#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>
#include <stdio.h>
#include <stdlib.h>
 
int main(int argc, char *argv[]) {
     Display *dpy = XOpenDisplay(NULL);
     if(dpy == NULL) {
          printf("Can't open display\n");
          exit(1);
     }
 
     // XSetErrorHandler
 
     int default_scr = XDefaultScreen(dpy);
 
     // DEBUG
     printf("Default screen number: %d\n", default_scr);
 
     // DEBUG
     printf("Screen count: %d\n", XScreenCount(dpy));
 
     Window root_win = XRootWindow(dpy, default_scr);
     int height = XDisplayHeight(dpy, default_scr);
     int width  = XDisplayWidth(dpy, default_scr);
 
     // DEBUG
     printf("width: %d, height: %d\n", width, height);
 
/*
     Window t1, t2;
     Window *first_level_windows;
     unsigned int first_level_windows_cnt;
     XQueryTree(dpy, root_win, &t1, &t2,
                &first_level_windows,
                &first_level_windows_cnt);
 
     // DEBUG
     printf("Number of 1st level windows: %u\n", first_level_windows_cnt);
 
     XClassHint *class_hint = XAllocClassHint();
     int i;
     int win_io_cnt = 0;
     for(i = 0; i < first_level_windows_cnt; i++) {
          Window win_cur = first_level_windows[i];
          XWindowAttributes win_attrs;
          XGetWindowAttributes(dpy, win_cur, &win_attrs);
 
          // dump info
          if(win_attrs.class == InputOutput) {
               if(i != 0) {
                    printf("\n");
               }
               printf("x: %d, y: %d, w: %d, h: %d\n",
                      win_attrs.x, win_attrs.y,
                      win_attrs.width, win_attrs.height);
 
//               Atom atom_ = XInternAtom(dpy, "WM_CLASS", False);
//               printf("%s\n", XGetAtomName(dpy, atom_));
 
               win_io_cnt++;
 
          XGetClassHint(dpy, win_cur, class_hint);
          printf("res_name: %s, res_class:%s\n",
                 class_hint->res_name, class_hint->res_class);
          // printf("class: %d\n", win_attrs.class);
          }
     }
//     printf("Number of IO windows: %d\n", win_io_cnt);
 
     XFree(class_hint);
     XFree(first_level_windows);
*/
 
     Atom actual_type_ret;
     int actual_fmt_ret;
     unsigned long nitems_ret;
     unsigned long bytes_after_ret;
     unsigned char *prop_ret;
 
     unsigned long i;
     int result;
 
     Atom virtual_roots_atom = XInternAtom(dpy, "_NET_VIRTUAL_ROOTS", False);
     result = XGetWindowProperty(dpy, root_win, virtual_roots_atom, 0,
                                 0x7fffffff, False, XA_WINDOW, 
                                 &actual_type_ret, &actual_fmt_ret,
                                 &nitems_ret, &bytes_after_ret, &prop_ret);
     /*
     if(result == Success) {
          printf("Success!\n");
     } else {
          printf("Fail...\n");
     }
     */
     int *virtual_roots_list = (int *)prop_ret;
     printf("number of virtual desktops: %lu\n", nitems_ret);
     for(i = 0; i < nitems_ret; i++) {
          printf("%d", virtual_roots_list[i]);
     }
     printf("\n");
 
     printf("\n === windows managed by the window manager === \n\n");
 
     Atom client_list_atom = XInternAtom(dpy, "_NET_CLIENT_LIST", False);
     result =
          XGetWindowProperty(dpy, root_win, client_list_atom, 0,
                             0x7fffffff, False, XA_WINDOW,
                             &actual_type_ret, &actual_fmt_ret,
                             &nitems_ret, &bytes_after_ret, &prop_ret);
 
     Window *win_list = (Window *)prop_ret;
     unsigned long win_list_cnt = nitems_ret;
 
     Atom net_wm_desktop_atom = XInternAtom(dpy, "_NET_WM_DESKTOP", False);
 
     XClassHint *class_hint = XAllocClassHint();
     for(i = 0; i < win_list_cnt; i++) {
          XGetClassHint(dpy, win_list[i], class_hint);
          if(i != 0) {printf("\n");} // add blank lines to break output
          printf("res_name: %s, res_class:%s\n",
                 class_hint->res_name, class_hint->res_class);
          result =
               XGetWindowProperty(dpy, win_list[i], net_wm_desktop_atom, 0,
                                  0x7fffffff, False, XA_CARDINAL,
                                  &actual_type_ret, &actual_fmt_ret,
                                  &nitems_ret, &bytes_after_ret, &prop_ret);
          // if(result == Success) {printf("S\n");} else {printf("F\n");}
          printf("on desktop:");
 
          printf(" #%d\n", ((int *)prop_ret)[0]);
          // unsigned long j;
          // for(j = 0; j < nitems_ret; j++) {
          //      printf(" #%d", ((int *)prop_ret)[j]);
          // }
          printf("\n");
     }
 
     XFree(class_hint);
     XCloseDisplay(dpy);
 
     return 0;
}