#pragma once
#include <vector>
#include "double3.h"

class External_gravity {
public:
    void apply(const int n_act, const std::vector<double3> &x, const std::vector<double3> &v, std::vector<double> &pot, std::vector<double3> &a, std::vector<double3> &adot)
    {
        for (int i=0; i<n_act; i++) {
            this->set_coordinates(x[i], v[i]);
            this->calc_gravity();
            pot[i]  += potential;
            a[i]    += acceleration;
            adot[i] += jerk;
        }
    }
    virtual void calc_gravity() = 0;
    bool is_active;
protected:
    double potential;
    double3 acceleration, jerk;
    double3 x, v;
    void set_coordinates(double3 x, double3 v)
    {
        this->x = x;
        this->v = v;
    }
};

class Plummer : public External_gravity {
public:
    Plummer(double m, double b) : m(m), b(b) {is_active=(m>0);}
    void calc_gravity();
private:
    double m, b;
};

class Miyamoto_Nagai : public External_gravity {
public:
    Miyamoto_Nagai(double m, double a, double b) : m(m), a(a), b(b) {is_active=(m>0);}
    void calc_gravity();
private:
    double m, a, b;
};

class Logarithmic_halo : public External_gravity {
public:
    Logarithmic_halo(double v_halo, double r_halo) : v2_halo(v_halo*v_halo), r2_halo(r_halo*r_halo) {is_active=(r_halo>0);}
    void calc_gravity();
private:
    double v2_halo, r2_halo;
};

class Dehnen : public External_gravity {
public:
    Dehnen(double m, double r, double gamma) : m(m), r(r), gamma(gamma) {is_active=(m>0);}
    void calc_gravity();
private:
    double m, r, gamma;
};