#include "metal-device.h"
#include "metal-backend.h"
#include "../resource-desc-utils.h"
#include "metal-command.h"
#include "metal-buffer.h"
#include "metal-shader-program.h"
#include "metal-texture.h"
#include "metal-utils.h"
#include "metal-input-layout.h"
#include "metal-fence.h"
#include "metal-query.h"
#include "metal-sampler.h"
#include "metal-shader-object-layout.h"
#include "metal-shader-object.h"
#include "metal-acceleration-structure.h"

#include "core/common.h"

#include <Foundation/NSProcessInfo.hpp>

#include <cstdlib>
#include <vector>

namespace rhi::metal {

DeviceImpl::DeviceImpl() {}

DeviceImpl::~DeviceImpl()
{
    if (captureEnabled())
    {
        MTL::CaptureManager* captureManager = MTL::CaptureManager::sharedCaptureManager();
        captureManager->stopCapture();
    }

    m_uploadHeap.release();
    m_readbackHeap.release();

    if (m_queue)
    {
        m_queue->shutdown();
        m_queue.setNull();
    }

    if (m_commandQueue && m_residencySet)
    {
        m_commandQueue->removeResidencySet(m_residencySet.get());
    }

    m_clearEngine.release();
}

void DeviceImpl::deferDelete(Resource* resource)
{
    SLANG_RHI_ASSERT(m_queue != nullptr);
    m_queue->deferDelete(resource);
    resource->breakStrongReferenceToDevice();
}

Result DeviceImpl::getNativeDeviceHandles(DeviceNativeHandles* outHandles)
{
    outHandles->handles[0].type = NativeHandleType::MTLDevice;
    outHandles->handles[0].value = (uint64_t)m_device.get();
    outHandles->handles[1] = {};
    outHandles->handles[2] = {};
    return SLANG_OK;
}

Result DeviceImpl::initialize(const DeviceDesc& desc, BackendImpl* backend)
{
    AUTORELEASEPOOL

    SLANG_RETURN_ON_FAIL(Device::initialize(desc));

    const AdapterImpl* adapter = nullptr;
    SLANG_RETURN_ON_FAIL(selectAdapter(this, backend->getAdapters(), desc, adapter));
    m_device = adapter->m_device;
    if (!m_device)
    {
        return SLANG_FAIL;
    }
    m_commandQueue = NS::TransferPtr(m_device->newCommandQueue(64));
    if (!m_commandQueue)
    {
        return SLANG_FAIL;
    }

    // Gate on Argument Buffers Tier 2 - the actual functional requirement
    // for gpuAddress() and bindless argument buffer access.
    if (m_device->argumentBuffersSupport() < MTL::ArgumentBuffersTier2)
    {
        handleMessage(
            DebugMessageType::Error,
            DebugMessageSource::Driver,
            "Metal backend requires Argument Buffers Tier 2"
        );
        return SLANG_FAIL;
    }

    if (!m_device->hasUnifiedMemory())
    {
        handleMessage(
            DebugMessageType::Warning,
            DebugMessageSource::Driver,
            "Non-UMA device detected; shared texture support may be limited"
        );
    }

    // Try residency set (requires GPUFamilyApple6 + runtime support).
    // Environment variable to force fallback path for testing.
    {
        bool forceUseResourceFallback = std::getenv("SLANG_RHI_METAL_NO_RESIDENCY_SET") != nullptr;
        if (forceUseResourceFallback)
        {
            handleMessage(
                DebugMessageType::Info,
                DebugMessageSource::Driver,
                "SLANG_RHI_METAL_NO_RESIDENCY_SET set; using per-encoder useResource fallback"
            );
        }
        else if (m_device->supportsFamily(MTL::GPUFamilyApple6))
        {
            NS::Error* error = nullptr;
            auto rsDesc = NS::TransferPtr(MTL::ResidencySetDescriptor::alloc()->init());
            m_residencySet = NS::TransferPtr(m_device->newResidencySet(rsDesc.get(), &error));
            if (m_residencySet)
            {
                m_commandQueue->addResidencySet(m_residencySet.get());
                m_hasResidencySet = true;
            }
            else
            {
                handleMessage(
                    DebugMessageType::Warning,
                    DebugMessageSource::Driver,
                    "MTLResidencySet creation failed; using per-encoder useResource fallback"
                );
            }
        }
        else
        {
            handleMessage(
                DebugMessageType::Info,
                DebugMessageSource::Driver,
                "GPUFamilyApple6 not supported; using per-encoder useResource fallback"
            );
        }
    }

    m_queue = new CommandQueueImpl(this, QueueType::Graphics);
    m_queue->init(m_commandQueue);
    m_queue->setInternalReferenceCount(1);

    // Setup capture manager.
    if (captureEnabled())
    {
        MTL::CaptureManager* captureManager = MTL::CaptureManager::sharedCaptureManager();
        MTL::CaptureDescriptor* d = MTL::CaptureDescriptor::alloc()->init();
        if (!captureManager->supportsDestination(MTL::CaptureDestinationGPUTraceDocument))
        {
            handleMessage(
                DebugMessageType::Error,
                DebugMessageSource::Layer,
                "Cannot capture MTL calls to document; ensure that Info.plist exists with 'MetalCaptureEnabled' set to "
                "'true'."
            );
            return SLANG_FAIL;
        }
        d->setDestination(MTL::CaptureDestinationGPUTraceDocument);
        d->setCaptureObject(m_device.get());
        NS::SharedPtr<NS::String> path = createString("frame.gputrace");
        NS::SharedPtr<NS::URL> url = NS::TransferPtr(NS::URL::alloc()->initFileURLWithPath(path.get()));
        d->setOutputURL(url.get());
        NS::Error* errorCode = NS::Error::alloc();
        if (!captureManager->startCapture(d, &errorCode))
        {
            NS::String* errorString = errorCode->description();
            std::string str(errorString->cString(NS::UTF8StringEncoding));
            str = "Start capture failure: " + str;
            handleMessage(DebugMessageType::Error, DebugMessageSource::Layer, str.c_str());
            return SLANG_FAIL;
        }
    }

    // Initialize device info.
    {
        m_info.deviceType = DeviceType::Metal;
        m_info.apiName = "Metal";
        m_info.adapterName = adapter->m_info.name;
        m_info.adapterLUID = adapter->m_info.luid;

        // TODO: Most limits cannot be queried through the Metal API but are described in
        // https://developer.apple.com/metal/Metal-Feature-Set-Tables.pdf
        // We should ideally query the OS version and GPU family to set more accurate limits.
        // For now we set some common values that should be safe across most devices.
        DeviceLimits& limits = m_info.limits;
        limits.maxBufferSize = static_cast<uint64_t>(m_device->maxBufferLength());

        limits.maxTextureDimension1D = 16384;
        limits.maxTextureDimension2D = 16384;
        limits.maxTextureDimension3D = 2048;
        limits.maxTextureDimensionCube = 16384;
        limits.maxTextureLayers = 2048;

        limits.maxVertexInputElements = 31;
        limits.maxVertexInputElementOffset = 2047;
        limits.maxVertexStreams = 31;
        limits.maxVertexStreamStride = 2048;

        MTL::Size maxThreadsPerThreadGroup = m_device->maxThreadsPerThreadgroup();
        limits.maxComputeThreadsPerGroup = static_cast<uint32_t>(
            maxThreadsPerThreadGroup.width * maxThreadsPerThreadGroup.height * maxThreadsPerThreadGroup.depth
        );
        limits.maxComputeThreadGroupSize[0] = static_cast<uint32_t>(maxThreadsPerThreadGroup.width);
        limits.maxComputeThreadGroupSize[1] = static_cast<uint32_t>(maxThreadsPerThreadGroup.height);
        limits.maxComputeThreadGroupSize[2] = static_cast<uint32_t>(maxThreadsPerThreadGroup.depth);
        limits.maxComputeDispatchThreadGroups[0] = 0xffffffff;
        limits.maxComputeDispatchThreadGroups[1] = 0xffffffff;
        limits.maxComputeDispatchThreadGroups[2] = 0xffffffff;

        limits.maxViewports = 16;
        limits.maxViewportDimensions[0] = 16384;
        limits.maxViewportDimensions[1] = 16384;
        limits.maxFramebufferDimensions[0] = 16384;
        limits.maxFramebufferDimensions[1] = 16384;
        limits.maxFramebufferDimensions[2] = 2048;

        limits.maxShaderVisibleSamplers = 16;
    }

    // Initialize features & capabilities.

    addFeature(Feature::HardwareDevice);
    addFeature(Feature::Surface);
    addFeature(Feature::Rasterization);

    if (m_device->supportsRaytracing())
    {
        addFeature(Feature::AccelerationStructure);
        addFeature(Feature::RayQuery);
    }

    m_hasArgumentBufferTier2 = m_device->argumentBuffersSupport() >= MTL::ArgumentBuffersTier2;
    if (m_hasArgumentBufferTier2)
    {
        addFeature(Feature::ArgumentBufferTier2);
        addFeature(Feature::ParameterBlock);
    }
    if (m_hasResidencySet)
    {
        addFeature(Feature::ResidencySet);
    }

    addCapability(Capability::metal);
    const auto osVersion = NS::ProcessInfo::processInfo()->operatingSystemVersion();
    if (osVersion.majorVersion >= 11)
        addCapability(Capability::metallib_2_3);
    if (osVersion.majorVersion >= 12)
        addCapability(Capability::metallib_2_4);
    if (osVersion.majorVersion >= 13)
        addCapability(Capability::metallib_3_0);
    if (osVersion.majorVersion >= 14)
        addCapability(Capability::metallib_3_1);
    if (osVersion.majorVersion >= 15)
        addCapability(Capability::metallib_3_2);
    // TODO: Re-enable once Slang passes -std=metal4.0 to the downstream Metal compiler.
    // Slang 2026.12.2 emits Metal 4.0-only attributes when this capability is enabled.
    // https://github.com/shader-slang/slang/issues/12325
    // if (osVersion.majorVersion >= 26)
    //     addCapability(Capability::metallib_4_0);

    auto supportsAnyGPUFamilyInRange = [&](MTL::GPUFamily first, MTL::GPUFamily last)
    {
        for (int family = int(first); family <= int(last); ++family)
        {
            if (m_device->supportsFamily(MTL::GPUFamily(family)))
                return true;
        }
        return false;
    };

    auto isBCFormat = [&](Format format)
    {
        return format >= Format::BC1Unorm && format <= Format::BC7UnormSrgb;
    };

    auto isASTCFormat = [&](Format format)
    {
        return format >= Format::ASTC4x4Unorm && format <= Format::ASTC8x8UnormSrgb;
    };

    // Match Metal Feature Set Tables:
    // - ASTC pixel formats: Apple2+
    // - BC pixel formats: query directly via supportsBCTextureCompression().
    const bool supportASTC = supportsAnyGPUFamilyInRange(MTL::GPUFamilyApple2, MTL::GPUFamilyApple9);
    const bool supportBC = m_device->supportsBCTextureCompression();

    // Initialize format support table.
    // TODO: add table based on https://developer.apple.com/metal/Metal-Feature-Set-Tables.pdf
    for (size_t formatIndex = 0; formatIndex < size_t(Format::_Count); ++formatIndex)
    {
        Format format = Format(formatIndex);
        FormatSupport formatSupport = FormatSupport::None;

        bool isFormatSupported = true;
        if (isBCFormat(format))
            isFormatSupported = supportBC;
        else if (isASTCFormat(format))
            isFormatSupported = supportASTC;

        if (isFormatSupported && translatePixelFormat(format) != MTL::PixelFormatInvalid)
        {
            // depth/stencil formats?
            formatSupport |= FormatSupport::CopySource;
            formatSupport |= FormatSupport::CopyDestination;
            formatSupport |= FormatSupport::Texture;
            if (isDepthFormat(format))
                formatSupport |= FormatSupport::DepthStencil;
            formatSupport |= FormatSupport::RenderTarget;
            formatSupport |= FormatSupport::Blendable;
            formatSupport |= FormatSupport::Resolvable;
            formatSupport |= FormatSupport::ShaderLoad;
            formatSupport |= FormatSupport::ShaderSample;
            formatSupport |= FormatSupport::ShaderUavLoad;
            formatSupport |= FormatSupport::ShaderUavStore;
            formatSupport |= FormatSupport::ShaderAtomic;
            formatSupport |= FormatSupport::Buffer;
        }
        if (translateVertexFormat(format) != MTL::VertexFormatInvalid)
        {
            formatSupport |= FormatSupport::VertexBuffer;
            formatSupport |= FormatSupport::CopySource;
            formatSupport |= FormatSupport::CopyDestination;
        }
        if (format == Format::R32Uint || format == Format::R16Uint)
        {
            formatSupport |= FormatSupport::IndexBuffer;
            formatSupport |= FormatSupport::CopySource;
            formatSupport |= FormatSupport::CopyDestination;
        }
        m_formatSupport[formatIndex] = formatSupport;
    }

    // Initialize slang context.
    SLANG_RETURN_ON_FAIL(m_slangContext.initialize(
        desc.slang,
        SLANG_METAL_LIB,
        nullptr,
        getCapabilities(),
        std::array{slang::PreprocessorMacroDesc{"__METAL__", "1"}}
    ));

    SLANG_RETURN_ON_FAIL(m_clearEngine.initialize(m_device.get()));

    SLANG_RETURN_ON_FAIL(checkRequiredFeatures(desc));

    return SLANG_OK;
}

Result DeviceImpl::getQueue(QueueType type, ICommandQueue** outQueue)
{
    AUTORELEASEPOOL

    if (type != QueueType::Graphics)
    {
        return SLANG_E_INVALID_ARG;
    }
    returnComPtr(outQueue, m_queue);
    return SLANG_OK;
}

Result DeviceImpl::readBuffer(IBuffer* buffer, Offset offset, Size size, void* outData)
{
    AUTORELEASEPOOL

    auto bufferImpl = checked_cast<BufferImpl*>(buffer);
    if (offset + size > bufferImpl->m_desc.size)
    {
        return SLANG_FAIL;
    }

    auto stagingOpts = makeResourceOptions(MTL::ResourceStorageModeShared);
    NS::SharedPtr<MTL::Buffer> stagingBuffer = NS::TransferPtr(m_device->newBuffer(size, stagingOpts));
    if (!stagingBuffer)
    {
        return SLANG_FAIL;
    }

    MTL::CommandBuffer* commandBuffer = m_commandQueue->commandBuffer();
    if (!commandBuffer)
        return SLANG_FAIL;
    MTL::BlitCommandEncoder* blitEncoder = commandBuffer->blitCommandEncoder();
    if (!blitEncoder)
        return SLANG_FAIL;
    blitEncoder->waitForFence(m_queue->m_queueFence.get());
    blitEncoder->copyFromBuffer(bufferImpl->m_buffer.get(), offset, stagingBuffer.get(), 0, size);
    blitEncoder->updateFence(m_queue->m_queueFence.get());
    blitEncoder->endEncoding();
    commandBuffer->commit();
    commandBuffer->waitUntilCompleted();

    std::memcpy(outData, stagingBuffer->contents(), size);

    return SLANG_OK;
}

Result DeviceImpl::getAccelerationStructureSizes(
    const AccelerationStructureBuildDesc& desc,
    AccelerationStructureSizes* outSizes
)
{
    AUTORELEASEPOOL

    AccelerationStructureBuildDescConverter converter;
    SLANG_RETURN_ON_FAIL(converter.convert(desc, nullptr, m_debugCallback));
    MTL::AccelerationStructureSizes sizes = m_device->accelerationStructureSizes(converter.descriptor.get());
    outSizes->accelerationStructureSize = sizes.accelerationStructureSize;
    outSizes->scratchSize = sizes.buildScratchBufferSize;
    outSizes->updateScratchSize = sizes.refitScratchBufferSize;

    return SLANG_OK;
}

uint32_t DeviceImpl::registerAccelerationStructure(MTL::AccelerationStructure* accelerationStructure)
{
    SLANG_RHI_ASSERT(accelerationStructure);

    uint32_t index = 0;
    if (!m_accelerationStructures.freeList.empty())
    {
        index = m_accelerationStructures.freeList.back();
        m_accelerationStructures.freeList.pop_back();
        m_accelerationStructures.list[index] = accelerationStructure;
    }
    else
    {
        index = uint32_t(m_accelerationStructures.list.size());
        m_accelerationStructures.list.push_back(accelerationStructure);
    }

    m_accelerationStructures.arrayDirty = true;
    m_accelerationStructures.resourcesDirty = true;

    return index;
}

void DeviceImpl::unregisterAccelerationStructure(uint32_t index, MTL::AccelerationStructure* accelerationStructure)
{
    SLANG_RHI_ASSERT(accelerationStructure);
    SLANG_RHI_ASSERT(index < m_accelerationStructures.list.size());
    SLANG_RHI_ASSERT(m_accelerationStructures.list[index] == accelerationStructure);

    m_accelerationStructures.freeList.push_back(index);
    m_accelerationStructures.list[index] = nullptr;

    m_accelerationStructures.arrayDirty = true;
    m_accelerationStructures.resourcesDirty = true;
}

NS::Array* DeviceImpl::getAccelerationStructureArray()
{
    if (m_accelerationStructures.arrayDirty)
    {
        m_accelerationStructures.array = NS::TransferPtr(
            NS::Array::alloc()->init(
                (const NS::Object* const*)m_accelerationStructures.list.data(),
                m_accelerationStructures.list.size()
            )
        );
        m_accelerationStructures.arrayDirty = false;
    }
    return m_accelerationStructures.array.get();
}

std::span<MTL::Resource* const> DeviceImpl::getAccelerationStructureResources()
{
    if (m_accelerationStructures.resourcesDirty)
    {
        m_accelerationStructures.resources.clear();
        for (auto* as : m_accelerationStructures.list)
        {
            if (as)
                m_accelerationStructures.resources.push_back(as);
        }
        m_accelerationStructures.resourcesDirty = false;
    }
    return std::span<MTL::Resource* const>(
        m_accelerationStructures.resources.data(),
        m_accelerationStructures.resources.size()
    );
}

Result DeviceImpl::getTextureAllocationInfo(const TextureDesc& desc_, Size* outSize, Size* outAlignment)
{
    AUTORELEASEPOOL

    auto alignTo = [&](Size size, Size alignment) -> Size
    {
        return ((size + alignment - 1) / alignment) * alignment;
    };

    TextureDesc desc = fixupTextureDesc(desc_);
    const FormatInfo& formatInfo = getFormatInfo(desc.format);
    MTL::PixelFormat pixelFormat = translatePixelFormat(desc.format);
    Size alignment = formatInfo.isCompressed ? 1 : m_device->minimumLinearTextureAlignmentForPixelFormat(pixelFormat);
    Size size = 0;
    Extent3D extent = desc.size;

    for (uint32_t i = 0; i < desc.mipCount; ++i)
    {
        Size rowSize =
            ((extent.width + formatInfo.blockWidth - 1) / formatInfo.blockWidth) * formatInfo.blockSizeInBytes;
        rowSize = alignTo(rowSize, alignment);
        Size sliceSize = rowSize * alignTo(extent.height, formatInfo.blockHeight);
        size += sliceSize * extent.depth;
        extent.width = max(1u, extent.width >> 1);
        extent.height = max(1u, extent.height >> 1);
        extent.depth = max(1u, extent.depth >> 1);
    }
    size *= desc.getLayerCount();

    *outSize = size;
    *outAlignment = alignment;

    return SLANG_OK;
}

Result DeviceImpl::getTextureRowAlignment(Format format, Size* outAlignment)
{
    AUTORELEASEPOOL
    if (format == Format::Undefined)
        return SLANG_FAIL;
    const FormatInfo& formatInfo = getFormatInfo(format);
    if (formatInfo.isCompressed)
    {
        *outAlignment = formatInfo.blockSizeInBytes;
    }
    else
    {
        MTL::PixelFormat pixelFormat = translatePixelFormat(format);
        *outAlignment = m_device->minimumLinearTextureAlignmentForPixelFormat(pixelFormat);
    }
    return SLANG_OK;
}

Result DeviceImpl::createShaderProgram(
    const ShaderProgramDesc& desc,
    IShaderProgram** outProgram,
    ISlangBlob** outDiagnosticBlob
)
{
    AUTORELEASEPOOL

    RefPtr<ShaderProgramImpl> shaderProgram = new ShaderProgramImpl(this, desc);
    SLANG_RETURN_ON_FAIL(shaderProgram->init());
    SLANG_RETURN_ON_FAIL(
        RootShaderObjectLayoutImpl::create(
            this,
            shaderProgram->linkedProgram,
            shaderProgram->linkedProgram->getLayout(),
            shaderProgram->m_rootObjectLayout.writeRef()
        )
    );
    returnComPtr(outProgram, shaderProgram);
    return SLANG_OK;
}

Result DeviceImpl::createShaderObjectLayout(
    slang::ISession* session,
    slang::TypeLayoutReflection* typeLayout,
    ShaderObjectLayout** outLayout
)
{
    AUTORELEASEPOOL

    RefPtr<ShaderObjectLayoutImpl> layout;
    SLANG_RETURN_ON_FAIL(ShaderObjectLayoutImpl::createForElementType(this, session, typeLayout, layout.writeRef()));
    returnRefPtrMove(outLayout, layout);
    return SLANG_OK;
}

Result DeviceImpl::createRootShaderObjectLayout(
    slang::IComponentType* program,
    slang::ProgramLayout* programLayout,
    ShaderObjectLayout** outLayout
)
{
    return SLANG_FAIL;
}

Result DeviceImpl::createShaderTable(const ShaderTableDesc& desc, IShaderTable** outShaderTable)
{
    AUTORELEASEPOOL

    return SLANG_E_NOT_IMPLEMENTED;
}

Result DeviceImpl::createQueryPool(const QueryPoolDesc& desc, IQueryPool** outPool)
{
    AUTORELEASEPOOL

    RefPtr<QueryPoolImpl> poolImpl = new QueryPoolImpl(this, desc);
    SLANG_RETURN_ON_FAIL(poolImpl->init());
    returnComPtr(outPool, poolImpl);
    return SLANG_OK;
}

void DeviceImpl::registerResource(MTL::Resource* resource)
{
    SLANG_RHI_ASSERT(resource);
    if (m_hasResidencySet)
    {
        std::lock_guard<std::mutex> lock(m_residencySetMutex);
        uint32_t& refCount = m_residencySetResourceRefCounts[resource];
        if (refCount == 0)
        {
            m_residencySet->addAllocation(resource);
            m_residencySetDirty = true;
        }
        refCount++;
    }
}

void DeviceImpl::unregisterResource(MTL::Resource* resource)
{
    SLANG_RHI_ASSERT(resource);
    if (m_hasResidencySet)
    {
        std::lock_guard<std::mutex> lock(m_residencySetMutex);
        auto it = m_residencySetResourceRefCounts.find(resource);
        SLANG_RHI_ASSERT(it != m_residencySetResourceRefCounts.end());
        if (it == m_residencySetResourceRefCounts.end())
        {
            return;
        }

        SLANG_RHI_ASSERT(it->second > 0);
        if (it->second <= 1)
        {
            m_residencySet->removeAllocation(resource);
            m_residencySetResourceRefCounts.erase(it);
            m_residencySetDirty = true;
        }
        else
        {
            it->second--;
        }
    }
}

} // namespace rhi::metal
