#include "base64.h"


static const std::string base64_chars_basic =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	"abcdefghijklmnopqrstuvwxyz"
	"0123456789+/";

static const std::string base64_chars_fsafe =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	"abcdefghijklmnopqrstuvwxyz"
	"0123456789-,";


static inline bool is_base64(unsigned char c)
{
    return ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || (c == '+') || (c == '/'));
}

std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len, BASE64_ALPHABET alphabet)
{
    std::string ret;
    int i = 0;
    int j = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];

	std::string b64chars;
	if (alphabet == BASE64_ALPHABET_FSAFE)
	{
		b64chars = base64_chars_fsafe;
	}
	else
	{
		b64chars = base64_chars_basic;
	}

    while (in_len--)
    {
        char_array_3[i++] = *(bytes_to_encode++);
        if (i == 3)
        {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;

            for (i = 0; (i <4) ; i++)
				ret += b64chars[char_array_4[i]];
            i = 0;
        }
    }

    if (i)
    {
        for (j = i; j < 3; j++)
            char_array_3[j] = '\0';

        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
        char_array_4[3] = char_array_3[2] & 0x3f;

        for (j = 0; (j < i + 1); j++)
            ret += b64chars[char_array_4[j]];

        while ((i++ < 3))
            ret += '=';

    }

    return ret;

}

std::string base64_decode(std::string const& encoded_string, BASE64_ALPHABET alphabet)
{
    int in_len = encoded_string.size();
    int i = 0;
    int j = 0;
    int in_ = 0;
    unsigned char char_array_4[4], char_array_3[3];
	std::string ret;

	std::string b64chars;
	if (alphabet == BASE64_ALPHABET_FSAFE)
	{
		b64chars = base64_chars_fsafe;
	}
	else
	{
		b64chars = base64_chars_basic;
	}	

    while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_]))
    {
        char_array_4[i++] = encoded_string[in_];
        in_++;
        if (i ==4)
        {
            for (i = 0; i <4; i++)
                char_array_4[i] = b64chars.find(char_array_4[i]);

            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

            for (i = 0; (i < 3); i++)
                ret += char_array_3[i];
            i = 0;
        }
    }

    if (i)
    {
        for (j = i; j <4; j++)
            char_array_4[j] = 0;

        for (j = 0; j <4; j++)
            char_array_4[j] = b64chars.find(char_array_4[j]);

        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
        char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

        for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
    }

    return ret;
}
