/*
** License Applicability. Except to the extent portions of this file are
** made subject to an alternative license as permitted in the SGI Free
** Software License B, Version 1.1 (the "License"), the contents of this
** file are subject only to the provisions of the License. You may not use
** this file except in compliance with the License. You may obtain a copy
** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
** 
** http://oss.sgi.com/projects/FreeB
** 
** Note that, as provided in the License, the Software is distributed on an
** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
** 
** Original Code. The Original Code is: OpenGL Sample Implementation,
** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
** Copyright in any portions created by third parties is as indicated
** elsewhere herein. All Rights Reserved.
** 
** Additional Notice Provisions: The application programming interfaces
** established by SGI in conjunction with the Original Code are The
** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
** Window System(R) (Version 1.3), released October 19, 1998. This software
** was created using the OpenGL(R) version 1.2.1 Sample Implementation
** published by SGI, but has not been independently verified as being
** compliant with the OpenGL(R) version 1.2.1 Specification.
**
*/

/**
 * \file glxcurrent.c
 * Client-side GLX interface for current context management.
 */

#include "glxclient.h"
#include "glapi.h"
#include "glheader.h"
#include "indirect_init.h"

/*
** We setup some dummy structures here so that the API can be used
** even if no context is current.
*/

static GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];

/*
** Dummy context used by small commands when there is no current context.
** All the
** gl and glx entry points are designed to operate as nop's when using
** the dummy context structure.
*/
static __GLXcontext dummyContext = {
    &dummyBuffer[0],
    &dummyBuffer[0],
    &dummyBuffer[0],
    &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
    sizeof(dummyBuffer),
};


/*
** All indirect rendering contexts will share the same indirect dispatch table.
*/
static __GLapi *IndirectAPI = NULL;


/*
 * Current context management and locking
 */

#if defined( USE_XTHREADS )

/* thread safe */
static GLboolean TSDinitialized = GL_FALSE;
static xthread_key_t ContextTSD;

__GLXcontext *__glXGetCurrentContext(void)
{
   if (!TSDinitialized) {
      xthread_key_create(&ContextTSD, NULL);
      TSDinitialized = GL_TRUE;
      return &dummyContext;
   }
   else {
      void *p;
      xthread_get_specific(ContextTSD, &p);
      if (!p)
         return &dummyContext;
      else
         return (__GLXcontext *) p;
   }
}

void __glXSetCurrentContext(__GLXcontext *c)
{
   if (!TSDinitialized) {
      xthread_key_create(&ContextTSD, NULL);
      TSDinitialized = GL_TRUE;
   }
   xthread_set_specific(ContextTSD, c);
}


/* Used by the __glXLock() and __glXUnlock() macros */
xmutex_rec __glXmutex;

#elif defined( PTHREADS )

pthread_mutex_t __glXmutex = PTHREAD_MUTEX_INITIALIZER;

# if defined( GLX_USE_TLS )

/**
 * Per-thread GLX context pointer.
 * 
 * \c __glXSetCurrentContext is written is such a way that this pointer can
 * \b never be \c NULL.  This is important!  Because of this
 * \c __glXGetCurrentContext can be implemented as trivial macro.
 */
__thread void * __glX_tls_Context __attribute__((tls_model("initial-exec")))
    = &dummyContext;

void __glXSetCurrentContext( __GLXcontext * c )
{
    __glX_tls_Context = (c != NULL) ? c : &dummyContext;
}

# else

static pthread_once_t once_control = PTHREAD_ONCE_INIT;

/**
 * Per-thread data key.
 * 
 * Once \c init_thread_data has been called, the per-thread data key will
 * take a value of \c NULL.  As each new thread is created the default
 * value, in that thread, will be \c NULL.
 */
static pthread_key_t ContextTSD;

/**
 * Initialize the per-thread data key.
 * 
 * This function is called \b exactly once per-process (not per-thread!) to
 * initialize the per-thread data key.  This is ideally done using the
 * \c pthread_once mechanism.
 */
static void init_thread_data( void )
{
    if ( pthread_key_create( & ContextTSD, NULL ) != 0 ) {
	perror( "pthread_key_create" );
	exit( -1 );
    }
}

void __glXSetCurrentContext( __GLXcontext * c )
{
    pthread_once( & once_control, init_thread_data );
    pthread_setspecific( ContextTSD, c );
}

__GLXcontext * __glXGetCurrentContext( void )
{
    void * v;

    pthread_once( & once_control, init_thread_data );

    v = pthread_getspecific( ContextTSD );
    return (v == NULL) ? & dummyContext : (__GLXcontext *) v;
}

# endif /* defined( GLX_USE_TLS ) */

#elif defined( THREADS )

#error Unknown threading method specified.

#else

/* not thread safe */
__GLXcontext *__glXcurrentContext = &dummyContext;

#endif


void __glXSetCurrentContextNull(Display *dpy)
{
  GLXContext gc;

  gc = __glXGetCurrentContext();
  if (dpy == gc->currentDpy) {
    __glXSetCurrentContext(&dummyContext);
#ifdef GLX_DIRECT_RENDERING
    _glapi_set_dispatch(NULL);  /* no-op functions */
#endif
    __glXFreeContext(gc);
  }
}


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

GLXContext glXGetCurrentContext(void)
{
    GLXContext cx = __glXGetCurrentContext();
    
    if (cx == &dummyContext) {
	return NULL;
    } else {
	return cx;
    }
}

GLXDrawable glXGetCurrentDrawable(void)
{
    GLXContext gc = __glXGetCurrentContext();
    return gc->currentDrawable;
}


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

/**
 * Sends a GLX protocol message to the specified display to make the context
 * and the drawables current.
 *
 * \param dpy     Display to send the message to.
 * \param opcode  Major opcode value for the display.
 * \param gc_id   Context tag for the context to be made current.
 * \param draw    Drawable ID for the "draw" drawable.
 * \param read    Drawable ID for the "read" drawable.
 * \param reply   Space to store the X-server's reply.
 *
 * \warning
 * This function assumes that \c dpy is locked with \c LockDisplay on entry.
 */
static Bool SendMakeCurrentRequest( Display *dpy, CARD8 opcode,
				    GLXContextID gc_id, GLXContextTag gc_tag,
				    GLXDrawable draw, GLXDrawable read,
				    xGLXMakeCurrentReply * reply )
{
    if ( draw == read ) {
	xGLXMakeCurrentReq *req;

	GetReq(GLXMakeCurrent,req);
	req->reqType = opcode;
	req->glxCode = X_GLXMakeCurrent;
	req->drawable = draw;
	req->context = gc_id;
	req->oldContextTag = gc_tag;
    }
    else {
	__GLXdisplayPrivate *priv = __glXInitialize(dpy);

	/* If the server can support the GLX 1.3 version, we should
	 * perfer that.  Not only that, some servers support GLX 1.3 but
	 * not the SGI extension.
	 */

	if ( (priv->majorVersion > 1) || (priv->minorVersion >= 3) ) {
	    xGLXMakeContextCurrentReq *req;

	    GetReq(GLXMakeContextCurrent,req);
	    req->reqType = opcode;
	    req->glxCode = X_GLXMakeContextCurrent;
	    req->drawable = draw;
	    req->readdrawable = read;
	    req->context = gc_id;
	    req->oldContextTag = gc_tag;
	}
	else {
	    xGLXVendorPrivateWithReplyReq *vpreq;
	    xGLXMakeCurrentReadSGIReq *req;

	    GetReqExtra(GLXVendorPrivateWithReply,
			sz_xGLXMakeCurrentReadSGIReq-sz_xGLXVendorPrivateWithReplyReq,vpreq);
	    req = (xGLXMakeCurrentReadSGIReq *)vpreq;
	    req->reqType = opcode;
	    req->glxCode = X_GLXVendorPrivateWithReply;
	    req->vendorCode = X_GLXvop_MakeCurrentReadSGI;
	    req->drawable = draw;
	    req->readable = read;
	    req->context = gc_id;
	    req->oldContextTag = gc_tag;
	}
    }

    return _XReply(dpy, (xReply*) reply, 0, False);
}


#ifdef GLX_DIRECT_RENDERING
static Bool BindContextWrapper( Display *dpy, GLXContext gc,
				GLXDrawable draw, GLXDrawable read )
{
    return (*gc->driContext.bindContext)(dpy, gc->screen, draw, read,
					 & gc->driContext);
}


static Bool UnbindContextWrapper( GLXContext gc )
{
    return (*gc->driContext.unbindContext)(gc->currentDpy, gc->screen, 
					   gc->currentDrawable,
					   gc->currentReadable,
					   & gc->driContext );
}
#endif /* GLX_DIRECT_RENDERING */


/*
** Make a particular context current.
** NOTE: this is in this file so that it can access dummyContext.
*/
USED static Bool MakeContextCurrent(Display *dpy, GLXDrawable draw,
                                    GLXDrawable read, GLXContext gc)
{
    xGLXMakeCurrentReply reply;
    GLXContext oldGC;
    CARD8 opcode, oldOpcode;
    Bool sentRequestToOldDpy = False;
    Bool bindReturnValue = True;

    opcode = __glXSetupForCommand(dpy);
    if (!opcode) {
	return GL_FALSE;
    }

    /*
    ** Make sure that the new context has a nonzero ID.  In the request,
    ** a zero context ID is used only to mean that we bind to no current
    ** context.
    */
    if ((gc != NULL) && (gc->xid == None)) {
	return GL_FALSE;
    }

    oldGC = __glXGetCurrentContext();
    oldOpcode = (gc == oldGC) ? opcode : __glXSetupForCommand(dpy);
    if (!oldOpcode) {
	return GL_FALSE;
    }

    if ((dpy != oldGC->currentDpy || (gc && gc->isDirect)) &&
	!oldGC->isDirect && oldGC != &dummyContext) {
	/*
	** We are either switching from one dpy to another and have to
	** send a request to the previous dpy to unbind the previous
	** context, or we are switching away from a indirect context to
	** a direct context and have to send a request to the dpy to
	** unbind the previous context.
	*/
	sentRequestToOldDpy = True;
        LockDisplay(oldGC->currentDpy);
	if ( ! SendMakeCurrentRequest( oldGC->currentDpy, oldOpcode, None,
				       oldGC->currentContextTag, None, None,
				       &reply ) ) {
	    /* The make current failed.  Just return GL_FALSE. */
	    UnlockDisplay(oldGC->currentDpy);
	    SyncHandle();
	    return GL_FALSE;
	}

	oldGC->currentContextTag = 0;
    }

    _glapi_check_multithread();

#ifdef GLX_DIRECT_RENDERING
    /* Unbind the old direct rendering context */
    if (oldGC->isDirect) {
	if (oldGC->driContext.private) {
	    if (! UnbindContextWrapper( oldGC )) {
		/* The make current failed.  Just return GL_FALSE. */
		return GL_FALSE;
	    }
	}
	oldGC->currentContextTag = 0;
    }

    /* Bind the direct rendering context to the drawable */
    if (gc && gc->isDirect) {
	if (gc->driContext.private) {
	    bindReturnValue = BindContextWrapper( dpy, gc, draw, read );
	}
    } else {
#endif
	/* Send a glXMakeCurrent request to bind the new context. */
	LockDisplay(dpy);

	bindReturnValue = SendMakeCurrentRequest( dpy, opcode, 
						  gc ? gc->xid : None,
						  oldGC->currentContextTag,
						  draw, read, &reply );
	UnlockDisplay(dpy);
#ifdef GLX_DIRECT_RENDERING
    }
#endif


    if (!bindReturnValue) {
	/* The make current failed. */
	if (gc && !gc->isDirect) {
	    SyncHandle();
	}

#ifdef GLX_DIRECT_RENDERING
	/* If the old context was direct rendering, then re-bind to it. */
	if (oldGC->isDirect) {
	    if (oldGC->driContext.private) {
		if (! BindContextWrapper( oldGC->currentDpy, oldGC,
					  oldGC->currentDrawable,
					  oldGC->currentReadable )) {
		    /*
		    ** The request failed; this cannot happen with the
		    ** current API.  If in the future the API is
		    ** extended to allow context sharing between
		    ** clients, then this may fail (because another
		    ** client may have grabbed the context); in that
		    ** case, we cannot undo the previous request, and
		    ** cannot adhere to the "no-op" behavior.
		    */
		}
	    }
	} else
#endif
	/*
	** If we had just sent a request to a previous dpy, we have to
	** undo that request (because if a command fails, it should act
	** like a no-op) by making current to the previous context and
	** drawable.
	*/
	if (sentRequestToOldDpy) {
	    if ( !SendMakeCurrentRequest( oldGC->currentDpy, oldOpcode,
					  oldGC->xid, 0, 
					  oldGC->currentDrawable,
					  oldGC->currentReadable, &reply ) ) {
		UnlockDisplay(oldGC->currentDpy);
		SyncHandle();
		/*
		** The request failed; this cannot happen with the
		** current API.  If in the future the API is extended to
		** allow context sharing between clients, then this may
		** fail (because another client may have grabbed the
		** context); in that case, we cannot undo the previous
		** request, and cannot adhere to the "no-op" behavior.
		*/
	    }
            else {
		UnlockDisplay(oldGC->currentDpy);
            }
	    oldGC->currentContextTag = reply.contextTag;
	}
	return GL_FALSE;
    }

    /* Update our notion of what is current */
    __glXLock();
    if (gc == oldGC) {
	/*
	** Even though the contexts are the same the drawable might have
	** changed.  Note that gc cannot be the dummy, and that oldGC
	** cannot be NULL, therefore if they are the same, gc is not
	** NULL and not the dummy.
	*/
	gc->currentDrawable = draw;
	gc->currentReadable = read;
    } else {
	if (oldGC != &dummyContext) {
	    /* Old current context is no longer current to anybody */
	    oldGC->currentDpy = 0;
	    oldGC->currentDrawable = None;
	    oldGC->currentReadable = None;
	    oldGC->currentContextTag = 0;

	    if (oldGC->xid == None) {
		/* 
		** We are switching away from a context that was
		** previously destroyed, so we need to free the memory
		** for the old handle.
		*/
#ifdef GLX_DIRECT_RENDERING
		/* Destroy the old direct rendering context */
		if (oldGC->isDirect) {
		    if (oldGC->driContext.private) {
			(*oldGC->driContext.destroyContext)
			    (dpy, oldGC->screen, oldGC->driContext.private);
			oldGC->driContext.private = NULL;
		    }
		}
#endif
		__glXFreeContext(oldGC);
	    }
	}
	if (gc) {
	    __glXSetCurrentContext(gc);
#ifdef GLX_DIRECT_RENDERING
            if (!gc->isDirect) {
               if (!IndirectAPI)
                  IndirectAPI = __glXNewIndirectAPI();
               _glapi_set_dispatch(IndirectAPI);
# ifdef GLX_USE_APPLEGL
               do {
                   extern void XAppleDRIUseIndirectDispatch(void);
                   XAppleDRIUseIndirectDispatch();
               } while (0);
# endif
            }
#else
            /* if not direct rendering, always need indirect dispatch */
            if (!IndirectAPI)
               IndirectAPI = __glXNewIndirectAPI();
            _glapi_set_dispatch(IndirectAPI);
#endif
	    gc->currentDpy = dpy;
	    gc->currentDrawable = draw;
	    gc->currentReadable = read;

	    if ( ! gc->isDirect ) {
		__GLXattribute * state = (__GLXattribute *)(gc->client_state_private);

		gc->currentContextTag = reply.contextTag;
		if ( state->array_state == NULL ) {
		    (void) glGetString( GL_EXTENSIONS );
		    (void) glGetString( GL_VERSION );
		    __glXInitVertexArrayState(gc);
		}
	    }
	    else {
		gc->currentContextTag = -1;
	    }
	} else {
	    __glXSetCurrentContext(&dummyContext);
#ifdef GLX_DIRECT_RENDERING
            _glapi_set_dispatch(NULL);  /* no-op functions */
#endif
	}
    }
    __glXUnlock();
    return GL_TRUE;
}


PUBLIC Bool glXMakeCurrent(Display *dpy, GLXDrawable draw, GLXContext gc)
{
    return MakeContextCurrent( dpy, draw, draw, gc );
}

PUBLIC GLX_ALIAS(Bool, glXMakeCurrentReadSGI,
	  (Display *dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
	  (dpy, d, r, ctx), MakeContextCurrent)

PUBLIC GLX_ALIAS(Bool, glXMakeContextCurrent,
	  (Display *dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
	  (dpy, d, r, ctx), MakeContextCurrent)