XCEngine/new_editor/src/XCUIBackend/XCUIHostedPreviewPresenter.h

#pragma once

#include <XCEngine/UI/DrawData.h>
#include <XCEngine/UI/Types.h>

#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
#include <utility>
#include <vector>

namespace XCEngine {
namespace Editor {
namespace XCUIBackend {

struct XCUIHostedPreviewFrame {
    const ::XCEngine::UI::UIDrawData* drawData = nullptr;
    ::XCEngine::UI::UIRect canvasRect = {};
    ::XCEngine::UI::UISize logicalSize = {};
    const char* debugName = nullptr;
    const char* debugSource = nullptr;
};

struct XCUIHostedPreviewStats {
    bool presented = false;
    bool queuedToNativePass = false;
    std::size_t submittedDrawListCount = 0;
    std::size_t submittedCommandCount = 0;
    std::size_t flushedDrawListCount = 0;
    std::size_t flushedCommandCount = 0;
};

struct XCUIHostedPreviewQueuedFrame {
    std::string debugName = {};
    std::string debugSource = {};
    ::XCEngine::UI::UIRect canvasRect = {};
    ::XCEngine::UI::UISize logicalSize = {};
    ::XCEngine::UI::UIDrawData drawData = {};
};

struct XCUIHostedPreviewSurfaceImage {
    ::XCEngine::UI::UITextureHandle texture = {};
    ::XCEngine::UI::UIPoint uvMin = {};
    ::XCEngine::UI::UIPoint uvMax = ::XCEngine::UI::UIPoint(1.0f, 1.0f);
    ::XCEngine::UI::UIRect renderedCanvasRect = {};
    std::uint32_t surfaceWidth = 0;
    std::uint32_t surfaceHeight = 0;

    bool IsValid() const {
        return texture.IsValid() && surfaceWidth > 0u && surfaceHeight > 0u;
    }
};

struct XCUIHostedPreviewDrainStats {
    std::size_t queuedFrameCount = 0;
    std::size_t queuedDrawListCount = 0;
    std::size_t queuedCommandCount = 0;
    std::size_t renderedFrameCount = 0;
    std::size_t renderedDrawListCount = 0;
    std::size_t renderedCommandCount = 0;
    std::size_t skippedFrameCount = 0;
    std::size_t skippedCommandCount = 0;
};

struct XCUIHostedPreviewSurfaceDescriptor {
    std::string debugName = {};
    std::string debugSource = {};
    ::XCEngine::UI::UIRect canvasRect = {};
    ::XCEngine::UI::UISize logicalSize = {};
    std::size_t queuedFrameIndex = 0;
    std::size_t submittedDrawListCount = 0;
    std::size_t submittedCommandCount = 0;
    bool queuedThisFrame = false;
    XCUIHostedPreviewSurfaceImage image = {};
};

class XCUIHostedPreviewSurfaceRegistry {
public:
    void BeginFrame() {
        for (XCUIHostedPreviewSurfaceDescriptor& descriptor : m_descriptors) {
            descriptor.queuedThisFrame = false;
        }
    }

    void RecordQueuedFrame(
        const XCUIHostedPreviewQueuedFrame& queuedFrame,
        std::size_t queuedFrameIndex = 0u) {
        if (queuedFrame.debugName.empty()) {
            return;
        }

        XCUIHostedPreviewSurfaceDescriptor* descriptor = FindMutableDescriptor(queuedFrame.debugName);
        if (descriptor == nullptr) {
            XCUIHostedPreviewSurfaceDescriptor newDescriptor = {};
            newDescriptor.debugName = queuedFrame.debugName;
            m_descriptors.push_back(std::move(newDescriptor));
            descriptor = &m_descriptors.back();
        }

        descriptor->debugSource = queuedFrame.debugSource;
        descriptor->canvasRect = queuedFrame.canvasRect;
        descriptor->logicalSize = queuedFrame.logicalSize;
        descriptor->queuedFrameIndex = queuedFrameIndex;
        descriptor->submittedDrawListCount = queuedFrame.drawData.GetDrawListCount();
        descriptor->submittedCommandCount = queuedFrame.drawData.GetTotalCommandCount();
        descriptor->queuedThisFrame = true;
    }

    void UpdateSurface(
        const std::string& debugName,
        const ::XCEngine::UI::UITextureHandle& texture,
        const ::XCEngine::UI::UIRect& renderedCanvasRect) {
        if (debugName.empty() || !texture.IsValid()) {
            return;
        }

        XCUIHostedPreviewSurfaceDescriptor* descriptor = FindMutableDescriptor(debugName);
        if (descriptor == nullptr) {
            XCUIHostedPreviewSurfaceDescriptor newDescriptor = {};
            newDescriptor.debugName = debugName;
            m_descriptors.push_back(std::move(newDescriptor));
            descriptor = &m_descriptors.back();
        }

        descriptor->image.texture = texture;
        descriptor->image.surfaceWidth = texture.width;
        descriptor->image.surfaceHeight = texture.height;
        descriptor->image.renderedCanvasRect = renderedCanvasRect;
        descriptor->image.uvMin = ::XCEngine::UI::UIPoint(
            renderedCanvasRect.x / static_cast<float>(texture.width),
            renderedCanvasRect.y / static_cast<float>(texture.height));
        descriptor->image.uvMax = ::XCEngine::UI::UIPoint(
            (renderedCanvasRect.x + renderedCanvasRect.width) / static_cast<float>(texture.width),
            (renderedCanvasRect.y + renderedCanvasRect.height) / static_cast<float>(texture.height));
    }

    bool TryGetSurfaceDescriptor(
        const char* debugName,
        XCUIHostedPreviewSurfaceDescriptor& outDescriptor) const {
        outDescriptor = {};
        if (debugName == nullptr || debugName[0] == '\0') {
            return false;
        }

        for (const XCUIHostedPreviewSurfaceDescriptor& descriptor : m_descriptors) {
            if (descriptor.debugName == debugName) {
                outDescriptor = descriptor;
                return true;
            }
        }

        return false;
    }

    bool TryGetSurfaceImage(const char* debugName, XCUIHostedPreviewSurfaceImage& outImage) const {
        outImage = {};
        XCUIHostedPreviewSurfaceDescriptor descriptor = {};
        if (!TryGetSurfaceDescriptor(debugName, descriptor)) {
            return false;
        }

        outImage = descriptor.image;
        return outImage.IsValid();
    }

    const std::vector<XCUIHostedPreviewSurfaceDescriptor>& GetDescriptors() const {
        return m_descriptors;
    }

private:
    XCUIHostedPreviewSurfaceDescriptor* FindMutableDescriptor(const std::string& debugName) {
        for (XCUIHostedPreviewSurfaceDescriptor& descriptor : m_descriptors) {
            if (descriptor.debugName == debugName) {
                return &descriptor;
            }
        }

        return nullptr;
    }

    std::vector<XCUIHostedPreviewSurfaceDescriptor> m_descriptors = {};
};

class XCUIHostedPreviewQueue {
public:
    void BeginFrame() {
        m_queuedFrames.clear();
    }

    bool Submit(const XCUIHostedPreviewFrame& frame, XCUIHostedPreviewStats* outStats = nullptr) {
        XCUIHostedPreviewStats stats = {};
        if (frame.drawData == nullptr) {
            if (outStats != nullptr) {
                *outStats = stats;
            }
            return false;
        }

        XCUIHostedPreviewQueuedFrame queuedFrame = {};
        if (frame.debugName != nullptr) {
            queuedFrame.debugName = frame.debugName;
        }
        if (frame.debugSource != nullptr) {
            queuedFrame.debugSource = frame.debugSource;
        }
        queuedFrame.canvasRect = frame.canvasRect;
        queuedFrame.logicalSize = frame.logicalSize.width > 0.0f && frame.logicalSize.height > 0.0f
            ? frame.logicalSize
            : ::XCEngine::UI::UISize(frame.canvasRect.width, frame.canvasRect.height);
        queuedFrame.drawData = *frame.drawData;

        stats.presented = true;
        stats.queuedToNativePass = true;
        stats.submittedDrawListCount = queuedFrame.drawData.GetDrawListCount();
        stats.submittedCommandCount = queuedFrame.drawData.GetTotalCommandCount();
        m_queuedFrames.push_back(std::move(queuedFrame));

        if (outStats != nullptr) {
            *outStats = stats;
        }
        return true;
    }

    const std::vector<XCUIHostedPreviewQueuedFrame>& GetQueuedFrames() const {
        return m_queuedFrames;
    }

    void SetLastDrainStats(const XCUIHostedPreviewDrainStats& stats) {
        m_lastDrainStats = stats;
    }

    const XCUIHostedPreviewDrainStats& GetLastDrainStats() const {
        return m_lastDrainStats;
    }

private:
    std::vector<XCUIHostedPreviewQueuedFrame> m_queuedFrames = {};
    XCUIHostedPreviewDrainStats m_lastDrainStats = {};
};

class IXCUIHostedPreviewPresenter {
public:
    virtual ~IXCUIHostedPreviewPresenter() = default;

    virtual bool Present(const XCUIHostedPreviewFrame& frame) = 0;
    virtual const XCUIHostedPreviewStats& GetLastStats() const = 0;
    virtual bool IsNativeQueued() const { return false; }
    virtual bool TryGetSurfaceImage(
        const char* debugName,
        XCUIHostedPreviewSurfaceImage& outImage) const {
        outImage = {};
        return false;
    }
    virtual bool TryGetSurfaceDescriptor(
        const char* debugName,
        XCUIHostedPreviewSurfaceDescriptor& outDescriptor) const {
        outDescriptor = {};
        return false;
    }
};

class NullXCUIHostedPreviewPresenter final : public IXCUIHostedPreviewPresenter {
public:
    bool Present(const XCUIHostedPreviewFrame& frame) override {
        m_lastStats = {};
        if (frame.drawData == nullptr) {
            return false;
        }

        m_lastStats.submittedDrawListCount = frame.drawData->GetDrawListCount();
        m_lastStats.submittedCommandCount = frame.drawData->GetTotalCommandCount();
        return false;
    }

    const XCUIHostedPreviewStats& GetLastStats() const override {
        return m_lastStats;
    }

private:
    XCUIHostedPreviewStats m_lastStats = {};
};

class QueuedNativeXCUIHostedPreviewPresenter final : public IXCUIHostedPreviewPresenter {
public:
    QueuedNativeXCUIHostedPreviewPresenter(
        XCUIHostedPreviewQueue& queue,
        XCUIHostedPreviewSurfaceRegistry& surfaceRegistry)
        : m_queue(queue)
        , m_surfaceRegistry(surfaceRegistry) {
    }

    bool Present(const XCUIHostedPreviewFrame& frame) override {
        m_lastStats = {};
        return m_queue.Submit(frame, &m_lastStats);
    }

    const XCUIHostedPreviewStats& GetLastStats() const override {
        return m_lastStats;
    }

    bool IsNativeQueued() const override {
        return true;
    }

    bool TryGetSurfaceImage(
        const char* debugName,
        XCUIHostedPreviewSurfaceImage& outImage) const override {
        return m_surfaceRegistry.TryGetSurfaceImage(debugName, outImage);
    }

    bool TryGetSurfaceDescriptor(
        const char* debugName,
        XCUIHostedPreviewSurfaceDescriptor& outDescriptor) const override {
        return m_surfaceRegistry.TryGetSurfaceDescriptor(debugName, outDescriptor);
    }

private:
    XCUIHostedPreviewQueue& m_queue;
    XCUIHostedPreviewSurfaceRegistry& m_surfaceRegistry;
    XCUIHostedPreviewStats m_lastStats = {};
};

inline std::unique_ptr<IXCUIHostedPreviewPresenter> CreateQueuedNativeXCUIHostedPreviewPresenter(
    XCUIHostedPreviewQueue& queue,
    XCUIHostedPreviewSurfaceRegistry& surfaceRegistry) {
    return std::make_unique<QueuedNativeXCUIHostedPreviewPresenter>(queue, surfaceRegistry);
}

inline std::unique_ptr<IXCUIHostedPreviewPresenter> CreateNullXCUIHostedPreviewPresenter() {
    return std::make_unique<NullXCUIHostedPreviewPresenter>();
}

} // namespace XCUIBackend
} // namespace Editor
} // namespace XCEngine