// Copyright 2019 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/HeapAllocatorD3D12.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"

namespace dawn_native::d3d12 {

    HeapAllocator::HeapAllocator(Device* device,
                                 D3D12_HEAP_TYPE heapType,
                                 D3D12_HEAP_FLAGS heapFlags,
                                 MemorySegment memorySegment)
        : mDevice(device),
          mHeapType(heapType),
          mHeapFlags(heapFlags),
          mMemorySegment(memorySegment) {
    }

    ResultOrError<std::unique_ptr<ResourceHeapBase>> HeapAllocator::AllocateResourceHeap(
        uint64_t size) {
        D3D12_HEAP_DESC heapDesc;
        heapDesc.SizeInBytes = size;
        heapDesc.Properties.Type = mHeapType;
        heapDesc.Properties.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
        heapDesc.Properties.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;
        heapDesc.Properties.CreationNodeMask = 0;
        heapDesc.Properties.VisibleNodeMask = 0;
        // It is preferred to use a size that is a multiple of the alignment.
        // However, MSAA heaps are always aligned to 4MB instead of 64KB. This means
        // if the heap size is too small, the VMM would fragment.
        // TODO(crbug.com/dawn/849): Consider having MSAA vs non-MSAA heaps.
        heapDesc.Alignment = D3D12_DEFAULT_MSAA_RESOURCE_PLACEMENT_ALIGNMENT;
        heapDesc.Flags = mHeapFlags;

        // CreateHeap will implicitly make the created heap resident. We must ensure enough free
        // memory exists before allocating to avoid an out-of-memory error when overcommitted.
        DAWN_TRY(mDevice->GetResidencyManager()->EnsureCanAllocate(size, mMemorySegment));

        ComPtr<ID3D12Heap> d3d12Heap;
        DAWN_TRY(CheckOutOfMemoryHRESULT(
            mDevice->GetD3D12Device()->CreateHeap(&heapDesc, IID_PPV_ARGS(&d3d12Heap)),
            "ID3D12Device::CreateHeap"));

        std::unique_ptr<ResourceHeapBase> heapBase =
            std::make_unique<Heap>(std::move(d3d12Heap), mMemorySegment, size);

        // Calling CreateHeap implicitly calls MakeResident on the new heap. We must track this to
        // avoid calling MakeResident a second time.
        mDevice->GetResidencyManager()->TrackResidentAllocation(ToBackend(heapBase.get()));
        return std::move(heapBase);
    }

    void HeapAllocator::DeallocateResourceHeap(std::unique_ptr<ResourceHeapBase> heap) {
        mDevice->ReferenceUntilUnused(static_cast<Heap*>(heap.get())->GetD3D12Heap());
    }

}  // namespace dawn_native::d3d12