// Copyright (C)2004 Landmark Graphics Corporation
// Copyright (C)2005, 2006 Sun Microsystems, Inc.
// Copyright (C)2011, 2014-2015, 2018-2021, 2023 D. R. Commander
//
// This library is free software and may be redistributed and/or modified under
// the terms of the wxWindows Library License, Version 3.1 or (at your option)
// any later version.  The full license is in the LICENSE.txt file included
// with this distribution.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// wxWindows Library License for more details.

// This is a container class that allows us to temporarily swap in a new
// drawable and then "pop the stack" after we're done with it.  It does nothing
// unless there is already a valid context established

#ifndef __TEMPCONTEXT_H__
#define __TEMPCONTEXT_H__

#include "faker-sym.h"
#include "ContextHash.h"


namespace faker
{
	class TempContext
	{
		public:

			TempContext(Display *dpy_, GLXDrawable draw, GLXDrawable read,
				GLXContext ctx, bool eglx_ = false) : dpy(dpy_), ctxChanged(false),
				eglx(eglx_)
			{
				if(eglx)
				{
					oldctx = (GLXContext)_eglGetCurrentContext();
					oldread = (GLXDrawable)_eglGetCurrentSurface(EGL_READ);
					olddraw = (GLXDrawable)_eglGetCurrentSurface(EGL_DRAW);
					oldapi = _eglQueryAPI();
				}
				else
				{
					oldctx = backend::getCurrentContext();
					oldread = backend::getCurrentReadDrawable();
					olddraw = backend::getCurrentDrawable();
				}

				if(!ctx) THROW("Invalid argument");
				if((read || draw)
					&& (oldread != read  || olddraw != draw || oldctx != ctx))
				{
					if(eglx)
					{
						_eglBindAPI(EGL_OPENGL_API);
						if(!_eglMakeCurrent((EGLDisplay)dpy, (EGLSurface)draw,
							(EGLSurface)read, (EGLContext)ctx))
							THROW("Could not bind OpenGL context to window (window may have disappeared)");
					}
					else
					{
						if(!backend::makeCurrent(dpy, draw, read, ctx))
							THROW("Could not bind OpenGL context to window (window may have disappeared)");
					}
					// If oldctx has already been destroyed, then we don't want to
					// restore it.  This can happen if the application is rendering to
					// the front buffer and glXDestroyContext() is called to destroy the
					// active context before glXMake*Current*() is called to switch it.
					if((oldctx && (eglx || CTXHASH.findConfig(oldctx)))
						|| (!oldread && !olddraw && !oldctx))
						ctxChanged = true;
				}
			}

			~TempContext(void)
			{
				if(ctxChanged)
				{
					if(eglx)
					{
						_eglMakeCurrent((EGLDisplay)dpy, (EGLSurface)olddraw,
							(EGLSurface)oldread, (EGLContext)oldctx);
						if(oldapi != EGL_NONE) _eglBindAPI(oldapi);
					}
					else
						backend::makeCurrent(dpy, olddraw, oldread, oldctx);
					ctxChanged = false;
				}
			}

		private:

			Display *dpy;
			GLXContext oldctx;
			GLXDrawable oldread, olddraw;
			EGLenum oldapi;
			bool ctxChanged;
			bool eglx;
	};
}

#endif  // __TEMPCONTEXT_H__
