// Copyright 2018 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/StagingBufferD3D12.h"
#include "dawn/native/d3d12/D3D12Error.h"
#include "dawn/native/d3d12/DeviceD3D12.h"
#include "dawn/native/d3d12/HeapD3D12.h"
#include "dawn/native/d3d12/ResidencyManagerD3D12.h"
#include "dawn/native/d3d12/UtilsD3D12.h"

namespace dawn::native::d3d12 {

StagingBuffer::StagingBuffer(size_t size, Device* device)
    : StagingBufferBase(size), mDevice(device) {}

MaybeError StagingBuffer::Initialize() {
    D3D12_RESOURCE_DESC resourceDescriptor;
    resourceDescriptor.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
    resourceDescriptor.Alignment = 0;
    resourceDescriptor.Width = GetSize();
    resourceDescriptor.Height = 1;
    resourceDescriptor.DepthOrArraySize = 1;
    resourceDescriptor.MipLevels = 1;
    resourceDescriptor.Format = DXGI_FORMAT_UNKNOWN;
    resourceDescriptor.SampleDesc.Count = 1;
    resourceDescriptor.SampleDesc.Quality = 0;
    resourceDescriptor.Layout = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
    resourceDescriptor.Flags = D3D12_RESOURCE_FLAG_NONE;

    DAWN_TRY_ASSIGN(mUploadHeap, mDevice->AllocateMemory(D3D12_HEAP_TYPE_UPLOAD, resourceDescriptor,
                                                         D3D12_RESOURCE_STATE_GENERIC_READ));

    // The mapped buffer can be accessed at any time, so it must be locked to ensure it is never
    // evicted. This buffer should already have been made resident when it was created.
    DAWN_TRY(
        mDevice->GetResidencyManager()->LockAllocation(ToBackend(mUploadHeap.GetResourceHeap())));

    SetDebugName(mDevice, GetResource(), "Dawn_StagingBuffer");

    return CheckHRESULT(GetResource()->Map(0, nullptr, &mMappedPointer), "ID3D12Resource::Map");
}

StagingBuffer::~StagingBuffer() {
    // Always check if the allocation is valid before Unmap.
    // The resource would not exist had it failed to allocate.
    if (mUploadHeap.GetInfo().mMethod == AllocationMethod::kInvalid) {
        return;
    }

    // The underlying heap was locked in residency upon creation. We must unlock it when this
    // buffer becomes unmapped.
    mDevice->GetResidencyManager()->UnlockAllocation(ToBackend(mUploadHeap.GetResourceHeap()));

    // Invalidate the CPU virtual address & flush cache (if needed).
    GetResource()->Unmap(0, nullptr);
    mMappedPointer = nullptr;

    mDevice->DeallocateMemory(mUploadHeap);
}

ID3D12Resource* StagingBuffer::GetResource() const {
    return mUploadHeap.GetD3D12Resource();
}
}  // namespace dawn::native::d3d12