#include "Viewport/SceneViewportRenderService.h"

#include "Engine/EditorEngineServices.h"
#include "Viewport/ViewportObjectIdPicker.h"

#include <utility>

namespace XCEngine::UI::Editor::App {

namespace {

ViewportRenderResult BuildFallbackResult(
    std::string statusText,
    float r,
    float g,
    float b,
    float a) {
    ViewportRenderResult result = {};
    result.rendered = false;
    result.requiresFallbackClear = true;
    result.statusText = std::move(statusText);
    result.fallbackClearR = r;
    result.fallbackClearG = g;
    result.fallbackClearB = b;
    result.fallbackClearA = a;
    return result;
}

void SetStatusIfEmpty(
    std::string& statusText,
    std::string_view message) {
    if (statusText.empty()) {
        statusText = std::string(message);
    }
}

} // namespace

SceneViewportRenderService::SceneViewportRenderService() = default;

SceneViewportRenderService::~SceneViewportRenderService() = default;

EditorViewportResourceRequirements
SceneViewportRenderService::GetViewportResourceRequirements() {
    EditorViewportResourceRequirements requirements = {};
    requirements.requiresDepthSampling = true;
    requirements.requiresObjectIdSurface = true;
    requirements.requiresSelectionMaskSurface = true;
    return requirements;
}

void SceneViewportRenderService::Initialize(
    const SceneViewportShaderPaths& shaderPaths,
    EditorEngineServices& engineServices) {
    m_engineServices = &engineServices;
    m_renderPassBundle.Initialize(shaderPaths, engineServices);
}

void SceneViewportRenderService::Shutdown() {
    m_renderRequest = {};
    m_renderPassBundle.Shutdown();
    m_engineServices = nullptr;
    m_device = nullptr;
    m_lastTargets = nullptr;
    m_lastRenderContext = {};
    m_lastObjectIdRequestRevision = 0u;
    m_objectIdFrameSerialCounter = 0u;
}

void SceneViewportRenderService::SetRenderRequest(
    SceneViewportRenderRequest request) {
    if (m_lastTargets != nullptr &&
        m_lastTargets->hasValidObjectIdFrame &&
        request.requestRevision != m_lastObjectIdRequestRevision) {
        InvalidateObjectIdFrame();
    }

    m_renderRequest = std::move(request);
}

const IViewportObjectPickerService& SceneViewportRenderService::GetObjectPicker() const {
    return *this;
}

ViewportRenderResult SceneViewportRenderService::Render(
    ViewportRenderTargets& targets,
    ::XCEngine::RHI::RHIDevice& device,
    const ::XCEngine::Rendering::RenderContext& renderContext) {
    m_device = &device;
    m_lastTargets = &targets;
    m_lastRenderContext = renderContext;

    if (!m_renderRequest.IsValid()) {
        return BuildFallbackResult(
            "Scene view camera is unavailable",
            0.18f,
            0.07f,
            0.07f,
            1.0f);
    }

    ::XCEngine::Rendering::RenderSurface surface =
        BuildViewportColorSurface(targets);
    ::XCEngine::Rendering::CameraFramePlan framePlan = {};
    const SceneViewportFramePlanBuildStatus buildStatus =
        m_engineServices != nullptr
            ? m_engineServices->BuildSceneViewportFramePlan(
                m_renderRequest,
                renderContext,
                surface,
                framePlan)
            : SceneViewportFramePlanBuildStatus::Failed;
    if (buildStatus == SceneViewportFramePlanBuildStatus::NoActiveScene) {
        return BuildFallbackResult(
            "No active scene",
            0.07f,
            0.08f,
            0.10f,
            1.0f);
    }
    if (buildStatus != SceneViewportFramePlanBuildStatus::Success ||
        !framePlan.IsValid()) {
        return BuildFallbackResult(
            "Scene renderer failed",
            0.18f,
            0.07f,
            0.07f,
            1.0f);
    }

    ViewportRenderResult result = {};
    SceneViewportRenderPlanBuildResult renderPlan =
        m_renderPassBundle.BuildRenderPlan(targets, m_renderRequest);
    ApplySceneViewportRenderPlan(
        targets,
        renderPlan.plan,
        framePlan);
    if (renderPlan.warningStatusText != nullptr) {
        SetStatusIfEmpty(result.statusText, renderPlan.warningStatusText);
    }

    if (m_engineServices == nullptr ||
        !m_engineServices->RenderSceneViewportFramePlan(framePlan)) {
        return BuildFallbackResult(
            "Scene renderer failed",
            0.18f,
            0.07f,
            0.07f,
            1.0f);
    }

    MarkSceneViewportRenderSuccess(
        targets,
        renderPlan.plan,
        framePlan);
    if (framePlan.request.objectId.IsRequested()) {
        ++m_objectIdFrameSerialCounter;
        if (m_objectIdFrameSerialCounter == 0u) {
            m_objectIdFrameSerialCounter = 1u;
        }
        targets.objectIdFrameSerial = m_objectIdFrameSerialCounter;
        m_lastObjectIdRequestRevision = m_renderRequest.requestRevision;
    } else {
        targets.objectIdFrameSerial = 0u;
        m_lastObjectIdRequestRevision = 0u;
    }
    result.rendered = true;
    return result;
}

ViewportObjectIdPickResult SceneViewportRenderService::PickObject(
    const ::XCEngine::UI::UISize& viewportSize,
    const ::XCEngine::UI::UIPoint& viewportMousePosition) const {
    if (!m_renderRequest.IsValid() ||
        m_device == nullptr ||
        m_lastTargets == nullptr) {
        return {};
    }

    ViewportObjectIdPickContext pickContext = {};
    pickContext.commandQueue = m_lastRenderContext.commandQueue;
    pickContext.texture = m_lastTargets->objectIdTexture;
    pickContext.textureState = m_lastTargets->objectIdState;
    pickContext.textureWidth = m_lastTargets->width;
    pickContext.textureHeight = m_lastTargets->height;
    pickContext.hasValidFrame = m_lastTargets->hasValidObjectIdFrame;
    pickContext.frameSerial = m_lastTargets->objectIdFrameSerial;
    pickContext.viewportSize = viewportSize;
    pickContext.viewportMousePosition = viewportMousePosition;

    ViewportObjectIdPickResult result = PickViewportRenderObjectId(
        pickContext,
        [this](
            const ViewportObjectIdReadbackRequest& request,
            std::array<std::uint8_t, 4>& outRgba) {
            return m_device->ReadTexturePixelRGBA8(
                request.commandQueue,
                request.texture,
                request.textureState,
                request.pixelX,
                request.pixelY,
                outRgba);
        });

    if (!result.HasResolvedSample() ||
        !::XCEngine::Rendering::IsValidRenderObjectId(result.renderObjectId)) {
        return result;
    }

    EditorSceneObjectId runtimeObjectId = kInvalidEditorSceneObjectId;
    if (m_engineServices == nullptr ||
        !m_engineServices->TryResolveActiveSceneRenderObjectId(
            result.renderObjectId,
            runtimeObjectId)) {
        return result;
    }

    result.resolvedEntityId = runtimeObjectId;
    return result;
}

void SceneViewportRenderService::InvalidateObjectIdFrame() {
    if (m_lastTargets != nullptr) {
        m_lastTargets->hasValidObjectIdFrame = false;
        m_lastTargets->objectIdFrameSerial = 0u;
    }

    m_lastObjectIdRequestRevision = 0u;
}

} // namespace XCEngine::UI::Editor::App