#pragma once

#include <array>
#include <cstddef>

namespace fluidsim::port {

// Lumped carburetor shared by two-stroke and four-stroke scenarios. The
// jets use liquid-orifice flow from a float bowl into the measured venturi
// depression. Delivered fuel is injected into the downstream fluid volume and
// is then transported as a conserved species; this class never doses a cylinder.
struct CarburetorConfig {
    float fuel_density{740.0f};
    float pilot_jet_diameter{0.00040f}, main_jet_diameter{0.00150f};
    float needle_jet_diameter{0.00190f};
    // Needle annulus area corrections at configured slide positions; jets meter
    // liquid fuel from measured pressure, without AFR feedback.
    float needle_low_scale{1.f}, needle_mid_scale{1.f};
    float needle_off_idle_scale{1.f}, needle_transition_scale{1.f}, needle_tip_scale{1.f};
    float needle_quarter_scale{1.f}, needle_upper_scale{1.f};
    float pilot_transition_scale{1.f}, pilot_tip_scale{1.f};
    float pilot_discharge_coefficient{0.62f}, main_discharge_coefficient{0.72f};
    float bowl_head_pressure{};
    float film_fraction{0.28f}, film_time_constant{0.11f};
    float bowl_capacity{0.008f}, bowl_refill_rate{0.0025f}; // kg, kg/s
    float overrun_rpm{4200.0f}, overrun_exit_rpm{3300.0f};

};

class Carburetor : public CarburetorConfig {
public:
    explicit Carburetor(float throat_diameter = 0.0381f);

    // air_mass_flow is positive from atmosphere toward the engine.
    void step(float dt, float pedal, float slide, float rpm, float air_mass_flow,
              float air_density, float upstream_pressure, float downstream_pressure);

    float indicated_afr() const { return indicated_afr_; }
    float fuel_flow() const { return delivered_fuel_flow_; }
    float film_mass() const { return film_mass_; }
    float bowl_level() const { return bowl_mass_ / bowl_capacity; }
    bool overrun_active() const { return overrun_; }
    bool fault() const { return fault_; }
    float venturi_depression() const { return venturi_depression_; }

private:
    float bowl_mass_{}, film_mass_{};
    float throat_area_{}, venturi_depression_{};
    float filtered_air_flow_{}, filtered_fuel_flow_{}, delivered_fuel_flow_{};
    float indicated_afr_{13.5f};
    float previous_pedal_{}, lift_enrichment_{};
    bool initialized_{}, overrun_{}, fault_{};
};

} // namespace fluidsim::port