#pragma once



/****************************************************************************************
 *                                                                                      *
 *                          MOUNT CONTROL COMPONENTS LIBRARY                            *
 *                                                                                      *
 *                                                                                      *
 *                        IMPLEMENTATION OF SERIALIZER CLASSES                          *
 *                                                                                      *
 ****************************************************************************************/



#include <atomic>
#include <concepts>

#include "mcc_concepts.h"
#include "mcc_constants.h"
#include "mcc_coordinate.h"
#include "mcc_epoch.h"
#include "mcc_error.h"
#include "mcc_traits.h"
#include "mcc_utils.h"

namespace mcc::impl
{

enum class MccSerializerErrorCode : int {
    ERROR_OK,
    ERROR_UNDERLYING_SERIALIZER,
    ERROR_INVALID_EPOCH,
    ERROR_COORD_TRANSFORM
};

}  // namespace mcc::impl



namespace std
{

template <>
class is_error_code_enum<mcc::impl::MccSerializerErrorCode> : public true_type
{
};

}  // namespace std


namespace mcc::impl
{


// error category
struct MccSerializerCategory : public std::error_category {
    MccSerializerCategory() : std::error_category() {}

    const char* name() const noexcept
    {
        return "MCC-SERIALIZER-ERR-CATEGORY";
    }

    std::string message(int ec) const
    {
        MccSerializerErrorCode err = static_cast<MccSerializerErrorCode>(ec);

        switch (err) {
            case MccSerializerErrorCode::ERROR_OK:
                return "OK";
            case MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER:
                return "error returned by underlying serializer";
            case MccSerializerErrorCode::ERROR_INVALID_EPOCH:
                return "invalid coordinate epoch";
            case MccSerializerErrorCode::ERROR_COORD_TRANSFORM:
                return "coordinates transformation error";
            default:
                return "UNKNOWN";
        }
    }

    static const MccSerializerCategory& get()
    {
        static const MccSerializerCategory constInst;
        return constInst;
    }
};


inline std::error_code make_error_code(MccSerializerErrorCode ec)
{
    return std::error_code(static_cast<int>(ec), MccSerializerCategory::get());
}



template <mcc_error_c RetT>
struct mcc_serializer_interface_t {
    virtual ~mcc_serializer_interface_t() = default;

    typedef RetT error_t;

    template <std::derived_from<mcc_serializer_interface_t> SelfT,
              traits::mcc_output_char_range R,
              typename ValueT,
              typename FmtT>
        requires(std::same_as<std::format_string<ValueT>, FmtT> || std::same_as<std::string_view, FmtT>)
    RetT operator()(this SelfT&& self, R& output, ValueT const& value, FmtT fmt)
    {
        return std::forward<SelfT>(self)(output, value, std::move(fmt));
    }

protected:
    mcc_serializer_interface_t() = default;
};

template <typename T>
concept mcc_serializer_c = std::derived_from<T, mcc_serializer_interface_t<typename T::error_t>>;


namespace details
{

struct MccSerializerBase : mcc_serializer_interface_t<impl::MccError>, utils::mcc_elem_sequence_with_delim_t {
    using typename mcc_serializer_interface_t<impl::MccError>::error_t;

    virtual ~MccSerializerBase() = default;

protected:
    MccSerializerBase() = default;

    template <typename VT, typename R>
        requires(std::ranges::input_range<R> && std::same_as<VT, std::ranges::range_value_t<R>>)
    error_t serializingRange(mcc_serializer_c auto& sr,
                             R const& r,
                             traits::mcc_output_char_range auto& output,
                             auto fmt) const
    {
        size_t i = 0, N = std::ranges::size(r);

        for (auto const& el : r) {
            auto err = sr(output, el, std::move(fmt));
            if (err) {
                return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
            }
            if (++i < N) {
                std::format_to(std::back_inserter(output), "{}", _seqDelimiter);
            }
        }

        return MccSerializerErrorCode::ERROR_OK;
    }
};

}  // namespace details


/*  fallback template */
template <typename VT>
class MccSerializer : public details::MccSerializerBase
// class MccSerializer : public mcc_serializer_interface_t<impl::MccError>
{
public:
    // default delimiter
    static constexpr std::string_view defaultRangeDelimiter{","};

    // typedef impl::MccError error_t;

    MccSerializer() = default;

    ~MccSerializer() = default;

    template <typename FmtT = std::nullptr_t>
    error_t operator()(traits::mcc_output_char_range auto& output, VT const& value, FmtT fmt = nullptr)
    {
        if constexpr (std::formattable<VT, char>) {
            if constexpr (std::is_null_pointer_v<FmtT>) {
                std::format_to(std::back_inserter(output), "{}", value);
            } else if constexpr (traits::mcc_input_char_range<FmtT>) {
                std::string_view sfmt{fmt.begin(), fmt.end()};
                std::vformat_to(std::back_inserter(output), sfmt, std::make_format_args(value));
            } else if constexpr (std::same_as<std::format_string<VT>, FmtT>) {
                std::format_to(std::back_inserter(output), std::move(fmt), value);
            } else {
                static_assert(false, "INVALID FORMAT STRING TYPE!!!");
            }
        } else if constexpr (std::convertible_to<VT, std::string>) {
            auto err = MccSerializer<std::string>{}(output, static_cast<std::string>(value), std::move(fmt));
            if (err) {
                return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
            }

        } else if constexpr (std::ranges::range<VT>) {
            using value_t = std::remove_cv_t<std::ranges::range_value_t<VT>>;

            // special range (character sequence)
            if constexpr (std::same_as<value_t, char>) {
                std::string str;
                std::ranges::copy(value, std::back_inserter(str));

                auto err = MccSerializer<std::string>{}(output, str, std::move(fmt));
                if (err) {
                    return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                }

            } else {
                MccSerializer<value_t> sr;

                return serializingRange<value_t>(sr, value, output, std::move(fmt));
            }
        } else {
            static_assert(false, "UNSUPPORTED TYPE!!!");
        }

        return MccSerializerErrorCode::ERROR_OK;
    }
};



/*                          SPECIALIZATION FOR THE SOME CONCEPTS                            */


template <typename VT>
    requires(traits::mcc_systime_c<VT> ||
             (std::ranges::input_range<VT> && traits::mcc_systime_c<std::remove_cv_t<std::ranges::range_value_t<VT>>>))
class MccSerializer<VT> : public details::MccSerializerBase
{
public:
    virtual ~MccSerializer() = default;

    template <typename FmtT = std::nullptr_t>
    error_t operator()(traits::mcc_output_char_range auto& output, VT const& value, FmtT fmt = nullptr)
    {
        if constexpr (std::ranges::input_range<VT>) {
            using value_t = std::remove_cv_t<std::ranges::range_value_t<VT>>;
            MccSerializer<value_t> sr;

            return serializingRange<value_t>(sr, value, output, std::move(fmt));
        } else {  // scalar
            if constexpr (std::is_null_pointer_v<FmtT>) {
                std::format_to(std::back_inserter(output), "{:%FT%T}", value);
            } else if constexpr (traits::mcc_input_char_range<FmtT>) {
                std::string_view sfmt{fmt.begin(), fmt.end()};
                if (sfmt == "{}") {
                    sfmt = "{:%FT%T}";
                }
                std::vformat_to(std::back_inserter(output), sfmt, std::make_format_args(value));
            } else if constexpr (std::same_as<std::format_string<VT>, FmtT>) {
                std::string_view sfmt{fmt.get().begin(), fmt.get().end()};
                if (sfmt == "{}") {
                    std::format_to(std::back_inserter(output), "{:%FT%T}", value);
                } else {
                    std::format_to(std::back_inserter(output), std::move(fmt), value);
                }
            } else {
                static_assert(false, "INVALID FORMAT STRING TYPE!!!");
            }
        }

        return MccSerializerErrorCode::ERROR_OK;
    }
};


template <typename VT>
    requires(!std::is_arithmetic_v<VT> &&
             (mcc_angle_c<VT> ||
              (std::ranges::input_range<VT> && mcc_angle_c<std::remove_cv_t<std::ranges::range_value_t<VT>>>)))
class MccSerializer<VT> : public virtual details::MccSerializerBase
// class MccSerializer<VT> : public mcc_serializer_interface_t<impl::MccError>
{
public:
    enum SerializedCoordFormat {
        CFMT_DEGREES,    // floating-point representation in degrees
        CFMT_SGM_HOURS,  // sexagesimal representation: HH:MM:SS.SSSSSS (hours:minutes:seconds)
        CFMT_SGM_DEGS    // sexagesimal representation: DD:MM:SS.SSSSS (degrees:arcmins::arcsecs)
    };

    struct SexagesimalCoordPrec {
        uint8_t hour_prec = 2;  // number of decimal places in hour seconds
        uint8_t deg_prec = 1;   // number of decimal places in arcseconds
    };

    // typedef impl::MccError error_t;

    virtual ~MccSerializer() = default;

    void setCoordFormat(SerializedCoordFormat format)
    {
        _coordFormat = format;
    }

    SerializedCoordFormat getCoordFormat() const
    {
        return _coordFormat;
    }


    void setCoordPrec(SexagesimalCoordPrec prec)
    {
        _coordPrec = std::move(prec);
    }

    SexagesimalCoordPrec getCoordPrec() const
    {
        return _coordPrec;
    }

    template <typename FmtT = std::nullptr_t>
    error_t operator()(traits::mcc_output_char_range auto& output, VT const& value, FmtT fmt = nullptr)
    {
        if constexpr (std::ranges::input_range<VT>) {
            using value_t = std::remove_cv_t<std::ranges::range_value_t<VT>>;
            MccSerializer<value_t> sr;
            sr.setCoordFormat(_coordFormat);
            sr.setCoordPrec(_coordPrec);

            return serializingRange<value_t>(sr, value, output, std::move(fmt));
        } else {                       // scalar
            double v = (double)value;  // radians
            std::string sgm;

            switch (_coordFormat) {
                case MccSerializer::CFMT_DEGREES:
                    v *= 180.0 / std::numbers::pi;
                    return MccSerializer<double>{}(output, v, std::move(fmt));
                case MccSerializer::CFMT_SGM_HOURS:
                    sgm = utils::rad2sxg(v, true, _coordPrec.load().hour_prec);
                    break;
                case MccSerializer::CFMT_SGM_DEGS:
                    sgm = utils::rad2sxg(v, false, _coordPrec.load().deg_prec);
                    break;
                default:
                    break;
            }
            auto err = MccSerializer<std::string>{}(output, sgm, std::move(fmt));
            if (err) {
                return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
            }
        }

        return MccSerializerErrorCode::ERROR_OK;
    }

protected:
    // std::atomic<SerializedCoordFormat> _coordFormat{MccSerializer::CFMT_DEGREES};
    std::atomic<SerializedCoordFormat> _coordFormat{MccSerializer::CFMT_SGM_DEGS};
    std::atomic<SexagesimalCoordPrec> _coordPrec{SexagesimalCoordPrec{.hour_prec = 2, .deg_prec = 1}};
};



template <typename VT>
    requires(mcc_coord_epoch_c<VT> ||
             (std::ranges::input_range<VT> && mcc_coord_epoch_c<std::remove_cv_t<std::ranges::range_value_t<VT>>>))
class MccSerializer<VT> : public virtual details::MccSerializerBase
{
public:
    enum TimePointFormat { TP_FORMAT_DATE, TP_FORMAT_MJD, TP_FORMAT_JEPOCH };

    virtual ~MccSerializer() = default;

    void setTimePointFormat(TimePointFormat format)
    {
        _tpFormat = format;
    }

    TimePointFormat getTimePointFormat() const
    {
        return _tpFormat;
    }


    template <typename FmtT = std::nullptr_t>
    error_t operator()(traits::mcc_output_char_range auto& output, VT const& value, FmtT fmt = nullptr)
    {
        if constexpr (std::ranges::input_range<VT>) {
            using value_t = std::remove_cv_t<std::ranges::range_value_t<VT>>;
            MccSerializer<value_t> sr;
            sr.setTimePointFormat(_tpFormat);

            return serializingRange<value_t>(sr, value, output, std::move(fmt));
        } else {
            switch (_tpFormat) {
                case TP_FORMAT_DATE: {
                    auto utc = value.UTC();
                    auto err = MccSerializer<std::remove_cvref_t<decltype(utc)>>{}(output, utc, std::move(fmt));
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }
                } break;
                case TP_FORMAT_MJD: {
                    double mjd = value.MJD();
                    auto err = MccSerializer<double>{}(output, mjd, std::move(fmt));
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }
                } break;
                case TP_FORMAT_JEPOCH: {
                    auto jepoch = value.JEpoch();
                    auto err = MccSerializer<std::remove_cvref_t<decltype(jepoch)>>{}(output, jepoch, std::move(fmt));
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }
                }
                default:
                    break;
            }

            return MccSerializerErrorCode::ERROR_OK;
        }
    }

protected:
    std::atomic<TimePointFormat> _tpFormat{TP_FORMAT_DATE};
};



template <typename VT>
    requires(mcc_coord_pair_c<VT> ||
             (std::ranges::input_range<VT> && mcc_coord_pair_c<std::remove_cv_t<std::ranges::range_value_t<VT>>>))
class MccSerializer<VT> : public std::conditional_t<std::ranges::input_range<VT>,
                                                    MccSerializer<std::vector<MccCelestialCoordEpoch>>,
                                                    MccSerializer<MccCelestialCoordEpoch>>,
                          public std::conditional_t<std::ranges::input_range<VT>,
                                                    MccSerializer<std::vector<MccAngle>>,
                                                    MccSerializer<MccAngle>>
// class MccSerializer<VT> : public mcc_serializer_interface_t<MccError>
{
protected:
    typedef std::conditional_t<std::ranges::input_range<VT>,
                               MccSerializer<std::vector<MccCelestialCoordEpoch>>,
                               MccSerializer<MccCelestialCoordEpoch>>
        base_ser_epoch_t;

    typedef std::
        conditional_t<std::ranges::input_range<VT>, MccSerializer<std::vector<MccAngle>>, MccSerializer<MccAngle>>
            base_ser_angle_t;

public:
    using typename details::MccSerializerBase::error_t;

    template <typename FmtT = std::nullptr_t>
    error_t operator()(traits::mcc_output_char_range auto& output, VT const& value, FmtT fmt = nullptr)
    {
        if constexpr (std::ranges::input_range<VT>) {
            using value_t = std::remove_cv_t<std::ranges::range_value_t<VT>>;
            MccSerializer<value_t> sr;

            sr.setTimePointFormat(this->_tpFormat);
            sr.setCoordFormat(this->_coordFormat);
            sr.setCoordPrec(this->_coordPrec);

            return serializingRange<value_t>(sr, value, output, std::move(fmt));
        } else {  // scalar: format X[elem-delimiter]Y[elem-delimiter]epoch[elem-delimiter]pair-kind

            // WARNING: still ignore format string!!!

            error_t err;

            // format to sexagesimal form according to celestial coordinate type (general XY-type is skipped)
            if (this->_coordFormat != base_ser_angle_t::CFMT_DEGREES) {
                auto prev_format = this->_coordFormat.load();

                if constexpr (VT::pairKind == MccCoordPairKind::COORDS_KIND_AZZD ||
                              VT::pairKind == MccCoordPairKind::COORDS_KIND_AZALT) {  // azimuth is in degrees

                    this->setCoordFormat(base_ser_angle_t::CFMT_SGM_DEGS);
                    err = base_ser_angle_t::operator()(output, MccAngle{(double)value.x()});
                } else {  // RA or HA are in hours
                    this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    err = base_ser_angle_t::operator()(output, MccAngle{(double)value.x()});
                }

                this->setCoordFormat(prev_format);  // restore previous value
            } else {                                // here all angles in deciamal degrees
                err = base_ser_angle_t::operator()(output, MccAngle{(double)value.x()});
            }

            if (err) {
                return err;
            }

            std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);

            // format to sexagesimal form according to celestial coordinate type (general XY-type is skipped)
            // Y-coordinate of the celestial point is always in degrees
            if (this->_coordFormat != base_ser_angle_t::CFMT_DEGREES) {
                auto prev_format = this->_coordFormat.load();
                this->setCoordFormat(base_ser_angle_t::CFMT_SGM_DEGS);

                err = base_ser_angle_t::operator()(output, MccAngle{(double)value.y()});

                this->setCoordFormat(prev_format);  // restore previous value
            } else {                                // here all angles in deciamal degrees
                err = base_ser_angle_t::operator()(output, MccAngle{(double)value.y()});
            }

            if (err) {
                return err;
            }

            std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);

            auto ep = value.epoch();
            if constexpr (std::convertible_to<decltype(ep), MccCelestialCoordEpoch>) {
                auto err_e = base_ser_epoch_t::operator()(output, MccCelestialCoordEpoch{ep});
                if (err_e) {
                    return err_e;
                }
            } else {
                MccCelestialCoordEpoch ep1;
                bool ok = ep1.fromMJD(ep.MJD());
                if (!ok) {
                    return MccSerializerErrorCode::ERROR_INVALID_EPOCH;
                }

                auto err_e = (*this)(output, ep1);
                if (err_e) {
                    return err_e;
                }
            }

            std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);

            auto err_s = MccSerializer<std::string_view>{}(output, MccCoordPairKindToStr(VT::pairKind));
            if (err_s) {
                return mcc_deduced_err(err_s, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
            }
        }

        return MccSerializerErrorCode::ERROR_OK;
    }
};


template <typename VT>
    requires(mcc_skypoint_c<VT> ||
             (std::ranges::input_range<VT> && mcc_skypoint_c<std::remove_cv_t<std::ranges::range_value_t<VT>>>))
class MccSerializer<VT> : public std::conditional_t<std::ranges::input_range<VT>,
                                                    MccSerializer<std::vector<MccCelestialCoordEpoch>>,
                                                    MccSerializer<MccCelestialCoordEpoch>>,
                          public std::conditional_t<std::ranges::input_range<VT>,
                                                    MccSerializer<std::vector<MccAngle>>,
                                                    MccSerializer<MccAngle>>
{
protected:
    typedef std::conditional_t<std::ranges::input_range<VT>,
                               MccSerializer<std::vector<MccCelestialCoordEpoch>>,
                               MccSerializer<MccCelestialCoordEpoch>>
        base_ser_epoch_t;

    typedef std::
        conditional_t<std::ranges::input_range<VT>, MccSerializer<std::vector<MccAngle>>, MccSerializer<MccAngle>>
            base_ser_angle_t;

public:
    using typename details::MccSerializerBase::error_t;

    enum SkyPointFormat {
        SKYPOINT_FORMAT_FULL,  // return RA_ICRS, DEC_ICRS, RA_APP, DEC_APP, RA_OBS, DEC_OBS, AZ, ZD, HA_APP,
                               // TIME-POINT
        SKYPOINT_FORMAT_OBS,   // return observed coordinates: RA_OBS, DEC_OBS, AZ, ZD, HA_OBS, TIME-POINT
        SKYPOINT_FORMAT_APP,   // return apparent (in vacuo) coordinates: RA_APP, DEC_APP, HA_APP, TIME-POINT
        SKYPOINT_FORMAT_PAIR   // return current stored coordinate pair: X, Y, TIME-POINT, PAIR-KIND
    };

    virtual ~MccSerializer() = default;

    void setSkyPointFormat(SkyPointFormat format)
    {
        _skptFormat = format;
    }

    SkyPointFormat getSkyPointFormat() const
    {
        return _skptFormat;
    }

    template <typename FmtT = std::nullptr_t>
    error_t operator()(traits::mcc_output_char_range auto& output, VT const& value, FmtT fmt = nullptr)
    {
        if constexpr (std::ranges::input_range<VT>) {
            using value_t = std::remove_cv_t<std::ranges::range_value_t<VT>>;
            MccSerializer<value_t> sr;

            sr.setTimePointFormat(this->_tpFormat);
            sr.setCoordFormat(this->_coordFormat);
            sr.setCoordPrec(this->_coordPrec);

            return serializingRange<value_t>(sr, value, output, std::move(fmt));
        } else {  // scalar

            auto serialize_pair_func = [&output, this]<typename PT>(PT const& pt) -> error_t {
                MccSerializer<PT> pt_sr;

                pt_sr.setTimePointFormat(this->_tpFormat);
                pt_sr.setCoordFormat(this->_coordFormat);
                pt_sr.setCoordPrec(this->_coordPrec);

                auto err = pt_sr(output, pt);
                if (err) {
                    return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                }

                return MccSerializerErrorCode::ERROR_OK;
            };

            // WARNING: still ignore format string!!!

            auto skpt_fmt = _skptFormat.load();

            if (skpt_fmt == SKYPOINT_FORMAT_PAIR) {
                switch (value.pairKind()) {
                    case MccCoordPairKind::COORDS_KIND_RADEC_ICRS:
                        return serialize_pair_func(value.operator MccSkyRADEC_ICRS());
                    case MccCoordPairKind::COORDS_KIND_RADEC_APP:
                        return serialize_pair_func(value.operator MccSkyRADEC_APP());
                    case MccCoordPairKind::COORDS_KIND_RADEC_OBS:
                        return serialize_pair_func(value.operator MccSkyRADEC_OBS());
                    case MccCoordPairKind::COORDS_KIND_HADEC_APP:
                        return serialize_pair_func(value.operator MccSkyHADEC_APP());
                    case MccCoordPairKind::COORDS_KIND_HADEC_OBS:
                        return serialize_pair_func(value.operator MccSkyHADEC_OBS());
                    case MccCoordPairKind::COORDS_KIND_AZZD:
                        return serialize_pair_func(value.operator MccSkyAZZD());
                    case MccCoordPairKind::COORDS_KIND_AZALT:
                        return serialize_pair_func(value.operator MccSkyAZALT());
                    case MccCoordPairKind::COORDS_KIND_XY:
                        return serialize_pair_func(value.operator MccGenXY());
                    default:
                        return serialize_pair_func(value.operator MccGenXY());  // ???????!!!!!!!!!!!
                }
            } else {
                MccSkyRADEC_ICRS radec_icrs;
                MccSkyRADEC_OBS radec_obs;
                MccSkyHADEC_OBS hadec_obs;
                MccSkyRADEC_APP radec_app;
                MccSkyHADEC_APP hadec_app;
                MccSkyAZZD azzd;
                // MccGenXY xy;

                if (value.pairKind() == MccCoordPairKind::COORDS_KIND_RADEC_ICRS) {
                    auto ep_now = MccCelestialCoordEpoch::now();
                    radec_obs.setEpoch(ep_now);
                    radec_app.setEpoch(ep_now);
                    hadec_obs.setEpoch(ep_now);
                    hadec_app.setEpoch(ep_now);
                    azzd.setEpoch(ep_now);
                } else {
                    auto ep = value.epoch();
                    radec_obs.setEpoch(ep);
                    radec_app.setEpoch(ep);
                    hadec_obs.setEpoch(ep);
                    hadec_app.setEpoch(ep);
                    azzd.setEpoch(ep);
                }

                auto prev_format = this->_coordFormat.load();

                if (skpt_fmt == SKYPOINT_FORMAT_FULL) {  // RA_ICRS, DEC_ICRS, RA_APP, DEC_APP
                    auto err = value.to(radec_icrs, radec_app);
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
                    }

                    // RA_ICRS is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    auto err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_icrs.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);


                    // DEC_ICRS is in sexagesimal degrees
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_DEGS);
                    }

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_icrs.y()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }

                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);

                    // RA_APP is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_app.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);


                    // DEC_APP is in sexagesimal degrees
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_DEGS);
                    }

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_app.y()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }

                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);
                }

                if (skpt_fmt == SKYPOINT_FORMAT_OBS || skpt_fmt == SKYPOINT_FORMAT_FULL) {  // RA_OBS, DEC_OBS, AZ, ZD
                    auto err = value.to(radec_obs, azzd);
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
                    }

                    // RA_OBS is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    auto err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_obs.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);


                    // DEC_OBS, AZ and ZD are in sexagesimal degrees
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_DEGS);
                    }

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_obs.y()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);


                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)azzd.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)azzd.y()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);
                }

                if (skpt_fmt == SKYPOINT_FORMAT_FULL) {  // HA_APP
                    auto err = value.to(hadec_app);
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
                    }

                    // HA_APP is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    auto err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)hadec_app.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }

                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);
                }

                if (skpt_fmt == SKYPOINT_FORMAT_OBS) {  // HA_OBS
                    auto err = value.to(hadec_obs);
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
                    }

                    // HA_OBS is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    auto err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)hadec_obs.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }

                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);
                }


                if (skpt_fmt == SKYPOINT_FORMAT_APP) {  // RA_APP, DEC_APP, HA_APP
                    auto err = value.to(radec_app, hadec_app);
                    if (err) {
                        return mcc_deduced_err(err, MccSerializerErrorCode::ERROR_COORD_TRANSFORM);
                    }

                    // RA_APP is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    auto err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_app.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);


                    // DEC_APP is in sexagesimal degrees
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_DEGS);
                    }

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)radec_app.y()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }


                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);

                    // HA_APP is in sexagesimal hours
                    if (prev_format != base_ser_angle_t::CFMT_DEGREES) {
                        this->setCoordFormat(base_ser_angle_t::CFMT_SGM_HOURS);
                    }

                    err_ang = base_ser_angle_t::operator()(output, MccAngle{(double)hadec_app.x()});
                    if (err_ang) {
                        return mcc_deduced_err(err_ang, MccSerializerErrorCode::ERROR_UNDERLYING_SERIALIZER);
                    }

                    std::format_to(std::back_inserter(output), "{}", this->_elementDelimiter);
                }

                this->setCoordFormat(prev_format);  // restore previous value


                // epoch of app/obs coordinates
                auto ep = value.epoch();
                if constexpr (std::convertible_to<decltype(ep), MccCelestialCoordEpoch>) {
                    auto err_e = base_ser_epoch_t::operator()(output, MccCelestialCoordEpoch{ep});
                    if (err_e) {
                        return err_e;
                    }
                } else {
                    MccCelestialCoordEpoch ep1;
                    bool ok = ep1.fromMJD(ep.MJD());
                    if (!ok) {
                        return MccSerializerErrorCode::ERROR_INVALID_EPOCH;
                    }

                    auto err_e = (*this)(output, ep1);
                    if (err_e) {
                        return err_e;
                    }
                }
            }

            return MccSerializerErrorCode::ERROR_OK;
        }
    }

protected:
    std::atomic<SkyPointFormat> _skptFormat{SKYPOINT_FORMAT_FULL};
};



static_assert(mcc_serializer_c<MccSerializer<float>>, "!!!");

static_assert(mcc_serializer_c<MccSerializer<impl::MccAngle>>, "!!!");

static_assert(std::atomic<MccSerializer<impl::MccAngle>::SerializedCoordFormat>::is_always_lock_free, "!!!");
static_assert(std::atomic<MccSerializer<impl::MccAngle>::SexagesimalCoordPrec>::is_always_lock_free, "!!!");

static_assert(std::formattable<impl::MccAngle, char>, "!!!");

void f()
{
    MccSerializer<impl::MccAngle> s;

    std::string str;
    s(str, impl::MccAngleALT{1.1});
}

}  // namespace mcc::impl