#ifndef SPHERE_H
#define SPHERE_H

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

struct sphere : hittable {
    /* Attributes */
    point3 center;
    double radius;
    std::shared_ptr<material> mat_ptr;

    /* Contructor */
    sphere(point3 c, double r, std::shared_ptr<material> m)
    {
        center = c;
        radius = r;
        mat_ptr = m;
    }

    /* 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
{
    rmt_ScopedCPUSample(Sphere_Hit, RMTSF_Aggregate);

    // Part 1

    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;


    // Part 2

    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
    // Part 3

    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;       
    }

    // Part 4

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

    return true;
}

#endif