// Copyright 2022 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "dawn/native/opengl/AdapterGL.h"

#include <memory>
#include <string>
#include <utility>

#include "dawn/common/GPUInfo.h"
#include "dawn/native/Instance.h"
#include "dawn/native/opengl/ContextEGL.h"
#include "dawn/native/opengl/DeviceGL.h"

namespace dawn::native::opengl {

namespace {

struct Vendor {
    const char* vendorName;
    uint32_t vendorId;
};

const Vendor kVendors[] = {{"ATI", gpu_info::kVendorID_AMD},
                           {"ARM", gpu_info::kVendorID_ARM},
                           {"Imagination", gpu_info::kVendorID_ImgTec},
                           {"Intel", gpu_info::kVendorID_Intel},
                           {"NVIDIA", gpu_info::kVendorID_Nvidia},
                           {"Qualcomm", gpu_info::kVendorID_Qualcomm}};

uint32_t GetVendorIdFromVendors(const char* vendor) {
    uint32_t vendorId = 0;
    for (const auto& it : kVendors) {
        // Matching vendor name with vendor string
        if (strstr(vendor, it.vendorName) != nullptr) {
            vendorId = it.vendorId;
            break;
        }
    }
    return vendorId;
}

}  // anonymous namespace

Adapter::Adapter(InstanceBase* instance,
                 wgpu::BackendType backendType,
                 const TogglesState& adapterToggle)
    : AdapterBase(instance, backendType, adapterToggle) {}

MaybeError Adapter::InitializeGLFunctions(void* (*getProc)(const char*)) {
    // Use getProc to populate the dispatch table
    mEGLFunctions.Init(getProc);
    return mFunctions.Initialize(getProc);
}

bool Adapter::SupportsExternalImages() const {
    // Via dawn::native::opengl::WrapExternalEGLImage
    return GetBackendType() == wgpu::BackendType::OpenGLES;
}

MaybeError Adapter::InitializeImpl() {
    if (mFunctions.GetVersion().IsES()) {
        ASSERT(GetBackendType() == wgpu::BackendType::OpenGLES);
    } else {
        ASSERT(GetBackendType() == wgpu::BackendType::OpenGL);
    }

    mName = reinterpret_cast<const char*>(mFunctions.GetString(GL_RENDERER));

    // Workaroud to find vendor id from vendor name
    const char* vendor = reinterpret_cast<const char*>(mFunctions.GetString(GL_VENDOR));
    mVendorId = GetVendorIdFromVendors(vendor);

    mDriverDescription = std::string("OpenGL version ") +
                         reinterpret_cast<const char*>(mFunctions.GetString(GL_VERSION));

    if (mName.find("SwiftShader") != std::string::npos) {
        mAdapterType = wgpu::AdapterType::CPU;
    }

    return {};
}

void Adapter::InitializeSupportedFeaturesImpl() {
    // TextureCompressionBC
    {
        // BC1, BC2 and BC3 are not supported in OpenGL or OpenGL ES core features.
        bool supportsS3TC =
            mFunctions.IsGLExtensionSupported("GL_EXT_texture_compression_s3tc") ||
            (mFunctions.IsGLExtensionSupported("GL_EXT_texture_compression_dxt1") &&
             mFunctions.IsGLExtensionSupported("GL_ANGLE_texture_compression_dxt3") &&
             mFunctions.IsGLExtensionSupported("GL_ANGLE_texture_compression_dxt5"));

        // COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT, COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT and
        // COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT requires both GL_EXT_texture_sRGB and
        // GL_EXT_texture_compression_s3tc on desktop OpenGL drivers.
        // (https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_sRGB.txt)
        bool supportsTextureSRGB = mFunctions.IsGLExtensionSupported("GL_EXT_texture_sRGB");

        // GL_EXT_texture_compression_s3tc_srgb is an extension in OpenGL ES.
        // NVidia GLES drivers don't support this extension, but they do support
        // GL_NV_sRGB_formats. (Note that GL_EXT_texture_sRGB does not exist on ES.
        // GL_EXT_sRGB does (core in ES 3.0), but it does not automatically provide S3TC
        // SRGB support even if S3TC is supported; see
        // https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_sRGB.txt.)
        bool supportsS3TCSRGB =
            mFunctions.IsGLExtensionSupported("GL_EXT_texture_compression_s3tc_srgb") ||
            mFunctions.IsGLExtensionSupported("GL_NV_sRGB_formats");

        // BC4 and BC5
        bool supportsRGTC = mFunctions.IsAtLeastGL(3, 0) ||
                            mFunctions.IsGLExtensionSupported("GL_ARB_texture_compression_rgtc") ||
                            mFunctions.IsGLExtensionSupported("GL_EXT_texture_compression_rgtc");

        // BC6 and BC7
        bool supportsBPTC = mFunctions.IsAtLeastGL(4, 2) ||
                            mFunctions.IsGLExtensionSupported("GL_ARB_texture_compression_bptc") ||
                            mFunctions.IsGLExtensionSupported("GL_EXT_texture_compression_bptc");

        if (supportsS3TC && (supportsTextureSRGB || supportsS3TCSRGB) && supportsRGTC &&
            supportsBPTC) {
            EnableFeature(dawn::native::Feature::TextureCompressionBC);
        }
    }

    // Non-zero baseInstance requires at least desktop OpenGL 4.2, and it is not supported in
    // OpenGL ES OpenGL:
    // https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glDrawElementsIndirect.xhtml
    // OpenGL ES:
    // https://www.khronos.org/registry/OpenGL-Refpages/es3/html/glDrawElementsIndirect.xhtml
    if (mFunctions.IsAtLeastGL(4, 2)) {
        EnableFeature(Feature::IndirectFirstInstance);
    }

    // ShaderF16
    if (mFunctions.IsGLExtensionSupported("GL_AMD_gpu_shader_half_float")) {
        EnableFeature(Feature::ShaderF16);
    }
}

MaybeError Adapter::InitializeSupportedLimitsImpl(CombinedLimits* limits) {
    GetDefaultLimits(&limits->v1);
    return {};
}

void Adapter::SetupBackendDeviceToggles(TogglesState* deviceToggles) const {
    const OpenGLFunctions& gl = mFunctions;

    bool supportsBaseVertex = gl.IsAtLeastGLES(3, 2) || gl.IsAtLeastGL(3, 2);

    bool supportsBaseInstance = gl.IsAtLeastGLES(3, 2) || gl.IsAtLeastGL(4, 2);

    // TODO(crbug.com/dawn/582): Use OES_draw_buffers_indexed where available.
    bool supportsIndexedDrawBuffers = gl.IsAtLeastGLES(3, 2) || gl.IsAtLeastGL(3, 0);

    bool supportsSnormRead =
        gl.IsAtLeastGL(4, 4) || gl.IsGLExtensionSupported("GL_EXT_render_snorm");

    bool supportsDepthRead = gl.IsAtLeastGL(3, 0) || gl.IsGLExtensionSupported("GL_NV_read_depth");

    bool supportsStencilRead =
        gl.IsAtLeastGL(3, 0) || gl.IsGLExtensionSupported("GL_NV_read_stencil");

    bool supportsDepthStencilRead =
        gl.IsAtLeastGL(3, 0) || gl.IsGLExtensionSupported("GL_NV_read_depth_stencil");

    // Desktop GL supports BGRA textures via swizzling in the driver; ES requires an extension.
    bool supportsBGRARead =
        gl.GetVersion().IsDesktop() || gl.IsGLExtensionSupported("GL_EXT_read_format_bgra");

    bool supportsSampleVariables = gl.IsAtLeastGL(4, 0) || gl.IsAtLeastGLES(3, 2) ||
                                   gl.IsGLExtensionSupported("GL_OES_sample_variables");

    // TODO(crbug.com/dawn/343): We can support the extension variants, but need to load the EXT
    // procs without the extension suffix.
    // We'll also need emulation of shader builtins gl_BaseVertex and gl_BaseInstance.

    // supportsBaseVertex |=
    //     (gl.IsAtLeastGLES(2, 0) &&
    //      (gl.IsGLExtensionSupported("OES_draw_elements_base_vertex") ||
    //       gl.IsGLExtensionSupported("EXT_draw_elements_base_vertex"))) ||
    //     (gl.IsAtLeastGL(3, 1) && gl.IsGLExtensionSupported("ARB_draw_elements_base_vertex"));

    // supportsBaseInstance |=
    //     (gl.IsAtLeastGLES(3, 1) && gl.IsGLExtensionSupported("EXT_base_instance")) ||
    //     (gl.IsAtLeastGL(3, 1) && gl.IsGLExtensionSupported("ARB_base_instance"));

    if (gl.IsAtLeastGLES(3, 1) && gl.IsGLExtensionSupported("GL_ANGLE_base_vertex_base_instance")) {
        supportsBaseVertex = true;
        supportsBaseInstance = true;
    }

    // TODO(crbug.com/dawn/343): Investigate emulation.
    deviceToggles->Default(Toggle::DisableBaseVertex, !supportsBaseVertex);
    deviceToggles->Default(Toggle::DisableBaseInstance, !supportsBaseInstance);
    deviceToggles->Default(Toggle::DisableIndexedDrawBuffers, !supportsIndexedDrawBuffers);
    deviceToggles->Default(Toggle::DisableSnormRead, !supportsSnormRead);
    deviceToggles->Default(Toggle::DisableDepthRead, !supportsDepthRead);
    deviceToggles->Default(Toggle::DisableStencilRead, !supportsStencilRead);
    deviceToggles->Default(Toggle::DisableDepthStencilRead, !supportsDepthStencilRead);
    deviceToggles->Default(Toggle::DisableBGRARead, !supportsBGRARead);
    deviceToggles->Default(Toggle::DisableSampleVariables, !supportsSampleVariables);
    deviceToggles->Default(Toggle::FlushBeforeClientWaitSync, gl.GetVersion().IsES());
    // For OpenGL ES, we must use a placeholder fragment shader for vertex-only render pipeline.
    deviceToggles->Default(Toggle::UsePlaceholderFragmentInVertexOnlyPipeline,
                           gl.GetVersion().IsES());
}

ResultOrError<Ref<DeviceBase>> Adapter::CreateDeviceImpl(const DeviceDescriptor* descriptor,
                                                         const TogglesState& deviceToggles) {
    EGLenum api =
        GetBackendType() == wgpu::BackendType::OpenGL ? EGL_OPENGL_API : EGL_OPENGL_ES_API;
    std::unique_ptr<Device::Context> context;
    DAWN_TRY_ASSIGN(context, ContextEGL::Create(mEGLFunctions, api));
    return Device::Create(this, descriptor, mFunctions, std::move(context), deviceToggles);
}

MaybeError Adapter::ValidateFeatureSupportedWithTogglesImpl(wgpu::FeatureName feature,
                                                            const TogglesState& toggles) const {
    return {};
}
}  // namespace dawn::native::opengl