/**
 *  @file base64.cc
 *  @brief Implementation of base64 Utilities
 *  @author Andreas Aardal Hanssen
 *  @date 2002-2005
 */

#include "base64.h"

#include <iostream>
#include <string>

using std::string;

typedef unsigned char bbyte;  // Byte type

#define TRUE  1
#define FALSE 0

#define LINELEN 72  // Encoded line length (max 76)

static bbyte dtable[256];

string Binc::base64encode(const string &s_in)
{
  int i;
  string result;

  // Fill dtable with character encodings.

  for (i = 0; i < 26; i++) {
    dtable[i] = 'A' + i;
    dtable[26 + i] = 'a' + i;
  }
  for (i = 0; i < 10; i++)
    dtable[52 + i] = '0' + i;
  dtable[62] = '+';
  dtable[63] = '/';

  string::const_iterator s_i = s_in.begin();
  while (s_i != s_in.end()) {
    bbyte igroup[3], ogroup[4];
    int c, n;

    igroup[0] = igroup[1] = igroup[2] = 0;
    for (n = 0; n < 3 && s_i != s_in.end(); n++) {
      c = *s_i++;
      igroup[n] = static_cast<bbyte>(c);
    }

    if (n > 0) {
      ogroup[0] = dtable[igroup[0] >> 2];
      ogroup[1] = dtable[((igroup[0] & 3) << 4) | (igroup[1] >> 4)];
      ogroup[2] = dtable[((igroup[1] & 0xF) << 2) | (igroup[2] >> 6)];
      ogroup[3] = dtable[igroup[2] & 0x3F];

      // Replace characters in output stream with "=" pad
      // characters if fewer than three characters were
      // read from the end of the input stream.

      if (n < 3) {
        ogroup[3] = '=';
        if (n < 2) ogroup[2] = '=';
      }

      for (i = 0; i < 4; i++)
        result += ogroup[i];
    }
  }

  return result;
}

string Binc::base64decode(const string &s_in)
{
  string result;
  int i;

  for (i = 0; i < 255; i++)
    dtable[i] = 0x80;
  for (i = 'A'; i <= 'Z'; i++)
    dtable[i] = 0 + (i - 'A');
  for (i = 'a'; i <= 'z'; i++)
    dtable[i] = 26 + (i - 'a');
  for (i = '0'; i <= '9'; i++)
    dtable[i] = 52 + (i - '0');
  dtable[(int)'+'] = 62;
  dtable[(int)'/'] = 63;
  dtable[(int)'='] = 0;

  /*CONSTANTCONDITION*/
  string::const_iterator s_i = s_in.begin();
  while (s_i != s_in.end()) {
    bbyte a[4], b[4], o[3];

    for (i = 0; i < 4 && s_i != s_in.end(); i++) {
      int c = *s_i++;
      if (dtable[c] & 0x80) return result;
      a[i] = (bbyte)c;
      b[i] = (bbyte)dtable[c];
    }

    o[0] = (b[0] << 2) | (b[1] >> 4);
    o[1] = (b[1] << 4) | (b[2] >> 2);
    o[2] = (b[2] << 6) | b[3];

    i = a[2] == '=' ? 1 : (a[3] == '=' ? 2 : 3);

    for (int j = 0; j < i; ++j)
      result += o[j];

    if (i < 3) break;
  }

  return result;
}