#include <stdio.h>
#include <string.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>

/* Compile with "gcc -o skip_taskbar -Wall skip_taskbar.c -lX11" */

/* Run as ./skip_taskbar [0|1] to select initial state */
/* Click middle mouse button on window to toggle */

/* Set window state hint to skip taskbar or not */
static void SetSkipTaskbarHint(Display* display, Window win, Bool toggle)
{
  fprintf(stderr, "Setting hint to %s on taskbar 0x%x\n", (toggle ? "hide" : "show"), (unsigned int)win);

  Atom skip_taskbar = XInternAtom(display, "_NET_WM_STATE_SKIP_TASKBAR",False);
  Atom net_wm_state = XInternAtom(display, "_NET_WM_STATE",False);

  if (toggle)
    {
      XChangeProperty(display, win, net_wm_state, XA_ATOM, 32, PropModeReplace, (unsigned char *)&skip_taskbar, 1);
    }
  else
    {
      XDeleteProperty(display, win, net_wm_state);
    }
}

int main(int argc, char** argv)
{
  if (argc != 2 || strcmp(argv[1], "-h") == 0)
    {
      fprintf(stderr, "Usage: %s [show_on_taskbar]\n", argv[0]);
      return 1;
    }

  Display* display = XOpenDisplay(NULL);
  if (!display) {
    fprintf(stderr, "Couldn't open display\n");
    return 1;
  }
  int screen = DefaultScreen(display);

  const int width = 300, height = 200;

  unsigned long black = BlackPixel(display, screen);
  unsigned long white = WhitePixel(display, screen);

  Window win = XCreateSimpleWindow(display,
                                   RootWindow(display, screen),
                                   0,       /* x */
                                   0,       /* y */
                                   width,
                                   height,
                                   0,       /* border_width */
                                   black,   /* border */
                                   white);  /* background */

  Bool toggle = (strcmp(argv[1], "0") != 0);
  SetSkipTaskbarHint(display, win, toggle);

  XSelectInput(display, win, ButtonPressMask);
  XMapWindow(display, win);

  while (1) {
    XEvent event;
    XNextEvent(display, &event);

    if (event.type == ButtonPress) {
      XButtonEvent be = event.xbutton;
      if (be.button == 2) {
        toggle = !toggle;
        SetSkipTaskbarHint(display, win, toggle);
      }
    }
  }

  return 0;
}