// 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/BufferD3D12.h"

#include <algorithm>

#include "dawn/common/Assert.h"
#include "dawn/common/Constants.h"
#include "dawn/common/Math.h"
#include "dawn/native/CommandBuffer.h"
#include "dawn/native/DynamicUploader.h"
#include "dawn/native/d3d/D3DError.h"
#include "dawn/native/d3d12/CommandRecordingContext.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"
#include "dawn/platform/DawnPlatform.h"
#include "dawn/platform/tracing/TraceEvent.h"

namespace dawn::native::d3d12 {

namespace {
D3D12_RESOURCE_FLAGS D3D12ResourceFlags(wgpu::BufferUsage usage) {
    D3D12_RESOURCE_FLAGS flags = D3D12_RESOURCE_FLAG_NONE;

    if (usage & (wgpu::BufferUsage::Storage | kInternalStorageBuffer)) {
        flags |= D3D12_RESOURCE_FLAG_ALLOW_UNORDERED_ACCESS;
    }

    return flags;
}

D3D12_RESOURCE_STATES D3D12BufferUsage(wgpu::BufferUsage usage) {
    D3D12_RESOURCE_STATES resourceState = D3D12_RESOURCE_STATE_COMMON;

    if (usage & wgpu::BufferUsage::CopySrc) {
        resourceState |= D3D12_RESOURCE_STATE_COPY_SOURCE;
    }
    if (usage & wgpu::BufferUsage::CopyDst) {
        resourceState |= D3D12_RESOURCE_STATE_COPY_DEST;
    }
    if (usage & (wgpu::BufferUsage::Vertex | wgpu::BufferUsage::Uniform)) {
        resourceState |= D3D12_RESOURCE_STATE_VERTEX_AND_CONSTANT_BUFFER;
    }
    if (usage & wgpu::BufferUsage::Index) {
        resourceState |= D3D12_RESOURCE_STATE_INDEX_BUFFER;
    }
    if (usage & (wgpu::BufferUsage::Storage | kInternalStorageBuffer)) {
        resourceState |= D3D12_RESOURCE_STATE_UNORDERED_ACCESS;
    }
    if (usage & kReadOnlyStorageBuffer) {
        resourceState |= (D3D12_RESOURCE_STATE_PIXEL_SHADER_RESOURCE |
                          D3D12_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE);
    }
    if (usage & wgpu::BufferUsage::Indirect) {
        resourceState |= D3D12_RESOURCE_STATE_INDIRECT_ARGUMENT;
    }
    if (usage & wgpu::BufferUsage::QueryResolve) {
        resourceState |= D3D12_RESOURCE_STATE_COPY_DEST;
    }

    return resourceState;
}

D3D12_HEAP_TYPE D3D12HeapType(wgpu::BufferUsage allowedUsage) {
    if (allowedUsage & wgpu::BufferUsage::MapRead) {
        return D3D12_HEAP_TYPE_READBACK;
    } else if (allowedUsage & wgpu::BufferUsage::MapWrite) {
        return D3D12_HEAP_TYPE_UPLOAD;
    } else {
        return D3D12_HEAP_TYPE_DEFAULT;
    }
}

size_t D3D12BufferSizeAlignment(wgpu::BufferUsage usage) {
    if ((usage & wgpu::BufferUsage::Uniform) != 0) {
        // D3D buffers are always resource size aligned to 64KB. However, D3D12's validation
        // forbids binding a CBV to an unaligned size. To prevent, one can always safely
        // align the buffer size to the CBV data alignment as other buffer usages
        // ignore it (no size check). The validation will still enforce bound checks with
        // the unaligned size returned by GetSize().
        // https://docs.microsoft.com/en-us/windows/win32/direct3d12/uploading-resources#buffer-alignment
        return D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT;
    }
    return 1;
}
}  // namespace

// static
ResultOrError<Ref<Buffer>> Buffer::Create(Device* device, const BufferDescriptor* descriptor) {
    Ref<Buffer> buffer = AcquireRef(new Buffer(device, descriptor));
    DAWN_TRY(buffer->Initialize(descriptor->mappedAtCreation));
    return buffer;
}

Buffer::Buffer(Device* device, const BufferDescriptor* descriptor)
    : BufferBase(device, descriptor) {}

MaybeError Buffer::Initialize(bool mappedAtCreation) {
    // Allocate at least 4 bytes so clamped accesses are always in bounds.
    uint64_t size = std::max(GetSize(), uint64_t(4u));
    size_t alignment = D3D12BufferSizeAlignment(GetUsage());
    if (size > std::numeric_limits<uint64_t>::max() - alignment) {
        // Alignment would overlow.
        return DAWN_OUT_OF_MEMORY_ERROR("Buffer allocation is too large");
    }
    mAllocatedSize = Align(size, alignment);

    D3D12_RESOURCE_DESC resourceDescriptor;
    resourceDescriptor.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
    resourceDescriptor.Alignment = 0;
    resourceDescriptor.Width = mAllocatedSize;
    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;
    // Add CopyDst for non-mappable buffer initialization with mappedAtCreation
    // and robust resource initialization.
    resourceDescriptor.Flags = D3D12ResourceFlags(GetUsage() | wgpu::BufferUsage::CopyDst);

    auto heapType = D3D12HeapType(GetUsage());
    auto bufferUsage = D3D12_RESOURCE_STATE_COMMON;

    // D3D12 requires buffers on the READBACK heap to have the D3D12_RESOURCE_STATE_COPY_DEST
    // state
    if (heapType == D3D12_HEAP_TYPE_READBACK) {
        bufferUsage |= D3D12_RESOURCE_STATE_COPY_DEST;
        mFixedResourceState = true;
        mLastUsage = wgpu::BufferUsage::CopyDst;
    }

    // D3D12 requires buffers on the UPLOAD heap to have the D3D12_RESOURCE_STATE_GENERIC_READ
    // state
    if (heapType == D3D12_HEAP_TYPE_UPLOAD) {
        bufferUsage |= D3D12_RESOURCE_STATE_GENERIC_READ;
        mFixedResourceState = true;
        mLastUsage = wgpu::BufferUsage::CopySrc;
    }

    DAWN_TRY_ASSIGN(
        mResourceAllocation,
        ToBackend(GetDevice())->AllocateMemory(heapType, resourceDescriptor, bufferUsage, 0));

    SetLabelImpl();

    // The buffers with mappedAtCreation == true will be initialized in
    // BufferBase::MapAtCreation().
    if (GetDevice()->IsToggleEnabled(Toggle::NonzeroClearResourcesOnCreationForTesting) &&
        !mappedAtCreation) {
        CommandRecordingContext* commandRecordingContext;
        DAWN_TRY_ASSIGN(commandRecordingContext,
                        ToBackend(GetDevice())->GetPendingCommandContext());

        DAWN_TRY(ClearBuffer(commandRecordingContext, uint8_t(1u)));
    }

    // Initialize the padding bytes to zero.
    if (GetDevice()->IsToggleEnabled(Toggle::LazyClearResourceOnFirstUse) && !mappedAtCreation) {
        uint32_t paddingBytes = GetAllocatedSize() - GetSize();
        if (paddingBytes > 0) {
            CommandRecordingContext* commandRecordingContext;
            DAWN_TRY_ASSIGN(commandRecordingContext,
                            ToBackend(GetDevice())->GetPendingCommandContext());

            uint32_t clearSize = paddingBytes;
            uint64_t clearOffset = GetSize();
            DAWN_TRY(ClearBuffer(commandRecordingContext, 0, clearOffset, clearSize));
        }
    }

    return {};
}

Buffer::~Buffer() = default;

ID3D12Resource* Buffer::GetD3D12Resource() const {
    return mResourceAllocation.GetD3D12Resource();
}

// When true is returned, a D3D12_RESOURCE_BARRIER has been created and must be used in a
// ResourceBarrier call. Failing to do so will cause the tracked state to become invalid and can
// cause subsequent errors.
bool Buffer::TrackUsageAndGetResourceBarrier(CommandRecordingContext* commandContext,
                                             D3D12_RESOURCE_BARRIER* barrier,
                                             wgpu::BufferUsage newUsage) {
    // Track the underlying heap to ensure residency.
    Heap* heap = ToBackend(mResourceAllocation.GetResourceHeap());
    commandContext->TrackHeapUsage(heap, GetDevice()->GetPendingCommandSerial());

    MarkUsedInPendingCommands();

    // Resources in upload and readback heaps must be kept in the COPY_SOURCE/DEST state
    if (mFixedResourceState) {
        ASSERT(mLastUsage == newUsage);
        return false;
    }

    D3D12_RESOURCE_STATES lastState = D3D12BufferUsage(mLastUsage);
    D3D12_RESOURCE_STATES newState = D3D12BufferUsage(newUsage);

    // If the transition is from-UAV-to-UAV, then a UAV barrier is needed.
    // If one of the usages isn't UAV, then other barriers are used.
    bool needsUAVBarrier = lastState == D3D12_RESOURCE_STATE_UNORDERED_ACCESS &&
                           newState == D3D12_RESOURCE_STATE_UNORDERED_ACCESS;

    if (needsUAVBarrier) {
        barrier->Type = D3D12_RESOURCE_BARRIER_TYPE_UAV;
        barrier->Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
        barrier->UAV.pResource = GetD3D12Resource();

        mLastUsage = newUsage;
        return true;
    }

    // We can skip transitions to already current usages.
    if (IsSubset(newUsage, mLastUsage)) {
        return false;
    }

    mLastUsage = newUsage;

    // The COMMON state represents a state where no write operations can be pending, which makes
    // it possible to transition to and from some states without synchronizaton (i.e. without an
    // explicit ResourceBarrier call). A buffer can be implicitly promoted to 1) a single write
    // state, or 2) multiple read states. A buffer that is accessed within a command list will
    // always implicitly decay to the COMMON state after the call to ExecuteCommandLists
    // completes - this is because all buffer writes are guaranteed to be completed before the
    // next ExecuteCommandLists call executes.
    // https://docs.microsoft.com/en-us/windows/desktop/direct3d12/using-resource-barriers-to-synchronize-resource-states-in-direct3d-12#implicit-state-transitions

    // To track implicit decays, we must record the pending serial on which a transition will
    // occur. When that buffer is used again, the previously recorded serial must be compared to
    // the last completed serial to determine if the buffer has implicity decayed to the common
    // state.
    const ExecutionSerial pendingCommandSerial = ToBackend(GetDevice())->GetPendingCommandSerial();
    if (pendingCommandSerial > mLastUsedSerial) {
        lastState = D3D12_RESOURCE_STATE_COMMON;
        mLastUsedSerial = pendingCommandSerial;
    }

    // All possible buffer states used by Dawn are eligible for implicit promotion from COMMON.
    // These are: COPY_SOURCE, VERTEX_AND_COPY_BUFFER, INDEX_BUFFER, COPY_DEST,
    // UNORDERED_ACCESS, and INDIRECT_ARGUMENT. Note that for implicit promotion, the
    // destination state cannot be 1) more than one write state, or 2) both a read and write
    // state. This goes unchecked here because it should not be allowed through render/compute
    // pass validation.
    if (lastState == D3D12_RESOURCE_STATE_COMMON) {
        return false;
    }

    // TODO(crbug.com/dawn/1024): The before and after states must be different. Remove this
    // workaround and use D3D12 states instead of WebGPU usages to manage the tracking of
    // barrier state.
    if (lastState == newState) {
        return false;
    }

    barrier->Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
    barrier->Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
    barrier->Transition.pResource = GetD3D12Resource();
    barrier->Transition.StateBefore = lastState;
    barrier->Transition.StateAfter = newState;
    barrier->Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;

    return true;
}

void Buffer::TrackUsageAndTransitionNow(CommandRecordingContext* commandContext,
                                        wgpu::BufferUsage newUsage) {
    D3D12_RESOURCE_BARRIER barrier;

    if (TrackUsageAndGetResourceBarrier(commandContext, &barrier, newUsage)) {
        commandContext->GetCommandList()->ResourceBarrier(1, &barrier);
    }
}

D3D12_GPU_VIRTUAL_ADDRESS Buffer::GetVA() const {
    return mResourceAllocation.GetGPUPointer();
}

bool Buffer::IsCPUWritableAtCreation() const {
    // We use a staging buffer for the buffers with mappedAtCreation == true and created on the
    // READBACK heap because for the buffers on the READBACK heap, the data written on the CPU
    // side won't be uploaded to GPU. When we enable zero-initialization, the CPU side memory
    // of the buffer is all written to 0 but not the GPU side memory, so on the next mapping
    // operation the zeroes get overwritten by whatever was in the GPU memory when the buffer
    // was created. With a staging buffer, the data on the CPU side will first upload to the
    // staging buffer, and copied from the staging buffer to the GPU memory of the current
    // buffer in the unmap() call.
    // TODO(enga): Handle CPU-visible memory on UMA
    return (GetUsage() & wgpu::BufferUsage::MapWrite) != 0;
}

MaybeError Buffer::MapInternal(bool isWrite, size_t offset, size_t size, const char* contextInfo) {
    // 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.
    TRACE_EVENT0(GetDevice()->GetPlatform(), General, "BufferD3D12::MapInternal");

    Heap* heap = ToBackend(mResourceAllocation.GetResourceHeap());
    DAWN_TRY(ToBackend(GetDevice())->GetResidencyManager()->LockAllocation(heap));

    D3D12_RANGE range = {offset, offset + size};
    // mMappedData is the pointer to the start of the resource, irrespective of offset.
    // MSDN says (note the weird use of "never"):
    //
    //   When ppData is not NULL, the pointer returned is never offset by any values in
    //   pReadRange.
    //
    // https://docs.microsoft.com/en-us/windows/win32/api/d3d12/nf-d3d12-id3d12resource-map
    DAWN_TRY(CheckHRESULT(GetD3D12Resource()->Map(0, &range, &mMappedData), contextInfo));

    if (isWrite) {
        mWrittenMappedRange = range;
    }

    return {};
}

MaybeError Buffer::MapAtCreationImpl() {
    // We will use a staging buffer for MapRead buffers instead so we just clear the staging
    // buffer and initialize the original buffer by copying the staging buffer to the original
    // buffer one the first time Unmap() is called.
    ASSERT((GetUsage() & wgpu::BufferUsage::MapWrite) != 0);

    // The buffers with mappedAtCreation == true will be initialized in
    // BufferBase::MapAtCreation().
    DAWN_TRY(MapInternal(true, 0, size_t(GetAllocatedSize()), "D3D12 map at creation"));

    return {};
}

MaybeError Buffer::MapAsyncImpl(wgpu::MapMode mode, size_t offset, size_t size) {
    // GetPendingCommandContext() call might create a new commandList. Dawn will handle
    // it in Tick() by execute the commandList and signal a fence for it even it is empty.
    // Skip the unnecessary GetPendingCommandContext() call saves an extra fence.
    if (NeedsInitialization()) {
        CommandRecordingContext* commandContext;
        DAWN_TRY_ASSIGN(commandContext, ToBackend(GetDevice())->GetPendingCommandContext());
        DAWN_TRY(EnsureDataInitialized(commandContext));
    }

    return MapInternal(mode & wgpu::MapMode::Write, offset, size, "D3D12 map async");
}

void Buffer::UnmapImpl() {
    GetD3D12Resource()->Unmap(0, &mWrittenMappedRange);
    mMappedData = nullptr;
    mWrittenMappedRange = {0, 0};

    // When buffers are mapped, they are locked to keep them in resident memory. We must unlock
    // them when they are unmapped.
    Heap* heap = ToBackend(mResourceAllocation.GetResourceHeap());
    ToBackend(GetDevice())->GetResidencyManager()->UnlockAllocation(heap);
}

void* Buffer::GetMappedPointer() {
    // The frontend asks that the pointer returned is from the start of the resource
    // irrespective of the offset passed in MapAsyncImpl, which is what mMappedData is.
    return mMappedData;
}

void Buffer::DestroyImpl() {
    if (mMappedData != nullptr) {
        // If the buffer is currently mapped, unmap without flushing the writes to the GPU
        // since the buffer cannot be used anymore. UnmapImpl checks mWrittenRange to know
        // which parts to flush, so we set it to an empty range to prevent flushes.
        mWrittenMappedRange = {0, 0};
    }
    BufferBase::DestroyImpl();

    ToBackend(GetDevice())->DeallocateMemory(mResourceAllocation);
}

bool Buffer::CheckIsResidentForTesting() const {
    Heap* heap = ToBackend(mResourceAllocation.GetResourceHeap());
    return heap->IsInList() || heap->IsResidencyLocked();
}

bool Buffer::CheckAllocationMethodForTesting(AllocationMethod allocationMethod) const {
    return mResourceAllocation.GetInfo().mMethod == allocationMethod;
}

MaybeError Buffer::EnsureDataInitialized(CommandRecordingContext* commandContext) {
    if (!NeedsInitialization()) {
        return {};
    }

    DAWN_TRY(InitializeToZero(commandContext));
    return {};
}

ResultOrError<bool> Buffer::EnsureDataInitializedAsDestination(
    CommandRecordingContext* commandContext,
    uint64_t offset,
    uint64_t size) {
    if (!NeedsInitialization()) {
        return {false};
    }

    if (IsFullBufferRange(offset, size)) {
        SetIsDataInitialized();
        return {false};
    }

    DAWN_TRY(InitializeToZero(commandContext));
    return {true};
}

MaybeError Buffer::EnsureDataInitializedAsDestination(CommandRecordingContext* commandContext,
                                                      const CopyTextureToBufferCmd* copy) {
    if (!NeedsInitialization()) {
        return {};
    }

    if (IsFullBufferOverwrittenInTextureToBufferCopy(copy)) {
        SetIsDataInitialized();
    } else {
        DAWN_TRY(InitializeToZero(commandContext));
    }

    return {};
}

void Buffer::SetLabelImpl() {
    SetDebugName(ToBackend(GetDevice()), mResourceAllocation.GetD3D12Resource(), "Dawn_Buffer",
                 GetLabel());
}

MaybeError Buffer::InitializeToZero(CommandRecordingContext* commandContext) {
    ASSERT(NeedsInitialization());

    // TODO(crbug.com/dawn/484): skip initializing the buffer when it is created on a heap
    // that has already been zero initialized.
    DAWN_TRY(ClearBuffer(commandContext, uint8_t(0u)));
    SetIsDataInitialized();
    GetDevice()->IncrementLazyClearCountForTesting();

    return {};
}

MaybeError Buffer::ClearBuffer(CommandRecordingContext* commandContext,
                               uint8_t clearValue,
                               uint64_t offset,
                               uint64_t size) {
    Device* device = ToBackend(GetDevice());
    size = size > 0 ? size : GetAllocatedSize();

    // The state of the buffers on UPLOAD heap must always be GENERIC_READ and cannot be
    // changed away, so we can only clear such buffer with buffer mapping.
    if (D3D12HeapType(GetUsage()) == D3D12_HEAP_TYPE_UPLOAD) {
        DAWN_TRY(MapInternal(true, static_cast<size_t>(offset), static_cast<size_t>(size),
                             "D3D12 map at clear buffer"));
        memset(mMappedData, clearValue, size);
        UnmapImpl();
    } else if (clearValue == 0u) {
        DAWN_TRY(device->ClearBufferToZero(commandContext, this, offset, size));
    } else {
        // TODO(crbug.com/dawn/852): use ClearUnorderedAccessView*() when the buffer usage
        // includes STORAGE.
        DynamicUploader* uploader = device->GetDynamicUploader();
        UploadHandle uploadHandle;
        DAWN_TRY_ASSIGN(uploadHandle, uploader->Allocate(size, device->GetPendingCommandSerial(),
                                                         kCopyBufferToBufferOffsetAlignment));

        memset(uploadHandle.mappedBuffer, clearValue, size);

        device->CopyFromStagingToBufferHelper(commandContext, uploadHandle.stagingBuffer,
                                              uploadHandle.startOffset, this, offset, size);
    }

    return {};
}
}  // namespace dawn::native::d3d12