eop.hpp

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#pragma once
 
#include "ffi_core.hpp"
#include <cmath>
#include <optional>
 
namespace tempoch {
 
// ============================================================================
// EopValues
// ============================================================================
 
struct EopValues {
  double mjd_utc;
  std::optional<double> pm_xp_arcsec;
  std::optional<double> pm_yp_arcsec;
  double ut1_minus_utc;
  std::optional<double> lod_milliseconds;
  std::optional<double> dx_milliarcsec;
  std::optional<double> dy_milliarcsec;
  bool ut1_observed;
};
 
// ============================================================================
// Free functions
// ============================================================================
 
inline bool eop_covers(double mjd_utc) noexcept { return tempoch_eop_covers(mjd_utc); }
 
inline std::optional<EopValues> eop_at(double mjd_utc) {
  tempoch_eop_values_t raw{};
  tempoch_status_t status = tempoch_eop_at(mjd_utc, &raw);
 
  if (status == TEMPOCH_STATUS_T_UT1_HORIZON_EXCEEDED)
    return std::nullopt;
 
  check_status(status, "eop_at");
 
  auto nan_to_opt = [](double v) -> std::optional<double> {
    return std::isnan(v) ? std::nullopt : std::optional<double>{v};
  };
 
  return EopValues{
      raw.mjd_utc,
      nan_to_opt(raw.pm_xp_arcsec),
      nan_to_opt(raw.pm_yp_arcsec),
      raw.ut1_minus_utc,
      nan_to_opt(raw.lod_milliseconds),
      nan_to_opt(raw.dx_milliarcsec),
      nan_to_opt(raw.dy_milliarcsec),
      raw.ut1_observed != 0,
  };
}
 
} // namespace tempoch