#include "Rendering/CameraRenderer.h"

#include "Rendering/Pipelines/BuiltinForwardPipeline.h"
#include "Rendering/RenderPipelineAsset.h"
#include "Rendering/RenderSurface.h"
#include "Scene/Scene.h"

namespace XCEngine {
namespace Rendering {

namespace {

bool InitializePassSequence(
    RenderPassSequence* sequence,
    const RenderContext& context,
    bool& initialized) {
    if (sequence == nullptr) {
        initialized = false;
        return true;
    }

    initialized = sequence->Initialize(context);
    if (!initialized) {
        sequence->Shutdown();
    }

    return initialized;
}

void ShutdownPassSequence(RenderPassSequence* sequence, bool initialized) {
    if (sequence != nullptr && initialized) {
        sequence->Shutdown();
    }
}

std::shared_ptr<const RenderPipelineAsset> CreateDefaultPipelineAsset() {
    static const std::shared_ptr<const RenderPipelineAsset> s_defaultPipelineAsset =
        std::make_shared<Pipelines::BuiltinForwardPipelineAsset>();
    return s_defaultPipelineAsset;
}

std::unique_ptr<RenderPipeline> CreatePipelineFromAsset(
    const std::shared_ptr<const RenderPipelineAsset>& pipelineAsset) {
    if (pipelineAsset != nullptr) {
        std::unique_ptr<RenderPipeline> pipeline = pipelineAsset->CreatePipeline();
        if (pipeline != nullptr) {
            return pipeline;
        }
    }

    return std::make_unique<Pipelines::BuiltinForwardPipeline>();
}

} // namespace

CameraRenderer::CameraRenderer()
    : CameraRenderer(CreateDefaultPipelineAsset()) {
}

CameraRenderer::CameraRenderer(std::unique_ptr<RenderPipeline> pipeline)
    : m_pipelineAsset(nullptr) {
    ResetPipeline(std::move(pipeline));
}

CameraRenderer::CameraRenderer(std::shared_ptr<const RenderPipelineAsset> pipelineAsset)
    : m_pipelineAsset(std::move(pipelineAsset)) {
    SetPipelineAsset(m_pipelineAsset);
}

CameraRenderer::~CameraRenderer() {
    if (m_pipeline) {
        m_pipeline->Shutdown();
    }
}

void CameraRenderer::SetPipeline(std::unique_ptr<RenderPipeline> pipeline) {
    m_pipelineAsset.reset();
    ResetPipeline(std::move(pipeline));
}

void CameraRenderer::SetPipelineAsset(std::shared_ptr<const RenderPipelineAsset> pipelineAsset) {
    m_pipelineAsset = pipelineAsset != nullptr ? std::move(pipelineAsset) : CreateDefaultPipelineAsset();
    ResetPipeline(CreatePipelineFromAsset(m_pipelineAsset));
}

void CameraRenderer::ResetPipeline(std::unique_ptr<RenderPipeline> pipeline) {
    if (m_pipeline != nullptr) {
        m_pipeline->Shutdown();
    }

    m_pipeline = std::move(pipeline);
    if (m_pipeline == nullptr) {
        m_pipelineAsset = CreateDefaultPipelineAsset();
        m_pipeline = CreatePipelineFromAsset(m_pipelineAsset);
    }
}

bool CameraRenderer::Render(
    const CameraRenderRequest& request) {
    if (!request.IsValid() || m_pipeline == nullptr) {
        return false;
    }

    if (request.surface.GetRenderAreaWidth() == 0 ||
        request.surface.GetRenderAreaHeight() == 0) {
        return false;
    }

    RenderSceneData sceneData = m_sceneExtractor.ExtractForCamera(
        *request.scene,
        *request.camera,
        request.surface.GetRenderAreaWidth(),
        request.surface.GetRenderAreaHeight());
    if (!sceneData.HasCamera()) {
        return false;
    }

    sceneData.cameraData.clearFlags = request.clearFlags;
    const RenderPassContext passContext = {
        request.context,
        request.surface,
        sceneData
    };

    bool preScenePassesInitialized = false;
    if (!InitializePassSequence(
            request.preScenePasses,
            request.context,
            preScenePassesInitialized)) {
        return false;
    }
    if (request.preScenePasses != nullptr &&
        !request.preScenePasses->Execute(passContext)) {
        ShutdownPassSequence(request.preScenePasses, preScenePassesInitialized);
        return false;
    }

    if (!m_pipeline->Render(request.context, request.surface, sceneData)) {
        ShutdownPassSequence(request.preScenePasses, preScenePassesInitialized);
        return false;
    }

    bool postScenePassesInitialized = false;
    if (!InitializePassSequence(
            request.postScenePasses,
            request.context,
            postScenePassesInitialized)) {
        ShutdownPassSequence(request.preScenePasses, preScenePassesInitialized);
        return false;
    }
    if (request.postScenePasses != nullptr &&
        !request.postScenePasses->Execute(passContext)) {
        ShutdownPassSequence(request.postScenePasses, postScenePassesInitialized);
        ShutdownPassSequence(request.preScenePasses, preScenePassesInitialized);
        return false;
    }

    ShutdownPassSequence(request.postScenePasses, postScenePassesInitialized);
    ShutdownPassSequence(request.preScenePasses, preScenePassesInitialized);

    return true;
}

} // namespace Rendering
} // namespace XCEngine