// Copyright 2017 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/d3d12/BindGroupD3D12.h"

#include <utility>

#include "dawn/common/BitSetIterator.h"
#include "dawn/native/ExternalTexture.h"
#include "dawn/native/d3d12/BindGroupLayoutD3D12.h"
#include "dawn/native/d3d12/BufferD3D12.h"
#include "dawn/native/d3d12/DeviceD3D12.h"
#include "dawn/native/d3d12/SamplerHeapCacheD3D12.h"
#include "dawn/native/d3d12/ShaderVisibleDescriptorAllocatorD3D12.h"
#include "dawn/native/d3d12/TextureD3D12.h"

namespace dawn::native::d3d12 {

// static
ResultOrError<Ref<BindGroup>> BindGroup::Create(Device* device,
                                                const BindGroupDescriptor* descriptor) {
    return ToBackend(descriptor->layout)->AllocateBindGroup(device, descriptor);
}

BindGroup::BindGroup(Device* device,
                     const BindGroupDescriptor* descriptor,
                     uint32_t viewSizeIncrement,
                     const CPUDescriptorHeapAllocation& viewAllocation)
    : BindGroupBase(this, device, descriptor) {
    BindGroupLayout* bgl = ToBackend(GetLayout());

    mCPUViewAllocation = viewAllocation;

    const auto& descriptorHeapOffsets = bgl->GetDescriptorHeapOffsets();

    ID3D12Device* d3d12Device = device->GetD3D12Device();

    // It's not necessary to create descriptors in the descriptor heap for dynamic resources.
    // This is because they are created as root descriptors which are never heap allocated.
    // Since dynamic buffers are packed in the front, we can skip over these bindings by
    // starting from the dynamic buffer count.
    for (BindingIndex bindingIndex = bgl->GetDynamicBufferCount();
         bindingIndex < bgl->GetBindingCount(); ++bindingIndex) {
        const BindingInfo& bindingInfo = bgl->GetBindingInfo(bindingIndex);

        // Increment size does not need to be stored and is only used to get a handle
        // local to the allocation with OffsetFrom().
        switch (bindingInfo.bindingType) {
            case BindingInfoType::Buffer: {
                BufferBinding binding = GetBindingAsBufferBinding(bindingIndex);

                ID3D12Resource* resource = ToBackend(binding.buffer)->GetD3D12Resource();
                if (resource == nullptr) {
                    // The Buffer was destroyed. Skip creating buffer views since there is no
                    // resource. This bind group won't be used as it is an error to submit a
                    // command buffer that references destroyed resources.
                    continue;
                }

                switch (bindingInfo.buffer.type) {
                    case wgpu::BufferBindingType::Uniform: {
                        D3D12_CONSTANT_BUFFER_VIEW_DESC desc;
                        desc.SizeInBytes =
                            Align(binding.size, D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT);
                        desc.BufferLocation = ToBackend(binding.buffer)->GetVA() + binding.offset;

                        d3d12Device->CreateConstantBufferView(
                            &desc, viewAllocation.OffsetFrom(viewSizeIncrement,
                                                             descriptorHeapOffsets[bindingIndex]));
                        break;
                    }
                    case wgpu::BufferBindingType::Storage:
                    case kInternalStorageBufferBinding: {
                        // Since Tint outputs HLSL shaders with RWByteAddressBuffer,
                        // we must use D3D12_BUFFER_UAV_FLAG_RAW when making the
                        // UNORDERED_ACCESS_VIEW_DESC. Using D3D12_BUFFER_UAV_FLAG_RAW requires
                        // that we use DXGI_FORMAT_R32_TYPELESS as the format of the view.
                        // DXGI_FORMAT_R32_TYPELESS requires that the element size be 4
                        // byte aligned. Since binding.size and binding.offset are in bytes,
                        // we need to divide by 4 to obtain the element size.
                        D3D12_UNORDERED_ACCESS_VIEW_DESC desc;
                        desc.Buffer.NumElements = binding.size / 4;
                        desc.Format = DXGI_FORMAT_R32_TYPELESS;
                        desc.ViewDimension = D3D12_UAV_DIMENSION_BUFFER;
                        desc.Buffer.FirstElement = binding.offset / 4;
                        desc.Buffer.StructureByteStride = 0;
                        desc.Buffer.CounterOffsetInBytes = 0;
                        desc.Buffer.Flags = D3D12_BUFFER_UAV_FLAG_RAW;

                        d3d12Device->CreateUnorderedAccessView(
                            resource, nullptr, &desc,
                            viewAllocation.OffsetFrom(viewSizeIncrement,
                                                      descriptorHeapOffsets[bindingIndex]));
                        break;
                    }
                    case wgpu::BufferBindingType::ReadOnlyStorage: {
                        // Like StorageBuffer, Tint outputs HLSL shaders for readonly
                        // storage buffer with ByteAddressBuffer. So we must use
                        // D3D12_BUFFER_SRV_FLAG_RAW when making the SRV descriptor. And it has
                        // similar requirement for format, element size, etc.
                        D3D12_SHADER_RESOURCE_VIEW_DESC desc;
                        desc.Format = DXGI_FORMAT_R32_TYPELESS;
                        desc.ViewDimension = D3D12_SRV_DIMENSION_BUFFER;
                        desc.Shader4ComponentMapping = D3D12_DEFAULT_SHADER_4_COMPONENT_MAPPING;
                        desc.Buffer.FirstElement = binding.offset / 4;
                        desc.Buffer.NumElements = binding.size / 4;
                        desc.Buffer.StructureByteStride = 0;
                        desc.Buffer.Flags = D3D12_BUFFER_SRV_FLAG_RAW;
                        d3d12Device->CreateShaderResourceView(
                            resource, &desc,
                            viewAllocation.OffsetFrom(viewSizeIncrement,
                                                      descriptorHeapOffsets[bindingIndex]));
                        break;
                    }
                    case wgpu::BufferBindingType::Undefined:
                        UNREACHABLE();
                }

                break;
            }

            case BindingInfoType::Texture: {
                auto* view = ToBackend(GetBindingAsTextureView(bindingIndex));
                auto& srv = view->GetSRVDescriptor();

                ID3D12Resource* resource = ToBackend(view->GetTexture())->GetD3D12Resource();
                if (resource == nullptr) {
                    // The Texture was destroyed. Skip creating the SRV since there is no
                    // resource. This bind group won't be used as it is an error to submit a
                    // command buffer that references destroyed resources.
                    continue;
                }

                d3d12Device->CreateShaderResourceView(
                    resource, &srv,
                    viewAllocation.OffsetFrom(viewSizeIncrement,
                                              descriptorHeapOffsets[bindingIndex]));
                break;
            }

            case BindingInfoType::StorageTexture: {
                TextureView* view = ToBackend(GetBindingAsTextureView(bindingIndex));

                ID3D12Resource* resource = ToBackend(view->GetTexture())->GetD3D12Resource();
                if (resource == nullptr) {
                    // The Texture was destroyed. Skip creating the SRV/UAV since there is no
                    // resource. This bind group won't be used as it is an error to submit a
                    // command buffer that references destroyed resources.
                    continue;
                }

                switch (bindingInfo.storageTexture.access) {
                    case wgpu::StorageTextureAccess::WriteOnly: {
                        D3D12_UNORDERED_ACCESS_VIEW_DESC uav = view->GetUAVDescriptor();
                        d3d12Device->CreateUnorderedAccessView(
                            resource, nullptr, &uav,
                            viewAllocation.OffsetFrom(viewSizeIncrement,
                                                      descriptorHeapOffsets[bindingIndex]));
                        break;
                    }

                    case wgpu::StorageTextureAccess::Undefined:
                        UNREACHABLE();
                }

                break;
            }

            case BindingInfoType::ExternalTexture: {
                UNREACHABLE();
            }

            case BindingInfoType::Sampler: {
                // No-op as samplers will be later initialized by CreateSamplers().
                break;
            }
        }
    }

    // Loop through the dynamic storage buffers and build a flat map from the index of the
    // dynamic storage buffer to its binding size. The index |dynamicStorageBufferIndex|
    // means that it is the i'th buffer that is both dynamic and storage, in increasing order
    // of BindingNumber.
    mDynamicStorageBufferLengths.resize(bgl->GetBindingCountInfo().dynamicStorageBufferCount);
    uint32_t dynamicStorageBufferIndex = 0;
    for (BindingIndex bindingIndex(0); bindingIndex < bgl->GetDynamicBufferCount();
         ++bindingIndex) {
        if (bgl->IsStorageBufferBinding(bindingIndex)) {
            mDynamicStorageBufferLengths[dynamicStorageBufferIndex++] =
                GetBindingAsBufferBinding(bindingIndex).size;
        }
    }
}

BindGroup::~BindGroup() = default;

void BindGroup::DestroyImpl() {
    BindGroupBase::DestroyImpl();
    ToBackend(GetLayout())->DeallocateBindGroup(this, &mCPUViewAllocation);
    ASSERT(!mCPUViewAllocation.IsValid());
}

bool BindGroup::PopulateViews(ShaderVisibleDescriptorAllocator* viewAllocator) {
    const BindGroupLayout* bgl = ToBackend(GetLayout());

    const uint32_t descriptorCount = bgl->GetCbvUavSrvDescriptorCount();
    if (descriptorCount == 0 || viewAllocator->IsAllocationStillValid(mGPUViewAllocation)) {
        return true;
    }

    // Attempt to allocate descriptors for the currently bound shader-visible heaps.
    // If either failed, return early to re-allocate and switch the heaps.
    Device* device = ToBackend(GetDevice());

    D3D12_CPU_DESCRIPTOR_HANDLE baseCPUDescriptor;
    if (!viewAllocator->AllocateGPUDescriptors(descriptorCount, device->GetPendingCommandSerial(),
                                               &baseCPUDescriptor, &mGPUViewAllocation)) {
        return false;
    }

    // CPU bindgroups are sparsely allocated across CPU heaps. Instead of doing
    // simple copies per bindgroup, a single non-simple copy could be issued.
    // TODO(dawn:155): Consider doing this optimization.
    device->GetD3D12Device()->CopyDescriptorsSimple(descriptorCount, baseCPUDescriptor,
                                                    mCPUViewAllocation.GetBaseDescriptor(),
                                                    D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV);

    return true;
}

D3D12_GPU_DESCRIPTOR_HANDLE BindGroup::GetBaseViewDescriptor() const {
    return mGPUViewAllocation.GetBaseDescriptor();
}

D3D12_GPU_DESCRIPTOR_HANDLE BindGroup::GetBaseSamplerDescriptor() const {
    ASSERT(mSamplerAllocationEntry != nullptr);
    return mSamplerAllocationEntry->GetBaseDescriptor();
}

bool BindGroup::PopulateSamplers(Device* device,
                                 ShaderVisibleDescriptorAllocator* samplerAllocator) {
    if (mSamplerAllocationEntry == nullptr) {
        return true;
    }
    return mSamplerAllocationEntry->Populate(device, samplerAllocator);
}

void BindGroup::SetSamplerAllocationEntry(Ref<SamplerHeapCacheEntry> entry) {
    mSamplerAllocationEntry = std::move(entry);
}

const BindGroup::DynamicStorageBufferLengths& BindGroup::GetDynamicStorageBufferLengths() const {
    return mDynamicStorageBufferLengths;
}

}  // namespace dawn::native::d3d12