/*
 *  Baltisot
 *  Copyright (C) 1999-2007 Nicolas "Pixel" Noble
 *
 *  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; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <Base64.h>

static char cb64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

String Base64::encode_block(unsigned char in_tab[3], int len) {
    char r[5];
    
    r[0] = cb64[in_tab[0] >> 2];
    r[1] = cb64[((in_tab[0] & 3) << 4) | ((in_tab[1] & 240) >> 4)];
    r[2] = len > 1 ? cb64[((in_tab[1] & 15) << 2) | ((in_tab[2] & 192) >> 6)] : '=';
    r[3] = len > 2 ? cb64[in_tab[2] & 63] : '=';
    r[4] = 0;
    
    return r;
}

String Base64::encode(const char * data, int stream_size) {
    String encoded = "";
    unsigned char in_tab[3];
    int len, i, s_pos;

    s_pos = 0;

    while (stream_size > 0) {
        in_tab[0] = 0;
        in_tab[1] = 0;
        in_tab[2] = 0;

        len = stream_size >= 3 ? 3 : stream_size;

        for (i = 0; i < len; i++) {
            in_tab[i] = data[s_pos + i];
        }

        encoded += encode_block(in_tab, len);

        s_pos += 3;
        stream_size -= 3;
    }

    return encoded;
}

int Base64::stri(char x) {
    char * p = strchr(cb64, x);
    return ((x == '=') || (p == 0)) ? -1 : (p - cb64);
}

int Base64::decode_block(char s1, char s2, char s3, char s4, unsigned char * out_tab) {
    int len, sb1, sb2, sb3, sb4;

    len = s3 == '=' ? 1 : s4 == '=' ? 2 : 3;
    s3 = (s3 == '=') || (s3 == 0) ? 'A' : s3;
    s4 = (s4 == '=') || (s4 == 0) ? 'A' : s4;
    
    sb1 = stri(s1);
    sb2 = stri(s2);
    sb3 = stri(s3);
    sb4 = stri(s4);
    
    out_tab[0] = (sb1 << 2) | (sb2 >> 4);
    out_tab[1] = ((sb2 << 4) & 255) | (sb3 >> 2);
    out_tab[2] = ((sb3 << 6) & 240) | sb4;
    
    return len;
}

unsigned char * Base64::decode(const String & str_in, int * len_out) {
    int s_len = str_in.strlen(), len = 0, i, j, t_len;
    char s1, s2, s3, s4;
    unsigned char t_out[3];
    unsigned char * out = (unsigned char *) malloc(s_len * 3 / 4 + 4);
    unsigned char * p = out;
    
    for (i = 0; i < s_len; i += 4) {
        s1 = str_in[i + 0];
        s2 = str_in[i + 1];
        s3 = str_in[i + 2];
        s4 = str_in[i + 3];
        t_len = decode_block(s1, s2, s3, s4, t_out);
        
        for (j = 0; j < t_len; j++) {
            *(p++) = t_out[j];
        }

        len += t_len;
    }
    
    if (len_out) {
        *len_out = len;
    }

    return out;
}