#ifndef SPHERE_H
#define SPHERE_H

#include "hittable.hpp"
#include "vec3.hpp"

struct sphere : hittable {
    /* Attributes */
    point3 center;
    double radius;

    /* Contructor */
    sphere(point3 c, double r)
    {
        center = c;
        radius = r;
    }

    /* Virtual methods declaration */
    virtual bool hit(const ray& r, double t_min, double t_max, hit_record& rec) const override;
};

/* Virtual method implementations */
bool sphere::hit(const ray& r, double t_min, double t_max, hit_record& rec) const
{
    vec3 oc = r.origin - center;
    double a = r.direction.length_squared();
    double half_b = dot(oc, r.direction);
    double c = oc.length_squared() - radius*radius;

    double discriminant = half_b*half_b - a*c;
    if (discriminant < 0)
        return false;
    double sqrtd = sqrt(discriminant);

    // Find the nearest root that lies in the acceptable range
    double root = (-half_b - sqrtd) / a;
    if (root < t_min || t_max < root)
    {
        root = (-half_b + sqrtd) / a;
        if (root < t_min || t_max < root)
            return false;       
    }

    rec.t = root;
    rec.p = r.at(rec.t);
    vec3 outward_normal = (rec.p - center) / radius;
    rec.set_face_normal(r, outward_normal);

    return true;
}

#endif