engine-sim-cpp/engine/engine.h

#pragma once

// Crankshaft rotational dynamics. Placeholder physics for now —
// real combustion/friction torque modeling comes later.
class Engine {
public:
    // load_torque_nm is the resistance fed back from the transmission
    // (via the vehicle), opposing crank rotation.
    void step(double dt, double load_torque_nm);

    double rpm() const;
    double torque_nm() const; // net torque produced this step

    void set_throttle(double throttle);
    double get_throttle();
    void reset();

private:
    double m_rpm = 0.0;
    double m_torque_nm = 0.0;

    // Fluids
    double m_oil_capacity = 0.0;
    double m_coolant_capacity = 0.0;

    double m_oil_temp = 0.0;
    double m_coolant_temp = 0.0;

    // User Input
    double m_throttle = 0.0;

    static constexpr double kIdleRpm = 1700.0;
    static constexpr double kCrankInertiaKgm2 = 0.15; // placeholder
};