/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "GLContext.h"
#include "nsPrintfCString.h"

namespace mozilla {
namespace gl {

const size_t kMAX_EXTENSION_GROUP_SIZE = 5;

enum class GLVersion : uint32_t {
    NONE  = 0,   // Feature is not supported natively by GL
    GL1_2 = 120,
    GL1_3 = 130,
    GL2   = 200,
    GL2_1 = 210,
    GL3   = 300,
    GL3_1 = 310,
    GL3_2 = 320,
    GL3_3 = 330,
    GL4   = 400,
    GL4_1 = 410,
    GL4_2 = 420,
    GL4_3 = 430,
};

enum class GLESVersion : uint32_t {
    NONE  = 0,   // Feature is not support natively by GL ES
    ES2   = 200,
    ES3   = 300,
    ES3_1 = 310,
    ES3_2 = 320,
};

// ARB_ES2_compatibility is natively supported in OpenGL 4.1.
static const GLVersion kGLCoreVersionForES2Compat = GLVersion::GL4_1;

// ARB_ES3_compatibility is natively supported in OpenGL 4.3.
static const GLVersion kGLCoreVersionForES3Compat = GLVersion::GL4_3;

struct FeatureInfo
{
    const char* mName;

    /* The (desktop) OpenGL version that provides this feature */
    GLVersion mOpenGLVersion;

    /* The OpenGL ES version that provides this feature */
    GLESVersion mOpenGLESVersion;

    /* If there is an ARB extension, and its function symbols are
     * not decorated with an ARB suffix, then its extension ID should go
     * here, and NOT in mExtensions.  For example, ARB_vertex_array_object
     * functions do not have an ARB suffix, because it is an extension that
     * was created to match core GL functionality and will never differ.
     * Some ARB extensions do have a suffix, if they were created before
     * a core version of the functionality existed.
     *
     * If there is no such ARB extension, pass 0 (GLContext::Extension_None)
     */
    GLContext::GLExtensions mARBExtensionWithoutARBSuffix;

    /* Extensions that also provide this feature */
    GLContext::GLExtensions mExtensions[kMAX_EXTENSION_GROUP_SIZE];
};

static const FeatureInfo sFeatureInfoArr[] = {
    {
        "bind_buffer_offset",
        GLVersion::NONE,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {

            GLContext::EXT_transform_feedback,
            GLContext::NV_transform_feedback2,
            GLContext::Extensions_End
        }
    },
    {
        "blend_minmax",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_blend_minmax,
            GLContext::Extensions_End
        }
    },
    {
        "clear_buffers",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
    },
    {
        "copy_buffer",
        GLVersion::GL3_1,
        GLESVersion::ES3,
        GLContext::ARB_copy_buffer,
        {
            GLContext::Extensions_End
        }
    },
    {
        "depth_texture",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_depth_texture,
            GLContext::OES_depth_texture,
            // Intentionally avoid putting ANGLE_depth_texture here,
            // it does not offer quite the same functionality.
            GLContext::Extensions_End
        }
    },
    {
        "draw_buffers",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_draw_buffers,
            GLContext::EXT_draw_buffers,
            GLContext::Extensions_End
        }
    },
    {
        "draw_instanced",
        GLVersion::GL3_1,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_draw_instanced,
            GLContext::EXT_draw_instanced,
            GLContext::NV_draw_instanced,
            GLContext::ANGLE_instanced_arrays,
            GLContext::Extensions_End
        }
    },
    {
        "draw_range_elements",
        GLVersion::GL1_2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_draw_range_elements,
            GLContext::Extensions_End
        }
    },
    {
        "element_index_uint",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::OES_element_index_uint,
            GLContext::Extensions_End
        }
    },
    {
        "ES2_compatibility",
        kGLCoreVersionForES2Compat,
        GLESVersion::ES2, // OpenGL ES version
        GLContext::ARB_ES2_compatibility, // no suffix on ARB extension
        {
            GLContext::Extensions_End
        }
    },
    {
        "ES3_compatibility",
        kGLCoreVersionForES3Compat,
        GLESVersion::ES3, // OpenGL ES version
        GLContext::ARB_ES3_compatibility, // no suffix on ARB extension
        {
            GLContext::Extensions_End
        }
    },
    {
        "EXT_color_buffer_float",
        GLVersion::GL3,
        GLESVersion::ES3_2,
        GLContext::Extension_None,
        {
            GLContext::EXT_color_buffer_float,
            GLContext::Extensions_End
        }
    },
    {
        // Removes clamping for float color outputs from frag shaders.
        "frag_color_float",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_color_buffer_float,
            GLContext::EXT_color_buffer_float,
            GLContext::EXT_color_buffer_half_float,
            GLContext::Extensions_End
        }
    },
    {
        "frag_depth",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_frag_depth,
            GLContext::Extensions_End
        }
    },
    {
        // Check for just the blit framebuffer blit part of
        // ARB_framebuffer_object
        "framebuffer_blit",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_framebuffer_object,
        {
            GLContext::ANGLE_framebuffer_blit,
            GLContext::EXT_framebuffer_blit,
            GLContext::NV_framebuffer_blit,
            GLContext::Extensions_End
        }
    },
    {
        // Check for just the multisample renderbuffer part of
        // ARB_framebuffer_object
        "framebuffer_multisample",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_framebuffer_object,
        {
            GLContext::ANGLE_framebuffer_multisample,
            GLContext::APPLE_framebuffer_multisample,
            GLContext::EXT_framebuffer_multisample,
            GLContext::EXT_multisampled_render_to_texture,
            GLContext::Extensions_End
        }
    },
    {
        // ARB_framebuffer_object support
        "framebuffer_object",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_framebuffer_object,
        {
            GLContext::Extensions_End
        }
    },
    {
        // EXT_framebuffer_object/OES_framebuffer_object support
        "framebuffer_object_EXT_OES",
        GLVersion::GL3,
        GLESVersion::ES2,
        GLContext::Extension_None,
        {
            GLContext::EXT_framebuffer_object,
            GLContext::OES_framebuffer_object,
            GLContext::Extensions_End
        }
    },
    {
        "get_integer_indexed",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_draw_buffers2,
            GLContext::Extensions_End
        }
    },
    {
        "get_integer64_indexed",
        GLVersion::GL3_2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
    },
    {
        "get_query_object_i64v",
        GLVersion::GL3_3,
        GLESVersion::NONE,
        GLContext::ARB_timer_query,
        {
            GLContext::ANGLE_timer_query,
            GLContext::EXT_disjoint_timer_query,
            GLContext::EXT_timer_query,
            GLContext::Extensions_End
        }
    },
    {
        "get_query_object_iv",
        GLVersion::GL2,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
        /*
         * XXX_get_query_object_iv only provide GetQueryObjectiv provided by
         * ARB_occlusion_query (added by OpenGL 2.0).
         */
    },
    {
        "get_string_indexed",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
        // glGetStringi
    },
    {
        "gpu_shader4",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_gpu_shader4,
            GLContext::Extensions_End
        }
    },
    {
        "gpu_shader5",
        GLVersion::GL4,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {
            GLContext::ARB_gpu_shader5,
            GLContext::EXT_gpu_shader5,
            GLContext::NV_gpu_shader5,
            GLContext::Extensions_End
        }
    },    
    {
        "instanced_arrays",
        GLVersion::GL3_3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_instanced_arrays,
            GLContext::NV_instanced_arrays,
            GLContext::ANGLE_instanced_arrays,
            GLContext::Extensions_End
        }
    },
    {
        "instanced_non_arrays",
        GLVersion::GL3_3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_instanced_arrays,
            GLContext::Extensions_End
        }
        /* This is an expanded version of `instanced_arrays` that allows for all
         * enabled active attrib arrays to have non-zero divisors.
         * ANGLE_instanced_arrays and NV_instanced_arrays forbid this, but GLES3
         * has no such restriction.
         */
    },
    {
        "internalformat_query",
        GLVersion::GL4_2,
        GLESVersion::ES3,
        GLContext::ARB_internalformat_query,
        {
            GLContext::Extensions_End
        }
    },
    {
        "invalidate_framebuffer",
        GLVersion::GL4_3,
        GLESVersion::ES3,
        GLContext::ARB_invalidate_subdata,
        {
            GLContext::Extensions_End
        }
    },
    {
        "map_buffer_range",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_map_buffer_range,
        {
            GLContext::Extensions_End
        }
    },
    {
        "occlusion_query",
        GLVersion::GL2,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
        // XXX_occlusion_query depend on ARB_occlusion_query (added in OpenGL 2.0)
    },
    {
        "occlusion_query_boolean",
        kGLCoreVersionForES3Compat,
        GLESVersion::ES3,
        GLContext::ARB_ES3_compatibility,
        {
            GLContext::EXT_occlusion_query_boolean,
            GLContext::Extensions_End
        }
        /*
         * XXX_occlusion_query_boolean provide ANY_SAMPLES_PASSED_CONSERVATIVE,
         * but EXT_occlusion_query_boolean is only a OpenGL ES extension. But
         * it is supported on desktop if ARB_ES3_compatibility because
         * EXT_occlusion_query_boolean (added in OpenGL ES 3.0).
         */
    },
    {
        "occlusion_query2",
        GLVersion::GL3_3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_occlusion_query2,
            GLContext::ARB_ES3_compatibility,
            GLContext::EXT_occlusion_query_boolean,
            GLContext::Extensions_End
        }
        /*
         * XXX_occlusion_query2 (add in OpenGL 3.3) provide ANY_SAMPLES_PASSED,
         * which is provided by ARB_occlusion_query2, EXT_occlusion_query_boolean
         * (added in OpenGL ES 3.0) and ARB_ES3_compatibility
         */
    },
    {
        "packed_depth_stencil",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_packed_depth_stencil,
            GLContext::OES_packed_depth_stencil,
            GLContext::Extensions_End
        }
    },
    {
        "prim_restart",
        GLVersion::GL3_1,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {
            //GLContext::NV_primitive_restart, // Has different enum values.
            GLContext::Extensions_End
        }
    },
    {
        "prim_restart_fixed",
        kGLCoreVersionForES3Compat,
        GLESVersion::ES3,
        GLContext::ARB_ES3_compatibility,
        {
            GLContext::Extensions_End
        }
    },
    {
        "query_counter",
        GLVersion::GL3_3,
        GLESVersion::NONE,
        GLContext::ARB_timer_query,
        {
            GLContext::ANGLE_timer_query,
            GLContext::EXT_disjoint_timer_query,
            // EXT_timer_query does NOT support GL_TIMESTAMP retrieval with
            // QueryCounter.
            GLContext::Extensions_End
        }
    },
    {
        "query_objects",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ANGLE_timer_query,
            GLContext::EXT_disjoint_timer_query,
            GLContext::EXT_occlusion_query_boolean,
            GLContext::Extensions_End
        }
        /*
         * XXX_query_objects only provide entry points commonly supported by
         * ARB_occlusion_query (added in OpenGL 2.0), EXT_occlusion_query_boolean
         * (added in OpenGL ES 3.0), and ARB_timer_query (added in OpenGL 3.3)
         */
    },
    {
        "query_time_elapsed",
        GLVersion::GL3_3,
        GLESVersion::NONE,
        GLContext::ARB_timer_query,
        {
            GLContext::ANGLE_timer_query,
            GLContext::EXT_disjoint_timer_query,
            GLContext::EXT_timer_query,
            GLContext::Extensions_End
        }
    },
    {
        "read_buffer",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
    },
    {
        "renderbuffer_color_float",
        GLVersion::GL3,
        GLESVersion::ES3_2,
        GLContext::Extension_None,
        {
            GLContext::ARB_texture_float,
            GLContext::EXT_color_buffer_float,
            GLContext::Extensions_End
        }
    },
    {
        "renderbuffer_color_half_float",
        GLVersion::GL3,
        GLESVersion::ES3_2,
        GLContext::Extension_None,
        {
            GLContext::ARB_texture_float,
            GLContext::EXT_color_buffer_float,
            GLContext::EXT_color_buffer_half_float,
            GLContext::Extensions_End
        }
    },
    {
        "robustness",
        GLVersion::NONE,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {
            GLContext::ARB_robustness,
            GLContext::EXT_robustness,
            GLContext::Extensions_End
        }
    },
    {
        "sRGB_framebuffer",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_framebuffer_sRGB,
        {
            GLContext::EXT_framebuffer_sRGB,
            GLContext::EXT_sRGB_write_control,
            GLContext::Extensions_End
        }
    },
    {
        "sRGB_texture",
        GLVersion::GL2_1,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_sRGB,
            GLContext::EXT_texture_sRGB,
            GLContext::Extensions_End
        }
    },
    {
        "sampler_objects",
        GLVersion::GL3_3,
        GLESVersion::ES3,
        GLContext::ARB_sampler_objects,
        {
            GLContext::Extensions_End
        }
    },
    {
        "seamless_cube_map_opt_in",
        GLVersion::GL3_2,
        GLESVersion::NONE,
        GLContext::ARB_seamless_cube_map,
        {
            GLContext::Extensions_End
        }
    },
    {
        "shader_texture_lod",
        GLVersion::NONE,
        GLESVersion::NONE,
        GLContext::Extension_None,
        {
            GLContext::ARB_shader_texture_lod,
            GLContext::EXT_shader_texture_lod,
            GLContext::Extensions_End
        }
    },
    {
        // Do we have separate DRAW and READ framebuffer bind points?
        "split_framebuffer",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_framebuffer_object,
        {
            GLContext::ANGLE_framebuffer_blit,
            GLContext::APPLE_framebuffer_multisample,
            GLContext::EXT_framebuffer_blit,
            GLContext::NV_framebuffer_blit,
            GLContext::Extensions_End
        }
    },
    {
        "standard_derivatives",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::OES_standard_derivatives,
            GLContext::Extensions_End
        }
    },
    {
        "sync",
        GLVersion::GL3_2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_sync,
            GLContext::APPLE_sync,
            GLContext::Extensions_End
        }
    },
    {
        "texture_3D",
        GLVersion::GL1_2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_texture3D,
            GLContext::OES_texture_3D,
            GLContext::Extensions_End
        }
    },
    {
        "texture_3D_compressed",
        GLVersion::GL1_3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_texture_compression,
            GLContext::OES_texture_3D,
            GLContext::Extensions_End
        }
    },
    {
        "texture_3D_copy",
        GLVersion::GL1_2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::EXT_copy_texture,
            GLContext::OES_texture_3D,
            GLContext::Extensions_End
        }
    },
    {
        "texture_float",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_texture_float,
            GLContext::OES_texture_float,
            GLContext::Extensions_End
        }
    },
    {
        "texture_float_linear",
        GLVersion::GL3_1,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_texture_float,
            GLContext::OES_texture_float_linear,
            GLContext::Extensions_End
        }
    },
    {
        "texture_half_float",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_half_float_pixel,
            GLContext::ARB_texture_float,
            GLContext::NV_half_float,
            GLContext::Extensions_End
        }
        /**
         * We are not including OES_texture_half_float in this feature, because:
         *   GL_HALF_FLOAT     = 0x140B
         *   GL_HALF_FLOAT_ARB = 0x140B == GL_HALF_FLOAT
         *   GL_HALF_FLOAT_NV  = 0x140B == GL_HALF_FLOAT
         *   GL_HALF_FLOAT_OES = 0x8D61 != GL_HALF_FLOAT
         * WebGL handles this specifically with an OES_texture_half_float check.
         */
    },
    {
        "texture_half_float_linear",
        GLVersion::GL3_1,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_half_float_pixel,
            GLContext::ARB_texture_float,
            GLContext::NV_half_float,
            GLContext::OES_texture_half_float_linear,
            GLContext::Extensions_End
        }
    },
    {
        "texture_non_power_of_two",
        GLVersion::GL2,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::ARB_texture_non_power_of_two,
            GLContext::OES_texture_npot,
            GLContext::Extensions_End
        }
    },
    {
        "texture_rg",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_texture_rg,
        {
            GLContext::Extensions_End
        }
    },
    {
        "texture_storage",
        GLVersion::GL4_2,
        GLESVersion::ES3,
        GLContext::ARB_texture_storage,
        {
            /*
             * Not including GL_EXT_texture_storage here because it
             * doesn't guarantee glTexStorage3D, which is required for
             * WebGL 2.
             */
            GLContext::Extensions_End
        }
    },
    {
        "texture_swizzle",
        GLVersion::GL3_3,
        GLESVersion::ES3,
        GLContext::ARB_texture_swizzle,
        {
            GLContext::Extensions_End
        }
    },
    {
        "transform_feedback2",
        GLVersion::GL4,
        GLESVersion::ES3,
        GLContext::ARB_transform_feedback2,
        {
            GLContext::NV_transform_feedback2,
            GLContext::Extensions_End
        }
    },
    {
        "uniform_buffer_object",
        GLVersion::GL3_1,
        GLESVersion::ES3,
        GLContext::ARB_uniform_buffer_object,
        {
            GLContext::Extensions_End
        }
    },
    {
        "uniform_matrix_nonsquare",
        GLVersion::GL2_1,
        GLESVersion::ES3,
        GLContext::Extension_None,
        {
            GLContext::Extensions_End
        }
    },
    {
        "vertex_array_object",
        GLVersion::GL3,
        GLESVersion::ES3,
        GLContext::ARB_vertex_array_object, // ARB extension
        {
            GLContext::OES_vertex_array_object,
            GLContext::APPLE_vertex_array_object,
            GLContext::Extensions_End
        }
    }
};

static inline const FeatureInfo&
GetFeatureInfo(GLFeature feature)
{
    static_assert(MOZ_ARRAY_LENGTH(sFeatureInfoArr) == size_t(GLFeature::EnumMax),
                  "Mismatched lengths for sFeatureInfoInfos and GLFeature enums");

    MOZ_ASSERT(feature < GLFeature::EnumMax,
               "GLContext::GetFeatureInfoInfo : unknown <feature>");

    return sFeatureInfoArr[size_t(feature)];
}

static inline uint32_t
ProfileVersionForFeature(GLFeature feature, ContextProfile profile)
{
    MOZ_ASSERT(profile != ContextProfile::Unknown,
               "GLContext::ProfileVersionForFeature : unknown <profile>");

    const FeatureInfo& featureInfo = GetFeatureInfo(feature);

    if (profile == ContextProfile::OpenGLES)
        return (uint32_t)featureInfo.mOpenGLESVersion;

    return (uint32_t)featureInfo.mOpenGLVersion;
}

bool
IsFeaturePartOfProfileVersion(GLFeature feature,
                              ContextProfile profile, unsigned int version)
{
    unsigned int profileVersion = ProfileVersionForFeature(feature, profile);

    /**
     * if `profileVersion` is zero, it means that no version of the profile
     * added support for the feature.
     */
    return profileVersion && version >= profileVersion;
}

bool
GLContext::IsFeatureProvidedByCoreSymbols(GLFeature feature)
{
    if (IsFeaturePartOfProfileVersion(feature, mProfile, mVersion))
        return true;

    if (IsExtensionSupported(GetFeatureInfo(feature).mARBExtensionWithoutARBSuffix))
        return true;

    return false;
}

const char*
GLContext::GetFeatureName(GLFeature feature)
{
    return GetFeatureInfo(feature).mName;
}

void
GLContext::InitFeatures()
{
    for (size_t featureId = 0; featureId < size_t(GLFeature::EnumMax); featureId++) {
        GLFeature feature = GLFeature(featureId);

        if (IsFeaturePartOfProfileVersion(feature, mProfile, mVersion)) {
            mAvailableFeatures[featureId] = true;
            continue;
        }

        mAvailableFeatures[featureId] = false;

        const FeatureInfo& featureInfo = GetFeatureInfo(feature);

        if (IsExtensionSupported(featureInfo.mARBExtensionWithoutARBSuffix)) {
            mAvailableFeatures[featureId] = true;
            continue;
        }

        for (size_t j = 0; true; j++) {
            MOZ_ASSERT(j < kMAX_EXTENSION_GROUP_SIZE,
                       "kMAX_EXTENSION_GROUP_SIZE too small");

            if (featureInfo.mExtensions[j] == GLContext::Extensions_End)
                break;

            if (IsExtensionSupported(featureInfo.mExtensions[j])) {
                mAvailableFeatures[featureId] = true;
                break;
            }
        }
    }

    if (ShouldDumpExts()) {
        for (size_t featureId = 0; featureId < size_t(GLFeature::EnumMax); featureId++) {
            GLFeature feature = GLFeature(featureId);
            printf_stderr("[%s] Feature::%s\n",
                          IsSupported(feature) ? "enabled" : "disabled",
                          GetFeatureName(feature));
        }
    }
}

void
GLContext::MarkUnsupported(GLFeature feature)
{
    mAvailableFeatures[size_t(feature)] = false;

    const FeatureInfo& featureInfo = GetFeatureInfo(feature);

    for (size_t i = 0; true; i++) {
        MOZ_ASSERT(i < kMAX_EXTENSION_GROUP_SIZE, "kMAX_EXTENSION_GROUP_SIZE too small");

        if (featureInfo.mExtensions[i] == GLContext::Extensions_End)
            break;

        MarkExtensionUnsupported(featureInfo.mExtensions[i]);
    }

    MOZ_ASSERT(!IsSupported(feature), "GLContext::MarkUnsupported has failed!");

    NS_WARNING(nsPrintfCString("%s marked as unsupported",
                               GetFeatureName(feature)).get());
}

} /* namespace gl */
} /* namespace mozilla */
