];
       int i1 = in[ip++];
       int i2 = ip < iEnd ? in[ip++] : 'A';
       int i3 = ip < iEnd ? in[ip++] : 'A';
       if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
          throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
       int b0 = map2[i0];
       int b1 = map2[i1];
       int b2 = map2[i2];
       int b3 = map2[i3];
       if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
          throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
       int o0 = ( b0       <<2) | (b1>>>4);
       int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
       int o2 = ((b2 &   3)<<6) |  b3;
       out[op++] = (byte)o0;
       if (op<oLen) out[op++] = (byte)o1;
       if (op<oLen) out[op++] = (byte)o2; }
    return out; }

    //Dummy constructor.
    private Base64Coder() {}
} // end class Base64Coder

