#pragma once


/*  MOUNT CONTROL COMPONENTS LIBRARY  */

/*  AN REFERENCE "PERIODIC-ERROR-CORRECTION" CLASS IMPLEMENTATION  */


#include <mutex>
#include "fitpack/fitpack.h"
#include "mcc_mount_coord.h"

namespace mcc
{


namespace traits
{

template <typename T, typename XT, typename YT>
concept mcc_mount_pec_c = requires(T t, const T t_const, XT x, YT y) {
    typename T::pec_data_t;
    typename T::pec_result_t;

    { t.setData(std::declval<typename T::pec_data_t>()) };
    { t_const.getData() } -> std::same_as<typename T::pec_data_t>;

    { t.compute(std::declval<const XT&>(), std::declval<const YT&>()) } -> std::same_as<typename T::pec_result_t>;
};

}  // namespace traits

// type of PEC corrections (algorithm used):
//     PEC_TYPE_GEOMETRY - "classic" geometry-based correction coefficients
//     PEC_TYPE_GEOMETRY_BSPLINE - previous one and additional 2D B-spline corrections
//     PEC_TYPE_BSPLINE - pure 2D B-spline corrections
enum class MccMountDefaultPECType { PEC_TYPE_GEOMETRY, PEC_TYPE_GEOMETRY_BSPLINE, PEC_TYPE_BSPLINE };

class MccMountDefaultPEC
{
public:
    struct pec_result_t {
        MccAngle dx, dy;
    };

    // "classic" geometric PEC coefficients
    struct pec_geom_coeffs_t {
        typedef double coeff_t;

        coeff_t zeroPointX;
        coeff_t zeroPointY;
        coeff_t collimationErr;  // tube collimation error
        coeff_t nonperpendErr;   // X-Y axes nonperpendicularity
        coeff_t misalignErr1;    // misalignment of hour-angle/azimuth axis: left-right for equatorial, East-West for
                                 // alt-azimuthal
        coeff_t misalignErr2;    // misalignment of hour-angle/azimuth axis: vertical for equatorial, North-South for
                                 // alt-azimuthal

        coeff_t tubeFlexure;
        coeff_t forkFlexure;
        coeff_t DECaxisFlexure;  // declination axis flexure
    };

    // B-splines coefficients
    struct pec_bspline_coeffs_t {
        typedef double knot_t;
        typedef double coeff_t;

        size_t bsplDegreeX = 3;
        size_t bsplDegreeY = 3;

        std::vector<knot_t> knotsX{};
        std::vector<knot_t> knotsY{};

        std::vector<coeff_t> coeffsX{};
        std::vector<coeff_t> coeffsY{};
    };

    struct pec_data_t {
        MccMountDefaultPECType type{MccMountDefaultPECType::PEC_TYPE_GEOMETRY};
        double siteLatitude{0.0};  // in radians
        pec_geom_coeffs_t geomCoefficients{};
        pec_bspline_coeffs_t bsplineCoefficients{};
    };

    // constructors

    MccMountDefaultPEC(pec_data_t pdata)
        : _pecData(std::move(pdata)),
          _phi(_pecData.siteLatitude),
          _geomCoeffs(_pecData.geomCoefficients),
          _bsplCoeffs(_pecData.bsplineCoefficients)
    {
    }


    void setData(pec_data_t pdata)
    {
        std::lock_guard lock(_pecDataMutex);

        _pecData = std::move(pdata);
        _phi = _pecData.siteLatitude;
        _geomCoeffs = _pecData.geomCoefficients;
        _bsplCoeffs = _pecData.bsplineCoefficients;
    }


    pec_data_t getData() const
    {
        std::lock_guard lock(_pecDataMutex);

        return _pecData;
    }

    void setType(MccMountDefaultPECType type)
    {
        std::lock_guard lock(_pecDataMutex);

        _pecData.type = type;
    }

    MccMountDefaultPECType getType() const
    {
        std::lock_guard lock(_pecDataMutex);

        return _pecData.type;
    }

    // X and Y axis encoder coordinates
    template <std::derived_from<MccAngle> XT, std::derived_from<MccAngle> YT>
    pec_result_t compute(const XT& x, const YT& y)
    {
        static constexpr MccCoordPairKind coord_kind = traits::mcc_type_pair_hash<XT, YT>();

        pec_result_t res{0.0, 0.0};

        std::lock_guard lock(_pecDataMutex);

        if constexpr (coord_kind == MccCoordPairKind::COORDS_KIND_HADEC_APP) {
            if (_pecData.type == MccMountDefaultPECType::PEC_TYPE_GEOMETRY) {
                const auto cosPhi = std::cos(_phi);
                const auto sinPhi = std::sin(_phi);
                const auto tanY = std::tan(y);
                const auto sinX = std::sin(x);
                const auto cosX = std::cos(x);
                const auto cosY = std::cos(y);


                if (utils::isEqual(cosY, 0.0)) {
                    res.dx = _geomCoeffs.zeroPointX;
                } else {
                    res.dx = _geomCoeffs.zeroPointX + _geomCoeffs.collimationErr / cosY +
                             _geomCoeffs.nonperpendErr * tanY - _geomCoeffs.misalignErr1 * cosX * tanY +
                             _geomCoeffs.misalignErr2 * sinX * tanY + _geomCoeffs.tubeFlexure * cosPhi * sinX / cosY -
                             _geomCoeffs.DECaxisFlexure * (cosPhi * cosX + sinPhi * tanY);
                }

                res.dy = _geomCoeffs.zeroPointY + _geomCoeffs.misalignErr1 * sinX + _geomCoeffs.misalignErr2 * cosX +
                         _geomCoeffs.tubeFlexure * (cosPhi * cosX * std::sin(y) - sinPhi * cosY);
                if (!utils::isEqual(cosX, 0.0)) {
                    res.dy += _geomCoeffs.forkFlexure / cosX;
                }
            }

            if (_pecData.type == MccMountDefaultPECType::PEC_TYPE_BSPLINE ||
                _pecData.type == MccMountDefaultPECType::PEC_TYPE_GEOMETRY_BSPLINE) {
                double spl_valX, spl_valY;

                int ret = fitpack::fitpack_eval_spl2d(_bsplCoeffs.knotsX, _bsplCoeffs.knotsY, _bsplCoeffs.coeffsX, x, y,
                                                      spl_valX, _bsplCoeffs.bsplDegreeX, _bsplCoeffs.bsplDegreeY);

                if (ret) {
                    res.dx = std::numeric_limits<double>::quiet_NaN();
                    res.dy = std::numeric_limits<double>::quiet_NaN();
                    return res;
                }


                ret = fitpack::fitpack_eval_spl2d(_bsplCoeffs.knotsX, _bsplCoeffs.knotsY, _bsplCoeffs.coeffsY, x, y,
                                                  spl_valY, _bsplCoeffs.bsplDegreeX, _bsplCoeffs.bsplDegreeY);

                if (ret) {
                    res.dx = std::numeric_limits<double>::quiet_NaN();
                    res.dy = std::numeric_limits<double>::quiet_NaN();
                    return res;
                }


                res.dx += spl_valX;
                res.dy += spl_valY;
            }
        } else if constexpr (coord_kind == MccCoordPairKind::COORDS_KIND_AZALT) {
        } else {
            static_assert(false, "UNSUPPORTED");
        }

        return res;
    }


    // X and Y apparent equatorial/altazimuthal coordinates (not corrected for refraction)
    template <std::derived_from<MccAngle> XT, std::derived_from<MccAngle> YT>
    pec_result_t computeInverse(const XT& x, const YT& y)
    {
        static constexpr MccCoordPairKind coord_kind = traits::mcc_type_pair_hash<XT, YT>();

        pec_result_t res{0.0, 0.0};

        if constexpr (coord_kind == MccCoordPairKind::COORDS_KIND_HADEC_APP) {
        } else if constexpr (coord_kind == MccCoordPairKind::COORDS_KIND_AZALT) {
        } else {
            static_assert(false, "UNSUPPORTED");
        }

        return res;
    }

private:
    pec_data_t _pecData;
    double& _phi;
    pec_geom_coeffs_t& _geomCoeffs;
    pec_bspline_coeffs_t& _bsplCoeffs;

    mutable std::mutex _pecDataMutex;
};

}  // namespace mcc