/**
 * @file	cf_codec.c
 * @author	myusgun <myusgun@gmail.com>
 */
#include "cf_codec.h"
#include "cf_error.h"

#include <string.h>
#include <stdio.h>

#define ASSERT_ARGS(x)	\
	if ((x))			\
		return CF_ERROR_CODEC_INVALID_ARGS

const static unsigned char g_ascii_HexDecode[] = {
#define ASCN	'0'	/* ascii number */
#define ASCU	'A' /* ascii upper */
#define ASCL	'a' /* ascii lower */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/*  00 -  15 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/*  16 -  31 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/*  32 -  47 */
	ASCN,ASCN,ASCN,ASCN,ASCN,ASCN,ASCN,ASCN,ASCN,ASCN,0x00,0x00,0x00,0x00,0x00,0x00,	/*  48 -  63 */
	0x00,ASCU,ASCU,ASCU,ASCU,ASCU,ASCU,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/*  64 -  79 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/*  80 -  95 */
	0x00,ASCL,ASCL,ASCL,ASCL,ASCL,ASCL,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/*  96 - 111 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 112 - 127 */
	/* end of ascii character */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 128 - 143 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 144 - 159 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 160 - 175 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 176 - 191 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 192 - 207 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 208 - 223 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 224 - 239 */
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,	/* 240 - 255 */
};

const static char g_table_Base64Encode[] = {
#define PADDING_CHAR_INDEX	64
	'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',		/* 00 - 07 */
	'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',		/* 08 - 15 */
	'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',		/* 16 - 23 */
	'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',		/* 24 - 31 */
	'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',		/* 32 - 39 */
	'o', 'p', 'q', 'r', 's', 't', 'u', 'v',		/* 40 - 47 */
	'w', 'x', 'y', 'z', '0', '1', '2', '3',		/* 48 - 55 */
	'4', '5', '6', '7', '8', '9', '+', '/',		/* 56 - 63 */
	'='											/* padding */
};

const static unsigned char g_ascii_Base64Decode[] = {
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/*  00 -  15 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/*  16 -  31 */
	99,99,99,99,99,99,99,99,99,99,99,62,99,99,99,63,	/*  32 -  47 */
	52,53,54,55,56,57,58,59,60,61,99,99,99,64,99,99,	/*  48 -  63 */
	99, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,	/*  64 -  79 */
	15,16,17,18,19,20,21,22,23,24,25,99,99,99,99,99,	/*  80 -  95 */
	99,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,	/*  96 - 111 */
	41,42,43,44,45,46,47,48,49,50,51,99,99,99,99,99,	/* 112 - 127 */
	/* end of ascii character */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 128 - 143 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 144 - 159 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 160 - 175 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 176 - 191 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 192 - 207 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 208 - 223 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 224 - 239 */
	99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,	/* 240 - 255 */
};


/**
 * hex-encode
 *
 * @return 성공 시, CF_OK; 실패 시, 오류 코드
 *
 * @param bin	바이너리 데이터
 * @param len	바이너리 데이터 길이
 * @param hex	16진수 문자열을 저장할 주소
 *
 * @remark
 * hex는 할당된 메모리이며, 크기는 '\0'를 포함하여 len * 2 + 1
 */
int
CF_Codec_Hex_Encode (const unsigned char	* bin,
					 const size_t			len,
					 char					* hex)
{
	size_t	iter = 0;
	size_t	hexlen = len * 2 + 1;

	const unsigned char	* ptr = bin;

	const static char	hexchar[] = {'0', '1', '2', '3',
									 '4', '5', '6', '7',
									 '8', '9', 'a', 'b',
									 'c', 'd', 'e', 'f'};

	ASSERT_ARGS (bin == NULL);
	ASSERT_ARGS (hex == NULL);

	for (iter = 0 ; iter < hexlen ; iter += 2, ptr++)
	{
		hex[iter    ] = hexchar[((*(ptr)) >> 4) & 0x0f];
		hex[iter + 1] = hexchar[((*(ptr))     ) & 0x0f];
	}
	hex[hexlen - 1] = '\0';

	return CF_OK;
}

/**
 * hex-decode
 *
 * @return 성공 시, CF_OK; 실패 시, 오류 코드
 *
 * @param hex	16진수 문자열
 * @param bin	바이너리 데이터를 저장할 주소
 * @param len	바이너리 데이터의 길이를 저장할 주소
 *
 * @remark
 * bin는 할당된 메모리이며, 크기는 strlen (hex) / 2
 */
int
CF_Codec_Hex_Decode (const char		* hex,
					 unsigned char	* bin,
					 size_t			* len)
{
	int		result = 0;

	size_t	length = strlen (hex);	/* absolutely even-number */
	size_t	iter = 0;
	size_t	binlen = length / 2;

	const char		* ptr = hex;
	char			buf = 0;
	unsigned char	val = 0;
	unsigned char	asciiHex = 0;

	ASSERT_ARGS (hex == NULL);
	ASSERT_ARGS (bin == NULL);
	ASSERT_ARGS (len == NULL);

	for (iter = 0 ; iter < binlen ; iter++)
	{
		val = 0;	/* init/re-init docoding-buffer */

		/* decode one character */
#define DECODE_HEX(x)								\
		do {										\
		buf = *(x);									\
		val = (unsigned char)(val << 4);			\
		asciiHex = g_ascii_HexDecode[(int)buf];		\
													\
		if (buf)									\
			val |=	(unsigned char)					\
					(buf - asciiHex + (asciiHex == ASCN ? 0 : 10));	\
		else										\
			return CF_ERROR_CODEC_NOT_HEXSTRING;	\
		} while (0)

		/* decode one byte by decode two character */
		DECODE_HEX (ptr++);
		DECODE_HEX (ptr++);

		bin[iter] = val;
	}

	*len = binlen;

	return result;
}

/**
 * Base64-encode
 *
 * @return 성공 시, CF_OK; 실패 시, 오류 코드
 *
 * @param bin		바이너리 데이터
 * @param len		바이너리 데이터 길이
 * @param base64	base64 문자열을 저장할 주소
 *
 * @remark
 * base64는 할당된 메모리이며, 크기는 '\0'를 포함하여 (((len + 2) / 3) * 4) + 1
 *
 * @see http://sourceforge.net/p/predef/wiki/Endianness/
 */
int
CF_Codec_Base64_Encode (const unsigned char	* bin,
						const size_t		len,
						char				* base64)
{
	size_t	iter = 0;
	char	* ptr = base64;

	ASSERT_ARGS (bin	== NULL);
	ASSERT_ARGS (base64	== NULL);

#define SEXTUPLE_E_1(__x,_idx)	((__x[_idx    ] >> 2) & 0x3f)
#define SEXTUPLE_E_2(__x,_idx)	((__x[_idx    ] << 4) & 0x30)
#define SEXTUPLE_E_3(__x,_idx)	((__x[_idx + 1] >> 4) & 0x0f)
#define SEXTUPLE_E_4(__x,_idx)	((__x[_idx + 1] << 2) & 0x3c)
#define SEXTUPLE_E_5(__x,_idx)	((__x[_idx + 2] >> 6) & 0x03)
#define SEXTUPLE_E_6(__x,_idx)	((__x[_idx + 2]     ) & 0x3f)

	for (iter = 0 ; iter < len - 2 ; iter += 3)
	{
		*ptr++ = g_table_Base64Encode[SEXTUPLE_E_1 (bin, iter)];
		*ptr++ = g_table_Base64Encode[SEXTUPLE_E_2 (bin, iter)|
									  SEXTUPLE_E_3 (bin, iter)];
		*ptr++ = g_table_Base64Encode[SEXTUPLE_E_4 (bin, iter)|
									  SEXTUPLE_E_5 (bin, iter)];
		*ptr++ = g_table_Base64Encode[SEXTUPLE_E_6 (bin, iter)];
	}

	if (iter < len)
	{
		*ptr++ = g_table_Base64Encode[SEXTUPLE_E_1 (bin, iter)];

		if (iter == (len - 1))
		{
			*ptr++ = g_table_Base64Encode[SEXTUPLE_E_2 (bin, iter)];
			*ptr++ = g_table_Base64Encode[PADDING_CHAR_INDEX];
		}
		else
		{
			*ptr++ = g_table_Base64Encode[SEXTUPLE_E_2 (bin, iter)|
										  SEXTUPLE_E_3 (bin, iter)];
			*ptr++ = g_table_Base64Encode[SEXTUPLE_E_4 (bin, iter)];
		}

		*ptr++ = g_table_Base64Encode[PADDING_CHAR_INDEX];
	}
	*ptr = '\0';

	return CF_OK;
}

/**
 * Base64-decode
 *
 * @return 성공 시, CF_OK; 실패 시, 오류 코드
 *
 * @param base64	base64 문자열
 * @param bin		바이너리 데이터를 저장할 주소
 * @param len		바이너리 데이터의 길이를 저장할 주소
 *
 * @remark
 * base64는 할당된 메모리이며, 크기는 (strlen (base64) - <'=' 개수>) / 4 * 3
 *
 * @see http://sourceforge.net/p/predef/wiki/Endianness/
 */
int
CF_Codec_Base64_Decode (const char		* base64,
						unsigned char	* bin,
						size_t			* len)
{
	size_t			remain = 0;
	const char		* src = base64;
	unsigned char	* dst = bin;
	size_t			binlen = 0;

	ASSERT_ARGS (base64	== NULL);
	ASSERT_ARGS (bin	== NULL);
	ASSERT_ARGS (len	== NULL);

	while (*src && g_ascii_Base64Decode[(int)*src] < PADDING_CHAR_INDEX) src++;

	if (*src)
		return CF_ERROR_CODEC_NOT_BASE64;

	remain = (size_t)(src - base64);
	binlen = ((remain + 3) / 4) * 3;

#define SEXTUPLE_D_1(src)	(g_ascii_Base64Decode[(int)src[0]] << 2)
#define SEXTUPLE_D_2(src)	(g_ascii_Base64Decode[(int)src[1]] >> 4)
#define SEXTUPLE_D_3(src)	(g_ascii_Base64Decode[(int)src[1]] << 4)
#define SEXTUPLE_D_4(src)	(g_ascii_Base64Decode[(int)src[2]] >> 2)
#define SEXTUPLE_D_5(src)	(g_ascii_Base64Decode[(int)src[2]] << 6)
#define SEXTUPLE_D_6(src)	(g_ascii_Base64Decode[(int)src[3]]     )

	for (src = base64, dst = bin ; remain > 4 ; remain -= 4, src += 4)
	{
		*dst++ = (unsigned char)(SEXTUPLE_D_1 (src) | SEXTUPLE_D_2 (src));
		*dst++ = (unsigned char)(SEXTUPLE_D_3 (src) | SEXTUPLE_D_4 (src));
		*dst++ = (unsigned char)(SEXTUPLE_D_5 (src) | SEXTUPLE_D_6 (src));
	}

	if (remain > 1)
		*dst++ = (unsigned char)(SEXTUPLE_D_1 (src) | SEXTUPLE_D_2 (src));

	if (remain > 2)
		*dst++ = (unsigned char)(SEXTUPLE_D_3 (src) | SEXTUPLE_D_4 (src));

	if (remain > 3)
		*dst++ = (unsigned char)(SEXTUPLE_D_5 (src) | SEXTUPLE_D_6 (src));

	*dst++ = '\0';
	*len = binlen;

	return CF_OK;
}