/*
 * conversion functions between pg_wchar and multi-byte streams.
 * Tatsuo Ishii
 * $Id: wchar.c,v 1.24 2001/10/15 01:19:15 ishii Exp $
 *
 * WIN1250 client encoding updated by Pavel Behal
 *
 */
/* can be used in either frontend or backend */
#ifdef FRONTEND
#include "postgres_fe.h"
#define Assert(condition)
#else
#include "postgres.h"
#endif

#include "mb/pg_wchar.h"


/*
 * conversion to pg_wchar is done by "table driven."
 * to add an encoding support, define mb2wchar_with_len(), mblen()
 * for the particular encoding. Note that if the encoding is only
 * supported in the client, you don't need to define
 * mb2wchar_with_len() function (SJIS is the case).
 */

/*
 * SQL/ASCII
 */
static int	pg_ascii2wchar_with_len
			(const unsigned char *from, pg_wchar * to, int len)
{
	int			cnt = 0;

	while (len > 0 && *from)
	{
		*to++ = *from++;
		len--;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

static int
pg_ascii_mblen(const unsigned char *s)
{
	return (1);
}

/*
 * EUC
 */

static int	pg_euc2wchar_with_len
			(const unsigned char *from, pg_wchar * to, int len)
{
	int			cnt = 0;

	while (len > 0 && *from)
	{
		if (*from == SS2 && len >= 2)
		{
			from++;
			*to = 0xff & *from++;
			len -= 2;
		}
		else if (*from == SS3 && len >= 3)
		{
			from++;
			*to = *from++ << 8;
			*to |= 0x3f & *from++;
			len -= 3;
		}
		else if ((*from & 0x80) && len >= 2)
		{
			*to = *from++ << 8;
			*to |= *from++;
			len -= 2;
		}
		else
		{
			*to = *from++;
			len--;
		}
		to++;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

static int
pg_euc_mblen(const unsigned char *s)
{
	int			len;

	if (*s == SS2)
		len = 2;
	else if (*s == SS3)
		len = 3;
	else if (*s & 0x80)
		len = 2;
	else
		len = 1;
	return (len);
}

/*
 * EUC_JP
 */
static int	pg_eucjp2wchar_with_len
			(const unsigned char *from, pg_wchar * to, int len)
{
	return (pg_euc2wchar_with_len(from, to, len));
}

static int
pg_eucjp_mblen(const unsigned char *s)
{
	return (pg_euc_mblen(s));
}

/*
 * EUC_KR
 */
static int	pg_euckr2wchar_with_len
			(const unsigned char *from, pg_wchar * to, int len)
{
	return (pg_euc2wchar_with_len(from, to, len));
}

static int
pg_euckr_mblen(const unsigned char *s)
{
	return (pg_euc_mblen(s));
}

/*
 * EUC_CN
 */
static int	pg_euccn2wchar_with_len
			(const unsigned char *from, pg_wchar * to, int len)
{
	int			cnt = 0;

	while (len > 0 && *from)
	{
		if (*from == SS2 && len >= 3)
		{
			from++;
			*to = 0x3f00 & (*from++ << 8);
			*to = *from++;
			len -= 3;
		}
		else if (*from == SS3 && len >= 3)
		{
			from++;
			*to = *from++ << 8;
			*to |= 0x3f & *from++;
			len -= 3;
		}
		else if ((*from & 0x80) && len >= 2)
		{
			*to = *from++ << 8;
			*to |= *from++;
			len -= 2;
		}
		else
		{
			*to = *from++;
			len--;
		}
		to++;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

static int
pg_euccn_mblen(const unsigned char *s)
{
	int			len;

	if (*s & 0x80)
		len = 2;
	else
		len = 1;
	return (len);
}

/*
 * EUC_TW
 */
static int	pg_euctw2wchar_with_len
			(const unsigned char *from, pg_wchar * to, int len)
{
	int			cnt = 0;

	while (len > 0 && *from)
	{
		if (*from == SS2 && len >= 4)
		{
			from++;
			*to = *from++ << 16;
			*to |= *from++ << 8;
			*to |= *from++;
			len -= 4;
		}
		else if (*from == SS3 && len >= 3)
		{
			from++;
			*to = *from++ << 8;
			*to |= 0x3f & *from++;
			len -= 3;
		}
		else if ((*from & 0x80) && len >= 2)
		{
			*to = *from++ << 8;
			*to |= *from++;
			len -= 2;
		}
		else
		{
			*to = *from++;
			len--;
		}
		to++;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

static int
pg_euctw_mblen(const unsigned char *s)
{
	int			len;

	if (*s == SS2)
		len = 4;
	else if (*s == SS3)
		len = 3;
	else if (*s & 0x80)
		len = 2;
	else
		len = 1;
	return (len);
}

/*
 * convert UTF-8 string to pg_wchar (UCS-2)
 * caller should allocate enough space for "to"
 * len: length of from.
 * "from" not necessarily null terminated.
 */
static int
pg_utf2wchar_with_len(const unsigned char *from, pg_wchar * to, int len)
{
	unsigned char c1,
				c2,
				c3;
	int			cnt = 0;

	while (len > 0 && *from)
	{
		if ((*from & 0x80) == 0)
		{
			*to = *from++;
			len--;
		}
		else if ((*from & 0xe0) == 0xc0 && len >= 2)
		{
			c1 = *from++ & 0x1f;
			c2 = *from++ & 0x3f;
			*to = c1 << 6;
			*to |= c2;
			len -= 2;
		}
		else if ((*from & 0xe0) == 0xe0 && len >= 3)
		{
			c1 = *from++ & 0x0f;
			c2 = *from++ & 0x3f;
			c3 = *from++ & 0x3f;
			*to = c1 << 12;
			*to |= c2 << 6;
			*to |= c3;
			len -= 3;
		}
		else
		{
			*to = *from++;
			len--;
		}
		to++;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

/*
 * returns the byte length of a UTF-8 word pointed to by s
 */
int
pg_utf_mblen(const unsigned char *s)
{
	int			len = 1;

	if ((*s & 0x80) == 0)
		len = 1;
	else if ((*s & 0xe0) == 0xc0)
		len = 2;
	else if ((*s & 0xe0) == 0xe0)
		len = 3;
	return (len);
}

/*
 * convert mule internal code to pg_wchar
 * caller should allocate enough space for "to"
 * len: length of from.
 * "from" not necessarily null terminated.
 */
static int
pg_mule2wchar_with_len(const unsigned char *from, pg_wchar * to, int len)
{
	int			cnt = 0;

	while (len > 0 && *from)
	{
		if (IS_LC1(*from) && len >= 2)
		{
			*to = *from++ << 16;
			*to |= *from++;
			len -= 2;
		}
		else if (IS_LCPRV1(*from) && len >= 3)
		{
			from++;
			*to = *from++ << 16;
			*to |= *from++;
			len -= 3;
		}
		else if (IS_LC2(*from) && len >= 3)
		{
			*to = *from++ << 16;
			*to |= *from++ << 8;
			*to |= *from++;
			len -= 3;
		}
		else if (IS_LCPRV2(*from) && len >= 4)
		{
			from++;
			*to = *from++ << 16;
			*to |= *from++ << 8;
			*to |= *from++;
			len -= 4;
		}
		else
		{						/* assume ASCII */
			*to = (unsigned char) *from++;
			len--;
		}
		to++;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

int
pg_mule_mblen(const unsigned char *s)
{
	int			len;

	if (IS_LC1(*s))
		len = 2;
	else if (IS_LCPRV1(*s))
		len = 3;
	else if (IS_LC2(*s))
		len = 3;
	else if (IS_LCPRV2(*s))
		len = 4;
	else
	{							/* assume ASCII */
		len = 1;
	}
	return (len);
}

/*
 * ISO8859-1
 */
static int
pg_latin12wchar_with_len(const unsigned char *from, pg_wchar * to, int len)
{
	int			cnt = 0;

	while (len > 0 && *from)
	{
		*to++ = *from++;
		len--;
		cnt++;
	}
	*to = 0;
	return (cnt);
}

static int
pg_latin1_mblen(const unsigned char *s)
{
	return (1);
}

/*
 * SJIS
 */
static int
pg_sjis_mblen(const unsigned char *s)
{
	int			len;

	if (*s >= 0xa1 && *s <= 0xdf)
	{							/* 1 byte kana? */
		len = 1;
	}
	else if (*s > 0x7f)
	{							/* kanji? */
		len = 2;
	}
	else
	{							/* should be ASCII */
		len = 1;
	}
	return (len);
}

/*
 * Big5
 */
static int
pg_big5_mblen(const unsigned char *s)
{
	int			len;

	if (*s > 0x7f)
	{							/* kanji? */
		len = 2;
	}
	else
	{							/* should be ASCII */
		len = 1;
	}
	return (len);
}

pg_wchar_tbl pg_wchar_table[] = {
	{pg_ascii2wchar_with_len, pg_ascii_mblen, 1},	/* 0; PG_SQL_ASCII  */
	{pg_eucjp2wchar_with_len, pg_eucjp_mblen, 3},	/* 1; PG_EUC_JP */
	{pg_euccn2wchar_with_len, pg_euccn_mblen, 3},	/* 2; PG_EUC_CN */
	{pg_euckr2wchar_with_len, pg_euckr_mblen, 3},	/* 3; PG_EUC_KR */
	{pg_euctw2wchar_with_len, pg_euctw_mblen, 3},	/* 4; PG_EUC_TW */
	{pg_utf2wchar_with_len, pg_utf_mblen, 3},	/* 5; PG_UNICODE */
	{pg_mule2wchar_with_len, pg_mule_mblen, 3},	/* 6; PG_MULE_INTERNAL */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 7; PG_LATIN1 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 8; PG_LATIN2 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 9; PG_LATIN3 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 10; PG_LATIN4 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 11; PG_LATIN5 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 12; PG_KOI8 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 13; PG_WIN1251 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 14; PG_ALT */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 15; ISO-8859-5 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 16; ISO-8859-6 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 17; ISO-8859-7 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 18; ISO-8859-8 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 19; ISO-8859-10 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 20; ISO-8859-13 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 21; ISO-8859-14 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 22; ISO-8859-15 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1},	/* 23; ISO-8859-16 */
	{0, pg_sjis_mblen, 2},				/* 24; PG_SJIS */
	{0, pg_big5_mblen, 2},				/* 25; PG_BIG5 */
	{pg_latin12wchar_with_len, pg_latin1_mblen, 1} 	/* 26; PG_WIN1250 */
};

/* returns the byte length of a word for mule internal code */
int
pg_mic_mblen(const unsigned char *mbstr)
{
	return (pg_mule_mblen(mbstr));
}

/*
 * Returns the byte length of a multi-byte word.
 */
int
pg_encoding_mblen(int encoding, const unsigned char *mbstr)
{
	Assert(PG_VALID_ENCODING(encoding));

	return( (encoding >= 0 && 
	         encoding < sizeof(pg_wchar_table)/sizeof(pg_wchar_tbl)) ? 
			((*pg_wchar_table[encoding].mblen) (mbstr)) : 
			((*pg_wchar_table[PG_SQL_ASCII].mblen) (mbstr)));
}

/*
 * fetch maximum length of a char encoding
 */
int
pg_encoding_max_length(int encoding)
{
	Assert(PG_VALID_ENCODING(encoding));

	return pg_wchar_table[encoding].maxmblen;
}

#ifndef FRONTEND
/*
 * Verify mbstr to make sure that it has a valid character sequence.
 * mbstr is not necessarily NULL terminated. length of mbstr is
 * specified by len. If an error was found, returns an error message.
 * Note that the message is kept in a static buffer, the next invocation
 * might break the message.
 * If no error was found, this function returns NULL.
 */
char *
pg_verifymbstr(const unsigned char *mbstr, int len)
{
	int	l;
	int	i, j;
	static char	buf[256];
	int	slen = 0;

	/* we do not check single byte encodings */
	if (pg_database_encoding_max_length() <= 1)
	    return NULL;

	while (len > 0 && *mbstr)
	{
		/* special UTF-8 check */
		if (GetDatabaseEncoding() == PG_UTF8 &&
		    (*mbstr & 0xf8) == 0xf0)
		{
		    snprintf(buf, sizeof(buf), "Unicode >= 0x10000 is not supoorted");
		    return(buf);
		}
		    
		l = pg_mblen(mbstr);

		/* multi-byte letter? */
		if (l > 1)
		{
		    for (i=1;i<l;i++)
		    {
			if (i > len || *(mbstr+i) == '\0' ||
			    /* we assume that every muti-byte letter
			     * consists of bytes being the 8th bit set
			     */
			    ((*(mbstr+i) & 0x80) == 0))
			{
			    int remains = sizeof(buf);
			    char *p = buf;

			    slen = snprintf(p, remains, "Invalid %s character sequence found (0x",
				     GetDatabaseEncodingName());
			    p += slen;
			    remains -= slen;

			    i = ((*(mbstr+i) & 0x80) == 0)?l:i;

			    for (j=0;j<i;j++)
			    {
				slen = snprintf(p, remains, "%02x",
						*(mbstr+j));
				p += slen;
				remains -= slen;
			    }
			    snprintf(p, remains, ")");
			    return(buf);
			}
		    }
		}
		len -= l;
		mbstr += l;
	}
	return NULL;
}

/*
 * fetch maximum length of a char encoding for the current database
 */
int
pg_database_encoding_max_length(void)
{
	return pg_wchar_table[GetDatabaseEncoding()].maxmblen;
}

#endif
