satellite.hpp

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// SPDX-License-Identifier: BSD-3-Clause
// Copyright (C) 2026 Vallés Puig, Ramon
 
#pragma once

 
#include <array>
#include <string_view>
 
#include "ffi_core.hpp"
#include "units/dimensionless.hpp"
#include "units/length.hpp"
#include "units/time.hpp"
#include "units/velocity.hpp"
 
namespace qtty {
namespace satellite {
 
// ── Compound kinematic unit aliases ─────────────────────────────────────────

using KmPerSeconds = Quantity<CompoundTag<KilometerTag, SecondTag>>;
 
// ── Gravitational parameter μ = G·M (km³/s²) ────────────────────────────────
 
struct GravitationalParameterTag {};

using GravitationalParameter = Quantity<GravitationalParameterTag>;
 
// Canonical μ values (km³/s²), matching qtty::dynamics.
inline const GravitationalParameter GM_EARTH{398600.4418};
inline const GravitationalParameter GM_SUN{1.32712440018e11};
inline const GravitationalParameter GM_MOON{4.902800066e3};
inline const GravitationalParameter GM_MERCURY{2.2031878328e4};
inline const GravitationalParameter GM_VENUS{3.24858592e5};
inline const GravitationalParameter GM_MARS{4.2828375816e4};
inline const GravitationalParameter GM_JUPITER{1.267127648e8};
inline const GravitationalParameter GM_SATURN{3.79405852e7};
inline const GravitationalParameter GM_URANUS{5.7945486e6};
inline const GravitationalParameter GM_NEPTUNE{6.8365271005e6};
inline const GravitationalParameter GM_PLUTO{9.770e2};
 
// ── Dimensionless astrodynamics coefficients ────────────────────────────────

class DragCoefficient {
public:
  constexpr explicit DragCoefficient(double value) : m_value(value) {}
  constexpr double value() const { return m_value; }
 
private:
  double m_value;
};

class SrpCoefficient {
public:
  constexpr explicit SrpCoefficient(double value) : m_value(value) {}
  constexpr double value() const { return m_value; }
 
private:
  double m_value;
};

class J2Coefficient {
public:
  constexpr explicit J2Coefficient(double value) : m_value(value) {}
  constexpr double value() const { return m_value; }
 
private:
  double m_value;
};

class StokesCoefficient {
public:
  constexpr explicit StokesCoefficient(double value) : m_value(value) {}
  constexpr double value() const { return m_value; }
 
private:
  double m_value;
};
 
// ── Integrator tolerances ───────────────────────────────────────────────────

class RelativeTolerance {
public:
  constexpr explicit RelativeTolerance(double value) : m_value(value) {}
  constexpr double value() const { return m_value; }
 
private:
  double m_value;
};

class AbsoluteTolerancePosition {
public:
  constexpr explicit AbsoluteTolerancePosition(Kilometer quantity) : m_value(quantity) {}
  static AbsoluteTolerancePosition new_km(double value) {
    return AbsoluteTolerancePosition(Kilometer(value));
  }
  double value() const { return m_value.value(); }
 
private:
  Kilometer m_value;
};

class AbsoluteToleranceVelocity {
public:
  constexpr explicit AbsoluteToleranceVelocity(KmPerSeconds quantity) : m_value(quantity) {}
  static AbsoluteToleranceVelocity new_km_s(double value) {
    return AbsoluteToleranceVelocity(KmPerSeconds(value));
  }
  double value() const { return m_value.value(); }
 
private:
  KmPerSeconds m_value;
};

struct IntegratorTolerances {
  RelativeTolerance rel;
  std::array<AbsoluteTolerancePosition, 3> abs_pos;
  std::array<AbsoluteToleranceVelocity, 3> abs_vel;

  static IntegratorTolerances uniform(double rel, double abs_pos_km, double abs_vel_km_s) {
    AbsoluteTolerancePosition p = AbsoluteTolerancePosition::new_km(abs_pos_km);
    AbsoluteToleranceVelocity v = AbsoluteToleranceVelocity::new_km_s(abs_vel_km_s);
    return IntegratorTolerances{RelativeTolerance(rel), {p, p, p}, {v, v, v}};
  }
};
 
} // namespace satellite
} // namespace qtty