/*
   +----------------------------------------------------------------------+
   | PHP version 4.0                                                      |
   +----------------------------------------------------------------------+
   | Copyright (c) 1997, 1998, 1999, 2000 The PHP Group                   |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.02 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available at through the world-wide-web at                           |
   | http://www.php.net/license/2_02.txt.                                 |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Author: Jim Winstead (jimw@php.net)                                  |
   +----------------------------------------------------------------------+
   */

#include <cstring>
#include <cstdlib>

#include "base64.h"

static char base64_table[] =
{
    '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', '+', '/', '\0'
};
static char base64_pad = '=';

unsigned char *php_base64_encode(const unsigned char *str, int length, int *ret_length) {
    const unsigned char *current = str;
    int i = 0;
    unsigned char *result = (unsigned char *)malloc(((length + 3 - length % 3) * 4 / 3 + 1) * sizeof(char));

    while (length > 2) { /* keep going until we have less than 24 bits */
        result[i++] = base64_table[current[0] >> 2];
        result[i++] = base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
        result[i++] = base64_table[((current[1] & 0x0f) << 2) + (current[2] >> 6)];
        result[i++] = base64_table[current[2] & 0x3f];

        current += 3;
        length -= 3; /* we just handle 3 octets of data */
    }

    /* now deal with the tail end of things */
    if (length != 0) {
        result[i++] = base64_table[current[0] >> 2];
        if (length > 1) {
            result[i++] = base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
            result[i++] = base64_table[(current[1] & 0x0f) << 2];
            result[i++] = base64_pad;
        }
        else {
            result[i++] = base64_table[(current[0] & 0x03) << 4];
            result[i++] = base64_pad;
            result[i++] = base64_pad;
        }
    }
    if(ret_length) {
        *ret_length = i;
    }
    result[i] = '\0';
    return result;
}

/* as above, but backwards. :) */
unsigned char *php_base64_decode(const unsigned char *str, int length, int *ret_length) {
    const unsigned char *current = str;
    int ch, i = 0, j = 0, k;
    /* this sucks for threaded environments */
    static short reverse_table[256];
    static int table_built;
    unsigned char *result;

    if (++table_built == 1) {
        char *chp;
        for(ch = 0; ch < 256; ch++) {
            chp = strchr(base64_table, ch);
            if(chp) {
                reverse_table[ch] = chp - base64_table;
            } else {
                reverse_table[ch] = -1;
            }
        }
    }

    result = (unsigned char *)malloc(length + 1);
    if (result == nullptr) {
        return nullptr;
    }

    /* run through the whole string, converting as we go */
    while ((ch = *current++) != '\0') {
        if (ch == base64_pad) break;

        /* When Base64 gets POSTed, all pluses are interpreted as spaces.
           This line changes them back.  It's not exactly the Base64 spec,
           but it is completely compatible with it (the spec says that
           spaces are invalid).  This will also save many people considerable
           headache.  - Turadg Aleahmad <turadg@wise.berkeley.edu>
           */

        if (ch == ' ') ch = '+'; 

        ch = reverse_table[ch];
        if (ch < 0) continue;

        switch(i % 4) {
            case 0:
                result[j] = ch << 2;
                break;
            case 1:
                result[j++] |= ch >> 4;
                result[j] = (ch & 0x0f) << 4;
                break;
            case 2:
                result[j++] |= ch >>2;
                result[j] = (ch & 0x03) << 6;
                break;
            case 3:
                result[j++] |= ch;
                break;
        }
        i++;
    }

    k = j;
    /* mop things up if we ended on a boundary */
    if (ch == base64_pad) {
        switch(i % 4) {
            case 0:
            case 1:
                free(result);
                return nullptr;
            case 2:
                k++;
            case 3:
                result[k++] = 0;
        }
    }
    if(ret_length) {
        *ret_length = j;
    }
    result[k] = '\0';
    return result;
}