use crate::scene::Ray;
use crate::vec3::Vec3;

pub struct Camera {
    origin: Vec3,
    lower_left_corner: Vec3,
    horizontal: Vec3,
    vertical: Vec3,
}

impl Camera {
    pub fn new(lookfrom: Vec3, lookat: Vec3, vup: Vec3, vfov: f64, aspect: f64, focus_dist: f64) -> Self {
        let half_height = (vfov.to_radians() / 2.0).tan();
        let half_width = aspect * half_height;
        let w = (lookfrom - lookat).normalize();
        let u = vup.cross(w).normalize();
        let v = w.cross(u);
        let horizontal = 2.0 * focus_dist * half_width * u;
        let vertical = 2.0 * focus_dist * half_height * v;
        let lower_left_corner = lookfrom - horizontal / 2.0 - vertical / 2.0 - focus_dist * w;
        Camera {
            origin: lookfrom,
            lower_left_corner,
            horizontal,
            vertical,
        }
    }

    pub fn get_ray(&self, s: f64, t: f64) -> Ray {
        let direction = self.lower_left_corner + s * self.horizontal + t * self.vertical - self.origin;
        Ray::new(self.origin, direction)
    }
}