// control keyboard backlight on apple M1
// tested on macbook pro 2021 model and m1pro macbook model
// works on xorg


// to build it libx11-dev and libxext-dev are needed
// on alpine linux next line will install then
// #sudo apk add libx11-dev libxext-dev
// build with next command
// gcc -o kbd-bklght kbd-bklght.c -lX11 -lXext -lXss


#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <syslog.h>
#include <time.h>
#include <signal.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/scrnsaver.h>

int GetIdleTime (void);
void change (char *what);

	FILE * cbf;
	int max = 30;
	char cb[6];
	int cbr;
	char LOGNAME[] = "kbd-bklght";

void INThandler(){
	change("0");
	exit(0);
}

void KILLhandler(){
	change("0");
	exit(0);
}

void TERMhandler(){
	change("0");
	exit(0);
}


void change (char *what) {
	cbf = fopen("/sys/class/leds//kbd_backlight/brightness", "w");
	if (cbf == NULL) {
		printf("problem with open\n");
		exit(EXIT_FAILURE);
	}
	fprintf(cbf, "%s", what);
	fclose(cbf);
}

int main(int argc, char **argv) {

	int option;
	int limit = 90;
  char brightness[4] = "30";
	int timeout = 5;
signal(SIGINT, INThandler);
signal(SIGKILL, KILLhandler);
signal(SIGTERM, TERMhandler);

while ((option = getopt(argc, argv, "b:t:uh")) != -1) {
	switch (option) {
		case 'h':
      puts("help");
      puts("-t timeout");
      puts("-b brightness");
      break;
    case 'b':
			sprintf(brightness, "%s", optarg);
			break;
    case 't':
			timeout = atoi(optarg);
			break;
		default:                          /* '?' */
      puts("unknown option");
    }
  }

	pid_t pid, sid;
	pid = fork();
	if (pid < 0) {
		exit(EXIT_FAILURE);
	}
	if (pid > 0) {
			exit(EXIT_SUCCESS);
	}

	umask(0);
	sid = setsid();
	if (sid < 0) {
		exit(EXIT_FAILURE);
	}

	if ((chdir("/")) < 0) {
		exit(EXIT_FAILURE);
	}

	close(STDIN_FILENO);
	close(STDOUT_FILENO);
	close(STDERR_FILENO);


	while (1) {
		int idle = GetIdleTime();
		if (idle > timeout) {
      cbf = fopen("/sys/class/leds//kbd_backlight/brightness", "r");
			fgets(cb, 3, cbf);
			fclose(cbf);
			cbr = atoi(cb);
			printf("idle: %d\n", idle);
			change("0");
		} else {
			change(brightness);
		}
		usleep(200000);
		//sleep(1);
	}

	exit(EXIT_SUCCESS);
}

int GetIdleTime () {
        time_t idle_time;
        static XScreenSaverInfo *mit_info;
        Display *display;
        int screen;
        mit_info = XScreenSaverAllocInfo();
        if((display=XOpenDisplay(NULL)) == NULL) { return(-1); }
        screen = DefaultScreen(display);
        XScreenSaverQueryInfo(display, RootWindow(display,screen), mit_info);
        idle_time = (mit_info->idle) / 1000;
        XFree(mit_info);
        XCloseDisplay(display); 
        return idle_time;
}