// need to link with -lX11 -lX11-xcb -lxcb -lxcb-glx

#include <stdlib.h>
#include <unistd.h>
#include <iostream>
#include <string>
#include <stdio.h>
#include <time.h>

#include <xcb/xcb.h>
#include <xcb/xproto.h>
#include <X11/Xlib.h>
#include <X11/Xlib-xcb.h>

#include <xcb/glx.h>

const std::string currentDateTime() {
    time_t now = time(0);
    struct tm tstruct;
    char buf[80];
    tstruct = *localtime(&now);
    strftime(buf, sizeof(buf), "%X", &tstruct);
    return buf;
}

bool initGLX(xcb_connection_t *conn)
{
    const xcb_query_extension_reply_t *reply = xcb_get_extension_data(conn, &xcb_glx_id);
    if (!reply || !reply->present)
        return false;

    xcb_generic_error_t *error = 0;
    xcb_glx_query_version_cookie_t xglx_query_cookie = xcb_glx_query_version(conn, XCB_GLX_MAJOR_VERSION, XCB_GLX_MINOR_VERSION);
    xcb_glx_query_version_reply_t *xglx_query = xcb_glx_query_version_reply(conn, xglx_query_cookie, &error);
    if (!xglx_query || error) {
        free(error);
        return false;
    }
    free(xglx_query);
}

// ture OR false, does not work for both cases
bool useXlib = false;

int main() {

    xcb_connection_t *conn;

    if (useXlib) {
        Display *dpy = XOpenDisplay(getenv("DISPLAY"));
        if (dpy) {
            conn = XGetXCBConnection(dpy);
            XSetEventQueueOwner(dpy, XCBOwnsEventQueue);
        }
    } else {
        conn = xcb_connect(NULL, NULL);
    }

    xcb_flush(conn);

    // ENABLE THIS LINE TO SEE HOW focus_reply WILL BLOCK THIS THREAD WHILE USERS HAS SWITCHED TO VIRTUAL CONSOLE
    //initGLX(conn);

    while(true) {

        std::cout << "syncX: " << currentDateTime() << std::endl;
        xcb_get_input_focus_cookie_t cookie = xcb_get_input_focus(conn);
        free(xcb_get_input_focus_reply(conn, cookie, 0));

        xcb_flush(conn);
        sleep(1);
    }

    return 0;
}