// Copyright 2023 The Dawn & Tint Authors
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#include "dawn/native/d3d11/PipelineLayoutD3D11.h"

#include "dawn/common/MatchVariant.h"
#include "dawn/native/BindGroupLayoutInternal.h"
#include "dawn/native/d3d11/DeviceD3D11.h"

namespace dawn::native::d3d11 {

// static
ResultOrError<Ref<PipelineLayout>> PipelineLayout::Create(
    Device* device,
    const UnpackedPtr<PipelineLayoutDescriptor>& descriptor) {
    Ref<PipelineLayout> pipelineLayout = AcquireRef(new PipelineLayout(device, descriptor));
    DAWN_TRY(pipelineLayout->Initialize(device));
    return pipelineLayout;
}

MaybeError PipelineLayout::Initialize(Device* device) {
    const PerStage<uint32_t> kInvalidSlots = PerStage<uint32_t>(PipelineLayout::kInvalidSlot);

    PerStage<uint32_t> constantBufferCounter(0);
    PerStage<uint32_t> samplerCounter(0);
    PerStage<uint32_t> shaderResourceViewCounter(0);

    // For d3d11 pixel shaders, the render targets and unordered-access views share the same
    // resource slots when being written out. So we assign UAV binding index decreasingly here.
    // https://learn.microsoft.com/en-us/windows/win32/api/d3d11/nf-d3d11-id3d11devicecontext-omsetrendertargetsandunorderedaccessviews
    // TODO(dawn:1818): Support testing on both FL11_0 and FL11_1.
    const uint32_t kUAVSlotCount = device->GetUAVSlotCount();
    PerStage<uint32_t> uavBindingCounter(kUAVSlotCount);

    // Reserve last several UAV slots for Pixel Local Storage attachments.
    uavBindingCounter[SingleShaderStage::Fragment] -=
        static_cast<uint32_t>(GetStorageAttachmentSlots().size());

    constexpr auto CountIncreasingIndex = [](wgpu::ShaderStage visibility,
                                             PerStage<uint32_t>* counters) {
        PerStage<uint32_t> nativeIndex(kInvalidSlot);
        for (SingleShaderStage stage : IterateStages(visibility)) {
            nativeIndex[stage] = (*counters)[stage]++;
        }
        return nativeIndex;
    };

    constexpr auto CountDecreasingIndex = [](wgpu::ShaderStage visibility,
                                             PerStage<uint32_t>* counters) {
        PerStage<uint32_t> nativeIndex(kInvalidSlot);
        for (SingleShaderStage stage : IterateStages(visibility)) {
            nativeIndex[stage] = --(*counters)[stage];
        }
        return nativeIndex;
    };

    for (BindGroupIndex group : GetBindGroupLayoutsMask()) {
        const BindGroupLayoutInternalBase* bgl = GetBindGroupLayout(group);
        mBindingTableIndexMap[group].resize(bgl->GetBindingCount());

        for (BindingIndex bindingIndex{0}; bindingIndex < bgl->GetBindingCount(); ++bindingIndex) {
            const BindingInfo& bindingInfo = bgl->GetBindingInfo(bindingIndex);

            mBindingTableIndexMap[group][bindingIndex] = MatchVariant(
                bindingInfo.bindingLayout,
                [&](const BufferBindingInfo& layout) -> PerStage<uint32_t> {
                    switch (layout.type) {
                        case wgpu::BufferBindingType::Uniform:
                            return CountIncreasingIndex(bindingInfo.visibility,
                                                        &constantBufferCounter);
                        case wgpu::BufferBindingType::Storage:
                        case kInternalStorageBufferBinding:
                            mUAVBindGroups.set(group);
                            return CountDecreasingIndex(bindingInfo.visibility, &uavBindingCounter);
                        case wgpu::BufferBindingType::ReadOnlyStorage:
                        case kInternalReadOnlyStorageBufferBinding:
                            return CountIncreasingIndex(bindingInfo.visibility,
                                                        &shaderResourceViewCounter);
                        case wgpu::BufferBindingType::BindingNotUsed:
                        case wgpu::BufferBindingType::Undefined:
                            DAWN_UNREACHABLE();
                    }
                    return kInvalidSlots;
                },
                [&](const SamplerBindingInfo&) -> PerStage<uint32_t> {
                    return CountIncreasingIndex(bindingInfo.visibility, &samplerCounter);
                },
                [&](const StaticSamplerBindingInfo&) -> PerStage<uint32_t> {
                    // Static samplers are implemented in the frontend on
                    // D3D11.
                    DAWN_UNREACHABLE();
                    return kInvalidSlots;
                },
                [&](const TextureBindingInfo&) -> PerStage<uint32_t> {
                    return CountIncreasingIndex(bindingInfo.visibility, &shaderResourceViewCounter);
                },
                [&](const StorageTextureBindingInfo& layout) -> PerStage<uint32_t> {
                    switch (layout.access) {
                        case wgpu::StorageTextureAccess::ReadWrite:
                        case wgpu::StorageTextureAccess::WriteOnly:
                            mUAVBindGroups.set(group);
                            return CountDecreasingIndex(bindingInfo.visibility, &uavBindingCounter);
                        case wgpu::StorageTextureAccess::ReadOnly:
                            return CountIncreasingIndex(bindingInfo.visibility,
                                                        &shaderResourceViewCounter);
                        case wgpu::StorageTextureAccess::BindingNotUsed:
                        case wgpu::StorageTextureAccess::Undefined:
                            DAWN_UNREACHABLE();
                    }
                    return kInvalidSlots;
                },
                [&](const TexelBufferBindingInfo&) -> PerStage<uint32_t> {
                    // D3D11 does not support texel buffers.
                    // TODO(crbug/382544164): Prototype texel buffer feature
                    DAWN_UNREACHABLE();
                },
                [](const InputAttachmentBindingInfo&) -> PerStage<uint32_t> { DAWN_UNREACHABLE(); },
                [](const ExternalTextureBindingInfo&) -> PerStage<uint32_t> {
                    DAWN_UNREACHABLE();
                });
        }
    }

    mUAVStartIndex = uavBindingCounter;
    for (SingleShaderStage stage : IterateStages(kAllStages)) {
        mUAVCount[stage] = kUAVSlotCount - mUAVStartIndex[stage];
    }

    for (SingleShaderStage stage : IterateStages(kAllStages)) {
        DAWN_ASSERT(constantBufferCounter[stage] <= kReservedConstantBufferSlot);
    }

    return {};
}

const PipelineLayout::BindingTableIndexMap& PipelineLayout::GetBindingTableIndexMap() const {
    return mBindingTableIndexMap;
}

const BindGroupMask& PipelineLayout::GetUAVBindGroupLayoutsMask() const {
    return mUAVBindGroups;
}

}  // namespace dawn::native::d3d11