/* setbklight.c
 *
 * bon, c'est juste pour foutre le backlight du Hercules ECafe, via le sysfs en root r/w!
 * donc du c plutôt que du bash, heh
 *
 * 2013/06/23 00:24:31 eak!
 */

#include <stdio.h>
#include <stdlib.h>

#include <errno.h>

#include <unistd.h>
#include <sys/types.h>

#define SYSDIR_BK "/sys/devices/platform/pwm-backlight.0/backlight/pwm-backlight.0"
#define SYSDIR_NAME "brightness"
#define SYSDIR_MAXNAME "max_brightness"

#define bufsz 32
#define reset 'r'
#define maxBright 140
#define minBright 5

//////////////////

int getBrightness() {
	FILE *fp;
	char buffer[bufsz];
	int current=-1;

	fp=fopen(SYSDIR_BK"/"SYSDIR_NAME, "r");
	if ( fp == NULL ) {
		perror("fp for read:");
		return(-1);
	}
	if (fgets(buffer, bufsz, fp) == NULL ) {
		perror("fgets:");
		return(-1);
	}
	current=atoi(buffer);
	if (fclose(fp)!=0 ) {
		perror("fclose:");
		return(-1);
	}

	return(current);
}

int setBrightness(int value) {
	FILE *fp;
	char buffer[bufsz];
	int sz, szdone, ecode=0;

	fp=fopen(SYSDIR_BK"/"SYSDIR_NAME, "r+b");
	if ( fp == NULL ) {
		perror("fp for write:");
		return(-1);
	}
	sz=snprintf(buffer, bufsz, "%d\n", value);
	szdone=fwrite(buffer, sizeof(char), sz, fp);
	if ( szdone < sz ) {
		perror("fwrite..:");
		ecode=1;
	}
	if ( fclose(fp) != 0 ) {
		perror("fclose?!@#%:");
		ecode++;
	}
	return(ecode);
}

void Usage(char *prog) {
	fprintf(stderr, "%s <count>\n", prog);
}

int main(int ac, char **av) {
	int *state;
	int current, count, new, max;
	FILE *fp;
	char *buffer;
	int ecode=1;

	if ( ac < 1 || ac > 2 ) {
		Usage(av[0]);
		return(-1);
	}

	if (av[1][0] == reset ) {
		current=0;
		buffer=*(av+1);
		count=atoi(buffer);
	} else {
		count=atoi(av[1]);
		current=getBrightness();
		if ( current < 0 ) {
			return(++ecode);
		}
	}
	new=current+count;
	if ( new < minBright || new > maxBright ) new=0;
	ecode=setBrightness(new);

  return(ecode);
}