/*

 * GStreamer

 * Copyright (C) 2012 Matthew Waters <ystreet00@gmail.com>

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * 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 GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <string.h>

#include "gstglfeature.h"

#include "gstglcontext.h"

#include "gstglfeature_private.h"

#include "gstglfuncs.h"

#define GST_CAT_DEFAULT gl_feature

GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

static void

_init_debug (void)

{

  static volatile gsize _init = 0;

  if (g_once_init_enter (&_init)) {

    GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "glfeature", 0,

        "OpenGL feature detection");

    g_once_init_leave (&_init, 1);

  }

}

/**

 * gst_gl_check_extension:

 * @name: the extension to search for

 * @ext: the list of possible extensions

 *

 * Returns: whether @name is in the space seperated list of @ext

 */

gboolean

gst_gl_check_extension (const char *name, const gchar * ext)

{

  char *end;

  int name_len, n;

  if (name == NULL || ext == NULL)

    return FALSE;

  end = (char *) (ext + strlen (ext));

  name_len = strlen (name);

  while (ext < end) {

    n = strcspn (ext, " ");

    if ((name_len == n) && (!strncmp (name, ext, n)))

      return TRUE;

    ext += (n + 1);

  }

  return FALSE;

}

/* Define a set of arrays containing the functions required from GL

   for each feature */

#define GST_GL_EXT_BEGIN(name,                                            \

                       gl_availability,                                 \

                       min_gl_major, min_gl_minor,                      \

                       min_gles_major, min_gles_minor,                  \

                       namespaces, extension_names)                     \

  static const GstGLFeatureFunction gst_gl_ext_ ## name ## _funcs[] = {

#define GST_GL_EXT_FUNCTION(ret, name, args)                          \

  { G_STRINGIFY (name), G_STRUCT_OFFSET (GstGLFuncs, name) },

#define GST_GL_EXT_END()                      \

  { NULL, 0 },                                  \

  };

#include "glprototypes/all_functions.h"

#undef GST_GL_EXT_BEGIN

#undef GST_GL_EXT_FUNCTION

#undef GST_GL_EXT_END

#define GST_GL_EXT_BEGIN(name,                                          \

                       gl_availability,                                 \

                       min_gl_major, min_gl_minor,                      \

                       min_gles_major, min_gles_minor,                  \

                       namespaces, extension_names)                     \

  { G_STRINGIFY (name), gl_availability, min_gl_major, min_gl_minor, min_gles_major,        \

    min_gles_minor, namespaces, extension_names,                        \

    gst_gl_ext_ ## name ## _funcs },

#define GST_GL_EXT_FUNCTION(ret, name, args)

#define GST_GL_EXT_END()

static const GstGLFeatureData gst_gl_feature_ext_functions_data[] = {

#include "glprototypes/all_functions.h"

};

#undef GST_GL_EXT_BEGIN

#undef GST_GL_EXT_FUNCTION

#undef GST_GL_EXT_END

static gboolean

_gst_gl_feature_check_for_extension (const GstGLFeatureData * data,

    const char *driver_prefix, const char *extensions_string,

    const char **suffix)

{

  const char *namespace, *namespace_suffix;

  unsigned int namespace_len;

  g_return_val_if_fail (suffix != NULL, FALSE);

  for (namespace = data->namespaces; *namespace;

      namespace += strlen (namespace) + 1) {

    const char *extension;

    GString *full_extension_name = g_string_new ("");

    /* If the namespace part contains a ':' then the suffix for

       the function names is different from the name space */

    if ((namespace_suffix = strchr (namespace, ':'))) {

      namespace_len = namespace_suffix - namespace;

      namespace_suffix++;

    } else {

      namespace_len = strlen (namespace);

      namespace_suffix = namespace;

    }

    for (extension = data->extension_names; *extension;

        extension += strlen (extension) + 1) {

      g_string_assign (full_extension_name, driver_prefix);

      g_string_append_c (full_extension_name, '_');

      g_string_append_len (full_extension_name, namespace, namespace_len);

      g_string_append_c (full_extension_name, '_');

      g_string_append (full_extension_name, extension);

      if (gst_gl_check_extension (full_extension_name->str, extensions_string)) {

        GST_TRACE ("found %s in extension string", full_extension_name->str);

        break;

      }

    }

    g_string_free (full_extension_name, TRUE);

    /* If we found an extension with this namespace then use it

       as the suffix */

    if (*extension) {

      *suffix = namespace_suffix;

      return TRUE;

    }

  }

  return FALSE;

}

gboolean

_gst_gl_feature_check (GstGLContext * context,

    const char *driver_prefix,

    const GstGLFeatureData * data,

    int gl_major, int gl_minor, const char *extensions_string)

{

  char *full_function_name = NULL;

  gboolean in_core = FALSE;

  const char *suffix = NULL;

  int func_num;

  GstGLFuncs *gst_gl = context->gl_vtable;

  guint gl_min = 0, gl_maj = 0;

  GstGLAPI gl_api = gst_gl_context_get_gl_api (context);

  if (gl_api & (GST_GL_API_OPENGL | GST_GL_API_OPENGL3)) {

    gl_maj = data->min_gl_major;

    gl_min = data->min_gl_minor;

  } else if (gl_api & (GST_GL_API_GLES1 | GST_GL_API_GLES2)) {

    gl_maj = data->min_gles_major;

    gl_min = data->min_gles_minor;

  }

  GST_DEBUG ("%s, 0x%x, %d.%d vs 0x%x, %d.%d", data->feature_name,

      data->gl_availability, gl_maj, gl_min,

      gst_gl_context_get_gl_api (context), gl_major, gl_minor);

  /* First check whether the functions should be directly provided by

     GL */

  if (gst_gl_context_check_gl_version (context, data->gl_availability, gl_maj,

          gl_min)) {

    in_core = TRUE;

    suffix = "";

  } else {

    /* Otherwise try all of the extensions */

    if (!_gst_gl_feature_check_for_extension (data, driver_prefix,

            extensions_string, &suffix))

      goto error;

  }

  /* If we couldn't find anything that provides the functions then

     give up */

  if (suffix == NULL)

    goto error;

  /* Try to get all of the entry points */

  for (func_num = 0; data->functions[func_num].name; func_num++) {

    void *func;

    g_free (full_function_name);

    full_function_name = g_strconcat ("gl", data->functions[func_num].name,

        suffix, NULL);

    GST_TRACE ("%s should %sbe in core", full_function_name,

        in_core ? "" : "not ");

    func = gst_gl_context_get_proc_address (context, full_function_name);

    if (func == NULL && in_core) {

      GST_TRACE ("%s was not found in core, trying the extension version",

          full_function_name);

      if (!_gst_gl_feature_check_for_extension (data, driver_prefix,

              extensions_string, &suffix)) {

        goto error;

      } else {

        g_free (full_function_name);

        full_function_name = g_strconcat ("gl", data->functions[func_num].name,

            suffix, NULL);

        func = gst_gl_context_get_proc_address (context, full_function_name);

      }

    }

    if (func == NULL) {

      goto error;

    }

    /* Set the function pointer in the context */

    *(void **) ((guint8 *) gst_gl +

        data->functions[func_num].pointer_offset) = func;

  }

  g_free (full_function_name);

  return TRUE;

  /* If the extension isn't found or one of the functions wasn't found

   * then set all of the functions pointers to NULL so we can safely

   * do feature testing by just looking at the function pointers */

error:

  GST_DEBUG ("failed to find feature %s", data->feature_name);

  for (func_num = 0; data->functions[func_num].name; func_num++) {

    *(void **) ((guint8 *) gst_gl +

        data->functions[func_num].pointer_offset) = NULL;

  }

  if (full_function_name) {

    GST_DEBUG ("failed to find function %s", full_function_name);

    g_free (full_function_name);

  }

  return FALSE;

}

void

_gst_gl_feature_check_ext_functions (GstGLContext * context,

    int gl_major, int gl_minor, const char *gl_extensions)

{

  int i;

  _init_debug ();

  for (i = 0; i < G_N_ELEMENTS (gst_gl_feature_ext_functions_data); i++) {

    _gst_gl_feature_check (context, "GL",

        gst_gl_feature_ext_functions_data + i, gl_major, gl_minor,

        gl_extensions);

  }

}