#include <stdlib.h>
#include <gtk/gtk.h>
#include <gdk/gdkx.h>

static gboolean
client_cb (GtkWidget      *widget,
	   GdkEventClient *event,
	   gpointer        data)
{
  if (event->message_type == gdk_atom_intern ("_NET_CHANGE_DISPLAY", FALSE))
    {
      g_print ("old window %#lx\n", event->data.l[0]);
      switch (event->data.l[1])
	{
	case GTK_WINDOW_CHANGE_SCREEN_SUCCESS:
	  g_print ("success\n");
 	  break;
	case GTK_WINDOW_CHANGE_SCREEN_NO_DISPLAY:
	  g_print ("no display\n");
 	  break;
	case GTK_WINDOW_CHANGE_SCREEN_NO_SCREEN:
	  g_print ("no screen\n");
 	  break;
	case GTK_WINDOW_CHANGE_SCREEN_NO_AUTH:
	  g_print ("no auth\n");
 	  break;
	case GTK_WINDOW_CHANGE_SCREEN_FAILURE:
	  g_print ("failure\n");
 	  break;
	case GTK_WINDOW_CHANGE_SCREEN_REFUSED:
	  g_print ("refused\n");
 	  break;
	default:
	  g_print ("unknown\n");
 	  break;
	}
      g_print ("new window %#lx\n", event->data.l[2]);
      
      gtk_main_quit ();
    }
}

static void
send_change_display (GdkDisplay  *display, 
                     gulong       id,
		     const gchar *display_name,
		     GdkWindow   *status_window)
{
  GdkWindow *window;
  GdkAtom atom;
  GdkEventClient event;

  window = gdk_window_foreign_new (id);
  atom = gdk_atom_intern ("_NET_CHANGE_DISPLAY", FALSE);
  gdk_property_change (window, 
		       atom,
		       gdk_atom_intern ("UTF8_STRING", FALSE),
		       8,
		       GDK_PROP_MODE_REPLACE,
		       display_name,
		       strlen (display_name) + 1);
  
  event.type = GDK_CLIENT_EVENT;
  event.window = status_window;
  event.data_format = 32;
  event.message_type = gdk_atom_intern ("WM_PROTOCOLS", FALSE);
  event.data.l[0] = gdk_x11_atom_to_xatom_for_display (display, atom);
  event.data.l[1] = gtk_get_current_event_time ();
  event.data.l[2] = gdk_x11_atom_to_xatom_for_display (display, atom);
  event.data.l[3] = GDK_WINDOW_XID (status_window);
  gdk_event_send_client_message_for_display (gdk_display_get_default (),
					     (GdkEvent *)&event,
					     id);
}

static void
usage (void)
{
  g_print ("usage: movewindow <window-id> <display>\n");
  exit (1);
}


int 
main (int argc, char *argv[])
{
  GtkWidget *status_window;
  gchar *display_name;
  gulong id;
  
  gtk_init (&argc, &argv);

  if (argc < 3)
    usage ();

  id = strtol (argv[1], NULL, 0);
  display_name = argv[2];

  status_window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  
  gtk_widget_realize (status_window);
  g_signal_connect (status_window, "client-event", 
		    G_CALLBACK (client_cb), NULL);

  send_change_display (gdk_display_get_default (),
		       id, display_name, status_window->window);
  
  gtk_main ();

  return 0;
}