#include "Rendering/Pipelines/BuiltinForwardPipeline.h"

#include "Debug/Logger.h"
#include "Rendering/Pipelines/Internal/BuiltinForwardMainSceneGraphBuilder.h"
#include "Rendering/Internal/RenderSurfacePipelineUtils.h"
#include "Rendering/RenderSurface.h"
#include "RHI/RHICommandList.h"

namespace XCEngine {
namespace Rendering {
namespace Pipelines {
namespace {

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

void TransitionMainDirectionalShadowForSampling(
    const RenderContext& context,
    const RenderSceneData& sceneData) {
    context.commandList->TransitionBarrier(
        sceneData.lighting.mainDirectionalShadow.shadowMap,
        RHI::ResourceStates::DepthWrite,
        RHI::ResourceStates::PixelShaderResource);
}

void RestoreMainDirectionalShadowAfterSampling(
    const RenderContext& context,
    const RenderSceneData& sceneData) {
    context.commandList->TransitionBarrier(
        sceneData.lighting.mainDirectionalShadow.shadowMap,
        RHI::ResourceStates::PixelShaderResource,
        RHI::ResourceStates::DepthWrite);
}

std::vector<RHI::RHIResourceView*> CollectSurfaceColorAttachments(const RenderSurface& surface) {
    std::vector<RHI::RHIResourceView*> renderTargets;
    const Core::uint32 colorAttachmentCount =
        ::XCEngine::Rendering::Internal::ResolveSurfaceColorAttachmentCount(surface);
    renderTargets.reserve(colorAttachmentCount);
    for (Core::uint32 attachmentIndex = 0; attachmentIndex < colorAttachmentCount; ++attachmentIndex) {
        RHI::RHIResourceView* renderTarget = surface.GetColorAttachments()[attachmentIndex];
        if (renderTarget == nullptr) {
            break;
        }

        renderTargets.push_back(renderTarget);
    }

    return renderTargets;
}

} // namespace

bool BuiltinForwardPipeline::ShouldSampleMainDirectionalShadowMap(const RenderSceneData& sceneData) {
    return sceneData.lighting.HasMainDirectionalShadow() &&
        sceneData.lighting.mainDirectionalShadow.shadowMap != nullptr &&
        IsDepthFormat(sceneData.lighting.mainDirectionalShadow.shadowMap->GetFormat());
}

bool BuiltinForwardPipeline::SupportsStageRenderGraph(
    CameraFrameStage stage) const {
    return SupportsCameraFramePipelineGraphRecording(stage);
}

bool BuiltinForwardPipeline::RecordStageRenderGraph(
    const RenderPipelineStageRenderGraphContext& context) {
    return context.stage == CameraFrameStage::MainScene &&
           Internal::BuiltinForwardMainSceneGraphBuilder::Record(*this, context);
}

bool BuiltinForwardPipeline::Render(
    const FrameExecutionContext& executionContext) {
    return ExecuteForwardSceneFrame(executionContext, true);
}

bool BuiltinForwardPipeline::ExecuteForwardSceneFrame(
    const FrameExecutionContext& executionContext,
    bool manageMainDirectionalShadowTransitions) {
    if (!Initialize(executionContext.renderContext)) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline::Render failed: Initialize returned false");
        return false;
    }

    if (!m_forwardSceneFeatureHost.Prepare(executionContext)) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline::Render failed: SceneRenderFeatureHost::Prepare returned false");
        return false;
    }

    const RenderPassContext passContext = BuildRenderPassContext(executionContext);

    if (!BeginForwardScenePass(passContext)) {
        Debug::Logger::Get().Error(
            Debug::LogCategory::Rendering,
            "BuiltinForwardPipeline::Render failed: BeginForwardScenePass returned false");
        return false;
    }

    const bool sampledDirectionalShadow =
        manageMainDirectionalShadowTransitions &&
        ShouldSampleMainDirectionalShadowMap(executionContext.sceneData);
    if (sampledDirectionalShadow) {
        TransitionMainDirectionalShadowForSampling(
            executionContext.renderContext,
            executionContext.sceneData);
    }

    const bool renderResult = ExecuteForwardScene(executionContext);

    if (sampledDirectionalShadow) {
        RestoreMainDirectionalShadowAfterSampling(
            executionContext.renderContext,
            executionContext.sceneData);
    }
    EndForwardScenePass(passContext);

    return renderResult;
}

bool BuiltinForwardPipeline::BeginForwardScenePass(
    const RenderPassContext& passContext,
    bool clearAttachments) {
    const RenderContext& context = passContext.renderContext;
    const RenderSurface& surface = passContext.surface;
    const RenderSceneData& sceneData = passContext.sceneData;
    RHI::RHIResourceView* depthAttachment = surface.GetDepthAttachment();

    std::vector<RHI::RHIResourceView*> renderTargets = CollectSurfaceColorAttachments(surface);
    if (renderTargets.empty()) {
        return false;
    }

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

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

        if (depthAttachment != nullptr) {
            commandList->TransitionBarrier(
                depthAttachment,
                surface.GetDepthStateBefore(),
                RHI::ResourceStates::DepthWrite);
        }
    }

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

    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 (clearAttachments &&
        HasRenderClearFlag(sceneData.cameraData.clearFlags, RenderClearFlags::Color) &&
        !HasSkybox(sceneData)) {
        for (RHI::RHIResourceView* renderTarget : renderTargets) {
            if (renderTarget != nullptr) {
                commandList->ClearRenderTarget(renderTarget, clearValues, 1, clearRects);
            }
        }
    }
    if (clearAttachments &&
        depthAttachment != nullptr &&
        HasRenderClearFlag(sceneData.cameraData.clearFlags, RenderClearFlags::Depth)) {
        commandList->ClearDepthStencil(depthAttachment, 1.0f, 0, 1, clearRects);
    }

    commandList->SetPrimitiveTopology(RHI::PrimitiveTopology::TriangleList);
    return true;
}

bool BuiltinForwardPipeline::Render(
    const RenderContext& context,
    const RenderSurface& surface,
    const RenderSceneData& sceneData) {
    return Render(FrameExecutionContext(context, surface, sceneData));
}

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

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

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

    if (depthAttachment != nullptr) {
        commandList->TransitionBarrier(
            depthAttachment,
            RHI::ResourceStates::DepthWrite,
            surface.GetDepthStateAfter());
    }
}

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