#pragma once

/*********************************
 *    MOUNT CONTROL COMPONENTS    *
 *                                *
 *      astrometry functions      *
 *********************************/

#include <chrono>
#include <xsimd/xsimd.hpp>


namespace mcc::traits
{

template <typename T>
concept mcc_scalar_or_simd_c = xsimd::is_batch<T>::value || std::is_arithmetic_v<T>;

}  // namespace mcc::traits


namespace mcc::astro
{

// modified Julian date (based on ERFA eraCal2jd)
// template <traits::mcc_scalar_or_simd_c T>
static int mcc_julday(const std::chrono::system_clock::time_point& start_time,
                      const std::chrono::system_clock::duration& step,
                      std::vector<double, xsimd::default_allocator<double>>& mjd)
{
    if (mjd.empty()) {
        return -100;
    }

    using namespace std::literals::chrono_literals;

    auto dd = std::chrono::floor<std::chrono::days>(start_time);
    std::chrono::year_month_day ymd{dd};

    static constexpr std::chrono::year MIN_YEAR = -4799y;

    if (ymd.year() < MIN_YEAR) {
        return -1;
    }
    if (!ymd.month().ok()) {
        return -2;
    }

    // my = (im - 14) / 12;
    // iypmy = (long) (iy + my);

    int64_t my = -(14 - (unsigned)ymd.month()) / 12;
    int64_t iypmy = (int)ymd.year() + my;

    // (1461L * (iypmy + 4800L)) / 4L
    //     + (367L * (long) (im - 2 - 12 * my)) / 12L
    //     - (3L * ((iypmy + 4900L) / 100L)) / 4L
    //     + (long) id - 2432076L

    // integer part of result MJD
    int64_t mjd_int = 1461LL * (iypmy + 480LL) / 4LL +
                      (367LL * ((int64_t)(unsigned)ymd.month() - 2LL - 12LL * my)) / 12LL -
                      (3LL * (iypmy + 4900LL) / 100LL) / 4LL + (int64_t)(unsigned)ymd.day() - 2432076LL;

    constexpr double nanosec = 1.0 / 24.0 / 3600.0 / 1.0E-9;  // 1 nanosecond in days

    double mjd_float = static_cast<double>(mjd_int) +
                       std::chrono::duration_cast<std::chrono::nanoseconds>(start_time - dd).count() * nanosec;
    double d_step = std::chrono::duration_cast<std::chrono::nanoseconds>(step).count() * nanosec;

    constexpr size_t reg_size = xsimd::batch<double>::size;
    size_t vec_size = mjd.size() - mjd.size() % reg_size;

    xsimd::batch<double> res_reg{mjd_float};
    xsimd::batch<double> step_reg = [d_step]<size_t... Is>(std::index_sequence<Is...>) {
        return xsimd::batch<double>{(Is * d_step)...};
    }(std::make_index_sequence<reg_size>{});

    // vectorized part
    size_t i = 0;
    for (; i < vec_size; i += vec_size) {
        res_reg += step_reg;

        res_reg.store_aligned(mjd.data() + i);
    }

    // scalar part
    for (size_t j = i; j < mjd.size(); ++j) {
        mjd[j] = mjd_float + j * d_step;
    }


    return 0;
}

template <traits::mcc_scalar_or_simd_c T, typename CT, typename DT>
T mcc_time_to_alt_limit(const T& alt_limit, const T& RA, const T& DEC, const std::chrono::time_point<CT, DT>& now)
{
}

}  // namespace mcc::astro