#include "Rendering/Pipelines/BuiltinForwardPipeline.h"

#include "Components/GameObject.h"
#include "Components/MeshFilterComponent.h"
#include "Components/MeshRendererComponent.h"
#include "Debug/Logger.h"
#include "Core/Asset/ResourceManager.h"
#include "RHI/RHICommandList.h"
#include "Rendering/RenderMaterialUtility.h"
#include "Rendering/RenderSurface.h"
#include "Resources/BuiltinResources.h"
#include "Resources/Material/Material.h"
#include "Resources/Shader/Shader.h"
#include "Resources/Texture/Texture.h"

#include <cstddef>

namespace XCEngine {
namespace Rendering {
namespace Pipelines {
namespace Detail {

class BuiltinForwardOpaquePass final : public RenderPass {
public:
    explicit BuiltinForwardOpaquePass(BuiltinForwardPipeline& pipeline)
        : m_pipeline(pipeline) {
    }

    const char* GetName() const override {
        return "BuiltinForwardOpaquePass";
    }

    bool Initialize(const RenderContext& context) override {
        return m_pipeline.EnsureInitialized(context);
    }

    void Shutdown() override {
        m_pipeline.DestroyPipelineResources();
    }

    bool Execute(const RenderPassContext& context) override {
        return m_pipeline.ExecuteForwardOpaquePass(context);
    }

private:
    BuiltinForwardPipeline& m_pipeline;
};

} // namespace Detail

namespace {

constexpr uint32_t kDescriptorFirstSet = 1;
constexpr uint32_t kDescriptorSetCount = 5;

Resources::ShaderBackend ToShaderBackend(RHI::RHIType backendType) {
    switch (backendType) {
    case RHI::RHIType::D3D12:
        return Resources::ShaderBackend::D3D12;
    case RHI::RHIType::Vulkan:
        return Resources::ShaderBackend::Vulkan;
    case RHI::RHIType::OpenGL:
    default:
        return Resources::ShaderBackend::OpenGL;
    }
}

RHI::ShaderLanguage ToRHIShaderLanguage(Resources::ShaderLanguage language) {
    switch (language) {
    case Resources::ShaderLanguage::HLSL:
        return RHI::ShaderLanguage::HLSL;
    case Resources::ShaderLanguage::SPIRV:
        return RHI::ShaderLanguage::SPIRV;
    case Resources::ShaderLanguage::GLSL:
    default:
        return RHI::ShaderLanguage::GLSL;
    }
}

std::wstring ToWideAscii(const Containers::String& value) {
    std::wstring wide;
    wide.reserve(value.Length());
    for (size_t index = 0; index < value.Length(); ++index) {
        wide.push_back(static_cast<wchar_t>(value[index]));
    }
    return wide;
}

bool ShaderPassHasGraphicsVariants(
    const Resources::Shader& shader,
    const Containers::String& passName,
    Resources::ShaderBackend backend) {
    return shader.FindVariant(passName, Resources::ShaderType::Vertex, backend) != nullptr &&
           shader.FindVariant(passName, Resources::ShaderType::Fragment, backend) != nullptr;
}

const Resources::ShaderPass* FindForwardCompatiblePass(
    const Resources::Shader& shader,
    const Resources::Material* material,
    Resources::ShaderBackend backend) {
    if (material != nullptr && !material->GetShaderPass().Empty()) {
        const Resources::ShaderPass* explicitPass = shader.FindPass(material->GetShaderPass());
        if (explicitPass != nullptr &&
            ShaderPassHasGraphicsVariants(shader, explicitPass->name, backend)) {
            return explicitPass;
        }
    }

    for (const Resources::ShaderPass& shaderPass : shader.GetPasses()) {
        if (ShaderPassMatchesBuiltinPass(shaderPass, BuiltinMaterialPass::ForwardLit) &&
            ShaderPassHasGraphicsVariants(shader, shaderPass.name, backend)) {
            return &shaderPass;
        }
    }

    const Resources::ShaderPass* defaultPass = shader.FindPass("ForwardLit");
    if (defaultPass != nullptr &&
        ShaderPassHasGraphicsVariants(shader, defaultPass->name, backend)) {
        return defaultPass;
    }

    defaultPass = shader.FindPass("Default");
    if (defaultPass != nullptr &&
        ShaderPassHasGraphicsVariants(shader, defaultPass->name, backend)) {
        return defaultPass;
    }

    if (shader.GetPassCount() > 0 &&
        ShaderPassHasGraphicsVariants(shader, shader.GetPasses()[0].name, backend)) {
        return &shader.GetPasses()[0];
    }

    return nullptr;
}

void ApplyShaderStageVariant(
    const Resources::ShaderStageVariant& variant,
    RHI::ShaderCompileDesc& compileDesc) {
    compileDesc.source.assign(
        variant.sourceCode.CStr(),
        variant.sourceCode.CStr() + variant.sourceCode.Length());
    compileDesc.sourceLanguage = ToRHIShaderLanguage(variant.language);
    compileDesc.entryPoint = ToWideAscii(variant.entryPoint);
    compileDesc.profile = ToWideAscii(variant.profile);
}

RHI::GraphicsPipelineDesc CreatePipelineDesc(
    RHI::RHIType backendType,
    RHI::RHIPipelineLayout* pipelineLayout,
    const Resources::Shader& shader,
    const Containers::String& passName,
    const Resources::Material* material) {
    RHI::GraphicsPipelineDesc pipelineDesc = {};
    pipelineDesc.pipelineLayout = pipelineLayout;
    pipelineDesc.topologyType = static_cast<uint32_t>(RHI::PrimitiveTopologyType::Triangle);
    pipelineDesc.renderTargetCount = 1;
    pipelineDesc.renderTargetFormats[0] = static_cast<uint32_t>(RHI::Format::R8G8B8A8_UNorm);
    pipelineDesc.depthStencilFormat = static_cast<uint32_t>(RHI::Format::D24_UNorm_S8_UInt);
    pipelineDesc.sampleCount = 1;
    ApplyMaterialRenderState(material, pipelineDesc);

    pipelineDesc.inputLayout = BuiltinForwardPipeline::BuildInputLayout();

    const Resources::ShaderBackend backend = ToShaderBackend(backendType);
    const Resources::ShaderStageVariant* vertexVariant =
        shader.FindVariant(passName, Resources::ShaderType::Vertex, backend);
    const Resources::ShaderStageVariant* fragmentVariant =
        shader.FindVariant(passName, Resources::ShaderType::Fragment, backend);
    if (vertexVariant != nullptr) {
        ApplyShaderStageVariant(*vertexVariant, pipelineDesc.vertexShader);
    }
    if (fragmentVariant != nullptr) {
        ApplyShaderStageVariant(*fragmentVariant, pipelineDesc.fragmentShader);
    }

    return pipelineDesc;
}

} // namespace

BuiltinForwardPipeline::BuiltinForwardPipeline() {
    m_passSequence.AddPass(std::make_unique<Detail::BuiltinForwardOpaquePass>(*this));
}

BuiltinForwardPipeline::~BuiltinForwardPipeline() {
    Shutdown();
}

std::unique_ptr<RenderPipeline> BuiltinForwardPipelineAsset::CreatePipeline() const {
    return std::make_unique<BuiltinForwardPipeline>();
}

RHI::InputLayoutDesc BuiltinForwardPipeline::BuildInputLayout() {
    RHI::InputLayoutDesc inputLayout = {};

    RHI::InputElementDesc position = {};
    position.semanticName = "POSITION";
    position.semanticIndex = 0;
    position.format = static_cast<uint32_t>(RHI::Format::R32G32B32_Float);
    position.inputSlot = 0;
    position.alignedByteOffset = 0;
    inputLayout.elements.push_back(position);

    RHI::InputElementDesc normal = {};
    normal.semanticName = "NORMAL";
    normal.semanticIndex = 0;
    normal.format = static_cast<uint32_t>(RHI::Format::R32G32B32_Float);
    normal.inputSlot = 0;
    normal.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, normal));
    inputLayout.elements.push_back(normal);

    RHI::InputElementDesc texcoord = {};
    texcoord.semanticName = "TEXCOORD";
    texcoord.semanticIndex = 0;
    texcoord.format = static_cast<uint32_t>(RHI::Format::R32G32_Float);
    texcoord.inputSlot = 0;
    texcoord.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, uv0));
    inputLayout.elements.push_back(texcoord);

    return inputLayout;
}

bool BuiltinForwardPipeline::Initialize(const RenderContext& context) {
    return m_passSequence.Initialize(context);
}

void BuiltinForwardPipeline::Shutdown() {
    m_passSequence.Shutdown();
}

bool BuiltinForwardPipeline::Render(
    const RenderContext& context,
    const RenderSurface& surface,
    const RenderSceneData& sceneData) {
    if (!Initialize(context)) {
        return false;
    }

    const RenderPassContext passContext = {
        context,
        surface,
        sceneData
    };

    return m_passSequence.Execute(passContext);
}

bool BuiltinForwardPipeline::ExecuteForwardOpaquePass(const RenderPassContext& passContext) {
    const RenderContext& context = passContext.renderContext;
    const RenderSurface& surface = passContext.surface;
    const RenderSceneData& sceneData = passContext.sceneData;

    const std::vector<RHI::RHIResourceView*>& colorAttachments = surface.GetColorAttachments();
    if (colorAttachments.empty()) {
        return false;
    }

    std::vector<RHI::RHIResourceView*> renderTargets = colorAttachments;
    RHI::RHICommandList* commandList = context.commandList;

    if (surface.IsAutoTransitionEnabled()) {
        for (RHI::RHIResourceView* renderTarget : renderTargets) {
            if (renderTarget != nullptr) {
                commandList->TransitionBarrier(
                    renderTarget,
                    surface.GetColorStateBefore(),
                    RHI::ResourceStates::RenderTarget);
            }
        }
    }

    commandList->SetRenderTargets(
        static_cast<uint32_t>(renderTargets.size()),
        renderTargets.data(),
        surface.GetDepthAttachment());

    const Math::RectInt renderArea = surface.GetRenderArea();
    if (renderArea.width <= 0 || renderArea.height <= 0) {
        return false;
    }

    const RHI::Viewport viewport = {
        static_cast<float>(renderArea.x),
        static_cast<float>(renderArea.y),
        static_cast<float>(renderArea.width),
        static_cast<float>(renderArea.height),
        0.0f,
        1.0f
    };
    const RHI::Rect scissorRect = {
        renderArea.x,
        renderArea.y,
        renderArea.x + renderArea.width,
        renderArea.y + renderArea.height
    };
    const RHI::Rect clearRects[] = { scissorRect };
    commandList->SetViewport(viewport);
    commandList->SetScissorRect(scissorRect);

    const Math::Color clearColor = surface.HasClearColorOverride()
        ? surface.GetClearColorOverride()
        : sceneData.cameraData.clearColor;
    const float clearValues[4] = { clearColor.r, clearColor.g, clearColor.b, clearColor.a };
    if (HasRenderClearFlag(sceneData.cameraData.clearFlags, RenderClearFlags::Color)) {
        for (RHI::RHIResourceView* renderTarget : renderTargets) {
            if (renderTarget != nullptr) {
                commandList->ClearRenderTarget(renderTarget, clearValues, 1, clearRects);
            }
        }
    }
    if (surface.GetDepthAttachment() != nullptr &&
        HasRenderClearFlag(sceneData.cameraData.clearFlags, RenderClearFlags::Depth)) {
        commandList->ClearDepthStencil(surface.GetDepthAttachment(), 1.0f, 0, 1, clearRects);
    }

    commandList->SetPrimitiveTopology(RHI::PrimitiveTopology::TriangleList);

    RHI::RHIPipelineState* currentPipelineState = nullptr;
    for (const VisibleRenderItem& visibleItem : sceneData.visibleItems) {
        const Resources::Material* material = ResolveMaterial(visibleItem);
        if (!MatchesBuiltinPass(material, BuiltinMaterialPass::ForwardLit)) {
            continue;
        }

        RHI::RHIPipelineState* pipelineState = GetOrCreatePipelineState(context, material);
        if (pipelineState == nullptr) {
            continue;
        }
        if (pipelineState != currentPipelineState) {
            commandList->SetPipelineState(pipelineState);
            currentPipelineState = pipelineState;
        }

        DrawVisibleItem(context, sceneData, visibleItem);
    }

    if (surface.IsAutoTransitionEnabled()) {
        for (RHI::RHIResourceView* renderTarget : renderTargets) {
            if (renderTarget != nullptr) {
                commandList->TransitionBarrier(
                    renderTarget,
                    RHI::ResourceStates::RenderTarget,
                    surface.GetColorStateAfter());
            }
        }
    }

    return true;
}

bool BuiltinForwardPipeline::EnsureInitialized(const RenderContext& context) {
    if (!context.IsValid()) {
        return false;
    }

    if (m_initialized &&
        m_device == context.device &&
        m_backendType == context.backendType) {
        return true;
    }

    DestroyPipelineResources();
    m_device = context.device;
    m_backendType = context.backendType;
    m_initialized = CreatePipelineResources(context);
    return m_initialized;
}

bool BuiltinForwardPipeline::CreatePipelineResources(const RenderContext& context) {
    m_builtinForwardShader = Resources::ResourceManager::Get().Load<Resources::Shader>(
        Resources::GetBuiltinForwardLitShaderPath());
    if (!m_builtinForwardShader.IsValid()) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline failed to load builtin forward shader resource");
        return false;
    }

    RHI::DescriptorSetLayoutBinding constantBinding = {};
    constantBinding.binding = 0;
    constantBinding.type = static_cast<uint32_t>(RHI::DescriptorType::CBV);
    constantBinding.count = 1;

    RHI::DescriptorSetLayoutDesc constantLayout = {};
    constantLayout.bindings = &constantBinding;
    constantLayout.bindingCount = 1;

    RHI::DescriptorSetLayoutDesc materialConstantLayout = {};
    materialConstantLayout.bindings = &constantBinding;
    materialConstantLayout.bindingCount = 1;

    RHI::DescriptorSetLayoutBinding textureBinding = {};
    textureBinding.binding = 0;
    textureBinding.type = static_cast<uint32_t>(RHI::DescriptorType::SRV);
    textureBinding.count = 1;

    RHI::DescriptorSetLayoutDesc textureLayout = {};
    textureLayout.bindings = &textureBinding;
    textureLayout.bindingCount = 1;

    RHI::DescriptorPoolDesc samplerPoolDesc = {};
    samplerPoolDesc.type = RHI::DescriptorHeapType::Sampler;
    samplerPoolDesc.descriptorCount = 1;
    samplerPoolDesc.shaderVisible = true;
    m_samplerPool = context.device->CreateDescriptorPool(samplerPoolDesc);
    if (m_samplerPool == nullptr) {
        return false;
    }

    RHI::DescriptorSetLayoutBinding samplerBinding = {};
    samplerBinding.binding = 0;
    samplerBinding.type = static_cast<uint32_t>(RHI::DescriptorType::Sampler);
    samplerBinding.count = 1;

    RHI::DescriptorSetLayoutDesc samplerLayout = {};
    samplerLayout.bindings = &samplerBinding;
    samplerLayout.bindingCount = 1;
    m_samplerSet = m_samplerPool->AllocateSet(samplerLayout);
    if (m_samplerSet == nullptr) {
        return false;
    }

    RHI::DescriptorSetLayoutBinding reservedBindings[3] = {};
    reservedBindings[0].binding = 0;
    reservedBindings[0].type = static_cast<uint32_t>(RHI::DescriptorType::CBV);
    reservedBindings[0].count = 1;
    reservedBindings[1].binding = 0;
    reservedBindings[1].type = static_cast<uint32_t>(RHI::DescriptorType::SRV);
    reservedBindings[1].count = 1;
    reservedBindings[2].binding = 0;
    reservedBindings[2].type = static_cast<uint32_t>(RHI::DescriptorType::Sampler);
    reservedBindings[2].count = 1;

    RHI::DescriptorSetLayoutDesc reservedLayout = {};
    reservedLayout.bindings = reservedBindings;
    reservedLayout.bindingCount = 3;

    RHI::DescriptorSetLayoutDesc setLayouts[kDescriptorSetCount] = {};
    setLayouts[0] = reservedLayout;
    setLayouts[1] = constantLayout;
    setLayouts[2] = materialConstantLayout;
    setLayouts[3] = textureLayout;
    setLayouts[4] = samplerLayout;

    RHI::RHIPipelineLayoutDesc pipelineLayoutDesc = {};
    pipelineLayoutDesc.setLayouts = setLayouts;
    pipelineLayoutDesc.setLayoutCount = kDescriptorSetCount;
    m_pipelineLayout = context.device->CreatePipelineLayout(pipelineLayoutDesc);
    if (m_pipelineLayout == nullptr) {
        return false;
    }

    RHI::SamplerDesc samplerDesc = {};
    samplerDesc.filter = static_cast<uint32_t>(RHI::FilterMode::Linear);
    samplerDesc.addressU = static_cast<uint32_t>(RHI::TextureAddressMode::Clamp);
    samplerDesc.addressV = static_cast<uint32_t>(RHI::TextureAddressMode::Clamp);
    samplerDesc.addressW = static_cast<uint32_t>(RHI::TextureAddressMode::Clamp);
    samplerDesc.mipLodBias = 0.0f;
    samplerDesc.maxAnisotropy = 1;
    samplerDesc.comparisonFunc = static_cast<uint32_t>(RHI::ComparisonFunc::Always);
    samplerDesc.minLod = 0.0f;
    samplerDesc.maxLod = 1000.0f;
    m_sampler = context.device->CreateSampler(samplerDesc);
    if (m_sampler == nullptr) {
        return false;
    }
    m_samplerSet->UpdateSampler(0, m_sampler);

    const unsigned char whitePixel[4] = { 255, 255, 255, 255 };
    RHI::TextureDesc textureDesc = {};
    textureDesc.width = 1;
    textureDesc.height = 1;
    textureDesc.depth = 1;
    textureDesc.mipLevels = 1;
    textureDesc.arraySize = 1;
    textureDesc.format = static_cast<uint32_t>(RHI::Format::R8G8B8A8_UNorm);
    textureDesc.textureType = static_cast<uint32_t>(RHI::TextureType::Texture2D);
    textureDesc.sampleCount = 1;
    textureDesc.sampleQuality = 0;
    textureDesc.flags = 0;
    m_fallbackTexture = context.device->CreateTexture(textureDesc, whitePixel, sizeof(whitePixel), 4);
    if (m_fallbackTexture == nullptr) {
        return false;
    }

    RHI::ResourceViewDesc textureViewDesc = {};
    textureViewDesc.format = static_cast<uint32_t>(RHI::Format::R8G8B8A8_UNorm);
    textureViewDesc.dimension = RHI::ResourceViewDimension::Texture2D;
    textureViewDesc.mipLevel = 0;
    m_fallbackTextureView = context.device->CreateShaderResourceView(m_fallbackTexture, textureViewDesc);
    if (m_fallbackTextureView == nullptr) {
        return false;
    }

    return true;
}

void BuiltinForwardPipeline::DestroyPipelineResources() {
    m_resourceCache.Shutdown();

    for (auto& pipelinePair : m_pipelineStates) {
        if (pipelinePair.second != nullptr) {
            pipelinePair.second->Shutdown();
            delete pipelinePair.second;
        }
    }
    m_pipelineStates.clear();

    for (auto& perObjectSetPair : m_perObjectSets) {
        DestroyOwnedDescriptorSet(perObjectSetPair.second);
    }
    m_perObjectSets.clear();

    for (auto& materialBindingPair : m_materialBindings) {
        DestroyOwnedDescriptorSet(materialBindingPair.second.constantSet);
        DestroyOwnedDescriptorSet(materialBindingPair.second.textureSet);
    }
    m_materialBindings.clear();

    if (m_fallbackTextureView != nullptr) {
        m_fallbackTextureView->Shutdown();
        delete m_fallbackTextureView;
        m_fallbackTextureView = nullptr;
    }

    if (m_fallbackTexture != nullptr) {
        m_fallbackTexture->Shutdown();
        delete m_fallbackTexture;
        m_fallbackTexture = nullptr;
    }

    if (m_sampler != nullptr) {
        m_sampler->Shutdown();
        delete m_sampler;
        m_sampler = nullptr;
    }

    if (m_pipelineLayout != nullptr) {
        m_pipelineLayout->Shutdown();
        delete m_pipelineLayout;
        m_pipelineLayout = nullptr;
    }

    if (m_samplerSet != nullptr) {
        m_samplerSet->Shutdown();
        delete m_samplerSet;
        m_samplerSet = nullptr;
    }

    if (m_samplerPool != nullptr) {
        m_samplerPool->Shutdown();
        delete m_samplerPool;
        m_samplerPool = nullptr;
    }

    m_device = nullptr;
    m_initialized = false;
    m_builtinForwardShader.Reset();
}

BuiltinForwardPipeline::ResolvedShaderPass BuiltinForwardPipeline::ResolveForwardShaderPass(
    const Resources::Material* material) const {
    ResolvedShaderPass resolved = {};
    const Resources::ShaderBackend backend = ToShaderBackend(m_backendType);

    if (material != nullptr && material->GetShader() != nullptr) {
        const Resources::Shader* materialShader = material->GetShader();
        if (const Resources::ShaderPass* shaderPass =
                FindForwardCompatiblePass(*materialShader, material, backend)) {
            resolved.shader = materialShader;
            resolved.pass = shaderPass;
            resolved.passName = shaderPass->name;
            return resolved;
        }
    }

    if (m_builtinForwardShader.IsValid()) {
        const Resources::Shader* builtinShader = m_builtinForwardShader.Get();
        if (const Resources::ShaderPass* shaderPass =
                FindForwardCompatiblePass(*builtinShader, nullptr, backend)) {
            resolved.shader = builtinShader;
            resolved.pass = shaderPass;
            resolved.passName = shaderPass->name;
        }
    }

    return resolved;
}

RHI::RHIPipelineState* BuiltinForwardPipeline::GetOrCreatePipelineState(
    const RenderContext& context,
    const Resources::Material* material) {
    const ResolvedShaderPass resolvedShaderPass = ResolveForwardShaderPass(material);
    if (resolvedShaderPass.shader == nullptr || resolvedShaderPass.pass == nullptr) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline could not resolve a valid ForwardLit shader pass");
        return nullptr;
    }

    PipelineStateKey pipelineKey = {};
    pipelineKey.renderState =
        material != nullptr ? material->GetRenderState() : Resources::MaterialRenderState();
    pipelineKey.shader = resolvedShaderPass.shader;
    pipelineKey.passName = resolvedShaderPass.passName;

    const auto existing = m_pipelineStates.find(pipelineKey);
    if (existing != m_pipelineStates.end()) {
        return existing->second;
    }

    const RHI::GraphicsPipelineDesc pipelineDesc =
        CreatePipelineDesc(
            context.backendType,
            m_pipelineLayout,
            *resolvedShaderPass.shader,
            resolvedShaderPass.passName,
            material);
    RHI::RHIPipelineState* pipelineState = context.device->CreatePipelineState(pipelineDesc);
    if (pipelineState == nullptr || !pipelineState->IsValid()) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline failed to create pipeline state");
        if (pipelineState != nullptr) {
            pipelineState->Shutdown();
            delete pipelineState;
        }
        return nullptr;
    }

    m_pipelineStates.emplace(pipelineKey, pipelineState);
    return pipelineState;
}

RHI::RHIDescriptorSet* BuiltinForwardPipeline::GetOrCreatePerObjectSet(Core::uint64 objectId) {
    const auto existing = m_perObjectSets.find(objectId);
    if (existing != m_perObjectSets.end()) {
        return existing->second.set;
    }

    RHI::DescriptorPoolDesc poolDesc = {};
    poolDesc.type = RHI::DescriptorHeapType::CBV_SRV_UAV;
    poolDesc.descriptorCount = 1;
    poolDesc.shaderVisible = false;

    OwnedDescriptorSet descriptorSet = {};
    descriptorSet.pool = m_device->CreateDescriptorPool(poolDesc);
    if (descriptorSet.pool == nullptr) {
        return nullptr;
    }

    RHI::DescriptorSetLayoutBinding binding = {};
    binding.binding = 0;
    binding.type = static_cast<uint32_t>(RHI::DescriptorType::CBV);
    binding.count = 1;

    RHI::DescriptorSetLayoutDesc layout = {};
    layout.bindings = &binding;
    layout.bindingCount = 1;
    descriptorSet.set = descriptorSet.pool->AllocateSet(layout);
    if (descriptorSet.set == nullptr) {
        DestroyOwnedDescriptorSet(descriptorSet);
        return nullptr;
    }

    const auto result = m_perObjectSets.emplace(objectId, descriptorSet);
    return result.first->second.set;
}

BuiltinForwardPipeline::CachedMaterialBindings* BuiltinForwardPipeline::GetOrCreateMaterialBindings(
    const Resources::Material* material,
    RHI::RHIResourceView* textureView) {
    if (textureView == nullptr) {
        return nullptr;
    }

    CachedMaterialBindings& cachedBindings = m_materialBindings[material];

    if (cachedBindings.constantSet.set == nullptr) {
        RHI::DescriptorPoolDesc constantPoolDesc = {};
        constantPoolDesc.type = RHI::DescriptorHeapType::CBV_SRV_UAV;
        constantPoolDesc.descriptorCount = 1;
        constantPoolDesc.shaderVisible = false;

        cachedBindings.constantSet.pool = m_device->CreateDescriptorPool(constantPoolDesc);
        if (cachedBindings.constantSet.pool == nullptr) {
            return nullptr;
        }

        RHI::DescriptorSetLayoutBinding constantBinding = {};
        constantBinding.binding = 0;
        constantBinding.type = static_cast<uint32_t>(RHI::DescriptorType::CBV);
        constantBinding.count = 1;

        RHI::DescriptorSetLayoutDesc constantLayout = {};
        constantLayout.bindings = &constantBinding;
        constantLayout.bindingCount = 1;
        cachedBindings.constantSet.set = cachedBindings.constantSet.pool->AllocateSet(constantLayout);
        if (cachedBindings.constantSet.set == nullptr) {
            DestroyOwnedDescriptorSet(cachedBindings.constantSet);
            return nullptr;
        }
    }

    if (cachedBindings.textureSet.set == nullptr) {
        RHI::DescriptorPoolDesc texturePoolDesc = {};
        texturePoolDesc.type = RHI::DescriptorHeapType::CBV_SRV_UAV;
        texturePoolDesc.descriptorCount = 1;
        texturePoolDesc.shaderVisible = true;

        cachedBindings.textureSet.pool = m_device->CreateDescriptorPool(texturePoolDesc);
        if (cachedBindings.textureSet.pool == nullptr) {
            DestroyOwnedDescriptorSet(cachedBindings.constantSet);
            return nullptr;
        }

        RHI::DescriptorSetLayoutBinding textureBinding = {};
        textureBinding.binding = 0;
        textureBinding.type = static_cast<uint32_t>(RHI::DescriptorType::SRV);
        textureBinding.count = 1;

        RHI::DescriptorSetLayoutDesc textureLayout = {};
        textureLayout.bindings = &textureBinding;
        textureLayout.bindingCount = 1;
        cachedBindings.textureSet.set = cachedBindings.textureSet.pool->AllocateSet(textureLayout);
        if (cachedBindings.textureSet.set == nullptr) {
            DestroyOwnedDescriptorSet(cachedBindings.textureSet);
            return nullptr;
        }
    }

    const Core::uint64 materialVersion = material != nullptr ? material->GetChangeVersion() : 0;
    if (cachedBindings.materialVersion != materialVersion || cachedBindings.textureView != textureView) {
        const BuiltinForwardMaterialData materialData = BuildBuiltinForwardMaterialData(material);
        const PerMaterialConstants materialConstants = {
            materialData.baseColorFactor
        };

        cachedBindings.constantSet.set->WriteConstant(0, &materialConstants, sizeof(materialConstants));
        cachedBindings.textureSet.set->Update(0, textureView);
        cachedBindings.materialVersion = materialVersion;
        cachedBindings.textureView = textureView;
    }

    return &cachedBindings;
}

void BuiltinForwardPipeline::DestroyOwnedDescriptorSet(OwnedDescriptorSet& descriptorSet) {
    if (descriptorSet.set != nullptr) {
        descriptorSet.set->Shutdown();
        delete descriptorSet.set;
        descriptorSet.set = nullptr;
    }

    if (descriptorSet.pool != nullptr) {
        descriptorSet.pool->Shutdown();
        delete descriptorSet.pool;
        descriptorSet.pool = nullptr;
    }
}

const Resources::Texture* BuiltinForwardPipeline::ResolveTexture(const Resources::Material* material) const {
    return ResolveBuiltinBaseColorTexture(material);
}

RHI::RHIResourceView* BuiltinForwardPipeline::ResolveTextureView(
    const VisibleRenderItem& visibleItem) {
    const Resources::Material* material = ResolveMaterial(visibleItem);
    const Resources::Texture* texture = ResolveTexture(material);
    if (texture != nullptr) {
        const RenderResourceCache::CachedTexture* cachedTexture = m_resourceCache.GetOrCreateTexture(m_device, texture);
        if (cachedTexture != nullptr && cachedTexture->shaderResourceView != nullptr) {
            return cachedTexture->shaderResourceView;
        }
    }

    return m_fallbackTextureView;
}

bool BuiltinForwardPipeline::DrawVisibleItem(
    const RenderContext& context,
    const RenderSceneData& sceneData,
    const VisibleRenderItem& visibleItem) {
    const RenderResourceCache::CachedMesh* cachedMesh = m_resourceCache.GetOrCreateMesh(m_device, visibleItem.mesh);
    if (cachedMesh == nullptr || cachedMesh->vertexBufferView == nullptr) {
        return false;
    }

    RHI::RHICommandList* commandList = context.commandList;

    RHI::RHIResourceView* vertexBuffers[] = { cachedMesh->vertexBufferView };
    const uint64_t offsets[] = { 0 };
    const uint32_t strides[] = { cachedMesh->vertexStride };
    commandList->SetVertexBuffers(0, 1, vertexBuffers, offsets, strides);
    if (cachedMesh->indexBufferView != nullptr) {
        commandList->SetIndexBuffer(cachedMesh->indexBufferView, 0);
    }

    const PerObjectConstants constants = {
        sceneData.cameraData.projection,
        sceneData.cameraData.view,
        visibleItem.localToWorld.Transpose(),
        visibleItem.localToWorld.Inverse(),
        sceneData.lighting.HasMainDirectionalLight()
            ? Math::Vector4(
                sceneData.lighting.mainDirectionalLight.direction.x,
                sceneData.lighting.mainDirectionalLight.direction.y,
                sceneData.lighting.mainDirectionalLight.direction.z,
                sceneData.lighting.mainDirectionalLight.intensity)
            : Math::Vector4::Zero(),
        sceneData.lighting.HasMainDirectionalLight()
            ? Math::Vector4(
                sceneData.lighting.mainDirectionalLight.color.r,
                sceneData.lighting.mainDirectionalLight.color.g,
                sceneData.lighting.mainDirectionalLight.color.b,
                1.0f)
            : Math::Vector4::Zero()
    };

    RHI::RHIResourceView* textureView = ResolveTextureView(visibleItem);
    if (textureView == nullptr) {
        return false;
    }

    const Resources::Material* material = ResolveMaterial(visibleItem);
    RHI::RHIDescriptorSet* constantSet = GetOrCreatePerObjectSet(
        visibleItem.gameObject != nullptr ? visibleItem.gameObject->GetID() : 0);
    CachedMaterialBindings* materialBindings = GetOrCreateMaterialBindings(material, textureView);
    if (constantSet == nullptr ||
        materialBindings == nullptr ||
        materialBindings->constantSet.set == nullptr ||
        materialBindings->textureSet.set == nullptr ||
        m_samplerSet == nullptr) {
        return false;
    }

    constantSet->WriteConstant(0, &constants, sizeof(constants));
    RHI::RHIDescriptorSet* descriptorSets[] = {
        constantSet,
        materialBindings->constantSet.set,
        materialBindings->textureSet.set,
        m_samplerSet
    };
    commandList->SetGraphicsDescriptorSets(kDescriptorFirstSet, 4, descriptorSets, m_pipelineLayout);

    if (visibleItem.hasSection) {
        const Containers::Array<Resources::MeshSection>& sections = visibleItem.mesh->GetSections();
        if (visibleItem.sectionIndex >= sections.Size()) {
            return false;
        }

        const Resources::MeshSection& section = sections[visibleItem.sectionIndex];
        if (cachedMesh->indexBufferView != nullptr && section.indexCount > 0) {
            // MeshLoader flattens section indices into a single global index buffer.
            commandList->DrawIndexed(section.indexCount, 1, section.startIndex, 0, 0);
        } else if (section.vertexCount > 0) {
            commandList->Draw(section.vertexCount, 1, section.baseVertex, 0);
        }

        return true;
    }

    if (cachedMesh->indexBufferView != nullptr && cachedMesh->indexCount > 0) {
        commandList->DrawIndexed(cachedMesh->indexCount, 1, 0, 0, 0);
    } else if (cachedMesh->vertexCount > 0) {
        commandList->Draw(cachedMesh->vertexCount, 1, 0, 0);
    }

    return true;
}

} // namespace Pipelines
} // namespace Rendering
} // namespace XCEngine