/*
 * sudo apt-get install libxss-dev
 * gcc -Wall idletime.c -o idletime -L/usr/X11R6/lib/ -lX11 -lXext -lXss
 */
#include <time.h>
#include <stdio.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/scrnsaver.h>

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;
}

void SwitchOffMonitor() {
    /* xset dpms force off */
    execl("/usr/bin/xset", "/usr/bin/xset", "dpms", "force", "off", (char*)0);
}

int main() {
    int idle_time = GetIdleTime();
    if (idle_time >= 60) {
        SwitchOffMonitor();
    }
        printf("%d\n", idle_time);
        return 0;
}