#include <stdio.h>
#include <stdlib.h>

#include <X11/X.h>
#include <X11/Xatom.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>

static Display *display;

static Status
recurse(unsigned int level, Window window) {
	Window root, parent;
	unsigned int i;

	char *name                = NULL;
	Window *children          = NULL;
	unsigned int num_children = 0;

	XFetchName(display, window, &name);

	for (i = 0; i < level; i++)
		printf("  ");
	printf("[0x%x] %s\n", (unsigned int)window, name ? name : "(no name)");

	if (name) XFree(name);

	if (!XQueryTree(display, window, &root, &parent, &children, &num_children))
		return False;

	if (children) {
		for (i = 0; i < num_children; i++) {
			if (!recurse(level + 1, children[i]))
				return False;
		}
		XFree(children);
	}

	return True;
}

int
main(int argc, char **argv) {
	int status = EXIT_FAILURE;

	display = XOpenDisplay(NULL);
	if (!display) {
		fprintf(stderr, "Could not open default display\n");
		goto out;
	}

	if (!recurse(0, DefaultRootWindow(display)))
		goto out_display; 

	status = EXIT_SUCCESS;

out_display:
	XCloseDisplay(display);
out:
	return 0;
}