#include <assert.h>
#include <stdio.h>
#include <GL/glx.h>

#define ATTRIBUTE GLX_HEIGHT

//callback for the next function
static Bool WaitForNotify(Display *d, XEvent *e, char *arg)
{
    return (e->type == MapNotify) && (e->xmap.window == *((Window*)arg));
}
// Create XWindow according to GLXConfig and wait for CreateNotify event.

Window tglCreateXWindow(Display* dpy, GLXFBConfig config)
{
    XEvent event;
    int height = 600;
    int width = 800;
    
	XVisualInfo* vi = glXGetVisualFromFBConfig(dpy, config);
    assert(vi != NULL);

    XSetWindowAttributes swa;
    swa.border_pixel = 0;
    swa.event_mask = StructureNotifyMask;
    swa.colormap = XCreateColormap( dpy, XRootWindow(dpy, vi->screen),
                                    vi->visual, AllocNone );

    int swaMask = CWBorderPixel | CWColormap | CWEventMask;

    Window win = XCreateWindow( dpy, XRootWindow(dpy, vi->screen), 0, 0, width, height,
                          0, vi->depth, InputOutput, vi->visual,
                          swaMask, &swa );
    XFree(vi);
	assert(win != 0);
    XMapWindow(dpy, win);
    XIfEvent(dpy, &event, WaitForNotify, (char*)(&win));
    
    return win;
}


int main()
{
    Window win = 0;
    GLXWindow glxWindow = 0;

    Display* display = XOpenDisplay(NULL);
    assert(display != NULL);

    int attribs[] = {
        GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
        GLX_DOUBLEBUFFER, True,
        GLX_RENDER_TYPE, GLX_RGBA_BIT,
        GLX_RED_SIZE, 1,
        GLX_GREEN_SIZE, 1,
        GLX_BLUE_SIZE, 1,
        None};
    int nelems;
    GLXFBConfig* configs = glXChooseFBConfig(display,
        DefaultScreen(display), attribs, &nelems);
	assert((configs != NULL) && (nelems != 0));

	GLXFBConfig config = configs[0];
	XFree(configs);
	
    win = tglCreateXWindow(display, config);
    assert(win != 0);

    glxWindow = glXCreateWindow(display, config, win, NULL);
    assert(glxWindow != 0);

    unsigned int value = -1;
    glXQueryDrawable(display, glxWindow, ATTRIBUTE, &value);
	printf("Value became %u.\n", value);
	//cleanup
	if(display)
    {
        if(glxWindow) glXDestroyWindow(display, glxWindow);
        if(win) XDestroyWindow(display, win);
        XCloseDisplay(display);
    }
	return 0;
}