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

#include <GL/glx.h>
#include <X11/Xlib.h>

typedef GLXContext (*glXCreateContextAttribsARBProc)(Display *, GLXFBConfig, GLXContext, int, const int *);

#ifdef VSYNC
	typedef int (*glXSwapIntervalMESAProc)(int);
#endif

int main(int argc, char **argv) {
	Display *display = XOpenDisplay(NULL);

	static int visual_attribs[] = {
		GLX_X_RENDERABLE, True,
		GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
		GLX_RENDER_TYPE, GLX_RGBA_BIT,
		GLX_X_VISUAL_TYPE, GLX_TRUE_COLOR,
		GLX_RED_SIZE, 8,
		GLX_GREEN_SIZE, 8,
		GLX_BLUE_SIZE, 8,
		GLX_ALPHA_SIZE, 8,
		GLX_DEPTH_SIZE, 24,
		GLX_STENCIL_SIZE, 8,
		GLX_DOUBLEBUFFER, True,
		None
	};

	int fbcount;
	GLXFBConfig* fbc = glXChooseFBConfig(display, DefaultScreen(display), visual_attribs, &fbcount);

	XVisualInfo *vi = glXGetVisualFromFBConfig(display, fbc[0]);

	XSetWindowAttributes swa;
	Colormap cmap;
	cmap = XCreateColormap(display, RootWindow(display, vi->screen), vi->visual, AllocNone);

	swa.colormap = cmap;
	swa.background_pixmap = None;
	swa.border_pixel = 0;
	swa.event_mask = StructureNotifyMask;
 
	Window window = XCreateWindow(display, RootWindow(display, vi->screen),
		100, 100, 800, 600, 0, vi->depth, InputOutput, vi->visual,
		CWBorderPixel | CWColormap | CWEventMask, &swa);

	XFree(vi);

	XStoreName(display, window, "OpenGL");

	glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;
	glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB((const GLubyte *)"glXCreateContextAttribsARB");

	int attribs[] = {
		GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
		GLX_CONTEXT_MINOR_VERSION_ARB, 2,
		None
	};

	GLXContext context = glXCreateContextAttribsARB(display, fbc[0], 0, True, attribs);

	free(fbc);

	glXMakeCurrent(display, window, context);

	#ifdef VSYNC
		glXSwapIntervalMESAProc glXSwapIntervalMESA = 0;
		glXSwapIntervalMESA = (glXSwapIntervalMESAProc)glXGetProcAddressARB((const GLubyte *)"glXSwapIntervalMESA");

		glXSwapIntervalMESA(1);
	#endif

	int i;
	for (i = 0; i < 1000; i++) {
		#ifndef NOSWAP
			glXSwapBuffers(display, window);

			#ifdef SLEEP
				sleep(1);
			#endif
		#endif

		fprintf(stderr, "loop\n");
	}

	glXMakeCurrent(display, 0, 0);
	glXDestroyContext(display, context);

	XDestroyWindow(display, window);
	XFreeColormap(display, cmap);
	XCloseDisplay(display);
	
	return 0;
}