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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2025                                                               *
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#include <modules/base/dashboard/dashboarditemframerate.h>

#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/engine/globals.h>
#include <openspace/engine/windowdelegate.h>
#include <ghoul/font/font.h>
#include <ghoul/font/fontmanager.h>
#include <ghoul/font/fontrenderer.h>
#include <ghoul/misc/profiling.h>
#include <optional>

namespace {
    enum FrametimeType {
        DtTime = 0,
        DtTimeAvg,
        DtTimeExtremes,
        DtStandardDeviation,
        DtCoefficientOfVariation,
        FPS,
        FPSAvg
    };

    constexpr openspace::properties::Property::PropertyInfo FrametimeInfo = {
        "FrametimeType",
        "Type of the frame time display",
        "This value determines the units in which the frame time is displayed.",
        openspace::properties::Property::Visibility::User
    };

    constexpr openspace::properties::Property::PropertyInfo ClearCacheInfo = {
        "ClearCache",
        "Clear cache",
        "Clears the cache of this DashboardItemFramerate item. If the selected option "
        "does not use any caching, this trigger does not do anything.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    [[nodiscard]] char* formatDt(std::vector<char>& buffer) {
        return std::format_to(
            buffer.data(),
            "Frametime: {:.2f} ms\0",
            openspace::global::windowDelegate->deltaTime()
        );
    }

    [[nodiscard]] char* formatDtAvg(std::vector<char>& buffer) {
        return std::format_to(
            buffer.data(),
            "Avg. Frametime: {:.2f} ms\0",
            openspace::global::windowDelegate->averageDeltaTime() * 1000.0
        );
    }

    [[nodiscard]] char* formatDtExtremes(std::vector<char>& buffer,
                                           double minFrametimeCache,
                                           double maxFrametimeCache)
    {
        return std::format_to(
            buffer.data(),
            "Last frametimes between: {:.2f} and {:.2f} ms\n"
            "Overall between: {:.2f} and {:.2f} ms\0",
            openspace::global::windowDelegate->minDeltaTime() * 1000.0,
            openspace::global::windowDelegate->maxDeltaTime() * 1000.0,
            minFrametimeCache,
            maxFrametimeCache
        );
    }

    [[nodiscard]] char* formatDtStandardDeviation(std::vector<char>& buffer) {
        return std::format_to(
            buffer.data(),
            "Frametime standard deviation : {:.2f} ms\0",
            openspace::global::windowDelegate->deltaTimeStandardDeviation() * 1000.0
        );
    }

    [[nodiscard]] char* formatDtCoefficientOfVariation(std::vector<char>& buffer) {
        return std::format_to(
            buffer.data(),
            "Frametime coefficient of variation : {:.2f} %\0",
            openspace::global::windowDelegate->deltaTimeStandardDeviation() /
            openspace::global::windowDelegate->averageDeltaTime() * 100.0
        );
    }

    [[nodiscard]] char* formatFps(std::vector<char>& buffer) {
        return std::format_to(
            buffer.data(),
            "FPS: {:3.2f}\0",
            1.0 / openspace::global::windowDelegate->deltaTime()
        );
    }

    [[nodiscard]] char* formatAverageFps(std::vector<char>& buffer) {
        return std::format_to(
            buffer.data(),
            "Avg. FPS: {:3.2f}\0",
            1.0 / openspace::global::windowDelegate->averageDeltaTime()
        );
    }

    [[nodiscard]] char* format(std::vector<char>& buffer, FrametimeType frametimeType,
                                       double minFrametimeCache, double maxFrametimeCache)
    {
        using namespace openspace;
        switch (frametimeType) {
            case FrametimeType::DtTime:
                return formatDt(buffer);
            case FrametimeType::DtTimeAvg:
                return formatDtAvg(buffer);
            case FrametimeType::DtTimeExtremes:
                return formatDtExtremes(buffer, minFrametimeCache, maxFrametimeCache);
            case FrametimeType::DtStandardDeviation:
                return formatDtStandardDeviation(buffer);
            case FrametimeType::DtCoefficientOfVariation:
                return formatDtCoefficientOfVariation(buffer);
            case FrametimeType::FPS:
                return formatFps(buffer);
            case FrametimeType::FPSAvg:
                return formatAverageFps(buffer);
            default:
                throw ghoul::MissingCaseException();
        }
    }

    // This `DashboardItem` provides information about the current framerate at which the
    // rendering updates. The `FrametimeType` can have different values that will show
    // different statistical aspects of the framerate.
    //
    //   - `Deltatime`: Shows the time in milliseconds it took to render the previous
    //                  frame
    //   - `Average Deltatime`: Shows the time that it took to render in milliseconds
    //                          averaged over the last 100 or so frames
    //   - `Deltatime extremes`: Shows the minimum and maximum values of the render time
    //                           in milliseconds over the last 100 or so frames
    //  - `Deltatime standard deviation`: Shows the standard deviation of the render time
    //                                    in milliseconds over the last 100 or so frames
    //  - `Deltatime coefficient of variation`: Shows the normalized root-mean-square
    //                                          deviation of the render time in
    //                                          milliseconds over the last 100 or so
    //                                          frames
    //  - `Frames per second`: Shows the inverse of the delta time it took the render the
    //                         last frame.
    //  - `Average frames per second`: Shows average number of frames that have been
    //                                 presented over the last 100 or so frames
    struct [[codegen::Dictionary(DashboardItemFramerate)]] Parameters {
        enum class [[codegen::map(FrametimeType)]] Type {
            DtTime [[codegen::key("Deltatime")]],
            DtTimeAvg [[codegen::key("Average Deltatime")]],
            DtTimeExtremes [[codegen::key("Deltatime extremes")]],
            DtStandardDeviation [[codegen::key("Deltatime standard deviation")]],
            DtCoefficientOfVariation
                [[codegen::key("Deltatime coefficient of variation")]],
            FPS [[codegen::key("Frames per second")]],
            FPSAvg [[codegen::key("Average frames per second")]]
        };

        // [[codegen::verbatim(FrametimeInfo.description)]]
        std::optional<Type> frametimeType;
    };
#include "dashboarditemframerate_codegen.cpp"
} // namespace

namespace openspace {

documentation::Documentation DashboardItemFramerate::Documentation() {
    return codegen::doc<Parameters>(
        "base_dashboarditem_framerate",
        DashboardTextItem::Documentation()
    );
}

DashboardItemFramerate::DashboardItemFramerate(const ghoul::Dictionary& dictionary)
    : DashboardTextItem(dictionary)
    , _frametimeType(FrametimeInfo)
    , _clearCache(ClearCacheInfo)
{
    const Parameters p = codegen::bake<Parameters>(dictionary);

    _frametimeType.addOptions({
        { static_cast<int>(FrametimeType::DtTime), "Deltatime" },
        { static_cast<int>(FrametimeType::DtTimeAvg), "Average Deltatime" },
        { static_cast<int>(FrametimeType::DtTimeExtremes), "Deltatime extremes" },
        {
            static_cast<int>(FrametimeType::DtStandardDeviation),
            "Deltatime standard deviation"
        },
        {
            static_cast<int>(FrametimeType::DtCoefficientOfVariation),
            "Deltatime coefficient of variation"
        },
        { static_cast<int>(FrametimeType::FPS), "Frames per second" },
        { static_cast<int>(FrametimeType::FPSAvg), "Average frames per second" }
    });

    if (p.frametimeType.has_value()) {
        _frametimeType = codegen::map<FrametimeType>(*p.frametimeType);
    }
    else {
        _frametimeType = static_cast<int>(FrametimeType::FPSAvg);
    }
    addProperty(_frametimeType);

    _clearCache.onChange([this]() {
        _shouldClearCache = true;
    });
    addProperty(_clearCache);
    _localBuffer.resize(128);
}

void DashboardItemFramerate::update() {
    ZoneScoped;

    if (_shouldClearCache) [[unlikely]] {
        _minDeltaTimeCache = 1.0;
        _maxDeltaTimeCache = -1.0;
        _shouldClearCache = false;
    }

    _minDeltaTimeCache = std::min(
        _minDeltaTimeCache,
        global::windowDelegate->minDeltaTime() * 1000.0
    );
    _maxDeltaTimeCache = std::max(
        _maxDeltaTimeCache,
        global::windowDelegate->maxDeltaTime() * 1000.0
    );

    const FrametimeType frametimeType = FrametimeType(_frametimeType.value());

    std::fill(_localBuffer.begin(), _localBuffer.end(), char(0));
    char* end = format(
        _localBuffer,
        frametimeType,
        _minDeltaTimeCache,
        _maxDeltaTimeCache
    );
    _buffer = std::string(_localBuffer.data(), end - _localBuffer.data());
}

} // namespace openspace