// 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/null/DeviceNull.h"

#include <limits>
#include <utility>

#include "dawn/native/BackendConnection.h"
#include "dawn/native/Commands.h"
#include "dawn/native/ErrorData.h"
#include "dawn/native/Instance.h"
#include "dawn/native/Surface.h"

namespace dawn::native::null {

    // Implementation of pre-Device objects: the null adapter, null backend connection and Connect()

    Adapter::Adapter(InstanceBase* instance) : AdapterBase(instance, wgpu::BackendType::Null) {
        mVendorId = 0;
        mDeviceId = 0;
        mName = "Null backend";
        mAdapterType = wgpu::AdapterType::CPU;
        MaybeError err = Initialize();
        ASSERT(err.IsSuccess());
    }

    Adapter::~Adapter() = default;

    bool Adapter::SupportsExternalImages() const {
        return false;
    }

    // Used for the tests that intend to use an adapter without all features enabled.
    void Adapter::SetSupportedFeatures(const std::vector<wgpu::FeatureName>& requiredFeatures) {
        mSupportedFeatures = {};
        for (wgpu::FeatureName f : requiredFeatures) {
            mSupportedFeatures.EnableFeature(f);
        }
    }

    MaybeError Adapter::InitializeImpl() {
        return {};
    }

    MaybeError Adapter::InitializeSupportedFeaturesImpl() {
        // Enable all features by default for the convenience of tests.
        mSupportedFeatures.featuresBitSet.set();
        return {};
    }

    MaybeError Adapter::InitializeSupportedLimitsImpl(CombinedLimits* limits) {
        GetDefaultLimits(&limits->v1);
        return {};
    }

    ResultOrError<Ref<DeviceBase>> Adapter::CreateDeviceImpl(const DeviceDescriptor* descriptor) {
        return Device::Create(this, descriptor);
    }

    class Backend : public BackendConnection {
      public:
        explicit Backend(InstanceBase* instance)
            : BackendConnection(instance, wgpu::BackendType::Null) {
        }

        std::vector<Ref<AdapterBase>> DiscoverDefaultAdapters() override {
            // There is always a single Null adapter because it is purely CPU based and doesn't
            // depend on the system.
            std::vector<Ref<AdapterBase>> adapters;
            Ref<Adapter> adapter = AcquireRef(new Adapter(GetInstance()));
            adapters.push_back(std::move(adapter));
            return adapters;
        }
    };

    BackendConnection* Connect(InstanceBase* instance) {
        return new Backend(instance);
    }

    struct CopyFromStagingToBufferOperation : PendingOperation {
        virtual void Execute() {
            destination->CopyFromStaging(staging, sourceOffset, destinationOffset, size);
        }

        StagingBufferBase* staging;
        Ref<Buffer> destination;
        uint64_t sourceOffset;
        uint64_t destinationOffset;
        uint64_t size;
    };

    // Device

    // static
    ResultOrError<Ref<Device>> Device::Create(Adapter* adapter,
                                              const DeviceDescriptor* descriptor) {
        Ref<Device> device = AcquireRef(new Device(adapter, descriptor));
        DAWN_TRY(device->Initialize(descriptor));
        return device;
    }

    Device::~Device() {
        Destroy();
    }

    MaybeError Device::Initialize(const DeviceDescriptor* descriptor) {
        return DeviceBase::Initialize(AcquireRef(new Queue(this, &descriptor->defaultQueue)));
    }

    ResultOrError<Ref<BindGroupBase>> Device::CreateBindGroupImpl(
        const BindGroupDescriptor* descriptor) {
        return AcquireRef(new BindGroup(this, descriptor));
    }
    ResultOrError<Ref<BindGroupLayoutBase>> Device::CreateBindGroupLayoutImpl(
        const BindGroupLayoutDescriptor* descriptor,
        PipelineCompatibilityToken pipelineCompatibilityToken) {
        return AcquireRef(new BindGroupLayout(this, descriptor, pipelineCompatibilityToken));
    }
    ResultOrError<Ref<BufferBase>> Device::CreateBufferImpl(const BufferDescriptor* descriptor) {
        DAWN_TRY(IncrementMemoryUsage(descriptor->size));
        return AcquireRef(new Buffer(this, descriptor));
    }
    ResultOrError<Ref<CommandBufferBase>> Device::CreateCommandBuffer(
        CommandEncoder* encoder,
        const CommandBufferDescriptor* descriptor) {
        return AcquireRef(new CommandBuffer(encoder, descriptor));
    }
    Ref<ComputePipelineBase> Device::CreateUninitializedComputePipelineImpl(
        const ComputePipelineDescriptor* descriptor) {
        return AcquireRef(new ComputePipeline(this, descriptor));
    }
    ResultOrError<Ref<PipelineLayoutBase>> Device::CreatePipelineLayoutImpl(
        const PipelineLayoutDescriptor* descriptor) {
        return AcquireRef(new PipelineLayout(this, descriptor));
    }
    ResultOrError<Ref<QuerySetBase>> Device::CreateQuerySetImpl(
        const QuerySetDescriptor* descriptor) {
        return AcquireRef(new QuerySet(this, descriptor));
    }
    Ref<RenderPipelineBase> Device::CreateUninitializedRenderPipelineImpl(
        const RenderPipelineDescriptor* descriptor) {
        return AcquireRef(new RenderPipeline(this, descriptor));
    }
    ResultOrError<Ref<SamplerBase>> Device::CreateSamplerImpl(const SamplerDescriptor* descriptor) {
        return AcquireRef(new Sampler(this, descriptor));
    }
    ResultOrError<Ref<ShaderModuleBase>> Device::CreateShaderModuleImpl(
        const ShaderModuleDescriptor* descriptor,
        ShaderModuleParseResult* parseResult) {
        Ref<ShaderModule> module = AcquireRef(new ShaderModule(this, descriptor));
        DAWN_TRY(module->Initialize(parseResult));
        return module;
    }
    ResultOrError<Ref<SwapChainBase>> Device::CreateSwapChainImpl(
        const SwapChainDescriptor* descriptor) {
        return AcquireRef(new OldSwapChain(this, descriptor));
    }
    ResultOrError<Ref<NewSwapChainBase>> Device::CreateSwapChainImpl(
        Surface* surface,
        NewSwapChainBase* previousSwapChain,
        const SwapChainDescriptor* descriptor) {
        return SwapChain::Create(this, surface, previousSwapChain, descriptor);
    }
    ResultOrError<Ref<TextureBase>> Device::CreateTextureImpl(const TextureDescriptor* descriptor) {
        return AcquireRef(new Texture(this, descriptor, TextureBase::TextureState::OwnedInternal));
    }
    ResultOrError<Ref<TextureViewBase>> Device::CreateTextureViewImpl(
        TextureBase* texture,
        const TextureViewDescriptor* descriptor) {
        return AcquireRef(new TextureView(texture, descriptor));
    }

    ResultOrError<std::unique_ptr<StagingBufferBase>> Device::CreateStagingBuffer(size_t size) {
        std::unique_ptr<StagingBufferBase> stagingBuffer =
            std::make_unique<StagingBuffer>(size, this);
        DAWN_TRY(stagingBuffer->Initialize());
        return std::move(stagingBuffer);
    }

    void Device::DestroyImpl() {
        ASSERT(GetState() == State::Disconnected);

        // Clear pending operations before checking mMemoryUsage because some operations keep a
        // reference to Buffers.
        mPendingOperations.clear();
        ASSERT(mMemoryUsage == 0);
    }

    MaybeError Device::WaitForIdleForDestruction() {
        mPendingOperations.clear();
        return {};
    }

    MaybeError Device::CopyFromStagingToBuffer(StagingBufferBase* source,
                                               uint64_t sourceOffset,
                                               BufferBase* destination,
                                               uint64_t destinationOffset,
                                               uint64_t size) {
        if (IsToggleEnabled(Toggle::LazyClearResourceOnFirstUse)) {
            destination->SetIsDataInitialized();
        }

        auto operation = std::make_unique<CopyFromStagingToBufferOperation>();
        operation->staging = source;
        operation->destination = ToBackend(destination);
        operation->sourceOffset = sourceOffset;
        operation->destinationOffset = destinationOffset;
        operation->size = size;

        AddPendingOperation(std::move(operation));

        return {};
    }

    MaybeError Device::CopyFromStagingToTexture(const StagingBufferBase* source,
                                                const TextureDataLayout& src,
                                                TextureCopy* dst,
                                                const Extent3D& copySizePixels) {
        return {};
    }

    MaybeError Device::IncrementMemoryUsage(uint64_t bytes) {
        static_assert(kMaxMemoryUsage <= std::numeric_limits<size_t>::max());
        if (bytes > kMaxMemoryUsage || mMemoryUsage > kMaxMemoryUsage - bytes) {
            return DAWN_OUT_OF_MEMORY_ERROR("Out of memory.");
        }
        mMemoryUsage += bytes;
        return {};
    }

    void Device::DecrementMemoryUsage(uint64_t bytes) {
        ASSERT(mMemoryUsage >= bytes);
        mMemoryUsage -= bytes;
    }

    MaybeError Device::TickImpl() {
        return SubmitPendingOperations();
    }

    ResultOrError<ExecutionSerial> Device::CheckAndUpdateCompletedSerials() {
        return GetLastSubmittedCommandSerial();
    }

    void Device::AddPendingOperation(std::unique_ptr<PendingOperation> operation) {
        mPendingOperations.emplace_back(std::move(operation));
    }

    MaybeError Device::SubmitPendingOperations() {
        for (auto& operation : mPendingOperations) {
            operation->Execute();
        }
        mPendingOperations.clear();

        DAWN_TRY(CheckPassedSerials());
        IncrementLastSubmittedCommandSerial();

        return {};
    }

    // BindGroupDataHolder

    BindGroupDataHolder::BindGroupDataHolder(size_t size)
        : mBindingDataAllocation(malloc(size))  // malloc is guaranteed to return a
                                                // pointer aligned enough for the allocation
    {
    }

    BindGroupDataHolder::~BindGroupDataHolder() {
        free(mBindingDataAllocation);
    }

    // BindGroup

    BindGroup::BindGroup(DeviceBase* device, const BindGroupDescriptor* descriptor)
        : BindGroupDataHolder(descriptor->layout->GetBindingDataSize()),
          BindGroupBase(device, descriptor, mBindingDataAllocation) {
    }

    // BindGroupLayout

    BindGroupLayout::BindGroupLayout(DeviceBase* device,
                                     const BindGroupLayoutDescriptor* descriptor,
                                     PipelineCompatibilityToken pipelineCompatibilityToken)
        : BindGroupLayoutBase(device, descriptor, pipelineCompatibilityToken) {
    }

    // Buffer

    Buffer::Buffer(Device* device, const BufferDescriptor* descriptor)
        : BufferBase(device, descriptor) {
        mBackingData = std::unique_ptr<uint8_t[]>(new uint8_t[GetSize()]);
        mAllocatedSize = GetSize();
    }

    bool Buffer::IsCPUWritableAtCreation() const {
        // Only return true for mappable buffers so we can test cases that need / don't need a
        // staging buffer.
        return (GetUsage() & (wgpu::BufferUsage::MapRead | wgpu::BufferUsage::MapWrite)) != 0;
    }

    MaybeError Buffer::MapAtCreationImpl() {
        return {};
    }

    void Buffer::CopyFromStaging(StagingBufferBase* staging,
                                 uint64_t sourceOffset,
                                 uint64_t destinationOffset,
                                 uint64_t size) {
        uint8_t* ptr = reinterpret_cast<uint8_t*>(staging->GetMappedPointer());
        memcpy(mBackingData.get() + destinationOffset, ptr + sourceOffset, size);
    }

    void Buffer::DoWriteBuffer(uint64_t bufferOffset, const void* data, size_t size) {
        ASSERT(bufferOffset + size <= GetSize());
        ASSERT(mBackingData);
        memcpy(mBackingData.get() + bufferOffset, data, size);
    }

    MaybeError Buffer::MapAsyncImpl(wgpu::MapMode mode, size_t offset, size_t size) {
        return {};
    }

    void* Buffer::GetMappedPointerImpl() {
        return mBackingData.get();
    }

    void Buffer::UnmapImpl() {
    }

    void Buffer::DestroyImpl() {
        BufferBase::DestroyImpl();
        ToBackend(GetDevice())->DecrementMemoryUsage(GetSize());
    }

    // CommandBuffer

    CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
        : CommandBufferBase(encoder, descriptor) {
    }

    // QuerySet

    QuerySet::QuerySet(Device* device, const QuerySetDescriptor* descriptor)
        : QuerySetBase(device, descriptor) {
    }

    // Queue

    Queue::Queue(Device* device, const QueueDescriptor* descriptor)
        : QueueBase(device, descriptor) {
    }

    Queue::~Queue() {
    }

    MaybeError Queue::SubmitImpl(uint32_t, CommandBufferBase* const*) {
        Device* device = ToBackend(GetDevice());

        // The Vulkan, D3D12 and Metal implementation all tick the device here,
        // for testing purposes we should also tick in the null implementation.
        DAWN_TRY(device->Tick());

        return device->SubmitPendingOperations();
    }

    MaybeError Queue::WriteBufferImpl(BufferBase* buffer,
                                      uint64_t bufferOffset,
                                      const void* data,
                                      size_t size) {
        ToBackend(buffer)->DoWriteBuffer(bufferOffset, data, size);
        return {};
    }

    // ComputePipeline
    MaybeError ComputePipeline::Initialize() {
        return {};
    }

    // RenderPipeline
    MaybeError RenderPipeline::Initialize() {
        return {};
    }

    // SwapChain

    // static
    ResultOrError<Ref<SwapChain>> SwapChain::Create(Device* device,
                                                    Surface* surface,
                                                    NewSwapChainBase* previousSwapChain,
                                                    const SwapChainDescriptor* descriptor) {
        Ref<SwapChain> swapchain = AcquireRef(new SwapChain(device, surface, descriptor));
        DAWN_TRY(swapchain->Initialize(previousSwapChain));
        return swapchain;
    }

    MaybeError SwapChain::Initialize(NewSwapChainBase* previousSwapChain) {
        if (previousSwapChain != nullptr) {
            // TODO(crbug.com/dawn/269): figure out what should happen when surfaces are used by
            // multiple backends one after the other. It probably needs to block until the backend
            // and GPU are completely finished with the previous swapchain.
            if (previousSwapChain->GetBackendType() != wgpu::BackendType::Null) {
                return DAWN_VALIDATION_ERROR("null::SwapChain cannot switch between APIs");
            }
        }

        return {};
    }

    SwapChain::~SwapChain() = default;

    MaybeError SwapChain::PresentImpl() {
        mTexture->APIDestroy();
        mTexture = nullptr;
        return {};
    }

    ResultOrError<Ref<TextureViewBase>> SwapChain::GetCurrentTextureViewImpl() {
        TextureDescriptor textureDesc = GetSwapChainBaseTextureDescriptor(this);
        mTexture = AcquireRef(
            new Texture(GetDevice(), &textureDesc, TextureBase::TextureState::OwnedInternal));
        return mTexture->CreateView();
    }

    void SwapChain::DetachFromSurfaceImpl() {
        if (mTexture != nullptr) {
            mTexture->APIDestroy();
            mTexture = nullptr;
        }
    }

    // ShaderModule

    MaybeError ShaderModule::Initialize(ShaderModuleParseResult* parseResult) {
        return InitializeBase(parseResult);
    }

    // OldSwapChain

    OldSwapChain::OldSwapChain(Device* device, const SwapChainDescriptor* descriptor)
        : OldSwapChainBase(device, descriptor) {
        const auto& im = GetImplementation();
        im.Init(im.userData, nullptr);
    }

    OldSwapChain::~OldSwapChain() {
    }

    TextureBase* OldSwapChain::GetNextTextureImpl(const TextureDescriptor* descriptor) {
        return GetDevice()->APICreateTexture(descriptor);
    }

    MaybeError OldSwapChain::OnBeforePresent(TextureViewBase*) {
        return {};
    }

    // NativeSwapChainImpl

    void NativeSwapChainImpl::Init(WSIContext* context) {
    }

    DawnSwapChainError NativeSwapChainImpl::Configure(WGPUTextureFormat format,
                                                      WGPUTextureUsage,
                                                      uint32_t width,
                                                      uint32_t height) {
        return DAWN_SWAP_CHAIN_NO_ERROR;
    }

    DawnSwapChainError NativeSwapChainImpl::GetNextTexture(DawnSwapChainNextTexture* nextTexture) {
        return DAWN_SWAP_CHAIN_NO_ERROR;
    }

    DawnSwapChainError NativeSwapChainImpl::Present() {
        return DAWN_SWAP_CHAIN_NO_ERROR;
    }

    wgpu::TextureFormat NativeSwapChainImpl::GetPreferredFormat() const {
        return wgpu::TextureFormat::RGBA8Unorm;
    }

    // StagingBuffer

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

    StagingBuffer::~StagingBuffer() {
        if (mBuffer) {
            mDevice->DecrementMemoryUsage(GetSize());
        }
    }

    MaybeError StagingBuffer::Initialize() {
        DAWN_TRY(mDevice->IncrementMemoryUsage(GetSize()));
        mBuffer = std::make_unique<uint8_t[]>(GetSize());
        mMappedPointer = mBuffer.get();
        return {};
    }

    uint32_t Device::GetOptimalBytesPerRowAlignment() const {
        return 1;
    }

    uint64_t Device::GetOptimalBufferToTextureCopyOffsetAlignment() const {
        return 1;
    }

    float Device::GetTimestampPeriodInNS() const {
        return 1.0f;
    }

}  // namespace dawn::native::null