#ifndef PHYSICS_H
#define PHYSICS_H

// Forward declaration
struct CelestialBody;

// 3D Vector
struct Vec3 {
    double x, y, z;
};

// Gravitational constant (m^3 kg^-1 s^-2)
const double G = 6.67430e-11;

// Vector math functions
Vec3 vec3_add(Vec3 a, Vec3 b);
Vec3 vec3_sub(Vec3 a, Vec3 b);
Vec3 vec3_cross(Vec3 a, Vec3 b);
Vec3 vec3_scale(Vec3 v, double s);
double vec3_magnitude(Vec3 v);
double vec3_distance(Vec3 a, Vec3 b);
Vec3 vec3_normalize(Vec3 v);

// Physics functions
Vec3 calculate_acceleration(Vec3 force, double mass);

// Forward declaration for RK4 context
struct SimulationState;

struct AccelerationContext {
    SimulationState* sim;
    CelestialBody* current_body;
    int body_index;
};

void rk4_step(CelestialBody* body, AccelerationContext* ctx, double dt);

#endif