// 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/DeviceD3D12.h"
#include "dawn_native/d3d12/ResourceAllocator.h"

namespace dawn_native { namespace 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;

        mUploadHeap = mDevice->GetResourceAllocator()->Allocate(
            D3D12_HEAP_TYPE_UPLOAD, resourceDescriptor, D3D12_RESOURCE_STATE_GENERIC_READ);

        // TODO(b-brber): Record the GPU pointer for generic non-upload usage.

        if (FAILED(mUploadHeap->Map(0, nullptr, &mMappedPointer))) {
            return DAWN_CONTEXT_LOST_ERROR("Unable to map staging buffer.");
        }

        return {};
    }

    StagingBuffer::~StagingBuffer() {
        // Invalidate the CPU virtual address & flush cache (if needed).
        mUploadHeap->Unmap(0, nullptr);
        mMappedPointer = nullptr;

        mDevice->GetResourceAllocator()->Release(mUploadHeap);
    }

    ID3D12Resource* StagingBuffer::GetResource() const {
        return mUploadHeap.Get();
    }

}}  // namespace dawn_native::d3d12