use aabb::AABB;
use hitable::Hit;
use hitable::HitRecord;
use material::Material;
use ray::Ray;
use vec3::dot;
use vec3::Vec3;

pub struct Sphere {
    center: Vec3,
    radius: f32,
    material: Box<Material>,
}

impl Sphere {
    pub fn new(center: Vec3, radius: f32, material: Box<Material>) -> Sphere {
        Sphere {
            center,
            radius,
            material,
        }
    }
}

impl Hit for Sphere {
    fn hit(&self, r: Ray, t_min: f32, t_max: f32) -> Option<HitRecord> {
        let oc = r.origin - self.center;
        let a = dot(r.direction, r.direction);
        let b = dot(oc, r.direction);
        let c = dot(oc, oc) - self.radius * self.radius;
        let discriminant = b * b - a * c;
        if discriminant > 0. {
            let temp = (-b - (b * b - a * c).sqrt()) / a;
            if temp < t_max && temp > t_min {
                let point = r.point_at_parameter(temp);
                return Some(HitRecord {
                    t: temp,
                    p: point,
                    normal: (point - self.center) / self.radius,
                    material: &*self.material,
                });
            }
            let temp = (-b + (b * b - a * c).sqrt()) / a;
            if temp < t_max && temp > t_min {
                let point = r.point_at_parameter(temp);
                return Some(HitRecord {
                    t: temp,
                    p: point,
                    normal: (point - self.center) / self.radius,
                    material: &*self.material,
                });
            }
        }
        None
    }

    fn bounding_box(&self, _t_min: f32, _t_max: f32) -> Option<AABB> {
        Some(AABB::new(
            self.center - Vec3::new(self.radius, self.radius, self.radius),
            self.center + Vec3::new(self.radius, self.radius, self.radius),
        ))
    }
}