/*
 * Routines to access and parse standard text config files.
 * $Id: config.c 1.2 Wed, 19 Mar 1997 12:44:53 -0500 dyfet $
 * Copyright (c) 1997 by Tycho Softworks.
 * For conditions of distribution and use see product license.
 *
 * Abstract:
 *	These routines are used to open and parse human readable '.conf'
 *	files, such as those which may be stored in the /etc directory.
 *	The .conf file is parsed as a sectioned text file, with the name 
 *	for each logical section appearing in []'s.  Entries within each
 *	section are typically in the format 'keyword = value', though
 *	there are exceptions for multi-line fixed size lists, in
 *	the form 'keyword = { list }', and repeated lines.  Comments may
 *	also appear within .conf files.
 * 
 * Functions:
 *	sys_config() - find and open a /etc or /etc/prior .conf file.
 *	open_config() - open any text file as a config file.
 *	read_config() - read a keyword = value pair from current section.
 *	seek_config() - seek a named [] section within the config file.
 *	get_config() - tests current input for a specified keyword.
 *	usr_config() - user specific resource config file.
 */

#include <other/config.h>
#include <other/strcvt.h>
#include <other/string.h>
#include <other/env.h>
#include <std/process.h>

/*
 * When searching for 'system' .conf files, which are normally held in
 *  /etc, also search in /etc/prior.  This is used so that a human
 * readable .conf file can momentarily be moved into '/etc/prior' and
 * still be usable while a GUI system management program is in the middle
 * building a new .conf file.
 */

#ifndef	CFGPATH
#define	CFGPATH	"/etc:/etc/prior"
#endif

/*
 * Maximum working space for single or multi-line input records being
 * parsed.
 */

#ifndef	LBUF
#define	LBUF	1024
#endif

#ifndef	SUFFIX
#define	SUFFIX	".conf"
#endif

/*
 * Open a system .conf file, as found in the system config directories.
 *
 * Abstract:
 * 	This function finds a .conf file in either the /etc or /etc/prior
 * 	directory.  /etc/prior is searched if the current .conf file is
 *	not found (in /etc), as may happen if it is in the middle of
 *	being re-built by a management application.  This provides an
 *	initial function which may be used to open most .conf files.
 *
 * Paramaters:
 *	cfg_name - 'base' filename of system .conf file to open.
 *
 * Returns:
 *	pointer to active CONFIG object for specified filename.
 *
 * Exceptions:
 * 	If the file is not found, a NULL pointer is returned.
 */

CONFIG	*sys_config(const char *cfg_name)
{
	char	cfgname[PATH_MAX + 1];

	strcpy(cfgname, cfg_name);
	strcat(cfgname, SUFFIX);
	return	open_config(search(CFGPATH, cfgname));
}

/*
 * Open any specified filename as a .conf file.
 *
 * Abstract:
 *	This function opens the specified file as a 'config' file for use
 *	in config file parsing routines.  Any filename may be specified
 *	and opened as a config file with this routine.
 *
 * Paramaters:
 *	config_name - full pathname of a .conf file to open.
 *
 * Returns:
 *	pointer to a newly allocated CONFIG parsing object for the
 *	specified filename.
 *
 * Exceptions:
 * 	If the file is not found, a NULL pointer is returned.
 */


CONFIG	*open_config(const char *config_name)
{
	CONFIG	*new;
	char	*env;

	if(NULL == (new = (CONFIG *)malloc(sizeof(CONFIG) + LBUF)))
		return NULL;

	if(NULL == (new->cfg_fp = fopen(config_name, "r")))
	{
		free(new);
		return NULL;
	}
	new->cfg_flag = FALSE;
	return new;
}

/*
 * Close an open config file and destroy the CONFIG parser object.
 */

void	close_config(CONFIG *cfg)
{
	if(!cfg)
		return;

	fclose(cfg->cfg_fp);
	free(cfg);
}

/* Read a line of ASCII text input from an open config file.
 *
 * Abstract:
 *	This routine extracts a line of input from an open config file.
 *	The input line extracted and returned is a "keyword = value" line
 *	found within the current [] section.  If the end of the current
 *	[] section has been reached, then no further input is returned.
 *
 *	Lines which contain comments are automatically skipped.  Comments
 *	include those lines which begin with a '#' or ';' character.
 *	Empty lines are also automatically skipped.
 *
 *	Special {} subsections may also be used to specify language
 *	variant .conf values.  When these subsection identifiers are found
 *	and the current language found in the ENV (LANG=) does not match
 *	the language for the specified {} section, the entire {} section
 *	is skipped. 
 *
 *	The input line retreived automatically has lead and trailing
 * 	whitespaces removed. 
 *
 * Paramaters:
 *	cfg - a 'config' parser object.
 *
 * Returns:
 *	ASCII text for 'keyword = value' item from config file.
 *
 * Exceptions:
 *	A NULL is returned when the current [] section has been completed,
 *	when at the end of the file, or if any error occurs while reading.		
 */
	
char	*read_config(CONFIG *cfg)
{
	char	*p, *q;
	int	skip = 0;

	if(!cfg)
		return NULL;

	if(!cfg->cfg_flag)
		return NULL;

	for(;;)
	{
		fgets(cfg->cfg_lbuf, LBUF - 1, cfg->cfg_fp);
		if(feof(cfg->cfg_fp) || cfg->cfg_lbuf[0] == '[' || ferror(cfg->cfg_fp))
		{
			cfg->cfg_flag = FALSE;
			return NULL;
		}
		p = strtrim(cfg->cfg_lbuf, __SPACES);

		if(*p == '{')
		{
			skip = 1;
			p = strtok(p, "{}| \t");
			while(p)
			{
				if(!stricmp(p, "all"))
					skip = 0;
				if(!stricmp(p, language()))
					skip = 0;
				p = strtok(NULL, "{}| \t");
			}	
			continue;
		}		
		
		if(!*p || *p == '!' || *p == '#' || *p == ';' || skip)
			continue;

		return p;
	}
}

/*
 * Seek a named [] section within the .conf file to begin input.
 *
 * Abstract:
 *	The named section is found within the .conf file.  Once
 *	found, all read_config() input will be returned from the
 *	specified [] section.  Section names are case insensitive.
 *
 * Paramaters:
 *	cfg - config object pointer.
 *	seek_name - name of config [] section to find.
 *
 * Returns:
 *	TRUE if the section name is found in the .conf file , FALSE if
 * 	not.
 *
 * Exceptions:
 *	If a NULL cfg or seek_name is passed, the search always fails.
 *	If a file error is found, the search always fails.  The maximum
 *	size of a [] section name that is tested is 22 characters.
 */

bool	seek_config(CONFIG *cfg, const char *seek_name)
{
	char	group[25];
	int	len;

	if(!cfg || !seek_name)
		return FALSE;

	cfg->cfg_flag = FALSE;	/* mark as outside old [] section */

	len = strlen(seek_name);
	if (len > 22)
		len = 22;

	memset(group, 0, sizeof(group));

	if(*seek_name != '[')
		strcpy(group, "[");

	strncat(group, seek_name, len);

	if(*seek_name != '[' && strlen(seek_name) < 23)
		strcat(group, "]");

	fseek(cfg->cfg_fp, 0l, SEEK_SET);
	len = strlen(group);		
	for(;;)
	{
		fgets(cfg->cfg_lbuf, LBUF - 1, cfg->cfg_fp);
		if(feof(cfg->cfg_fp) || ferror(cfg->cfg_fp))
			return FALSE;
		
		if(!strnicmp(group, cfg->cfg_lbuf, len))	
		{
			cfg->cfg_flag = TRUE;
			return TRUE;
		}
	}
}

/*
 * Parse and test a keyword value pair from current config input.
 *
 * Abstract:
 *	This routine is commonly used to search the current input line
 *	that is returned by read_config() for a specified keyword.  The
 *	current input line is assumed to be in the form 'keyword = value'.
 *	lead and trailing spaces around the '=' are ignored, as is keyword
 *	case.  White spaces within a keyword are also ignored.
 *
 *	Assuming the keyword requested is found in the current input line,
 *	the 'value' string is returned.  If the keyword being tested is
 *	a multi-line keyword = { list }, then all lines for the value are
 *	scanned and loaded into the config line buffer.  If the special
 *	'+' entry is found in the config file, then the keyword is assumed
 *	to be a continuation of the last one found.
 *
 *	A value is normally stripped of all lead and trailing spaces.  If
 *	these need to be preserved, then the value may be put in single
 *	or double quotes.
 *
 *	Since get_config() only looks at the current input line buffered
 *	by read_config(), a test for every possible keyword the application
 *	may need should be performed after each successful read_config()
 *	for a given [] section.
 *
 * Paramaters:
 *	cfg - config object pointer.
 *	keyword - keyword to test for.
 *
 * Returns:
 *	Value string if keyword is found in current input line, else NULL.
 *
 * Exceptions:
 *	If a NULL pointer or keyword is used, a NULL value is returned.
 */

char	*get_config(CONFIG *cfg, const char *keyword)
{
	char	*cbuf;
	char	*out, *p;
	int	pos = 0;	
	bool	found = FALSE;
	
	if(!cfg || !keyword)
		return NULL;

	cbuf = cfg->cfg_lbuf;

	if(*cbuf == '+')	/* alternate multi-line syntax */
	{
		if(!stricmp(cfg->cfg_test, keyword))
			return strltrim(++cbuf, __SPACES);
		else
			return NULL;
	}

	while((pos < 33) && *cbuf && (*cbuf != '='))
	{
		if((*cbuf != ' ') && (*cbuf != '_') && (*cbuf != '\t'))
			cfg->cfg_test[pos++] = *(cbuf++);
		else
			++cbuf;
	}
	cfg->cfg_test[pos] = 0;
	out = p = strltrim(++cbuf, __SPACES);
	switch(*p)
	{
	case '{':
		cbuf = p;
		while(!found)
		{
			while(*(++p))
			{
				if(*p == '}')
				{
					found = TRUE;	
					*p = 0;
				}
				else
					*(cbuf++) = *p;
			}

			if(!found)
			{
				p = cbuf;
				fgets(p, LBUF - 1 + (int)(cfg->cfg_lbuf - p), cfg->cfg_fp);
				if(feof(cfg->cfg_fp) || *p == '[')
				{
					cfg->cfg_flag = FALSE;
					*p = 0;
					break;
				}
				*(cbuf++) = '\n';
				p = strtrim(p, __SPACES);
			}	
		}
		*cbuf = 0;
		out = strltrim(++out, __SPACES);
		break;
	case '\'':
	case '\"':
		while(*(++p))
		{
			if(*p == *out)
			{
				*p = 0;
				break;
			}
		}
		out = strltrim(++out, __SPACES);
		break;	
	}
	if(!stricmp(cfg->cfg_test, keyword))
		return out;
	else
		return NULL;
}

/*
 * Find config file in user's home directory.
 *
 * Abstract:
 * 	In addition to searching for a master config file in /etc, many
 *	applications may support an optional user specific 'rc' or config 
 *	file in the user's own home directory, which, if found, may
 *	override global defaults.  This ability is easily supported with
 *	the usr_config() service, which looks for a named .config file
 *	in the user's home.
 *
 * Paramaters:
 *	Filename of '.config' file to look for in a user's home directory,
 * 	without the leading '.'.
 *
 * Returns:
 *	Config object pointer if file is found in user's home, otherwise
 *	a NULL pointer.
 *
 * Exceptions:
 *	A NULL filename will result in a NULL object being returned.
 */
 	
CONFIG	*usr_config(const char *name)
{
	char	path[NAME_MAX + 1];
	
	if(!name)
		return NULL;

	strcpy(path, homedir());
	fncat(path, ".");
	strcat(path, name);
	return open_config(path);
}