/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 2010  VMware, 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, sublicense,
 * 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 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 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.
 */


#include "imports.h"
#include "mtypes.h"
#include "version.h"
#include "git_sha1.h"

/**
 * Scans 'string' to see if it ends with 'ending'.
 */
static GLboolean
check_for_ending(char *string, const char *ending)
{
   int len1, len2;

   len1 = strlen(string);
   len2 = strlen(ending);

   if (len2 > len1) {
      return GL_FALSE;
   }

   if (strcmp(string + (len1 - len2), ending) == 0) {
      return GL_TRUE;
   } else {
      return GL_FALSE;
   }
}

/**
 * Builds the MESA version string.
 */
static void
create_version_string(struct gl_context *ctx, const char *prefix)
{
   static const int max = 100;

   ctx->VersionString = malloc(max);
   if (ctx->VersionString) {
      _mesa_snprintf(ctx->VersionString, max,
		     "%s%u.%u%s Mesa " MESA_VERSION_STRING
#ifdef MESA_GIT_SHA1
		     " (" MESA_GIT_SHA1 ")"
#endif
		     ,
		     prefix,
		     ctx->Version / 10, ctx->Version % 10,
		     (ctx->API == API_OPENGL_CORE) ? " (Core Profile)" : ""
		     );
   }
}

/**
 * Override the context's version and/or API type if the
 * environment variable MESA_GL_VERSION_OVERRIDE is set.
 *
 * Example uses of MESA_GL_VERSION_OVERRIDE:
 *
 * 2.1: select a compatibility (non-Core) profile with GL version 2.1
 * 3.0: select a compatibility (non-Core) profile with GL version 3.0
 * 3.0FC: select a Core+Forward Compatible profile with GL version 3.0
 * 3.1: select a Core profile with GL version 3.1
 * 3.1FC: select a Core+Forward Compatible profile with GL version 3.1
 */
void
_mesa_override_gl_version(struct gl_context *ctx)
{
   const char *env_var = "MESA_GL_VERSION_OVERRIDE";
   const char *version;
   int n;
   int major, minor;
   GLboolean fc_suffix;

   version = getenv(env_var);
   if (!version) {
      return;
   }

   fc_suffix = check_for_ending(version, "FC");

   n = sscanf(version, "%u.%u", &major, &minor);
   if (n != 2) {
      fprintf(stderr, "error: invalid value for %s: %s\n", env_var, version);
   } else {
      ctx->Version = major * 10 + minor;
      if (ctx->Version < 30 && fc_suffix) {
         fprintf(stderr, "error: invalid value for %s: %s\n", env_var, version);
      } else {
         if (ctx->Version >= 30 && fc_suffix) {
            ctx->API = API_OPENGL_CORE;
            ctx->Const.ContextFlags |= GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT;
         } else if (ctx->Version >= 31) {
            ctx->API = API_OPENGL_CORE;
         } else {
            ctx->API = API_OPENGL;
         }
         create_version_string(ctx, "");
      }
   }
}

/**
 * Override the context's GLSL version if the environment variable
 * MESA_GLSL_VERSION_OVERRIDE is set. Valid values for
 * MESA_GLSL_VERSION_OVERRIDE are integers, such as "130".
 */
void
_mesa_override_glsl_version(struct gl_context *ctx)
{
   const char *env_var = "MESA_GLSL_VERSION_OVERRIDE";
   const char *version;
   int n;

   version = getenv(env_var);
   if (!version) {
      return;
   }

   n = sscanf(version, "%u", &ctx->Const.GLSLVersion);
   if (n != 1) {
      fprintf(stderr, "error: invalid value for %s: %s\n", env_var, version);
      return;
   }
}

/**
 * Examine enabled GL extensions to determine GL version.
 */
static void
compute_version(struct gl_context *ctx)
{
   GLuint major, minor;

   const GLboolean ver_1_3 = (ctx->Extensions.ARB_texture_border_clamp &&
                              ctx->Extensions.ARB_texture_cube_map &&
                              ctx->Extensions.ARB_texture_env_combine &&
                              ctx->Extensions.ARB_texture_env_dot3);
   const GLboolean ver_1_4 = (ver_1_3 &&
                              ctx->Extensions.ARB_depth_texture &&
                              ctx->Extensions.ARB_shadow &&
                              ctx->Extensions.ARB_texture_env_crossbar &&
                              ctx->Extensions.ARB_window_pos &&
                              ctx->Extensions.EXT_blend_color &&
                              ctx->Extensions.EXT_blend_func_separate &&
                              ctx->Extensions.EXT_blend_minmax &&
                              ctx->Extensions.EXT_fog_coord &&
                              ctx->Extensions.EXT_point_parameters &&
                              ctx->Extensions.EXT_secondary_color);
   const GLboolean ver_1_5 = (ver_1_4 &&
                              ctx->Extensions.ARB_occlusion_query &&
                              ctx->Extensions.EXT_shadow_funcs);
   const GLboolean ver_2_0 = (ver_1_5 &&
                              ctx->Extensions.ARB_point_sprite &&
                              ctx->Extensions.ARB_shader_objects &&
                              ctx->Extensions.ARB_vertex_shader &&
                              ctx->Extensions.ARB_fragment_shader &&
                              ctx->Extensions.ARB_texture_non_power_of_two &&
                              ctx->Extensions.EXT_blend_equation_separate &&

			      /* Technically, 2.0 requires the functionality
			       * of the EXT version.  Enable 2.0 if either
			       * extension is available, and assume that a
			       * driver that only exposes the ATI extension
			       * will fallback to software when necessary.
			       */
			      (ctx->Extensions.EXT_stencil_two_side
			       || ctx->Extensions.ATI_separate_stencil));
   const GLboolean ver_2_1 = (ver_2_0 &&
                              ctx->Const.GLSLVersion >= 120 &&
                              ctx->Extensions.EXT_pixel_buffer_object &&
                              ctx->Extensions.EXT_texture_sRGB);
   const GLboolean ver_3_0 = (ver_2_1 &&
                              ctx->Const.GLSLVersion >= 130 &&
                              ctx->Const.MaxSamples >= 4 &&
                              ctx->Extensions.ARB_color_buffer_float &&
                              ctx->Extensions.ARB_depth_buffer_float &&
                              ctx->Extensions.ARB_half_float_pixel &&
                              ctx->Extensions.ARB_half_float_vertex &&
                              ctx->Extensions.ARB_map_buffer_range &&
                              ctx->Extensions.ARB_shader_texture_lod &&
                              ctx->Extensions.ARB_texture_float &&
                              ctx->Extensions.ARB_texture_rg &&
                              ctx->Extensions.ARB_texture_compression_rgtc &&
                              ctx->Extensions.EXT_draw_buffers2 &&
                              ctx->Extensions.ARB_framebuffer_object &&
                              ctx->Extensions.EXT_framebuffer_sRGB &&
                              ctx->Extensions.EXT_packed_float &&
                              ctx->Extensions.EXT_texture_array &&
                              ctx->Extensions.EXT_texture_shared_exponent &&
                              ctx->Extensions.EXT_transform_feedback &&
                              ctx->Extensions.NV_conditional_render);
   const GLboolean ver_3_1 = (ver_3_0 &&
                              ctx->Const.GLSLVersion >= 140 &&
                              ctx->Extensions.ARB_copy_buffer &&
                              ctx->Extensions.ARB_draw_instanced &&
                              ctx->Extensions.ARB_texture_buffer_object &&
                              ctx->Extensions.ARB_uniform_buffer_object &&
                              ctx->Extensions.EXT_texture_snorm &&
                              ctx->Extensions.NV_primitive_restart &&
                              ctx->Extensions.NV_texture_rectangle &&
                              ctx->Const.MaxVertexTextureImageUnits >= 16);
   const GLboolean ver_3_2 = (ver_3_1 &&
                              ctx->Const.GLSLVersion >= 150 &&
                              ctx->Extensions.ARB_depth_clamp &&
                              ctx->Extensions.ARB_draw_elements_base_vertex &&
                              ctx->Extensions.ARB_fragment_coord_conventions &&
                              ctx->Extensions.ARB_geometry_shader4 &&
                              ctx->Extensions.EXT_provoking_vertex &&
                              ctx->Extensions.ARB_seamless_cube_map &&
                              ctx->Extensions.ARB_sync &&
                              ctx->Extensions.ARB_texture_multisample &&
                              ctx->Extensions.EXT_vertex_array_bgra);
   const GLboolean ver_3_3 = (ver_3_2 &&
                              ctx->Const.GLSLVersion >= 330 &&
                              ctx->Extensions.ARB_blend_func_extended &&
                              ctx->Extensions.ARB_explicit_attrib_location &&
                              ctx->Extensions.ARB_instanced_arrays &&
                              ctx->Extensions.ARB_occlusion_query2 &&
                              ctx->Extensions.ARB_shader_bit_encoding &&
                              ctx->Extensions.ARB_texture_rgb10_a2ui &&
                              ctx->Extensions.ARB_timer_query &&
                              ctx->Extensions.ARB_vertex_type_2_10_10_10_rev &&
                              ctx->Extensions.EXT_texture_swizzle);
                              /* ARB_sampler_objects is always enabled in mesa */

   if (ver_3_3) {
      major = 3;
      minor = 3;
   }
   else if (ver_3_2) {
      major = 3;
      minor = 2;
   }
   else if (ver_3_1) {
      major = 3;
      minor = 1;
   }
   else if (ver_3_0) {
      major = 3;
      minor = 0;
   }
   else if (ver_2_1) {
      major = 2;
      minor = 1;
   }
   else if (ver_2_0) {
      major = 2;
      minor = 0;
   }
   else if (ver_1_5) {
      major = 1;
      minor = 5;
   }
   else if (ver_1_4) {
      major = 1;
      minor = 4;
   }
   else if (ver_1_3) {
      major = 1;
      minor = 3;
   }
   else {
      major = 1;
      minor = 2;
   }

   ctx->Version = major * 10 + minor;

   create_version_string(ctx, "");
}

static void
compute_version_es1(struct gl_context *ctx)
{
   /* OpenGL ES 1.0 is derived from OpenGL 1.3 */
   const GLboolean ver_1_0 = (ctx->Extensions.ARB_texture_env_combine &&
                              ctx->Extensions.ARB_texture_env_dot3);
   /* OpenGL ES 1.1 is derived from OpenGL 1.5 */
   const GLboolean ver_1_1 = (ver_1_0 &&
                              ctx->Extensions.EXT_point_parameters);

   if (ver_1_1) {
      ctx->Version = 11;
   } else if (ver_1_0) {
      ctx->Version = 10;
   } else {
      _mesa_problem(ctx, "Incomplete OpenGL ES 1.0 support.");
   }

   create_version_string(ctx, "OpenGL ES-CM ");
}

static void
compute_version_es2(struct gl_context *ctx)
{
   /* OpenGL ES 2.0 is derived from OpenGL 2.0 */
   const GLboolean ver_2_0 = (ctx->Extensions.ARB_texture_cube_map &&
                              ctx->Extensions.EXT_blend_color &&
                              ctx->Extensions.EXT_blend_func_separate &&
                              ctx->Extensions.EXT_blend_minmax &&
                              ctx->Extensions.ARB_shader_objects &&
                              ctx->Extensions.ARB_vertex_shader &&
                              ctx->Extensions.ARB_fragment_shader &&
                              ctx->Extensions.ARB_texture_non_power_of_two &&
                              ctx->Extensions.EXT_blend_equation_separate);
   if (ver_2_0) {
      ctx->Version = 20;
   } else {
      _mesa_problem(ctx, "Incomplete OpenGL ES 2.0 support.");
   }

   create_version_string(ctx, "OpenGL ES ");
}

/**
 * Set the context's Version and VersionString fields.
 * This should only be called once as part of context initialization
 * or to perform version check for GLX_ARB_create_context_profile.
 */
void
_mesa_compute_version(struct gl_context *ctx)
{
   if (ctx->Version)
      return;

   switch (ctx->API) {
   case API_OPENGL:
   case API_OPENGL_CORE:
      compute_version(ctx);
      break;
   case API_OPENGLES:
      compute_version_es1(ctx);
      break;
   case API_OPENGLES2:
      compute_version_es2(ctx);
      break;
   }

}