#include "Rendering/Pipelines/BuiltinForwardPipeline.h"

#include "Debug/Logger.h"
#include "Core/Asset/ResourceManager.h"
#include "RHI/RHICommandList.h"
#include "Rendering/Materials/RenderMaterialResolve.h"
#include "Rendering/RenderSurface.h"
#include "Resources/BuiltinResources.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;
};

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

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

    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.ExecuteForwardTransparentPass(context);
    }

private:
    BuiltinForwardPipeline& m_pipeline;
};

} // namespace Detail

namespace {

bool IsDepthFormat(RHI::Format format) {
    return format == RHI::Format::D24_UNorm_S8_UInt ||
           format == RHI::Format::D32_Float;
}

} // namespace

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

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

    std::vector<RHI::RHIResourceView*> renderTargets = colorAttachments;
    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);
    return true;
}

void BuiltinForwardPipeline::EndForwardScenePass(const RenderPassContext& passContext) {
    const RenderContext& context = passContext.renderContext;
    const RenderSurface& surface = passContext.surface;
    const std::vector<RHI::RHIResourceView*>& colorAttachments = surface.GetColorAttachments();
    RHI::RHICommandList* commandList = context.commandList;

    if (!surface.IsAutoTransitionEnabled()) {
        return;
    }

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

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

    if (!BeginForwardScenePass(passContext)) {
        return false;
    }

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

    return DrawVisibleItems(context, sceneData, false);
}

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

    const bool drawResult = DrawVisibleItems(context, sceneData, true);

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

    EndForwardScenePass(passContext);

    return drawResult;
}

bool BuiltinForwardPipeline::DrawVisibleItems(
    const RenderContext& context,
    const RenderSceneData& sceneData,
    bool drawTransparentItems) {
    RHI::RHICommandList* commandList = context.commandList;
    RHI::RHIPipelineState* currentPipelineState = nullptr;
    for (const VisibleRenderItem& visibleItem : sceneData.visibleItems) {
        const bool isTransparentItem = IsTransparentRenderQueue(visibleItem.renderQueue);
        if (isTransparentItem != drawTransparentItems) {
            continue;
        }

        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);
    }

    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();
}

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