#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/Detail/ShaderVariantUtils.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 <algorithm>
#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 {

bool TryResolveSurfacePassType(
    const Resources::Material* material,
    BuiltinMaterialPass& outPass) {
    if (MatchesBuiltinPass(material, BuiltinMaterialPass::Unlit)) {
        outPass = BuiltinMaterialPass::Unlit;
        return true;
    }

    if (MatchesBuiltinPass(material, BuiltinMaterialPass::ForwardLit)) {
        outPass = BuiltinMaterialPass::ForwardLit;
        return true;
    }

    return false;
}

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

    for (const Resources::ShaderPass& shaderPass : shader.GetPasses()) {
        if (ShaderPassMatchesBuiltinPass(shaderPass, pass) &&
            ::XCEngine::Rendering::Detail::ShaderPassHasGraphicsVariants(shader, shaderPass.name, backend)) {
            return &shaderPass;
        }
    }

    if (pass != BuiltinMaterialPass::ForwardLit) {
        return nullptr;
    }

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

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

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

    return nullptr;
}

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 = ::XCEngine::Rendering::Detail::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) {
        ::XCEngine::Rendering::Detail::ApplyShaderStageVariant(*vertexVariant, pipelineDesc.vertexShader);
    }
    if (fragmentVariant != nullptr) {
        ::XCEngine::Rendering::Detail::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);

    if (sceneData.lighting.HasMainDirectionalShadow()) {
        commandList->TransitionBarrier(
            sceneData.lighting.mainDirectionalShadow.shadowMap,
            RHI::ResourceStates::DepthWrite,
            RHI::ResourceStates::PixelShaderResource);
    }

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

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

        DrawVisibleItem(context, sceneData, visibleItem);
    }

    if (sceneData.lighting.HasMainDirectionalShadow()) {
        commandList->TransitionBarrier(
            sceneData.lighting.mainDirectionalShadow.shadowMap,
            RHI::ResourceStates::PixelShaderResource,
            RHI::ResourceStates::DepthWrite);
    }

    if (surface.IsAutoTransitionEnabled()) {
        commandList->EndRenderPass();
        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;
    }

    m_builtinUnlitShader = Resources::ResourceManager::Get().Load<Resources::Shader>(
        Resources::GetBuiltinUnlitShaderPath());
    if (!m_builtinUnlitShader.IsValid()) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline failed to load builtin unlit shader resource");
        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;
    }

    RHI::SamplerDesc shadowSamplerDesc = samplerDesc;
    shadowSamplerDesc.filter = static_cast<uint32_t>(RHI::FilterMode::Point);
    m_shadowSampler = context.device->CreateSampler(shadowSamplerDesc);
    if (m_shadowSampler == nullptr) {
        return false;
    }

    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& descriptorSetPair : m_dynamicDescriptorSets) {
        DestroyOwnedDescriptorSet(descriptorSetPair.second.descriptorSet);
    }
    m_dynamicDescriptorSets.clear();

    for (auto& passLayoutPair : m_passResourceLayouts) {
        DestroyPassResourceLayout(passLayoutPair.second);
    }
    m_passResourceLayouts.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_shadowSampler != nullptr) {
        m_shadowSampler->Shutdown();
        delete m_shadowSampler;
        m_shadowSampler = nullptr;
    }

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

BuiltinForwardPipeline::ResolvedShaderPass BuiltinForwardPipeline::ResolveSurfaceShaderPass(
    const Resources::Material* material) const {
    ResolvedShaderPass resolved = {};
    BuiltinMaterialPass pass = BuiltinMaterialPass::ForwardLit;
    if (!TryResolveSurfacePassType(material, pass)) {
        return resolved;
    }

    const Resources::ShaderBackend backend = ::XCEngine::Rendering::Detail::ToShaderBackend(m_backendType);

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

    const Resources::ResourceHandle<Resources::Shader>* builtinShaderHandle =
        pass == BuiltinMaterialPass::Unlit ? &m_builtinUnlitShader : &m_builtinForwardShader;
    if (builtinShaderHandle->IsValid()) {
        const Resources::Shader* builtinShader = builtinShaderHandle->Get();
        if (const Resources::ShaderPass* shaderPass =
                FindCompatibleSurfacePass(*builtinShader, nullptr, pass, backend)) {
            resolved.shader = builtinShader;
            resolved.pass = shaderPass;
            resolved.passName = shaderPass->name;
        }
    }

    return resolved;
}

BuiltinForwardPipeline::PassResourceLayout* BuiltinForwardPipeline::GetOrCreatePassResourceLayout(
    const RenderContext& context,
    const ResolvedShaderPass& resolvedShaderPass) {
    if (resolvedShaderPass.shader == nullptr || resolvedShaderPass.pass == nullptr) {
        return nullptr;
    }

    PassLayoutKey passLayoutKey = {};
    passLayoutKey.shader = resolvedShaderPass.shader;
    passLayoutKey.passName = resolvedShaderPass.passName;

    const auto existing = m_passResourceLayouts.find(passLayoutKey);
    if (existing != m_passResourceLayouts.end()) {
        return &existing->second;
    }

    PassResourceLayout passLayout = {};
    auto failLayout = [this, &passLayout](const char* message) -> PassResourceLayout* {
        Debug::Logger::Get().Error(Debug::LogCategory::Rendering, message);
        DestroyPassResourceLayout(passLayout);
        return nullptr;
    };

    Containers::Array<Resources::ShaderResourceBindingDesc> resourceBindings = resolvedShaderPass.pass->resources;
    if (resourceBindings.Empty()) {
        resourceBindings = BuildLegacyBuiltinForwardPassResourceBindings();
    }

    BuiltinPassResourceBindingPlan bindingPlan = {};
    Containers::String bindingPlanError;
    if (!TryBuildBuiltinPassResourceBindingPlan(resourceBindings, bindingPlan, &bindingPlanError)) {
        return failLayout(bindingPlanError.CStr());
    }

    const bool hasAnyResource = !bindingPlan.bindings.Empty();
    if (hasAnyResource) {
        Containers::String setLayoutError;
        if (!TryBuildBuiltinPassSetLayouts(bindingPlan, passLayout.setLayouts, &setLayoutError)) {
            return failLayout(setLayoutError.CStr());
        }
        passLayout.staticDescriptorSets.resize(passLayout.setLayouts.size());
        passLayout.firstDescriptorSet = bindingPlan.firstDescriptorSet;
        passLayout.descriptorSetCount = bindingPlan.descriptorSetCount;
    }

    passLayout.perObject = bindingPlan.perObject;
    passLayout.material = bindingPlan.material;
    passLayout.shadowReceiver = bindingPlan.shadowReceiver;
    passLayout.baseColorTexture = bindingPlan.baseColorTexture;
    passLayout.linearClampSampler = bindingPlan.linearClampSampler;
    passLayout.shadowMapTexture = bindingPlan.shadowMapTexture;
    passLayout.shadowMapSampler = bindingPlan.shadowMapSampler;

    if (!passLayout.perObject.IsValid()) {
        return failLayout("BuiltinForwardPipeline requires a PerObject resource binding");
    }

    if (hasAnyResource &&
        passLayout.firstDescriptorSet > 0 &&
        !passLayout.setLayouts.empty() &&
        passLayout.setLayouts[0].bindings.empty()) {
        BuiltinPassSetLayoutMetadata& compatibilitySet = passLayout.setLayouts[0];
        if (bindingPlan.usesConstantBuffers) {
            compatibilitySet.bindings.push_back({
                0,
                static_cast<uint32_t>(RHI::DescriptorType::CBV),
                1,
                0
            });
        }
        if (bindingPlan.usesTextures) {
            compatibilitySet.bindings.push_back({
                0,
                static_cast<uint32_t>(RHI::DescriptorType::SRV),
                1,
                0
            });
        }
        if (bindingPlan.usesSamplers) {
            compatibilitySet.bindings.push_back({
                0,
                static_cast<uint32_t>(RHI::DescriptorType::Sampler),
                1,
                0
            });
        }
        RefreshBuiltinPassSetLayoutMetadata(compatibilitySet);
    }

    std::vector<RHI::DescriptorSetLayoutDesc> nativeSetLayouts(passLayout.setLayouts.size());
    for (size_t i = 0; i < passLayout.setLayouts.size(); ++i) {
        nativeSetLayouts[i] = passLayout.setLayouts[i].layout;
    }

    RHI::RHIPipelineLayoutDesc pipelineLayoutDesc = {};
    pipelineLayoutDesc.setLayouts = nativeSetLayouts.empty() ? nullptr : nativeSetLayouts.data();
    pipelineLayoutDesc.setLayoutCount = static_cast<uint32_t>(nativeSetLayouts.size());
    passLayout.pipelineLayout = context.device->CreatePipelineLayout(pipelineLayoutDesc);
    if (passLayout.pipelineLayout == nullptr) {
        return failLayout("BuiltinForwardPipeline failed to create a pipeline layout from shader pass resources");
    }

    const auto result = m_passResourceLayouts.emplace(passLayoutKey, passLayout);
    PassResourceLayout& storedPassLayout = result.first->second;
    RefreshBuiltinPassSetLayouts(storedPassLayout.setLayouts);
    return &storedPassLayout;
}

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

    PassResourceLayout* passLayout = GetOrCreatePassResourceLayout(context, resolvedShaderPass);
    if (passLayout == nullptr || passLayout->pipelineLayout == nullptr) {
        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,
            passLayout->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;
}

bool BuiltinForwardPipeline::CreateOwnedDescriptorSet(
    const BuiltinPassSetLayoutMetadata& setLayout,
    OwnedDescriptorSet& descriptorSet) {
    RHI::DescriptorPoolDesc poolDesc = {};
    poolDesc.type = setLayout.heapType;
    poolDesc.descriptorCount = CountBuiltinPassHeapDescriptors(setLayout.heapType, setLayout.bindings);
    poolDesc.shaderVisible = setLayout.shaderVisible;

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

    descriptorSet.set = descriptorSet.pool->AllocateSet(setLayout.layout);
    if (descriptorSet.set == nullptr) {
        DestroyOwnedDescriptorSet(descriptorSet);
        return false;
    }

    return true;
}

RHI::RHIDescriptorSet* BuiltinForwardPipeline::GetOrCreateStaticDescriptorSet(
    PassResourceLayout& passLayout,
    Core::uint32 setIndex) {
    if (setIndex >= passLayout.setLayouts.size() ||
        setIndex >= passLayout.staticDescriptorSets.size()) {
        return nullptr;
    }

    OwnedDescriptorSet& descriptorSet = passLayout.staticDescriptorSets[setIndex];
    if (descriptorSet.set == nullptr) {
        if (!CreateOwnedDescriptorSet(passLayout.setLayouts[setIndex], descriptorSet)) {
            return nullptr;
        }

        if (passLayout.setLayouts[setIndex].usesSampler) {
            RHI::RHISampler* sampler = nullptr;
            Core::uint32 binding = 0;

            if (passLayout.setLayouts[setIndex].usesLinearClampSampler) {
                sampler = m_sampler;
                if (!passLayout.linearClampSampler.IsValid() ||
                    passLayout.linearClampSampler.set != setIndex) {
                    DestroyOwnedDescriptorSet(descriptorSet);
                    return nullptr;
                }
                binding = passLayout.linearClampSampler.binding;
            } else if (passLayout.setLayouts[setIndex].usesShadowMapSampler) {
                sampler = m_shadowSampler;
                if (!passLayout.shadowMapSampler.IsValid() ||
                    passLayout.shadowMapSampler.set != setIndex) {
                    DestroyOwnedDescriptorSet(descriptorSet);
                    return nullptr;
                }
                binding = passLayout.shadowMapSampler.binding;
            }

            if (sampler == nullptr) {
                DestroyOwnedDescriptorSet(descriptorSet);
                return nullptr;
            }

            descriptorSet.set->UpdateSampler(binding, sampler);
        }
    }

    return descriptorSet.set;
}

BuiltinForwardPipeline::CachedDescriptorSet* BuiltinForwardPipeline::GetOrCreateDynamicDescriptorSet(
    const PassLayoutKey& passLayoutKey,
    const PassResourceLayout& passLayout,
    const BuiltinPassSetLayoutMetadata& setLayout,
    Core::uint32 setIndex,
    Core::uint64 objectId,
    const Resources::Material* material,
    const MaterialConstantPayloadView& materialConstants,
    const ShadowReceiverConstants& shadowReceiverConstants,
    RHI::RHIResourceView* baseColorTextureView,
    RHI::RHIResourceView* shadowMapTextureView) {
    DynamicDescriptorSetKey key = {};
    key.passLayout = passLayoutKey;
    key.setIndex = setIndex;
    key.objectId = objectId;
    key.material = material;

    CachedDescriptorSet& cachedDescriptorSet = m_dynamicDescriptorSets[key];
    if (cachedDescriptorSet.descriptorSet.set == nullptr) {
        if (!CreateOwnedDescriptorSet(setLayout, cachedDescriptorSet.descriptorSet)) {
            return nullptr;
        }
    }

    const Core::uint64 materialVersion = material != nullptr ? material->GetChangeVersion() : 0;
    if (setLayout.usesMaterial) {
        if (!passLayout.material.IsValid() || passLayout.material.set != setIndex) {
            return nullptr;
        }
        if (!materialConstants.IsValid()) {
            return nullptr;
        }
        if (cachedDescriptorSet.materialVersion != materialVersion) {
            cachedDescriptorSet.descriptorSet.set->WriteConstant(
                passLayout.material.binding,
                materialConstants.data,
                materialConstants.size);
        }
    }

    if (setLayout.usesShadowReceiver) {
        if (!passLayout.shadowReceiver.IsValid() || passLayout.shadowReceiver.set != setIndex) {
            return nullptr;
        }
        cachedDescriptorSet.descriptorSet.set->WriteConstant(
            passLayout.shadowReceiver.binding,
            &shadowReceiverConstants,
            sizeof(shadowReceiverConstants));
    }

    if (setLayout.usesBaseColorTexture) {
        if (baseColorTextureView == nullptr ||
            !passLayout.baseColorTexture.IsValid() ||
            passLayout.baseColorTexture.set != setIndex) {
            return nullptr;
        }
        if (cachedDescriptorSet.baseColorTextureView != baseColorTextureView) {
            cachedDescriptorSet.descriptorSet.set->Update(
                passLayout.baseColorTexture.binding,
                baseColorTextureView);
        }
    }

    if (setLayout.usesShadowMapTexture) {
        if (shadowMapTextureView == nullptr ||
            !passLayout.shadowMapTexture.IsValid() ||
            passLayout.shadowMapTexture.set != setIndex) {
            return nullptr;
        }
        if (cachedDescriptorSet.shadowMapTextureView != shadowMapTextureView) {
            cachedDescriptorSet.descriptorSet.set->Update(
                passLayout.shadowMapTexture.binding,
                shadowMapTextureView);
        }
    }

    cachedDescriptorSet.materialVersion = materialVersion;
    cachedDescriptorSet.baseColorTextureView = baseColorTextureView;
    cachedDescriptorSet.shadowMapTextureView = shadowMapTextureView;

    return &cachedDescriptorSet;
}

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;
    }
}

void BuiltinForwardPipeline::DestroyPassResourceLayout(PassResourceLayout& passLayout) {
    for (OwnedDescriptorSet& descriptorSet : passLayout.staticDescriptorSets) {
        DestroyOwnedDescriptorSet(descriptorSet);
    }
    passLayout.staticDescriptorSets.clear();

    if (passLayout.pipelineLayout != nullptr) {
        passLayout.pipelineLayout->Shutdown();
        delete passLayout.pipelineLayout;
        passLayout.pipelineLayout = nullptr;
    }

    passLayout.setLayouts.clear();
    passLayout.firstDescriptorSet = 0;
    passLayout.descriptorSetCount = 0;
    passLayout.perObject = {};
    passLayout.material = {};
    passLayout.shadowReceiver = {};
    passLayout.baseColorTexture = {};
    passLayout.linearClampSampler = {};
    passLayout.shadowMapTexture = {};
    passLayout.shadowMapSampler = {};
}

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()
    };
    const ShadowReceiverConstants shadowReceiverConstants = {
        sceneData.lighting.HasMainDirectionalShadow()
            ? sceneData.lighting.mainDirectionalShadow.viewProjection
            : Math::Matrix4x4::Identity(),
        sceneData.lighting.HasMainDirectionalShadow()
            ? sceneData.lighting.mainDirectionalShadow.shadowParams
            : Math::Vector4::Zero(),
        sceneData.lighting.HasMainDirectionalShadow()
            ? Math::Vector4(1.0f, 0.0f, 0.0f, 0.0f)
            : Math::Vector4::Zero()
    };

    const Resources::Material* material = ResolveMaterial(visibleItem);
    const ResolvedShaderPass resolvedShaderPass = ResolveSurfaceShaderPass(material);
    if (resolvedShaderPass.shader == nullptr || resolvedShaderPass.pass == nullptr) {
        return false;
    }

    PassLayoutKey passLayoutKey = {};
    passLayoutKey.shader = resolvedShaderPass.shader;
    passLayoutKey.passName = resolvedShaderPass.passName;

    PassResourceLayout* passLayout = GetOrCreatePassResourceLayout(context, resolvedShaderPass);
    if (passLayout == nullptr || passLayout->pipelineLayout == nullptr) {
        return false;
    }

    RHI::RHIResourceView* baseColorTextureView = ResolveTextureView(visibleItem);
    if (passLayout->baseColorTexture.IsValid() && baseColorTextureView == nullptr) {
        return false;
    }

    RHI::RHIResourceView* shadowMapTextureView = sceneData.lighting.HasMainDirectionalShadow()
        ? sceneData.lighting.mainDirectionalShadow.shadowMap
        : m_fallbackTextureView;
    if (passLayout->shadowMapTexture.IsValid() && shadowMapTextureView == nullptr) {
        return false;
    }

    MaterialConstantPayloadView materialConstants = ResolveSchemaMaterialConstantPayload(material);
    FallbackPerMaterialConstants fallbackMaterialConstants = {};
    if (!materialConstants.IsValid()) {
        const BuiltinForwardMaterialData materialData = BuildBuiltinForwardMaterialData(material);
        fallbackMaterialConstants.baseColorFactor = materialData.baseColorFactor;
        static const Resources::MaterialConstantFieldDesc kFallbackMaterialConstantField = {
            Containers::String("baseColorFactor"),
            Resources::MaterialPropertyType::Float4,
            0,
            sizeof(FallbackPerMaterialConstants),
            sizeof(FallbackPerMaterialConstants)
        };
        materialConstants.data = &fallbackMaterialConstants;
        materialConstants.size = sizeof(fallbackMaterialConstants);
        materialConstants.layout = {
            &kFallbackMaterialConstantField,
            1,
            sizeof(fallbackMaterialConstants)
        };
    }

    if (passLayout->descriptorSetCount > 0) {
        std::vector<RHI::RHIDescriptorSet*> descriptorSets(passLayout->descriptorSetCount, nullptr);

        for (Core::uint32 descriptorOffset = 0; descriptorOffset < passLayout->descriptorSetCount; ++descriptorOffset) {
            const Core::uint32 setIndex = passLayout->firstDescriptorSet + descriptorOffset;
            if (setIndex >= passLayout->setLayouts.size()) {
                return false;
            }

            const BuiltinPassSetLayoutMetadata& setLayout = passLayout->setLayouts[setIndex];
            RHI::RHIDescriptorSet* descriptorSet = nullptr;

            if (setLayout.usesPerObject ||
                setLayout.usesMaterial ||
                setLayout.usesShadowReceiver ||
                setLayout.usesTexture) {
                const Core::uint64 objectId =
                    (setLayout.usesPerObject && visibleItem.gameObject != nullptr)
                        ? visibleItem.gameObject->GetID()
                        : 0;
                const Resources::Material* materialKey =
                    (setLayout.usesMaterial || setLayout.usesBaseColorTexture) ? material : nullptr;

                CachedDescriptorSet* cachedDescriptorSet = GetOrCreateDynamicDescriptorSet(
                    passLayoutKey,
                    *passLayout,
                    setLayout,
                    setIndex,
                    objectId,
                    materialKey,
                    materialConstants,
                    shadowReceiverConstants,
                    baseColorTextureView,
                    shadowMapTextureView);
                if (cachedDescriptorSet == nullptr || cachedDescriptorSet->descriptorSet.set == nullptr) {
                    return false;
                }

                descriptorSet = cachedDescriptorSet->descriptorSet.set;
                if (setLayout.usesPerObject) {
                    if (!passLayout->perObject.IsValid() || passLayout->perObject.set != setIndex) {
                        return false;
                    }

                    descriptorSet->WriteConstant(
                        passLayout->perObject.binding,
                        &constants,
                        sizeof(constants));
                }
            } else {
                descriptorSet = GetOrCreateStaticDescriptorSet(*passLayout, setIndex);
                if (descriptorSet == nullptr) {
                    return false;
                }
            }

            descriptorSets[descriptorOffset] = descriptorSet;
        }

        commandList->SetGraphicsDescriptorSets(
            passLayout->firstDescriptorSet,
            passLayout->descriptorSetCount,
            descriptorSets.data(),
            passLayout->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