#include <stdio.h>
#include <glob.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>

#include "config.h"
#include "trace.h"

static int parse_config_line(char *line, char **variable, char **value)
{
#define SKIP_UNTIL(_str, _cond)		\
	while (*_str && (_cond))	\
		_str++;

	SKIP_UNTIL(line, isspace(*line));

	/* Skip comments */
	if (*line == '#')
		return -1;

	/* The actual variable name begins here */
	*variable = line;

	/* Find where the variable name ends */
	SKIP_UNTIL(line, !isspace(*line) && *line != '=');

	if (*line == '=') {
		*line = '\0';
		line++;
		goto value_start;
	}

	/* If we encounter line end already, the line can't be valid */
	if (!*line)
		return -1;

	/* Terminate the variable name */
	*line = '\0';
	line++;
	 
	/* Find the equal sign */
	SKIP_UNTIL(line, *line != '=');

	if (*line != '=')
		return -1;
	line++;

	SKIP_UNTIL(line, isspace(*line));

value_start:
	*value = line;

	SKIP_UNTIL(line, *line != '\n' && *line != '#');
	*line = 0;

	return 0;
}

static int store_variable_value_to_plotter_config(const char *variable,
						const char *value,
						struct plotter_config *cfg)
{
#define TEST_STR_STORE_STR_RETURN(_cfg, _variable, _str, _value)	\
	if (!strcmp(_variable, #_str) && !cfg->_str) {			\
		cfg->_str = strdup(_value);				\
		return 0;						\
	}

#define TEST_STR_STORE_INT_RETURN(_cfg, _variable, _str, _value)	\
	if (!strcmp(_variable, #_str)) {				\
		cfg->_str = atoi(_value);				\
		return 0;						\
	}

	TEST_STR_STORE_STR_RETURN(cfg, variable, charger_name, value);
	TEST_STR_STORE_STR_RETURN(cfg, variable, plotter_scripts_dir, value);
	TEST_STR_STORE_STR_RETURN(cfg, variable, images_output_dir, value);
	TEST_STR_STORE_STR_RETURN(cfg, variable, device_path, value);
	TEST_STR_STORE_STR_RETURN(cfg, variable, log_path, value);
	TEST_STR_STORE_INT_RETURN(cfg, variable, baudrate, value);

	return -1;
}

static int read_config_file(FILE *file, struct plotter_config *cfg)
{
	char line[1024];
	char *variable, *value;

	while (fgets(line, sizeof(line), file)) {
		if (parse_config_line(line, &variable, &value))
			continue;

		if (!store_variable_value_to_plotter_config(variable, value,
								cfg))
			continue;

		pr_debug("Discarding unsupported config variable %s\n",
			variable);
	}

	return 0;
}

int populate_config_data_from_file(const char *path,
				struct plotter_config *cfg)
{
	glob_t globbuf;
	FILE *file;
	int ret;

	ret = glob(path, GLOB_TILDE, NULL, &globbuf);
	if (ret)
		return -1;

	if (globbuf.gl_pathc == 0) {
		pr_debug("No config file foud from path %s\n", path);
		return -1;
	}

	if (globbuf.gl_pathc > 1) {
		pr_warn("Found multiple config files from path %s, using the first one\n",
			path);
	}

	file = fopen(globbuf.gl_pathv[0], "r");
	if (!file) {
		pr_err("Failed to open config file %s: %m\n",
			globbuf.gl_pathv[0]);
		return -1;
	}

	return read_config_file(file, cfg);
}