/*
 * Copyright (C) 2008 - 2012 Vivien Malerba <malerba@gnome-db.org>
 * Copyright (C) 2009 Bas Driessen <bas.driessen@xobas.com>
 * Copyright (C) 2009 Murray Cumming <murrayc@murrayc.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301, USA.
 */

#include <string.h>
#include <libgda/sql-parser/gda-statement-struct.h>

/**
 * gda_sql_value_stringify
 * @value: a #GValue pointer
 *
 * Simplified version of gda_value_stringify().
 *
 * Returns: a new string
 */
gchar *
gda_sql_value_stringify (const GValue *value)
{
        if (value && !GDA_VALUE_HOLDS_NULL (value)) {
                if (g_value_type_transformable (G_VALUE_TYPE (value), G_TYPE_STRING)) {
                        GValue *string;
                        gchar *str;

                        string = g_value_init (g_new0 (GValue, 1), G_TYPE_STRING);
                        g_value_transform (value, string);
                        str = g_value_dup_string (string);
			gda_value_free (string);
                        return str;
                }
                else {
                        GType type = G_VALUE_TYPE (value);
                        if (type == G_TYPE_DATE) {
                                GDate *date;
                                date = (GDate *) g_value_get_boxed (value);
                                if (date) {
                                        if (g_date_valid (date))
                                                return g_strdup_printf ("%04u-%02u-%02u",
                                                                        g_date_get_year (date),
                                                                        g_date_get_month (date),
                                                                        g_date_get_day (date));
                                        else
                                                return g_strdup_printf ("%04u-%02u-%02u",
                                                                        date->year, date->month, date->day);
                                }
                                else
                                        return g_strdup ("0000-00-00");
                        }
			else
                                return g_strdup ("<type not transformable to string>");
		}
	}
	else
		return g_strdup ("NULL");
}

/* Returns: @str */
gchar *
_remove_quotes (gchar *str)
{
        glong total;
        gchar *ptr;
        glong offset = 0;
	char delim;
	
	if (!str)
		return NULL;
	delim = *str;
	if ((delim != '\'') && (delim != '"'))
		return str;

        total = strlen (str);
        if (str[total-1] == delim) {
		/* string is correctly terminated by a double quote */
		memmove (str, str+1, total-2);
		total -=2;
	}
	else {
		/* string is _not_ correctly terminated by a double quote */
		memmove (str, str+1, total-1);
		total -=1;
	}
        str[total] = 0;

        ptr = (gchar *) str;
        while (offset < total) {
                /* we accept the "''" as a synonym of "\'" */
                if (*ptr == delim) {
                        if (*(ptr+1) == delim) {
                                memmove (ptr+1, ptr+2, total - offset);
                                offset += 2;
                        }
                        else {
                                *str = 0;
                                return str;
                        }
                }
                else if (*ptr == '"') {
                        if (*(ptr+1) == '"') {
                                memmove (ptr+1, ptr+2, total - offset);
                                offset += 2;
                        }
                        else {
				*str = 0;
				return str;
                        }
                }
		else if (*ptr == '\\') {
                        if (*(ptr+1) == '\\') {
                                memmove (ptr+1, ptr+2, total - offset);
                                offset += 2;
                        }
                        else {
                                if (*(ptr+1) == delim) {
                                        *ptr = delim;
                                        memmove (ptr+1, ptr+2, total - offset);
                                        offset += 2;
                                }
                                else {
                                        *str = 0;
                                        return str;
                                }
                        }
                }
                else
                        offset ++;

                ptr++;
        }

        return str;
}

/**
 * gda_sql_identifier_force_quotes
 * @str: an SQL identifier
 *
 * Add double quotes around the @str identifier. This function is normally used only by database provider's
 * implementation. Any double quote character is replaced by two double quote characters.
 *
 * For other uses, see gda_sql_identifier_quote().
 *
 * Since: 5.0
 */
gchar *
gda_sql_identifier_force_quotes (const gchar *str)
{
	gchar *retval, *rptr;
	const gchar *sptr;
	gint len;

	if (!str)
		return NULL;

	len = strlen (str);
	retval = g_new (gchar, 2*len + 3);
	*retval = '"';
	for (rptr = retval+1, sptr = str; *sptr; sptr++, rptr++) {
		if (*sptr == '"') {
			*rptr = '"';
			rptr++;
			*rptr = *sptr;
		}
		else
			*rptr = *sptr;
	}
	*rptr = '"';
	rptr++;
	*rptr = 0;
	return retval;
}

gchar *
_json_quote_string (const gchar *str)
{
	gchar *retval, *rptr;
	const gchar *sptr;
	gint len;

	if (!str)
		return g_strdup ("null");

	len = strlen (str);
	retval = g_new (gchar, 2*len + 3);
	*retval = '"';
	for (rptr = retval+1, sptr = str; *sptr; sptr++, rptr++) {
		switch (*sptr) {
		case '"':
			*rptr = '\\';
			rptr++;
			*rptr = *sptr;
			break;
		case '\\':
			*rptr = '\\';
			rptr++;
			*rptr = *sptr;
			break;
		case '/':
			*rptr = '\\';
			rptr++;
			*rptr = *sptr;
			break;
		case '\b':
			*rptr = '\\';
			rptr++;
			*rptr = 'b';
			break;
		case '\f':
			*rptr = '\\';
			rptr++;
			*rptr = 'f';
			break;
		case '\n':
			*rptr = '\\';
			rptr++;
			*rptr = 'n';
			break;
		case '\r':
			*rptr = '\\';
			rptr++;
			*rptr = 'r';
			break;
		case '\t':
			*rptr = '\\';
			rptr++;
			*rptr = 't';
			break;
		default:
			*rptr = *sptr;
			break;
		}
	}
	*rptr = '"';
	rptr++;
	*rptr = 0;
	return retval;
}

/*
** If X is a character that can be used in an identifier then
** IdChar(X) will be true.  Otherwise it is false.
**  
** For ASCII, any character with the high-order bit set is
** allowed in an identifier.  For 7-bit characters, 
** sqlite3IsIdChar[X] must be 1. 
*/
static const char AsciiIdChar[] = {
     /* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
	0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 2x */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 3x */
	0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 4x */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,  /* 5x */
	0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 6x */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,  /* 7x */
};
#define IdChar(C) (((c=C)&0x80)!=0 || (c>0x1f && AsciiIdChar[c-0x20]))
gboolean
_string_is_identifier (const gchar *str)
{
	const gchar *ptr;
	gchar *endptr;
	gchar c;

	if (!str || !(*str)) 
		return FALSE;
	if ((*str == '"') || (*str == '`'))
		ptr = str + 1;
	else
		ptr = str;
	for (; IdChar(*ptr) ||
		     (*ptr == '*') ||
		     (*ptr == '.') ||
		     (*ptr == '-') ||
		     ((*ptr == '"') && (ptr[1] == '"')) ||
		     (((*ptr == '"') || (*ptr == '`')) && ptr[1] == 0);
	     ptr++) {
		if ((*ptr == '"') && (ptr[1] == '"'))
			ptr++;
	}
	if (*ptr) 
		return FALSE;
	if (((*str == '"') && (ptr[-1] == '"')) ||
	    ((*str == '`') && (ptr[-1] == '`')))
		return TRUE;

	/* @str is composed only of character that can be used in an identifier */
	g_ascii_strtod (str, &endptr);
	if (!*endptr)
		/* @str is a number */
		return FALSE;
	return TRUE;
}

/**
 * gda_sql_identifier_prepare_for_compare
 * @str: a quoted string
 *
 * Prepares @str to be compared:
 * <itemizedlist>
 * <listitem><para>if surrounded by double quotes or single quotes, then just remove the quotes</para></listitem>
 * <listitem><para>otherwise convert to lower case</para></listitem>
 * </itemizedlist>
 *
 * The quoted string:
 * <itemizedlist>
 *   <listitem><para>must start and finish with the same single or double quotes character</para></listitem>
 *   <listitem><para>can contain the delimiter character (the single or double quotes) in the string if every instance
 *     of it is preceeded with a backslash character or with the delimiter character itself</para></listitem>
 * </itemizedlist>
 *
 * This function is normally used only by database provider's implementation.
 *
 * WARNING: @str must NOT be a composed identifier (&lt;part1&gt;."&lt;part2&gt;" for example)
 * 
 * Returns: @str
 *
 * Since: 5.0
 */
gchar *
gda_sql_identifier_prepare_for_compare (gchar *str)
{
	if (!str)
		return NULL;
	if ((*str == '"') || (*str == '\''))
		return _remove_quotes (str);
	else {
		gchar *ptr;
		for (ptr = str; *ptr; ptr++)
			*ptr = g_ascii_tolower (*ptr);
		return str;
	}
}

/*
 * Reuses @str and fills in @remain and @last
 *
 * @str "swallowed" by the function and must be allocated memory, and @remain and @last are
 * also allocated memory.
 *
 * Accepted notations for each individual part:
 *   - aaa
 *   - "aaa"
 *
 * So "aaa".bbb, aaa.bbb, "aaa"."bbb", aaa."bbb" are Ok.
 *
 * Returns TRUE:
 * if @str has the <part1>.<part2> form, then @last will contain <part2> and @remain will contain <part1>
 * if @str has the <part1> form, then @last will contain <part1> and @remain will contain NULL
 * 
 * Returns FALSE (in any case @str is also freed)
 * if @str is NULL:
 * if @str is "":
 * if @str is malformed:
 *              @last and @remain will contain NULL
 */
gboolean
_split_identifier_string (gchar *str, gchar **remain, gchar **last)
{
	gchar *ptr;
	gboolean inq = FALSE;
	gint len;

	*remain = NULL;
	*last = NULL;
	if (!str)
		return FALSE;
	g_strchomp (str);
	if (!*str) {
		g_free (str);
		return FALSE;
	}

	len = strlen (str) - 1;
	if (len > 1) {
		if (((str[len] == '"') && (str[len-1] == '.')) ||
		    (str[len] == '.')) {
			g_free (str);
			return FALSE;
		}
	}

	if (((str[0] == '"') && (str[1] == '.')) ||
	    (str[0] == '.')) {
		g_free (str);
		return FALSE;
	}

	for (ptr = str + strlen (str) - 1; ptr >= str; ptr--) {
		if (*ptr == '"') {
			if ((ptr > str) && (ptr[-1] == '"')) {
				ptr--;
				continue;
			}
			inq = !inq;
		}
		else if ((*ptr == '.') && !inq) {
			*ptr = 0;
			*remain = str;
			*last = g_strdup (ptr+1);
			break;
		}
	}
	if (!(*last) && !(*remain))
		*last = str;

	if (*last && !_string_is_identifier (*last)) {
		g_free (*last);
		*last = NULL;
		g_free (*remain);
		*remain = NULL;
		return FALSE;
	}
	return TRUE;
}