#include "shadermeh.h"

#ifndef GLX_ARB_create_context
#define GLX_CONTEXT_MAJOR_VERSION_ARB             0x2091
#define GLX_CONTEXT_MINOR_VERSION_ARB             0x2092
#define GLX_CONTEXT_FLAGS_ARB                     0x2094
#endif

#ifndef GLX_ARB_create_context_profile
#define GLX_CONTEXT_PROFILE_MASK_ARB              0x9126
#define GLX_CONTEXT_CORE_PROFILE_BIT_ARB          0x00000001
#define GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB 0x00000002
#endif

typedef GLXContext (*CREATECONTEXTATTRIBSPROC)(Display *, GLXFBConfig,
					       GLXContext, Bool,
					       const int *);

typedef void (*SWAPINTERVALEXTPROC)(Display *, GLXDrawable, int);

static int glversions[][2] = { {4,5}, {4,4}, {4,3}, {4,2}, {4,1}, {4,0},
			       {3,3}, {3,2}, {3,1}, {3,0} };

static Display *dpy;
static int dpy_ref = 0;
static Atom atom_wm_delete;
static XContext xctx;

static int xlib_swallow_errors(Display *display, XErrorEvent *event)
{
	(void)display; (void)event;
	return 0;
}

/****************************************************************************/

window *window_create(unsigned int width, unsigned int height,
		      const char *caption)
{
	CREATECONTEXTATTRIBSPROC CreateContextAttribs;
	XSetWindowAttributes swa;
	int fbcount, attr[20];
	GLXFBConfig fbc, *fbl;
	unsigned int i = 0;
	XSizeHints hints;
	XVisualInfo *vi;
	window *this;

	this = calloc(1, sizeof(*this));
	if (!this)
		return NULL;

	if (dpy) {
		++dpy_ref;
	} else {
		dpy = XOpenDisplay(0);
		dpy_ref = 1;

		if (!dpy) {
			free(this);
			return NULL;
		}

		XSetErrorHandler(xlib_swallow_errors);
		atom_wm_delete = XInternAtom(dpy, "WM_DELETE_WINDOW", True);

		xctx = XUniqueContext();
	}

	attr[ 0] = GLX_BUFFER_SIZE;  attr[ 1] = 32;
	attr[ 2] = GLX_RED_SIZE;     attr[ 3] = 8;
	attr[ 4] = GLX_GREEN_SIZE;   attr[ 5] = 8;
	attr[ 6] = GLX_BLUE_SIZE;    attr[ 7] = 8;
	attr[ 8] = GLX_ALPHA_SIZE;   attr[ 9] = 8;
	attr[10] = GLX_DEPTH_SIZE;   attr[11] = 24;
	attr[12] = GLX_STENCIL_SIZE; attr[13] = 8;
	attr[14] = GLX_DOUBLEBUFFER; attr[15] = True;
	attr[16] = None;

	fbl = glXChooseFBConfig(dpy, DefaultScreen(dpy), attr, &fbcount);

	if (!fbl || !fbcount) {
		window_destroy(this);
		return NULL;
	}

	fbc = fbl[0];
	vi = glXGetVisualFromFBConfig(dpy, fbl[0]);
	XFree(fbl);

	if (!vi) {
		window_destroy(this);
		return NULL;
	}

	swa.colormap = XCreateColormap(dpy, RootWindow(dpy,vi->screen),
				       vi->visual, AllocNone);

	if (!swa.colormap) {
		XFree(vi);
		window_destroy(this);
		return NULL;
	}

	swa.border_pixel = 0;

	this->wnd = XCreateWindow(dpy, RootWindow(dpy,vi->screen), 0, 0,
				  width, height, 0, vi->depth, InputOutput,
				  vi->visual, CWBorderPixel|CWColormap, &swa);
	XFree(vi);

	if (!this->wnd) {
		window_destroy(this);
		return NULL;
	}

	CreateContextAttribs = (CREATECONTEXTATTRIBSPROC)
		glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");

	if (CreateContextAttribs) {
		attr[0] = GLX_CONTEXT_MAJOR_VERSION_ARB;
		attr[1] = 0;
		attr[2] = GLX_CONTEXT_MINOR_VERSION_ARB;
		attr[3] = 0;
		attr[4] = GLX_CONTEXT_PROFILE_MASK_ARB;
		attr[5] = GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
		attr[6] = GLX_CONTEXT_FLAGS_ARB;
		attr[7] = GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
		attr[8] = None;

		for (i = 0; !this->gl && i < sizeof(glversions) /
			     sizeof(glversions[0]); ++i) {
			attr[1] = glversions[i][0];
			attr[3] = glversions[i][1];

			this->gl = CreateContextAttribs(dpy, fbc, 0,
							True, attr);
		}
	}

	if (!this->gl) {
		this->gl = glXCreateNewContext(dpy, fbc, GLX_RGBA_TYPE,
					       0, GL_TRUE);
	}

	if (!this->gl) {
		window_destroy(this);
		return NULL;
	}

	hints.flags = PSize | PMinSize | PMaxSize;
	hints.min_width = hints.max_width = hints.base_width = width;
	hints.min_height = hints.max_height = hints.base_height = height;

	XSetWMNormalHints(dpy, this->wnd, &hints);

	XSelectInput(dpy, this->wnd, StructureNotifyMask |
		     KeyPressMask | KeyReleaseMask |
		     PointerMotionMask | PropertyChangeMask |
		     ButtonPressMask | ButtonReleaseMask);
	XSetWMProtocols(dpy, this->wnd, &atom_wm_delete, 1);
	XFlush(dpy);

	XStoreName(dpy, this->wnd, caption);
	XMapWindow(dpy, this->wnd);
	XSaveContext(dpy, this->wnd, xctx, (XPointer)this);
	XFlush(dpy);
	return this;
}

void window_make_current(window *this)
{
	if (this) {
		glXMakeContextCurrent(dpy, this->wnd, this->wnd, this->gl);
	} else {
		glXMakeContextCurrent(dpy, 0, 0, 0);
	}
}

void window_swap_buffers(window *this)
{
	glXSwapBuffers(dpy, this->wnd);
}

void window_set_vsync(window *this, int enable)
{
	SWAPINTERVALEXTPROC SwapIntervalEXT;

	SwapIntervalEXT = (SWAPINTERVALEXTPROC)
		glXGetProcAddress((const GLubyte *)"glXSwapIntervalEXT");

	if (SwapIntervalEXT)
		SwapIntervalEXT(dpy, this->wnd, enable ? 1 : 0);
}

void window_destroy(window *this)
{
	if (this->gl) {
		glXMakeContextCurrent(dpy, 0, 0, 0);
		glXDestroyContext(dpy, this->gl);
	}

	if (this->wnd) {
		XDeleteContext(dpy, this->wnd, xctx);
		XDestroyWindow(dpy, this->wnd);
	}

	if ((--dpy_ref) <= 0) {
		XCloseDisplay(dpy);
		dpy_ref = 0;
		dpy = NULL;
	}

	free(this);
}

int window_handle_events(void)
{
	window *this;
	XEvent e;

	if (XPending(dpy)) {
		XNextEvent(dpy, &e);
		XFindContext(dpy, e.xany.window, xctx, (XPointer *)&this);

		switch (e.type) {
		case ClientMessage:
			if (e.xclient.data.l[0] == (long)atom_wm_delete) {
				XUnmapWindow(dpy, e.xany.window);
				--dpy_ref;
			}
			break;
		}
	}

	return (dpy_ref > 0);
}