/*====================================================================*
 *
 *   Copyright (c) 2013 Qualcomm Atheros, Inc.
 *
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or
 *   without modification, are permitted (subject to the limitations
 *   in the disclaimer below) provided that the following conditions
 *   are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   * Redistributions in binary form must reproduce the above
 *     copyright notice, this list of conditions and the following
 *     disclaimer in the documentation and/or other materials
 *     provided with the distribution.
 *
 *   * Neither the name of Qualcomm Atheros nor the names of
 *     its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written
 *     permission.
 *
 *   NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE
 *   GRANTED BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE
 *   COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 *   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 *   PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
 *   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *   NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 *   OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *--------------------------------------------------------------------*/

/*====================================================================*
 *
 *   config.c - configuration file reader;
 *
 *   configuration files contain named parts where each part may
 *   contain one of more named items that have text definitions;
 *
 *   the named file can be searched for the first occurance of a
 *   named part then the first occurance of a named item;
 *
 *   [part1]
 *   item1=text
 *   item2=text
 *
 *   [part2]
 *   item1=text
 *   item2=text
 *
 *--------------------------------------------------------------------*/

#ifndef CONFIG_SOURCE
#define CONFIG_SOURCE

/*====================================================================*
 *   system header files;
 *--------------------------------------------------------------------*/

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

/*====================================================================*
 *   custom header files;
 *--------------------------------------------------------------------*/

#include "../tools/config.h"
#include "../tools/types.h"
#include "../tools/chars.h"

/*====================================================================*
 *   program variables;
 *--------------------------------------------------------------------*/

static char buffer [1024] = "";
static signed c;

/*====================================================================*
 *
 *   bool compare (FILE * fp, char const *sp);
 *
 *   compare file and text characters until they differ or until end
 *   of text, line or file occurs; a match is declared when the text
 *   ends before the line or file;
 *
 *   spaces and tabs within the argument string or file string are
 *   ignored such that "item1", " item1 " and "item 1" all match;
 *
 *--------------------------------------------------------------------*/

static bool compare (FILE * fp, char const * sp)

{
	while (isblank (*sp))
	{
		sp++;
	}
	while ((*sp) && (c != '\n') && (c != EOF))
	{
		if (toupper (c) != toupper (*sp))
		{
			return (0);
		}
		do
		{
			sp++;
		}
		while (isblank (*sp));
		do
		{
			c = getc (fp);
		}
		while (isblank (c));
	}
	return (!*sp);
}


/*====================================================================*
 *
 *   void collect (FILE * fp);
 *
 *   collect text to end of line; remove leading and trailing space
 *   but preserve embedded space; replace selected escape sequences;
 *
 *--------------------------------------------------------------------*/

static void collect (FILE * fp)

{
	char *bp = buffer;
	char *cp = buffer;
	while ((c != ';') && (c != '\n') && (c != EOF))
	{
		if (c == '\\')
		{
			c = getc (fp);
			if (c == 'n')
			{
				c = '\n';
			}
			if (c == 't')
			{
				c = '\t';
			}
		}
		if ((cp - buffer) < (signed)(sizeof (buffer) - 1))
		{
			*cp++ = c;
		}
		if (!isblank (c))
		{
			bp = cp;
		}
		c = getc (fp);
	}
	*bp = '\0';
	return;
}


/*====================================================================*
 *
 *   void discard (FILE * fp);
 *
 *   read and discard characters until end-of-line or end-of-file
 *   is detected; read the first character of next line if end of
 *   file has not been detected;
 *
 *--------------------------------------------------------------------*/

static void discard (FILE * fp)

{
	while ((c != '\n') && (c != EOF))
	{
		c = getc (fp);
	}
	if (c != EOF)
	{
		c = getc (fp);
	}
	return;
}


/*====================================================================*
 *
 *   Const char * configstring (char const * file, char const * part, char const * item, char const * text)
 *
 *   open the named file, locate the named part and return the named
 *   item text, if present; return alternative text if the file part
 *   or item is missing; the calling function must preserve returned
 *   text because it may be over-written on successive calls;
 *
 *--------------------------------------------------------------------*/

char const * configstring (char const * file, char const * part, char const * item, char const * text)

{
	FILE *fp;
	if ((!file) || (!part) || (!item))
	{
		return (text);
	}
	if ((fp = fopen (file, "rb")))
	{
		for (c = getc (fp); c != EOF; discard (fp))
		{
			while (isblank (c))
			{
				c = getc (fp);
			}
			if (c != '[')
			{
				continue;
			}
			do
			{
				c = getc (fp);
			}
			while (isblank (c));
			if (!compare (fp, part))
			{
				continue;
			}
			if (c != ']')
			{
				continue;
			}
			for (discard (fp); (c != '[') && (c != EOF); discard (fp))
			{
				while (isblank (c))
				{
					c = getc (fp);
				}
				if (c == ';')
				{
					continue;
				}
				if (!compare (fp, item))
				{
					continue;
				}
				if (c != '=')
				{
					continue;
				}
				do
				{
					c = getc (fp);
				}
				while (isblank (c));
				collect (fp);
				text = strdup (buffer);
				break;
			}
			break;
		}
		fclose (fp);
	}
	return (text);
}


/*====================================================================*
 *
 *   unsigned confignumber (char const * file, char const * part, char const * item, unsigned number)
 *
 *   open the named file, locate the named part and return the named
 *   item as an unsigned integer, if present; return a default number
 *   if the file, part or item is missing;
 *
 *--------------------------------------------------------------------*/

unsigned confignumber (char const * file, char const * part, char const * item, unsigned number)

{
	unsigned value = 0;
	char const * string = configstring (file, part, item, "");
	if ((string) && (* string))
	{
		while (isdigit (* string))
		{
			value *= 10;
			value += * string++ - '0';
		}
		if (! (* string))
		{
			number = value;
		}
	}
	return (number);
}

/*====================================================================*
 *
 *   unsigned confignumber_range (char const * file, char const * part, char const * item, unsigned number, unsigned min, unsigned max)
 *
 *   open the named file, locate the named part and return the named
 *   item as an unsigned integer, if present; return a default number
 *   if the file, part or item is missing or item is out of range;
 *
 *--------------------------------------------------------------------*/

unsigned confignumber_range (char const * file, char const * part, char const * item, unsigned number, unsigned min, unsigned max)

{
	unsigned value = 0;
	char const * string = configstring (file, part, item, "");
	if ((string) && (* string))
	{
		while (isdigit (* string))
		{
			value *= 10;
			value += * string++ - '0';
		}
		if (! (* string))
		{
			if ((value >= min) && (value <= max))
			{
			    number = value;
			}
		}
	}
	return (number);
}

/*====================================================================*
 *
 *   int main (int argc, char const * argv []);
 *
 *   demo/test program; arguments are file, part, item and text in
 *   that order; you can construct your own configuration file and
 *   observe behaviour;
 *
 *--------------------------------------------------------------------*/

#if 0

#include <stdio.h>

int main (int argc, char const * argv [])

{
	char const * text = configstring (argv [1], argv [2], argv [3], argv [4]);
	printf ("file=[%s] part=[%s] item=[%s] text=[%s]\n", argv [1], argv [2], argv [3], text);
	return (0);
}


#endif

/*====================================================================*
 *
 *--------------------------------------------------------------------*/

#endif