mcc/mcc_concepts.h

#pragma once


/****************************************************************************************
 *                                                                                      *
 *                          MOUNT CONTROL COMPONENTS LIBRARY                            *
 *                                                                                      *
 *                                                                                      *
 *                            COMPONENT CLASSES CONCEPTS                                *
 *                                                                                      *
 ****************************************************************************************/


#include <cstdint>
// #include <expected>
#include <string_view>


#include "mcc_angle.h"
#include "mcc_traits.h"

namespace mcc
{


/*                          LIBRARY-WIDE CONCEPT FOR LOGGER CLASS                            */

template <typename T>
concept mcc_logger_c = requires(T t, const T t_const) {
    { t.logError(std::declval<const std::string&>()) };
    { t.logDebug(std::declval<const std::string&>()) };
    { t.logWarn(std::declval<const std::string&>()) };
    { t.logInfo(std::declval<const std::string&>()) };
    { t.logTrace(std::declval<const std::string&>()) };
};


/*  CLASS TO EMULATE NO LOGGING  */
struct MccNullLogger {
    void logError(const std::string&) {}
    void logDebug(const std::string&) {}
    void logWarn(const std::string&) {}
    void logInfo(const std::string&) {}
    void logTrace(const std::string&) {}
};



/*                          LIBRARY-WIDE TYPES DEFINITION OF OPERATIONAL ERROR                            */
/*                                  AND CLASS METHODS RETURNED VALUE                                      */

template <typename T>
concept mcc_error_c = std::default_initializable<T> && (std::convertible_to<T, bool> || requires(const T t) {
                          // std::formattable<T, char> && std::default_initializable<T> && (std::convertible_to<T, bool>
                          // || requires(const T t) {
                          (bool)T() == false;  // default constucted value must be a "non-error"!
                      });


template <mcc_error_c ErrT, mcc_error_c DefErrT>
auto mcc_deduced_err(ErrT const& err, DefErrT const& default_err)
// DefErrT mcc_deduced_err(ErrT const& err, DefErrT const& default_err)
{
    if constexpr (std::same_as<ErrT, DefErrT>) {
        return err;
    } else if constexpr (std::is_error_code_enum_v<DefErrT>) {
        if constexpr (std::same_as<ErrT, std::error_code>) {
            return err;
        } else {
            return default_err;
        }
    } else if constexpr (std::is_error_condition_enum_v<DefErrT>) {
        if constexpr (std::same_as<ErrT, std::error_condition>) {
            return err;
        } else {
            return default_err;
        }
    } else {
        return default_err;
    }
}


// template <typename T, typename VT>
// concept mcc_retval_c = requires(T t) {
//     //
//     []<mcc_error_c ErrT>(std::expected<VT, ErrT>) {}(t);
// };


// // deduce an error from mcc_retval_c and default error value
// template <typename VT, mcc_retval_c<VT> RetT, mcc_error_c DefErrT>
// DefErrT mcc_deduced_err(RetT const& ret, DefErrT const& default_err)
// {
//     if (ret) {
//         return DefErrT{};  // no error
//     }

//     if constexpr (std::same_as<typename RetT::error_type, DefErrT>) {
//         return ret.error();
//     } else {
//         return default_err;
//     }
// }


/*                          MOUNT CONSTRUCTION-RELATED STUFF                            */

// mount construction type (only the most common ones)
enum class MccMountType : uint8_t { GERMAN_TYPE, FORK_TYPE, CROSSAXIS_TYPE, ALTAZ_TYPE };

template <MccMountType TYPE>
static constexpr std::string_view MccMountTypeStr = TYPE == MccMountType::GERMAN_TYPE      ? "GERMAN"
                                                    : TYPE == MccMountType::FORK_TYPE      ? "FORK"
                                                    : TYPE == MccMountType::CROSSAXIS_TYPE ? "CROSSAXIS"
                                                    : TYPE == MccMountType::ALTAZ_TYPE     ? "ALTAZ"
                                                                                           : "UNKNOWN";

template <MccMountType TYPE>
static constexpr bool mcc_is_equatorial_mount = TYPE == MccMountType::GERMAN_TYPE      ? true
                                                : TYPE == MccMountType::FORK_TYPE      ? true
                                                : TYPE == MccMountType::CROSSAXIS_TYPE ? true
                                                : TYPE == MccMountType::ALTAZ_TYPE     ? false
                                                                                       : false;
template <MccMountType TYPE>
static constexpr bool mcc_is_altaz_mount = TYPE == MccMountType::GERMAN_TYPE      ? false
                                           : TYPE == MccMountType::FORK_TYPE      ? false
                                           : TYPE == MccMountType::CROSSAXIS_TYPE ? false
                                           : TYPE == MccMountType::ALTAZ_TYPE     ? true
                                                                                  : false;

static consteval bool mccIsEquatorialMount(const MccMountType type)
{
    return type == MccMountType::GERMAN_TYPE      ? true
           : type == MccMountType::FORK_TYPE      ? true
           : type == MccMountType::CROSSAXIS_TYPE ? true
           : type == MccMountType::ALTAZ_TYPE     ? false
                                                  : false;
};

static consteval bool mccIsAltAzMount(const MccMountType type)
{
    return type == MccMountType::GERMAN_TYPE      ? false
           : type == MccMountType::FORK_TYPE      ? false
           : type == MccMountType::CROSSAXIS_TYPE ? false
           : type == MccMountType::ALTAZ_TYPE     ? true
                                                  : false;
};



/*                          FLOATING-POINT LIKE CLASS CONCEPT                           */

template <typename T>
concept mcc_fp_type_like_c =
    std::floating_point<T> ||
    (std::convertible_to<T, double> && std::constructible_from<T, double> && std::default_initializable<T>);



/*                          GEOMETRICAL ANGLE REPRESENTATION CLASS CONCEPT                           */

/*    REQUIREMENT: in the MCC-library it is assumed that an arithmetic representation of angles are measured in the
                   radians!!! This means that possible conversion operator 'SOME_USER_ANGLE_CLASS::operator double()'
                   must return an angle in radians!
 */

template <typename T>
concept mcc_angle_c = mcc_fp_type_like_c<T> && requires(T v, double vd) {
    // mandatory arithmetic operations
    { v + v } -> std::same_as<T>;
    { v - v } -> std::same_as<T>;
    { v += v } -> std::same_as<T&>;
    { v -= v } -> std::same_as<T&>;

    { vd + v } -> std::same_as<T>;
    { vd - v } -> std::same_as<T>;
    { v + vd } -> std::same_as<T>;
    { v - vd } -> std::same_as<T>;
    { v += vd } -> std::same_as<T&>;
    { v -= vd } -> std::same_as<T&>;

    { v * vd } -> std::same_as<T>;
    { v / vd } -> std::same_as<T>;
};



/*                          CELESTIAL COORDINATES EPOCH CLASS CONCEPT                           */

struct mcc_coord_epoch_interface_t {
    virtual ~mcc_coord_epoch_interface_t() = default;

    static constexpr double MJD0 = 2400000.5;

    template <std::derived_from<mcc_coord_epoch_interface_t> SelfT, traits::mcc_input_char_range IR>
    bool fromCharRange(this SelfT&& self, IR&& str)
    {
        return std::forward<decltype(self)>(self).fromCharRange(std::forward<IR>(str));
    }

    template <std::derived_from<mcc_coord_epoch_interface_t> SelfT, typename ClockT, typename DurT>
    bool fromTimePoint(this SelfT&& self, std::chrono::time_point<ClockT, DurT>&& tp)
    {
        return std::forward<decltype(self)>(self).fromTimePoint(std::forward<decltype(tp)>(tp));
    }

    template <std::derived_from<mcc_coord_epoch_interface_t> SelfT, typename VT>
    bool fromMJD(this SelfT&& self, VT&& mjd)
        requires std::is_arithmetic_v<VT>
    {
        return std::forward<decltype(self)>(self).fromMJD(std::forward<VT>(mjd));
    }

    template <std::derived_from<mcc_coord_epoch_interface_t> SelfT, traits::mcc_time_duration_c DT>
    SelfT& operator+=(this SelfT& self, DT&& dt)
    {
        return std::forward<decltype(self)>(self).operator+=(std::forward<DT>(dt));
    }

    template <std::derived_from<mcc_coord_epoch_interface_t> SelfT, traits::mcc_time_duration_c DT>
    SelfT& operator-=(this SelfT& self, DT&& dt)
    {
        return std::forward<decltype(self)>(self).operator-=(std::forward<DT>(dt));
    }
};

template <typename T>
concept mcc_coord_epoch_c = std::derived_from<T, mcc_coord_epoch_interface_t> && requires(T t1, T t2, const T t_const) {
    { t_const.MJD() } -> std::convertible_to<double>;
    { t_const.UTC() } -> traits::mcc_systime_c;
    { t_const.JEpoch() } -> traits::mcc_output_char_range;

    { t1 <=> t2 };

    { T::now() } -> std::same_as<T>;
};



/*                          CELESTIAL COORDINATE TRANSFORMATION ENGINE CLASS CONCEPT                            */

template <typename RetT>
struct mcc_ccte_engine_interface_t {
    virtual ~mcc_ccte_engine_interface_t() = default;

    // returns geographical site coordinates for underlying transformation calculations
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT, mcc_angle_c LAT_T, mcc_angle_c LON_T>
    void geoPosition(this SelfT&& self, std::pair<LAT_T, LON_T>* pos)
    {
        std::forward<SelfT>(self).geoPosition(pos);
    }

    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT, mcc_angle_c StT, mcc_coord_epoch_c EpT>
    auto apparentSideralTime(this SelfT&& self, EpT const& ep, StT* st, bool isLocal)
    {
        return std::forward<SelfT>(self).apparentSideralTime(ep, st, isLocal);
    }

    // from ICRS to observed (taking into account atmospheric refraction) coordinate transformation
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT,
              mcc_angle_c RA_ICRS_T,
              mcc_angle_c DEC_ICRS_T,
              mcc_coord_epoch_c EpT,
              mcc_angle_c RA_OBS_T,
              mcc_angle_c DEC_OBS_T,
              mcc_angle_c HA_OBS_T,
              mcc_angle_c AZ_T,
              mcc_angle_c ZD_T>
    RetT icrsToObs(this SelfT&& self,
                   RA_ICRS_T const& ra_icrs,
                   DEC_ICRS_T const& dec_icrs,
                   EpT const& ep,
                   RA_OBS_T* ra,
                   DEC_OBS_T* dec,
                   HA_OBS_T* ha,
                   AZ_T* az,
                   ZD_T* zd)
    {
        return std::forward<SelfT>(self).icrsToObs(ra_icrs, dec_icrs, ep, ra, dec, ha, az, zd);
    }


    // from ICRS to apparent (in vacuo) coordinate transformation
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT,
              mcc_angle_c RA_ICRS_T,
              mcc_angle_c DEC_ICRS_T,
              mcc_coord_epoch_c EpT,
              mcc_angle_c RA_APP_T,
              mcc_angle_c DEC_APP_T,
              mcc_angle_c HA_APP_T,
              mcc_angle_c AZ_T,
              mcc_angle_c ZD_T>
    RetT icrsToApp(this SelfT&& self,
                   RA_ICRS_T const& ra_icrs,
                   DEC_ICRS_T const& dec_icrs,
                   EpT const& ep,
                   RA_APP_T* ra,
                   DEC_APP_T* dec,
                   HA_APP_T* ha,
                   AZ_T* az,
                   ZD_T* zd)
    {
        return std::forward<SelfT>(self).icrsToApp(ra_icrs, dec_icrs, ep, ra, dec, ha, az, zd);
    }


    // from observed (taking into account atmospheric refraction) to ICRS coordinate transformation
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT,
              mcc_coord_epoch_c EpT,
              mcc_angle_c CO_LON_T,
              mcc_angle_c CO_LAT_T,
              mcc_angle_c RA_ICRS_T,
              mcc_angle_c DEC_ICRS_T>
    RetT obsToICRS(this SelfT&& self,
                   impl::MccCoordPairKind obs_type,
                   EpT const& epoch,
                   CO_LON_T const& co_lon,
                   CO_LAT_T const& co_lat,
                   RA_ICRS_T* ra_icrs,
                   DEC_ICRS_T* dec_icrs)
    {
        return std::forward<SelfT>(self).obsToICRS(epoch, obs_type, co_lon, co_lat, ra_icrs, dec_icrs);
    }


    // from apparent (in vacuo) to ICRS coordinate transformation
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT,
              mcc_coord_epoch_c EpT,
              mcc_angle_c CO_LON_T,
              mcc_angle_c CO_LAT_T,
              mcc_angle_c RA_ICRS_T,
              mcc_angle_c DEC_ICRS_T>
    RetT appToICRS(this SelfT&& self,
                   impl::MccCoordPairKind app_type,
                   EpT const& epoch,
                   CO_LON_T const& co_lon,
                   CO_LAT_T const& co_lat,
                   RA_ICRS_T* ra_icrs,
                   DEC_ICRS_T* dec_icrs)
    {
        return std::forward<SelfT>(self).appToICRS(epoch, app_type, co_lon, co_lat, ra_icrs, dec_icrs);
    }

    // compute equation of origins EO = ERA-GAST
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT, mcc_coord_epoch_c EpT, mcc_angle_c EO_T>
    RetT equationOrigins(this SelfT&& self, EpT const& epoch, EO_T* eo)
    {
        return std::forward<SelfT>(self).equationOrigins(epoch, eo);
    }


    // compute refraction correction from observed zenithal distance
    // (Zapp = Zobs + dZ)
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT, mcc_angle_c ZD_OBS_T, mcc_angle_c DZ_T>
    RetT refractionCorrection(this SelfT&& self, ZD_OBS_T const& zd_obs, DZ_T* dZ)
    {
        return std::forward<SelfT>(self).refractionCorrection(zd_obs, dZ);
    }


    // compute refraction correction from apparent (in vacuo) zenithal distance
    // (Zobs = Zapp - dZ)
    template <std::derived_from<mcc_ccte_engine_interface_t> SelfT, mcc_angle_c ZD_APP_T, mcc_angle_c DZ_T>
    RetT refractionInverseCorrection(this SelfT&& self, ZD_APP_T const& zd_app, DZ_T* dZ)
    {
        return std::forward<SelfT>(self).refractionInverseCorrection(zd_app, dZ);
    }
};


template <typename T>
concept mcc_ccte_c = std::derived_from<T, mcc_ccte_engine_interface_t<typename T::error_t>> && requires {
    // error type
    requires mcc_error_c<typename T::error_t>;

    // static const variable with name of CCTE
    requires std::formattable<decltype(T::ccteName), char> && std::is_const_v<decltype(T::ccteName)>;
};



/*                          COORDINATES PAIR CLASS CONCEPT                          */

struct mcc_coord_pair_interface_t {
    virtual ~mcc_coord_pair_interface_t() = default;

    template <std::derived_from<mcc_coord_pair_interface_t> SelfT, mcc_coord_epoch_c EpT>
    auto setEpoch(this SelfT&& self, EpT const& ep)
    {
        return std::forward<SelfT>(self).setEpoch(ep);
    }
};

template <typename T>
concept mcc_coord_pair_c = std::derived_from<T, mcc_coord_pair_interface_t> && requires(T t, const T t_const) {
    // the 'T' class must contain static constexpr member of 'pairKind' of some type
    // (usually just a enum: see mcc_coordinate.h for an example of the implementation)
    []() {
        [[maybe_unused]] static constexpr auto val = T::pairKind;
    }();  // to ensure 'pairKind' can be used in compile-time context

    requires mcc_angle_c<typename T::x_t>;  // co-longitude coordinate type
    requires mcc_angle_c<typename T::y_t>;  // co-latitude coordinate type

    // std::constructible_from<T, typename T::x_t const&, typename T::y_t const&>;

    { t_const.x() } -> std::same_as<typename T::x_t>;
    { t_const.y() } -> std::same_as<typename T::y_t>;

    { t_const.epoch() } -> mcc_coord_epoch_c;

    { t.setX(std::declval<typename T::x_t const&>()) };
    { t.setY(std::declval<typename T::y_t const&>()) };
};



/*                          SKY POINT CLASS CONCEPT                         */


struct mcc_skypoint_interface_t {
    virtual ~mcc_skypoint_interface_t() = default;

    template <std::derived_from<mcc_skypoint_interface_t> SelfT, mcc_coord_pair_c PT>
    auto from(this SelfT&& self, PT&& cpair)
    {
        return std::forward<SelfT>(self).from(std::forward<PT>(cpair));
    }

    template <std::derived_from<mcc_skypoint_interface_t> SelfT, mcc_coord_pair_c PT>
    auto operator=(this SelfT&& self, PT&& cpair)
    {
        return std::forward<SelfT>(self).operator=(std::forward<PT>(cpair));
    }


    template <std::derived_from<mcc_skypoint_interface_t> SelfT, mcc_coord_pair_c PT, mcc_coord_pair_c... PTs>
    auto to(this SelfT&& self, PT& cpair, PTs&... cpairs)
    {
        return std::forward<SelfT>(self).to(cpair, cpairs...);
    }

    template <std::derived_from<mcc_skypoint_interface_t> SelfT, mcc_coord_pair_c PT>
    operator PT(this SelfT&& self)
    {
        return std::forward<SelfT>(self).operator PT();
    }

    // mandatory specialization conversional operator to
    // get geographic coordinates used in underlying transformation calculations
    // (it are geographic site coordinates mandatory used in celestial coordinate transformation engine
    // of any implementation of skypoint class)
    template <std::derived_from<mcc_skypoint_interface_t> SelfT, mcc_coord_pair_c PT>
        requires(PT::pairKind == impl::MccCoordPairKind::COORDS_KIND_LONLAT)
    operator PT(this SelfT&& self)
    {
        return std::forward<SelfT>(self).operator PT();
    }


    // return coordinates pair at same epoch as 'this' sky point
    template <std::derived_from<mcc_skypoint_interface_t> SelfT, mcc_coord_pair_c PT, mcc_coord_pair_c... PTs>
    auto toAtSameEpoch(this SelfT&& self, PT& cpair, PTs&... cpairs)
    {
        return std::forward<SelfT>(self).to(cpair, cpairs...);
    }


    // Refraction correction for given celestial point.
    // It is assumed that for the apparent (in vacuo) and ICRS kinds of coordinates this correction is 0!
    // The returned refraction correction must be calculated as the correction applied to observed (affected by
    // refraction) zenithal distance to compute apparent (in vacuo) one, i.e., Z_app = Z_obs + refr_corr
    template <std::derived_from<mcc_skypoint_interface_t> SelfT>
    auto refractCorrection(this SelfT&& self, mcc_angle_c auto* dZ)
    {
        return std::forward<SelfT>(self).refractCorrection(dZ);
    }

    // As above but the returned correction must be calculated as the correction applied to apparent (in vacuo)
    // zenithal distance to compute observed (affected by refraction) one, i.e., Z_obs = Z_app - refr_corr.
    // It is assumed that for the observed and ICRS kinds of coordinates this correction is 0!
    template <std::derived_from<mcc_skypoint_interface_t> SelfT>
    auto refractInverseCorrection(this SelfT&& self, mcc_angle_c auto* dZ)
    {
        return std::forward<SelfT>(self).refractInverseCorrection(dZ);
    }

    // returns apparent sideral time (Greenwich or local) for the epoch of the celestial point
    template <std::derived_from<mcc_skypoint_interface_t> SelfT>
    auto appSideralTime(this SelfT&& self, mcc_angle_c auto* st, bool is_local)
    {
        return std::forward<SelfT>(self).appSideralTime(st, is_local);
    }

    // returns equation of origins for the epoch of the celestial point
    template <std::derived_from<mcc_skypoint_interface_t> SelfT>
    auto EO(this SelfT&& self, mcc_angle_c auto* eo)
    {
        return std::forward<SelfT>(self).EO(eo);
    }
};

template <typename T>
concept mcc_skypoint_c = std::derived_from<T, mcc_skypoint_interface_t> && requires(const T t_const) {
    { t_const.epoch() } -> mcc_coord_epoch_c;

    // currently stored coordinates pair
    { t_const.pairKind() } -> std::same_as<impl::MccCoordPairKind>;
};



/*                          POINTING CORRECTION MODEL CLASS CONCEPT                         */



// The result of PCM calculations must be at least corrections along both mount axes
template <typename T>
concept mcc_pcm_result_c = requires(T t) {
    requires mcc_angle_c<decltype(t.pcmX)>;
    requires mcc_angle_c<decltype(t.pcmY)>;
};


template <typename RetT>
struct mcc_pcm_interface_t {
    virtual ~mcc_pcm_interface_t() = default;

    template <std::derived_from<mcc_pcm_interface_t> SelfT, mcc_coord_pair_c HW_COORD_T>
    RetT computePCM(this SelfT&& self,
                    HW_COORD_T const& hw_coord,
                    mcc_pcm_result_c auto* result,
                    mcc_skypoint_c auto* obs_pt)
    {
        return std::forward<SelfT>(self).computePCM(hw_coord, result, obs_pt);
    }


    template <std::derived_from<mcc_pcm_interface_t> SelfT, mcc_coord_pair_c HW_COORD_T>
    RetT computeInversePCM(this SelfT&& self,
                           mcc_skypoint_c auto const& obs_pt,
                           mcc_pcm_result_c auto* inv_result,
                           HW_COORD_T* hw_coord)
    {
        return std::forward<SelfT>(self).computeInversePCM(obs_pt, inv_result, hw_coord);
    }
};


template <typename T>
concept mcc_pcm_c = std::derived_from<T, mcc_pcm_interface_t<typename T::error_t>> && requires {
    // error type
    requires mcc_error_c<typename T::error_t>;

    // the 'T' class must contain static constexpr member of 'MccMountType' type
    requires std::same_as<decltype(T::mountType), const MccMountType>;
    []() {
        [[maybe_unused]] static constexpr MccMountType val = T::mountType;
    }();  // to ensure 'mountType' can be used in compile-time context

    // static const variable with name of PCM
    requires std::formattable<decltype(T::pcmName), char> && std::is_const_v<decltype(T::pcmName)>;
};



/*                          MOUNT HARDWARE ABSTRACTION CLASS CONCEPT                            */


// a type that defines at least HW_MOVE_ERROR, HW_MOVE_STOPPED, HW_MOVE_SLEWING, HW_MOVE_ADJUSTING, HW_MOVE_TRACKING
// and HW_MOVE_GUIDING compile-time constants.
//
// e.g. an implementations can be as follows:
//     enum class hardware_movement_state_t: int {HW_MOVE_ERROR = -1, HW_MOVE_STOPPED = 0, HW_MOVE_SLEWING,
//     HW_MOVE_ADJUSTING, HW_MOVE_TRACKING, HW_MOVE_GUIDING}
//
//     struct hardware_movement_state_t {
//         static constexpr uint16_t HW_MOVE_STOPPED = 0;
//         static constexpr uint16_t HW_MOVE_SLEWING = 111;
//         static constexpr uint16_t HW_MOVE_ADJUSTING = 222;
//         static constexpr uint16_t HW_MOVE_TRACKING = 333;
//         static constexpr uint16_t HW_MOVE_GUIDING = 444;
//         static constexpr uint16_t HW_MOVE_ERROR = 555;
//     }
template <typename T>
concept mcc_hardware_movement_state_c = std::formattable<T, char> && requires {
    []() {
        // // mount axes were stopped
        // [[maybe_unused]] static constexpr auto v0 = T::HW_MOVE_STOPPED;

        // // hardware was asked for slewing (move to given celestial point)
        // [[maybe_unused]] static constexpr auto v1 = T::HW_MOVE_SLEWING;

        // // hardware was asked for adjusting after slewing
        // // (adjusting actual mount position to align with target celestial point at the end of slewing process)
        // [[maybe_unused]] static constexpr auto v2 = T::HW_MOVE_ADJUSTING;

        // // hardware was asked for tracking (track target celestial point)
        // [[maybe_unused]] static constexpr auto v3 = T::HW_MOVE_TRACKING;

        // // hardware was asked for guiding
        // // (small corrections to align actual mount position with target celestial point)
        // [[maybe_unused]] static constexpr auto v4 = T::HW_MOVE_GUIDING;

        // // to detect possible hardware error
        // [[maybe_unused]] static constexpr auto v5 = T::HW_MOVE_ERROR;

        [[maybe_unused]] static constexpr std::array arr{
            // mount hardware was asked to stop
            T::HW_MOVE_STOPPING,

            // mount axes were stopped
            T::HW_MOVE_STOPPED,

            // move to given celestial point
            T::HW_MOVE_SLEWING,

            // adjusting after slewing
            T::HW_MOVE_ADJUSTING,

            // tracking (track target celestial point)
            T::HW_MOVE_TRACKING,

            // guiding (small corrections to align actual mount position with target celestial point)
            T::HW_MOVE_GUIDING,

            // to detect possible hardware error
            T::HW_MOVE_ERROR};
    }();
};


template <typename T>
concept mcc_hardware_state_c = requires(T state) {
    // encoder co-longitude and co-latiitude positions, as well as its measurement time point
    requires mcc_coord_pair_c<decltype(state.XY)> &&
                 (decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_GENERIC ||
                  decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_XY);

    // co-longitude and co-latiitude axis angular speeds, as well as its measurement/computation time point
    requires mcc_coord_pair_c<decltype(state.speedXY)> &&
                 (decltype(state.speedXY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_GENERIC ||
                  decltype(state.speedXY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_XY);


    requires mcc_hardware_movement_state_c<decltype(state.movementState)>;
};


template <typename T>
concept mcc_hardware_c = requires(T t) {
    // error type
    requires mcc_error_c<typename T::error_t>;

    // static const variable with name of hardware
    requires std::formattable<decltype(T::hardwareName), char> && std::is_const_v<decltype(T::hardwareName)>;

    // a type that defines at least HW_MOVE_ERROR, HW_MOVE_STOPPING, HW_MOVE_STOPPED, HW_MOVE_SLEWING,
    // HW_MOVE_ADJUSTING, HW_MOVE_TRACKING and HW_MOVE_GUIDING compile-time constants. The main purpose of this type is
    // a possible tunning of hardware hardwareSetState-related commands and detect the stop and error states from
    // hardware
    //
    // e.g. an implementations can be as follows:
    //     enum class hardware_movement_state_t: int {HW_MOVE_ERROR = -1, HW_MOVE_STOPPED = 0, HW_MOVE_STOPPING,
    //     HW_MOVE_SLEWING, HW_MOVE_ADJUSTING, HW_MOVE_TRACKING, HW_MOVE_GUIDING}
    //
    //     struct hardware_movement_state_t {
    //         static constexpr uint16_t HW_MOVE_STOPPED = 0;
    //         static constexpr uint16_t HW_MOVE_SLEWING = 111;
    //         static constexpr uint16_t HW_MOVE_ADJUSTING = 222;
    //         static constexpr uint16_t HW_MOVE_TRACKING = 333;
    //         static constexpr uint16_t HW_MOVE_GUIDING = 444;
    //         static constexpr uint16_t HW_MOVE_ERROR = 555;
    //         static constexpr uint16_t HW_MOVE_STOPPING = 666;
    //     }

    requires mcc_hardware_movement_state_c<typename T::hardware_movement_state_t>;

    // requires requires(typename T::hardware_movement_state_t type) {
    //     []() {
    //         // mount axes were stopped
    //         static constexpr auto v0 = T::hardware_movement_state_t::HW_MOVE_STOPPED;

    //         // hardware was asked for slewing (move to given celestial point)
    //         static constexpr auto v1 = T::hardware_movement_state_t::HW_MOVE_SLEWING;

    //         // hardware was asked for adjusting after slewing
    //         // (adjusting actual mount position to align with target celestial point at the end of slewing process)
    //         static constexpr auto v2 = T::hardware_movement_state_t::HW_MOVE_ADJUSTING;

    //         // hardware was asked for tracking (track target celestial point)
    //         static constexpr auto v3 = T::hardware_movement_state_t::HW_MOVE_TRACKING;

    //         // hardware was asked for guiding
    //         // (small corrections to align actual mount position with target celestial point)
    //         static constexpr auto v4 = T::hardware_movement_state_t::HW_MOVE_GUIDING;

    //         // to detect possible hardware error
    //         static constexpr auto v5 = T::hardware_movement_state_t::HW_MOVE_ERROR;
    //     }();
    // };

    requires mcc_hardware_state_c<typename T::hardware_state_t> && requires(typename T::hardware_state_t state) {
        requires std::same_as<decltype(state.movementState), typename T::hardware_movement_state_t>;
    };

    // requires requires(typename T::hardware_state_t state) {
    //     // encoder co-longitude and co-latiitude positions, as well as its measurement time point
    //     // the given constrains on coordinate pair kind can be used to deduce mount type
    //     requires mcc_coord_pair_c<decltype(state.XY)> &&
    //                  (  // for equathorial mount:
    //                      decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_HADEC_OBS ||
    //                      // for alt-azimuthal mount:
    //                      decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_AZALT ||
    //                      decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_AZZD);

    //     // co-longitude and co-latiitude axis angular speeds, as well as its measurement/computation time point
    //     requires mcc_coord_pair_c<decltype(state.speedXY)> &&
    //                  (decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_GENERIC ||
    //                   decltype(state.XY)::pairKind == impl::MccCoordPairKind::COORDS_KIND_XY);


    //     requires std::same_as<typename T::hardware_movement_state_t, decltype(state.movementState)>;
    // };


    // set hardware state:
    { t.hardwareSetState(std::declval<typename T::hardware_state_t const&>()) } -> std::same_as<typename T::error_t>;

    // get current state
    { t.hardwareGetState(std::declval<typename T::hardware_state_t*>()) } -> std::same_as<typename T::error_t>;

    // { t.hardwareStop() } -> std::same_as<typename T::error_t>;  // stop any moving
    { t.hardwareInit() } -> std::same_as<typename T::error_t>;  // initialize hardware
};


/*                          MOUNT TELEMETRY DATA CLASS CONCEPT                          */

template <typename T>
concept mcc_telemetry_data_c = requires(T t) {
    // target celestial point (position on sky where mount must be slewed)
    requires mcc_skypoint_c<decltype(t.targetPos)>;

    // mount current celestial position
    requires mcc_skypoint_c<decltype(t.mountPos)>;

    // hardware state
    requires mcc_hardware_state_c<decltype(t.hwState)>;

    // corrections to transform hardware encoder coordinates to observed celestial ones
    requires mcc_pcm_result_c<decltype(t.pcmCorrection)>;

    // requires mcc_angle_c<decltype(t.pcmX)>;  // PCM correction along X-axis
    // requires mcc_angle_c<decltype(t.pcmY)>;  // PCM correction along Y-axis

    // // atmospheric refraction correction for current zenithal distance
    // requires mcc_angle_c<decltype(t.refCorr)>;


    // // current local apparent sideral time
    // requires mcc_angle_c<decltype(t.LST)>;

    // // equation of the origins (ERA-GST)
    // requires mcc_angle_c<decltype(t.EO)>;

    // // target celestial point
    // { t.targetPos() } -> mcc_skypoint_c;

    // // mount current celestial position
    // { t.mountPos() } -> mcc_skypoint_c;

    // // hardware state
    // { t.hwState() } -> mcc_hardware_c;

    // // corrections to transform hardware encoder coordinates to observed celestial ones
    // { t.pcmData() } -> mcc_pcm_result_c;

    // // // atmospheric refraction correction for current mount zenithal distance
    // // { t.refractionCorr() } -> mcc_angle_c;

    // // current local apparent sideral time
    // { t.LST() } -> mcc_angle_c;

    // // equation of the origins (ERA-GST)
    // { t.EO() } -> mcc_angle_c;
};


/*                          MOUNT TELEMETRY CLASS CONCEPT                          */

template <typename RetT>
struct mcc_telemetry_interface_t {
    virtual ~mcc_telemetry_interface_t() = default;

    // set target position
    template <std::derived_from<mcc_telemetry_interface_t> SelfT>
    RetT setTarget(this SelfT&& self, mcc_skypoint_c auto const& pt)
    {
        return std::forward<SelfT>(self).setTarget(pt);
    }

    // get entered target position
    template <std::derived_from<mcc_telemetry_interface_t> SelfT>
    RetT setTarget(this SelfT&& self, mcc_skypoint_c auto* pt)
    {
        return std::forward<SelfT>(self).getTarget(pt);
    }
};

template <typename T>
concept mcc_telemetry_c = std::derived_from<T, mcc_telemetry_interface_t<typename T::error_t>> && requires(T t) {
    // error type
    requires mcc_error_c<typename T::error_t>;

    // telemetry data type definition
    requires mcc_telemetry_data_c<typename T::telemetry_data_t>;

    // get telemetry data
    { t.telemetryData(std::declval<typename T::telemetry_data_t*>()) } -> std::same_as<typename T::error_t>;
};



/*                          PROHIBITED ZONE CLASS CONCEPT                           */


enum class MccProhibitedZonePolicy : int {
    PZ_POLICY_STOP,  // stop mount near the zone
    PZ_POLICY_FLIP   // flip mount, e.g., near the meridian, near HA-axis encoder limit switch
};


template <typename RetT>
struct mcc_pzone_interface_t {
    virtual ~mcc_pzone_interface_t() = default;

    template <std::derived_from<mcc_pzone_interface_t> SelfT>
    RetT inPZone(this SelfT&& self, mcc_skypoint_c auto const& coords, bool* result)
    {
        return std::forward<SelfT>(self).inPZone(coords, result);
    }

    template <std::derived_from<mcc_pzone_interface_t> SelfT>
    RetT timeToPZone(this SelfT&& self, mcc_skypoint_c auto const& coords, traits::mcc_time_duration_c auto* res_time)
    {
        return std::forward<SelfT>(self).timeToPZone(coords, res_time);
    }

    template <std::derived_from<mcc_pzone_interface_t> SelfT>
    RetT timeFromPZone(this SelfT&& self, mcc_skypoint_c auto const& coords, traits::mcc_time_duration_c auto* res_time)
    {
        return std::forward<SelfT>(self).timeFromPZone(coords, res_time);
    }
};


template <typename T>
concept mcc_pzone_c = std::derived_from<T, mcc_pzone_interface_t<typename T::error_t>> && requires(T t) {
    // error type
    requires mcc_error_c<typename T::error_t>;

    // static constant member with prohibitted zone name
    requires std::formattable<decltype(T::pzoneName), char> && std::is_const_v<decltype(T::pzoneName)>;

    // the 'T' class must contain static constexpr member of 'MccProhibitedZonePolicy' type
    requires std::same_as<decltype(T::pzPolicy), const MccProhibitedZonePolicy>;
    []() {
        [[maybe_unused]] static constexpr MccProhibitedZonePolicy val = T::pzPolicy;
    }();  // to ensure 'pzPolicy' can be used in compile-time context
};


/*                          PROHIBITED ZONES CONTAINER CLASS CONCEPT                           */

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


    template <std::derived_from<mcc_pzone_container_interface_t> SelfT>
    size_t addPZone(this SelfT&& self, mcc_pzone_c auto zone)
    {
        return std::forward<SelfT>(self).addPZone(std::move(zone));
    }


    template <std::derived_from<mcc_pzone_container_interface_t> SelfT>
    void clearPZones(this SelfT&& self)
    {
        return std::forward<SelfT>(self).clearPZones();
    }


    template <std::derived_from<mcc_pzone_container_interface_t> SelfT>
    size_t sizePZones(this SelfT&& self)
    {
        return std::forward<SelfT>(self).sizePZones();
    }


    template <std::derived_from<mcc_pzone_container_interface_t> SelfT>
    RetT inPZone(this SelfT&& self,
                 mcc_skypoint_c auto const& coords,
                 bool* at_least_one,
                 std::ranges::output_range<bool> auto* result)
    {
        return std::forward<SelfT>(self).inPZone(coords, at_least_one, result);
    }


    template <std::derived_from<mcc_pzone_container_interface_t> SelfT, traits::mcc_time_duration_c DT>
    RetT timeToPZone(this SelfT&& self, mcc_skypoint_c auto const& coords, std::ranges::output_range<DT> auto* res_time)
    {
        return std::forward<SelfT>(self).timeToPZone(coords, res_time);
    }

    template <std::derived_from<mcc_pzone_container_interface_t> SelfT, traits::mcc_time_duration_c DT>
    RetT timeFromPZone(this SelfT&& self,
                       mcc_skypoint_c auto const& coords,
                       std::ranges::output_range<DT> auto* res_time)
    {
        return std::forward<SelfT>(self).timeFromPZone(coords, res_time);
    }
};


template <typename T>
concept mcc_pzone_container_c = std::derived_from<T, mcc_pzone_container_interface_t<typename T::error_t>> && requires {
    // error type
    requires mcc_error_c<typename T::error_t>;
};



/*                          A CONCEPT FOR MOUNT MOVEMENT CONTROLS CLASS                         */


template <typename T>
concept mcc_movement_controls_c = requires(T t) {
    // error type
    requires mcc_error_c<typename T::error_t>;

    // movement parameters holder type
    typename T::movement_params_t;

    // argument of the method:
    //     true - slew and stop
    //     false - slew and track
    { t.slewToTarget(std::declval<bool>()) } -> std::same_as<typename T::error_t>;

    { t.trackTarget() } -> std::same_as<typename T::error_t>;

    { t.stopMount() } -> std::same_as<typename T::error_t>;

    { t.setMovementParams(std::declval<typename T::movement_params_t const&>()) } -> std::same_as<typename T::error_t>;

    { t.getMovementParams() } -> std::same_as<typename T::movement_params_t>;
};



/*                          GENERIC MOUNT CLASS CONCEPT                         */


// minimal set of the mount status constants
template <typename T>
concept mcc_mount_status_c = requires {
    []() {
        [[maybe_unused]]
        static constexpr std::array arr = {T::MOUNT_STATUS_ERROR,          T::MOUNT_STATUS_IDLE,
                                           T::MOUNT_STATUS_INITIALIZATION, T::MOUNT_STATUS_STOPPED,
                                           T::MOUNT_STATUS_SLEWING,        T::MOUNT_STATUS_ADJUSTING,
                                           T::MOUNT_STATUS_GUIDING,        T::MOUNT_STATUS_TRACKING};
    };  // to ensure mount status is compile-time constants
};



template <typename T>
concept mcc_generic_mount_c =
    mcc_logger_c<T> && mcc_pzone_container_c<T> && mcc_telemetry_c<T> && mcc_movement_controls_c<T> && requires(T t) {
        // error type
        requires mcc_error_c<typename T::error_t>;

        requires mcc_mount_status_c<typename T::mount_status_t>;

        { t.initMount() } -> std::same_as<typename T::error_t>;

        { t.mountStatus() } -> std::same_as<typename T::mount_status_t>;
    };


}  // namespace mcc