/**************************************************************************
 *
 * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
 * Copyright 2009-2010 Chia-I Wu <olvaffe@gmail.com>
 * Copyright 2010-2011 LunarG, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/


/**
 * Functions related to EGLDisplay.
 */

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "eglcontext.h"
#include "eglsurface.h"
#include "egldisplay.h"
#include "egldriver.h"
#include "eglglobals.h"
#include "eglmutex.h"
#include "egllog.h"

/* Includes for _eglNativePlatformDetectNativeDisplay */
#ifdef HAVE_MINCORE
#include <unistd.h>
#include <sys/mman.h>
#endif
#ifdef HAVE_WAYLAND_PLATFORM
#include <wayland-client.h>
#endif
#ifdef HAVE_DRM_PLATFORM
#include <gbm.h>
#endif
#ifdef HAVE_FBDEV_PLATFORM
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#endif


/**
 * Map --with-egl-platforms names to platform types.
 */
static const struct {
   _EGLPlatformType platform;
   const char *name;
} egl_platforms[_EGL_NUM_PLATFORMS] = {
   { _EGL_PLATFORM_WINDOWS, "gdi" },
   { _EGL_PLATFORM_X11, "x11" },
   { _EGL_PLATFORM_WAYLAND, "wayland" },
   { _EGL_PLATFORM_DRM, "drm" },
   { _EGL_PLATFORM_FBDEV, "fbdev" },
   { _EGL_PLATFORM_NULL, "null" },
   { _EGL_PLATFORM_ANDROID, "android" }
};


/**
 * Return the native platform by parsing EGL_PLATFORM.
 */
static _EGLPlatformType
_eglGetNativePlatformFromEnv(void)
{
   _EGLPlatformType plat = _EGL_INVALID_PLATFORM;
   const char *plat_name;
   EGLint i;

   plat_name = getenv("EGL_PLATFORM");
   /* try deprecated env variable */
   if (!plat_name || !plat_name[0])
      plat_name = getenv("EGL_DISPLAY");
   if (!plat_name || !plat_name[0])
      return _EGL_INVALID_PLATFORM;

   for (i = 0; i < _EGL_NUM_PLATFORMS; i++) {
      if (strcmp(egl_platforms[i].name, plat_name) == 0) {
         plat = egl_platforms[i].platform;
         break;
      }
   }

   return plat;
}


/**
 * Perform validity checks on a generic pointer.
 */
static EGLBoolean
_eglPointerIsDereferencable(void *p)
{
#ifdef HAVE_MINCORE
   uintptr_t addr = (uintptr_t) p;
   unsigned char valid = 0;
   const long page_size = getpagesize();

   if (p == NULL)
      return EGL_FALSE;

   /* align addr to page_size */
   addr &= ~(page_size - 1);

   if (mincore((void *) addr, page_size, &valid) < 0) {
      _eglLog(_EGL_DEBUG, "mincore failed: %m");
      return EGL_FALSE;
   }

   return (valid & 0x01) == 0x01;
#else
   return p != NULL;
#endif
}


/**
 * Try detecting native platform with the help of native display characteristcs.
 */
static _EGLPlatformType
_eglNativePlatformDetectNativeDisplay(EGLNativeDisplayType nativeDisplay)
{
#ifdef HAVE_FBDEV_PLATFORM
   struct stat buf;
#endif

   if (nativeDisplay == EGL_DEFAULT_DISPLAY)
      return _EGL_INVALID_PLATFORM;

#ifdef HAVE_FBDEV_PLATFORM
   /* fbdev is the only platform that can be a file descriptor. */
   if (fstat((intptr_t) nativeDisplay, &buf) == 0 && S_ISCHR(buf.st_mode))
      return _EGL_PLATFORM_FBDEV;
#endif

   if (_eglPointerIsDereferencable(nativeDisplay)) {
      void *first_pointer = *(void **) nativeDisplay;

#ifdef HAVE_WAYLAND_PLATFORM
      /* wl_display is a wl_proxy, which is a wl_object.
       * wl_object's first element points to the interfacetype. */
      if (first_pointer == &wl_display_interface)
         return _EGL_PLATFORM_WAYLAND;
#endif

#ifdef HAVE_DRM_PLATFORM
      /* gbm has a pointer to its constructor as first element. */
      if (first_pointer == gbm_create_device)
         return _EGL_PLATFORM_DRM;
#endif

#ifdef HAVE_X11_PLATFORM
      /* If not matched to any other platform, fallback to x11. */
      return _EGL_PLATFORM_X11;
#endif
   }

   return _EGL_INVALID_PLATFORM;
}


/**
 * Return the native platform.  It is the platform of the EGL native types.
 */
_EGLPlatformType
_eglGetNativePlatform(EGLNativeDisplayType nativeDisplay)
{
   static _EGLPlatformType native_platform = _EGL_INVALID_PLATFORM;
   char *detection_method = NULL;

   if (native_platform == _EGL_INVALID_PLATFORM) {
      native_platform = _eglGetNativePlatformFromEnv();
      detection_method = "environment overwrite";
      if (native_platform == _EGL_INVALID_PLATFORM) {
         native_platform = _eglNativePlatformDetectNativeDisplay(nativeDisplay);
         detection_method = "autodetected";
         if (native_platform == _EGL_INVALID_PLATFORM) {
            native_platform = _EGL_NATIVE_PLATFORM;
            detection_method = "build-time configuration";
         }
      }
   }

   if (detection_method != NULL)
      _eglLog(_EGL_DEBUG, "Native platform type: %s (%s)",
              egl_platforms[native_platform].name, detection_method);

   return native_platform;
}


/**
 * Finish display management.
 */
void
_eglFiniDisplay(void)
{
   _EGLDisplay *dpyList, *dpy;

   /* atexit function is called with global mutex locked */
   dpyList = _eglGlobal.DisplayList;
   while (dpyList) {
      EGLint i;

      /* pop list head */
      dpy = dpyList;
      dpyList = dpyList->Next;

      for (i = 0; i < _EGL_NUM_RESOURCES; i++) {
         if (dpy->ResourceLists[i]) {
            _eglLog(_EGL_DEBUG, "Display %p is destroyed with resources", dpy);
            break;
         }
      }

      free(dpy);
   }
   _eglGlobal.DisplayList = NULL;
}


/**
 * Find the display corresponding to the specified native display, or create a
 * new one.
 */
_EGLDisplay *
_eglFindDisplay(_EGLPlatformType plat, void *plat_dpy)
{
   _EGLDisplay *dpy;

   if (plat == _EGL_INVALID_PLATFORM)
      return NULL;

   _eglLockMutex(_eglGlobal.Mutex);

   /* search the display list first */
   dpy = _eglGlobal.DisplayList;
   while (dpy) {
      if (dpy->Platform == plat && dpy->PlatformDisplay == plat_dpy)
         break;
      dpy = dpy->Next;
   }

   /* create a new display */
   if (!dpy) {
      dpy = (_EGLDisplay *) calloc(1, sizeof(_EGLDisplay));
      if (dpy) {
         _eglInitMutex(&dpy->Mutex);
         dpy->Platform = plat;
         dpy->PlatformDisplay = plat_dpy;

         /* add to the display list */ 
         dpy->Next = _eglGlobal.DisplayList;
         _eglGlobal.DisplayList = dpy;
      }
   }

   _eglUnlockMutex(_eglGlobal.Mutex);

   return dpy;
}


/**
 * Destroy the contexts and surfaces that are linked to the display.
 */
void
_eglReleaseDisplayResources(_EGLDriver *drv, _EGLDisplay *display)
{
   _EGLResource *list;

   list = display->ResourceLists[_EGL_RESOURCE_CONTEXT];
   while (list) {
      _EGLContext *ctx = (_EGLContext *) list;
      list = list->Next;

      _eglUnlinkContext(ctx);
      drv->API.DestroyContext(drv, display, ctx);
   }
   assert(!display->ResourceLists[_EGL_RESOURCE_CONTEXT]);

   list = display->ResourceLists[_EGL_RESOURCE_SURFACE];
   while (list) {
      _EGLSurface *surf = (_EGLSurface *) list;
      list = list->Next;

      _eglUnlinkSurface(surf);
      drv->API.DestroySurface(drv, display, surf);
   }
   assert(!display->ResourceLists[_EGL_RESOURCE_SURFACE]);
}


/**
 * Free all the data hanging of an _EGLDisplay object, but not
 * the object itself.
 */
void
_eglCleanupDisplay(_EGLDisplay *disp)
{
   if (disp->Configs) {
      _eglDestroyArray(disp->Configs, free);
      disp->Configs = NULL;
   }

   /* XXX incomplete */
}


/**
 * Return EGL_TRUE if the given handle is a valid handle to a display.
 */
EGLBoolean
_eglCheckDisplayHandle(EGLDisplay dpy)
{
   _EGLDisplay *cur;

   _eglLockMutex(_eglGlobal.Mutex);
   cur = _eglGlobal.DisplayList;
   while (cur) {
      if (cur == (_EGLDisplay *) dpy)
         break;
      cur = cur->Next;
   }
   _eglUnlockMutex(_eglGlobal.Mutex);
   return (cur != NULL);
}


/**
 * Return EGL_TRUE if the given resource is valid.  That is, the display does
 * own the resource.
 */
EGLBoolean
_eglCheckResource(void *res, _EGLResourceType type, _EGLDisplay *dpy)
{
   _EGLResource *list = dpy->ResourceLists[type];
   
   if (!res)
      return EGL_FALSE;

   while (list) {
      if (res == (void *) list) {
         assert(list->Display == dpy);
         break;
      }
      list = list->Next;
   }

   return (list != NULL);
}


/**
 * Initialize a display resource.
 */
void
_eglInitResource(_EGLResource *res, EGLint size, _EGLDisplay *dpy)
{
   memset(res, 0, size);
   res->Display = dpy;
   res->RefCount = 1;
}


/**
 * Increment reference count for the resource.
 */
void
_eglGetResource(_EGLResource *res)
{
   assert(res && res->RefCount > 0);
   /* hopefully a resource is always manipulated with its display locked */
   res->RefCount++;
}


/**
 * Decrement reference count for the resource.
 */
EGLBoolean
_eglPutResource(_EGLResource *res)
{
   assert(res && res->RefCount > 0);
   res->RefCount--;
   return (!res->RefCount);
}


/**
 * Link a resource to its display.
 */
void
_eglLinkResource(_EGLResource *res, _EGLResourceType type)
{
   assert(res->Display);

   res->IsLinked = EGL_TRUE;
   res->Next = res->Display->ResourceLists[type];
   res->Display->ResourceLists[type] = res;
   _eglGetResource(res);
}


/**
 * Unlink a linked resource from its display.
 */
void
_eglUnlinkResource(_EGLResource *res, _EGLResourceType type)
{
   _EGLResource *prev;

   prev = res->Display->ResourceLists[type];
   if (prev != res) {
      while (prev) {
         if (prev->Next == res)
            break;
         prev = prev->Next;
      }
      assert(prev);
      prev->Next = res->Next;
   }
   else {
      res->Display->ResourceLists[type] = res->Next;
   }

   res->Next = NULL;
   res->IsLinked = EGL_FALSE;
   _eglPutResource(res);

   /* We always unlink before destroy.  The driver still owns a reference */
   assert(res->RefCount);
}