// 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/metal/DeviceMTL.h"

#include "dawn/common/GPUInfo.h"
#include "dawn/common/Platform.h"
#include "dawn/native/BackendConnection.h"
#include "dawn/native/BindGroupLayout.h"
#include "dawn/native/Commands.h"
#include "dawn/native/ErrorData.h"
#include "dawn/native/metal/BindGroupLayoutMTL.h"
#include "dawn/native/metal/BindGroupMTL.h"
#include "dawn/native/metal/BufferMTL.h"
#include "dawn/native/metal/CommandBufferMTL.h"
#include "dawn/native/metal/ComputePipelineMTL.h"
#include "dawn/native/metal/PipelineLayoutMTL.h"
#include "dawn/native/metal/QuerySetMTL.h"
#include "dawn/native/metal/QueueMTL.h"
#include "dawn/native/metal/RenderPipelineMTL.h"
#include "dawn/native/metal/SamplerMTL.h"
#include "dawn/native/metal/ShaderModuleMTL.h"
#include "dawn/native/metal/StagingBufferMTL.h"
#include "dawn/native/metal/SwapChainMTL.h"
#include "dawn/native/metal/TextureMTL.h"
#include "dawn/native/metal/UtilsMetal.h"
#include "dawn/platform/DawnPlatform.h"
#include "dawn/platform/tracing/TraceEvent.h"

#include <type_traits>

namespace dawn::native::metal {

    namespace {

        // The time interval for each round of kalman filter
        static constexpr uint64_t kFilterIntervalInMs = static_cast<uint64_t>(NSEC_PER_SEC / 10);

        struct KalmanInfo {
            float filterValue;  // The estimation value
            float kalmanGain;   // The kalman gain
            float R;            // The covariance of the observation noise
            float P;            // The a posteriori estimate covariance
        };

        // A simplified kalman filter for estimating timestamp period based on measured values
        float KalmanFilter(KalmanInfo* info, float measuredValue) {
            // Optimize kalman gain
            info->kalmanGain = info->P / (info->P + info->R);

            // Correct filter value
            info->filterValue =
                info->kalmanGain * measuredValue + (1.0 - info->kalmanGain) * info->filterValue;
            // Update estimate covariance
            info->P = (1.0f - info->kalmanGain) * info->P;
            return info->filterValue;
        }

        void API_AVAILABLE(macos(10.15), ios(14))
            UpdateTimestampPeriod(id<MTLDevice> device,
                                  KalmanInfo* info,
                                  MTLTimestamp* cpuTimestampStart,
                                  MTLTimestamp* gpuTimestampStart,
                                  float* timestampPeriod) {
            // The filter value is converged to an optimal value when the kalman gain is less than
            // 0.01. At this time, the weight of the measured value is too small to change the next
            // filter value, the sampling and calculations do not need to continue anymore.
            if (info->kalmanGain < 0.01f) {
                return;
            }

            MTLTimestamp cpuTimestampEnd = 0, gpuTimestampEnd = 0;
            [device sampleTimestamps:&cpuTimestampEnd gpuTimestamp:&gpuTimestampEnd];

            // Update the timestamp start values when timestamp reset happens
            if (cpuTimestampEnd < *cpuTimestampStart || gpuTimestampEnd < *gpuTimestampStart) {
                *cpuTimestampStart = cpuTimestampEnd;
                *gpuTimestampStart = gpuTimestampEnd;
                return;
            }

            if (cpuTimestampEnd - *cpuTimestampStart >= kFilterIntervalInMs) {
                // The measured timestamp period
                float measurement = (cpuTimestampEnd - *cpuTimestampStart) /
                                    static_cast<float>(gpuTimestampEnd - *gpuTimestampStart);

                // Measurement update
                *timestampPeriod = KalmanFilter(info, measurement);

                *cpuTimestampStart = cpuTimestampEnd;
                *gpuTimestampStart = gpuTimestampEnd;
            }
        }

    }  // namespace

    // static
    ResultOrError<Ref<Device>> Device::Create(AdapterBase* adapter,
                                              NSPRef<id<MTLDevice>> mtlDevice,
                                              const DeviceDescriptor* descriptor) {
        Ref<Device> device = AcquireRef(new Device(adapter, std::move(mtlDevice), descriptor));
        DAWN_TRY(device->Initialize());
        return device;
    }

    Device::Device(AdapterBase* adapter,
                   NSPRef<id<MTLDevice>> mtlDevice,
                   const DeviceDescriptor* descriptor)
        : DeviceBase(adapter, descriptor), mMtlDevice(std::move(mtlDevice)), mCompletedSerial(0) {
    }

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

    MaybeError Device::Initialize() {
        InitTogglesFromDriver();

        mCommandQueue.Acquire([*mMtlDevice newCommandQueue]);
        if (mCommandQueue == nil) {
            return DAWN_INTERNAL_ERROR("Failed to allocate MTLCommandQueue.");
        }

        DAWN_TRY(mCommandContext.PrepareNextCommandBuffer(*mCommandQueue));

        if (IsFeatureEnabled(Feature::TimestampQuery) &&
            !IsToggleEnabled(Toggle::DisableTimestampQueryConversion)) {
            // Make a best guess of timestamp period based on device vendor info, and converge it to
            // an accurate value by the following calculations.
            mTimestampPeriod = gpu_info::IsIntel(GetAdapter()->GetVendorId()) ? 83.333f : 1.0f;

            // Initialize kalman filter parameters
            mKalmanInfo = std::make_unique<KalmanInfo>();
            mKalmanInfo->filterValue = 0.0f;
            mKalmanInfo->kalmanGain = 0.5f;
            mKalmanInfo->R =
                0.0001f;  // The smaller this value is, the smaller the error of measured value is,
                          // the more we can trust the measured value.
            mKalmanInfo->P = 1.0f;

            if (@available(macos 10.15, iOS 14.0, *)) {
                // Sample CPU timestamp and GPU timestamp for first time at device creation
                [*mMtlDevice sampleTimestamps:&mCpuTimestamp gpuTimestamp:&mGpuTimestamp];
            }
        }

        return DeviceBase::Initialize(new Queue(this));
    }

    void Device::InitTogglesFromDriver() {
        {
            bool haveStoreAndMSAAResolve = false;
#if defined(DAWN_PLATFORM_MACOS)
            if (@available(macOS 10.12, *)) {
                haveStoreAndMSAAResolve =
                    [*mMtlDevice supportsFeatureSet:MTLFeatureSet_macOS_GPUFamily1_v2];
            }
#elif defined(DAWN_PLATFORM_IOS)
            haveStoreAndMSAAResolve =
                [*mMtlDevice supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily3_v2];
#endif
            // On tvOS, we would need MTLFeatureSet_tvOS_GPUFamily2_v1.
            SetToggle(Toggle::EmulateStoreAndMSAAResolve, !haveStoreAndMSAAResolve);

            bool haveSamplerCompare = true;
#if defined(DAWN_PLATFORM_IOS)
            haveSamplerCompare = [*mMtlDevice supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily3_v1];
#endif
            // TODO(crbug.com/dawn/342): Investigate emulation -- possibly expensive.
            SetToggle(Toggle::MetalDisableSamplerCompare, !haveSamplerCompare);

            bool haveBaseVertexBaseInstance = true;
#if defined(DAWN_PLATFORM_IOS)
            haveBaseVertexBaseInstance =
                [*mMtlDevice supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily3_v1];
#endif
            // TODO(crbug.com/dawn/343): Investigate emulation.
            SetToggle(Toggle::DisableBaseVertex, !haveBaseVertexBaseInstance);
            SetToggle(Toggle::DisableBaseInstance, !haveBaseVertexBaseInstance);
        }

        // Vertex buffer robustness is implemented by using programmable vertex pulling. Enable
        // that code path if it isn't explicitly disabled.
        if (IsRobustnessEnabled()) {
            SetToggle(Toggle::MetalEnableVertexPulling, true);
        }

        // TODO(crbug.com/dawn/846): tighten this workaround when the driver bug is fixed.
        SetToggle(Toggle::AlwaysResolveIntoZeroLevelAndLayer, true);

        uint32_t deviceId = GetAdapter()->GetDeviceId();
        uint32_t vendorId = GetAdapter()->GetVendorId();

        // TODO(crbug.com/dawn/847): Use MTLStorageModeShared instead of MTLStorageModePrivate when
        // creating MTLCounterSampleBuffer in QuerySet on Intel platforms, otherwise it fails to
        // create the buffer. Change to use MTLStorageModePrivate when the bug is fixed.
        if (@available(macOS 10.15, iOS 14.0, *)) {
            bool useSharedMode = gpu_info::IsIntel(vendorId);
            SetToggle(Toggle::MetalUseSharedModeForCounterSampleBuffer, useSharedMode);
        }

        // TODO(crbug.com/dawn/1071): r8unorm and rg8unorm textures with multiple mip levels don't
        // clear properly on Intel Macs.
        if (gpu_info::IsIntel(vendorId)) {
            SetToggle(Toggle::DisableR8RG8Mipmaps, true);
        }

        // On some Intel GPU vertex only render pipeline get wrong depth result if no fragment
        // shader provided. Create a dummy fragment shader module to work around this issue.
        if (gpu_info::IsIntel(vendorId)) {
            bool useDummyFragmentShader = true;
            if (gpu_info::IsSkylake(deviceId)) {
                useDummyFragmentShader = false;
            }
            SetToggle(Toggle::UseDummyFragmentInVertexOnlyPipeline, useDummyFragmentShader);
        }
    }

    ResultOrError<Ref<BindGroupBase>> Device::CreateBindGroupImpl(
        const BindGroupDescriptor* descriptor) {
        return BindGroup::Create(this, descriptor);
    }
    ResultOrError<Ref<BindGroupLayoutBase>> Device::CreateBindGroupLayoutImpl(
        const BindGroupLayoutDescriptor* descriptor,
        PipelineCompatibilityToken pipelineCompatibilityToken) {
        return BindGroupLayout::Create(this, descriptor, pipelineCompatibilityToken);
    }
    ResultOrError<Ref<BufferBase>> Device::CreateBufferImpl(const BufferDescriptor* descriptor) {
        return Buffer::Create(this, descriptor);
    }
    ResultOrError<Ref<CommandBufferBase>> Device::CreateCommandBuffer(
        CommandEncoder* encoder,
        const CommandBufferDescriptor* descriptor) {
        return CommandBuffer::Create(encoder, descriptor);
    }
    Ref<ComputePipelineBase> Device::CreateUninitializedComputePipelineImpl(
        const ComputePipelineDescriptor* descriptor) {
        return ComputePipeline::CreateUninitialized(this, descriptor);
    }
    ResultOrError<Ref<PipelineLayoutBase>> Device::CreatePipelineLayoutImpl(
        const PipelineLayoutDescriptor* descriptor) {
        return PipelineLayout::Create(this, descriptor);
    }
    ResultOrError<Ref<QuerySetBase>> Device::CreateQuerySetImpl(
        const QuerySetDescriptor* descriptor) {
        return QuerySet::Create(this, descriptor);
    }
    Ref<RenderPipelineBase> Device::CreateUninitializedRenderPipelineImpl(
        const RenderPipelineDescriptor* descriptor) {
        return RenderPipeline::CreateUninitialized(this, descriptor);
    }
    ResultOrError<Ref<SamplerBase>> Device::CreateSamplerImpl(const SamplerDescriptor* descriptor) {
        return Sampler::Create(this, descriptor);
    }
    ResultOrError<Ref<ShaderModuleBase>> Device::CreateShaderModuleImpl(
        const ShaderModuleDescriptor* descriptor,
        ShaderModuleParseResult* parseResult) {
        return ShaderModule::Create(this, descriptor, parseResult);
    }
    ResultOrError<Ref<SwapChainBase>> Device::CreateSwapChainImpl(
        const SwapChainDescriptor* descriptor) {
        return OldSwapChain::Create(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 Texture::Create(this, descriptor);
    }
    ResultOrError<Ref<TextureViewBase>> Device::CreateTextureViewImpl(
        TextureBase* texture,
        const TextureViewDescriptor* descriptor) {
        return TextureView::Create(texture, descriptor);
    }
    void Device::InitializeComputePipelineAsyncImpl(Ref<ComputePipelineBase> computePipeline,
                                                    WGPUCreateComputePipelineAsyncCallback callback,
                                                    void* userdata) {
        ComputePipeline::InitializeAsync(std::move(computePipeline), callback, userdata);
    }
    void Device::InitializeRenderPipelineAsyncImpl(Ref<RenderPipelineBase> renderPipeline,
                                                   WGPUCreateRenderPipelineAsyncCallback callback,
                                                   void* userdata) {
        RenderPipeline::InitializeAsync(std::move(renderPipeline), callback, userdata);
    }

    ResultOrError<ExecutionSerial> Device::CheckAndUpdateCompletedSerials() {
        uint64_t frontendCompletedSerial{GetCompletedCommandSerial()};
        if (frontendCompletedSerial > mCompletedSerial) {
            // sometimes we increase the serials, in which case the completed serial in
            // the device base will surpass the completed serial we have in the metal backend, so we
            // must update ours when we see that the completed serial from device base has
            // increased.
            mCompletedSerial = frontendCompletedSerial;
        }
        return ExecutionSerial(mCompletedSerial.load());
    }

    MaybeError Device::TickImpl() {
        DAWN_TRY(SubmitPendingCommandBuffer());

        // Just run timestamp period calculation when timestamp feature is enabled.
        if (IsFeatureEnabled(Feature::TimestampQuery)) {
            if (@available(macos 10.15, iOS 14.0, *)) {
                UpdateTimestampPeriod(GetMTLDevice(), mKalmanInfo.get(), &mCpuTimestamp,
                                      &mGpuTimestamp, &mTimestampPeriod);
            }
        }

        return {};
    }

    id<MTLDevice> Device::GetMTLDevice() {
        return mMtlDevice.Get();
    }

    id<MTLCommandQueue> Device::GetMTLQueue() {
        return mCommandQueue.Get();
    }

    CommandRecordingContext* Device::GetPendingCommandContext() {
        mCommandContext.MarkUsed();
        return &mCommandContext;
    }

    MaybeError Device::SubmitPendingCommandBuffer() {
        if (!mCommandContext.WasUsed()) {
            return {};
        }

        IncrementLastSubmittedCommandSerial();

        // Acquire the pending command buffer, which is retained. It must be released later.
        NSPRef<id<MTLCommandBuffer>> pendingCommands = mCommandContext.AcquireCommands();

        // Replace mLastSubmittedCommands with the mutex held so we avoid races between the
        // schedule handler and this code.
        {
            std::lock_guard<std::mutex> lock(mLastSubmittedCommandsMutex);
            mLastSubmittedCommands = pendingCommands;
        }

        // Make a local copy of the pointer to the commands because it's not clear how ObjC blocks
        // handle types with copy / move constructors being referenced in the block..
        id<MTLCommandBuffer> pendingCommandsPointer = pendingCommands.Get();
        [*pendingCommands addScheduledHandler:^(id<MTLCommandBuffer>) {
            // This is DRF because we hold the mutex for mLastSubmittedCommands and pendingCommands
            // is a local value (and not the member itself).
            std::lock_guard<std::mutex> lock(mLastSubmittedCommandsMutex);
            if (this->mLastSubmittedCommands.Get() == pendingCommandsPointer) {
                this->mLastSubmittedCommands = nullptr;
            }
        }];

        // Update the completed serial once the completed handler is fired. Make a local copy of
        // mLastSubmittedSerial so it is captured by value.
        ExecutionSerial pendingSerial = GetLastSubmittedCommandSerial();
        // this ObjC block runs on a different thread
        [*pendingCommands addCompletedHandler:^(id<MTLCommandBuffer>) {
            TRACE_EVENT_ASYNC_END0(GetPlatform(), GPUWork, "DeviceMTL::SubmitPendingCommandBuffer",
                                   uint64_t(pendingSerial));
            ASSERT(uint64_t(pendingSerial) > mCompletedSerial.load());
            this->mCompletedSerial = uint64_t(pendingSerial);
        }];

        TRACE_EVENT_ASYNC_BEGIN0(GetPlatform(), GPUWork, "DeviceMTL::SubmitPendingCommandBuffer",
                                 uint64_t(pendingSerial));
        [*pendingCommands commit];

        return mCommandContext.PrepareNextCommandBuffer(*mCommandQueue);
    }

    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);
    }

    MaybeError Device::CopyFromStagingToBuffer(StagingBufferBase* source,
                                               uint64_t sourceOffset,
                                               BufferBase* destination,
                                               uint64_t destinationOffset,
                                               uint64_t size) {
        // Metal validation layers forbid  0-sized copies, assert it is skipped prior to calling
        // this function.
        ASSERT(size != 0);

        ToBackend(destination)
            ->EnsureDataInitializedAsDestination(GetPendingCommandContext(), destinationOffset,
                                                 size);

        id<MTLBuffer> uploadBuffer = ToBackend(source)->GetBufferHandle();
        id<MTLBuffer> buffer = ToBackend(destination)->GetMTLBuffer();
        [GetPendingCommandContext()->EnsureBlit() copyFromBuffer:uploadBuffer
                                                    sourceOffset:sourceOffset
                                                        toBuffer:buffer
                                               destinationOffset:destinationOffset
                                                            size:size];
        return {};
    }

    // In Metal we don't write from the CPU to the texture directly which can be done using the
    // replaceRegion function, because the function requires a non-private storage mode and Dawn
    // sets the private storage mode by default for all textures except IOSurfaces on macOS.
    MaybeError Device::CopyFromStagingToTexture(const StagingBufferBase* source,
                                                const TextureDataLayout& dataLayout,
                                                TextureCopy* dst,
                                                const Extent3D& copySizePixels) {
        Texture* texture = ToBackend(dst->texture.Get());
        EnsureDestinationTextureInitialized(GetPendingCommandContext(), texture, *dst,
                                            copySizePixels);

        RecordCopyBufferToTexture(GetPendingCommandContext(), ToBackend(source)->GetBufferHandle(),
                                  source->GetSize(), dataLayout.offset, dataLayout.bytesPerRow,
                                  dataLayout.rowsPerImage, texture, dst->mipLevel, dst->origin,
                                  dst->aspect, copySizePixels);
        return {};
    }

    Ref<Texture> Device::CreateTextureWrappingIOSurface(const ExternalImageDescriptor* descriptor,
                                                        IOSurfaceRef ioSurface) {
        const TextureDescriptor* textureDescriptor = FromAPI(descriptor->cTextureDescriptor);

        if (ConsumedError(ValidateTextureDescriptor(this, textureDescriptor))) {
            return nullptr;
        }
        if (ConsumedError(ValidateIOSurfaceCanBeWrapped(this, textureDescriptor, ioSurface))) {
            return nullptr;
        }

        Ref<Texture> result;
        if (ConsumedError(Texture::CreateFromIOSurface(this, descriptor, ioSurface), &result)) {
            return nullptr;
        }
        return result;
    }

    void Device::WaitForCommandsToBeScheduled() {
        if (ConsumedError(SubmitPendingCommandBuffer())) {
            return;
        }

        // Only lock the object while we take a reference to it, otherwise we could block further
        // progress if the driver calls the scheduled handler (which also acquires the lock) before
        // finishing the waitUntilScheduled.
        NSPRef<id<MTLCommandBuffer>> lastSubmittedCommands;
        {
            std::lock_guard<std::mutex> lock(mLastSubmittedCommandsMutex);
            lastSubmittedCommands = mLastSubmittedCommands;
        }
        [*lastSubmittedCommands waitUntilScheduled];
    }

    MaybeError Device::WaitForIdleForDestruction() {
        // Forget all pending commands.
        mCommandContext.AcquireCommands();
        DAWN_TRY(CheckPassedSerials());

        // Wait for all commands to be finished so we can free resources
        while (GetCompletedCommandSerial() != GetLastSubmittedCommandSerial()) {
            usleep(100);
            DAWN_TRY(CheckPassedSerials());
        }

        return {};
    }

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

        // Forget all pending commands.
        mCommandContext.AcquireCommands();

        mCommandQueue = nullptr;
        mMtlDevice = nullptr;
    }

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

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

    float Device::GetTimestampPeriodInNS() const {
        return mTimestampPeriod;
    }

}  // namespace dawn::native::metal