/**
 * 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"


/**
 * Return the native platform by parsing EGL_PLATFORM.
 */
static _EGLPlatformType
_eglGetNativePlatformFromEnv(void)
{
   /* 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" }
   };
   _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;
}


/**
 * Return the native platform.  It is the platform of the EGL native types.
 */
_EGLPlatformType
_eglGetNativePlatform(void)
{
   static _EGLPlatformType native_platform = _EGL_INVALID_PLATFORM;

   if (native_platform == _EGL_INVALID_PLATFORM) {
      native_platform = _eglGetNativePlatformFromEnv();
      if (native_platform == _EGL_INVALID_PLATFORM)
         native_platform = _EGL_NATIVE_PLATFORM;
   }

   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);
}