/*
	xdeadzone - create a window and don't allow the mouse pointer to enter it.

	compile me with:

	gcc -Wall -o xdeadzone xdeadzone.c -lX11

	run me with ./xdeadzone, and be prepared to hit ^C or use kill to exit,
	since it doesn't have any other way to exit (currently).
*/

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

#ifndef VERSION
#  define VERSION "UnknownVersion"
#endif

#define NAME "XDeadZone"

const char *exename;

void set_exename(const char *p) {
	exename = p;
	while(*p) {
		if(*p == '/') exename = p + 1;
		p++;
	}
	printf("exename: %s\n", exename);
}

void usage(char *name, int ret) {
	printf(
			NAME " " VERSION "\n"
			"Usage:\n  %s "
			"[-nw | -ne | -sw | -se | -abs xpos ypos] [width] [height]"
			"\n",
			name);
	exit(ret);
}

void errmsg(char *name, char *msg) {
	fprintf(stderr, "%s: %s\n", name, msg);
	usage(name, 1);
}

int main(int argc, char **argv) {
	Display *d;
	Window w;
	XEvent ev;
	Atom dock_atom;
	XWindowAttributes attr;
	XSetWindowAttributes setattr;
	int screen;

	int done = 0;
	int x = 0, y = 0, width = 0, height = 0;

	if(argc == 2 && strcmp(argv[1], "--help") == 0)
		usage(argv[0], 0);

	if(strcmp(argv[1], "-abs") == 0) {
		if(argc != 6)
			errmsg(argv[0], "wrong number of arguments for -abs");
		x = atoi(argv[2]);
		y = atoi(argv[3]);
		width = atoi(argv[4]);
		height = atoi(argv[5]);
	} else {
		if(argc != 4)
			errmsg(argv[0], "wrong number of arguments for -nw/-ne/-sw/-se");
		width = atoi(argv[2]);
		height = atoi(argv[3]);
		if(strcmp(argv[1], "-nw") == 0) {
			x = 0; y = 0;
		} else if(strcmp(argv[1], "-ne") == 0) {
			x = -width; y = 0;
		} else if(strcmp(argv[1], "-sw") == 0) {
			x = 0; y = -height;
		} else if(strcmp(argv[1], "-se") == 0) {
			x = -width; y = -height;
		} else {
			errmsg(argv[0], "invalid 1st argument (not -abs/-nw/-ne/-sw/-se)");
		}
	}

	if(width <= 0 || height <= 0)
		errmsg(argv[0], "width and height must be positive and non-zero");

	if(!(d = XOpenDisplay(NULL)))
		errmsg(argv[0], "can't open X display");

	XGetWindowAttributes(d, DefaultRootWindow(d), &attr);
	if(x < 0) x = attr.width  + x;
	if(y < 0) y = attr.height + y;

	printf("X size %d x %d, x %d, y %d, width %d, height %d\n", attr.width, attr.height, x, y, width, height);

	/* Create window with override_redirect enabled, to tell the window
		manager not to decorate it with a titlebar or resize frame.
		Also, we really only care about EnterNotify events.
		Set the window to solid white, to make it easy to see during testing.
		In actual use, the window won't be visible, it'll be in the dead zone,
		right?
	 */
	screen = DefaultScreen(d);
	setattr.override_redirect = True;
	setattr.background_pixel = WhitePixel(d, screen);
	setattr.event_mask = EnterWindowMask;

	w = XCreateWindow(d,
			RootWindow(d, screen),
			x, y, width, height, 0,
			DefaultDepth(d, screen),
			InputOutput,
			DefaultVisual(d, screen),
			CWBackPixel | CWOverrideRedirect | CWEventMask,
			&setattr);

	XStoreName(d, w, NAME);

	/* On most window managers, this makes the window stay on top and
		be present on all virtual desktops. Tested, works with WindowMaker, Fvwm2,
		KDE5, XFCE4, BlackBox, and FluxBox. On all but Fvwm2, it also
		disappears the titlebar and resize frame... but we already took
		care of that with override_redirect, above.
		ref: http://standards.freedesktop.org/wm-spec/wm-spec-latest.html
	 */
	dock_atom = XInternAtom(d, "_NET_WM_WINDOW_TYPE_DOCK", False);
	XChangeProperty(d,
			w,
			XInternAtom(d, "_NET_WM_WINDOW_TYPE", False),
			XA_ATOM,
			32,
			PropModeReplace,
			(unsigned char *) &dock_atom,
			1);

	XMapWindow(d, w);

	/* have to do this after it's mapped, since the window manager might have
	  	ignored the x and y in the XCreateWindow(). */
	XMoveWindow(d, w, x, y);

	while(!done) {
		XNextEvent(d, &ev);
		if(ev.type == EnterNotify) {
			// printf("entered at %d, %d\n", ev.xcrossing.x_root, ev.xcrossing.y_root);
			XWarpPointer(d,
					None,
					DefaultRootWindow(d),
					0, 0, 0, 0,
					ev.xcrossing.x_root,
					(y == 0 ? y + height : y - 1));
		}
	}

	XUnmapWindow(d, w);
	XDestroyWindow(d, w);
	XCloseDisplay(d);

	return 0;
}