extern crate rand;
extern crate rtiow;

use rand::Rng;

use rtiow::camera::Camera;
use rtiow::hitable::Hit;
use rtiow::hitable_list::HitableList;
use rtiow::material::Dielectric;
use rtiow::material::Lambertian;
use rtiow::material::Metal;
use rtiow::ray::Ray;
use rtiow::sphere::Sphere;
use rtiow::vec3::Vec3;

fn color(r: Ray, world: &Hit, depth: usize) -> Vec3 {
    if let Some(rec) = world.hit(r, 0.001, std::f32::MAX) {
        let scatter_response = rec.material.scatter(&r, &rec);
        if depth < 50 && scatter_response.reflected {
            return scatter_response.attenutation
                * color(scatter_response.scattered, world, depth + 1);
        }
        return Default::default();
    }

    // No hit, choose color from background.
    let unit_direction = r.direction().unit_vector();
    let t = 0.5 * (unit_direction.y + 1.);
    Vec3::new(1., 1., 1.) * (1. - t) + Vec3::new(0.5, 0.7, 1.) * t
}

fn main() -> Result<(), std::io::Error> {
    let mut rng = rand::thread_rng();
    let nx = 200;
    let ny = 100;
    let ns = 100;
    println!("P3\n{} {}\n255", nx, ny);
    let objects = vec![
        Sphere::new(
            Vec3::new(0., 0., -1.),
            0.5,
            Box::new(Lambertian::new(Vec3::new(0.1, 0.2, 0.5))),
        ),
        Sphere::new(
            Vec3::new(0., -100.5, -1.),
            100.,
            Box::new(Lambertian::new(Vec3::new(0.8, 0.8, 0.))),
        ),
        Sphere::new(
            Vec3::new(1., 0., -1.),
            0.5,
            Box::new(Metal::new(Vec3::new(0.8, 0.6, 0.2), 0.2)),
        ),
        Sphere::new(Vec3::new(-1., 0., -1.), 0.5, Box::new(Dielectric::new(1.5))),
        Sphere::new(
            Vec3::new(-1., 0., -1.),
            -0.45,
            Box::new(Dielectric::new(1.5)),
        ),
    ];
    let cam = Camera::new_lookfrom_vfov(
        Vec3::new(-2., 2., 1.),
        Vec3::new(0., 0., -1.),
        Vec3::new(0., 1., 0.),
        90.,
        nx as f32 / ny as f32,
    );
    let world = HitableList::new(objects.iter().map(|o| o).collect());
    for j in (0..ny).rev() {
        for i in 0..nx {
            let mut col: Vec3 = Default::default();
            for _ in 0..ns {
                let u = (rng.gen_range::<f32>(0., 1.) + i as f32) / nx as f32;
                let v = (rng.gen_range::<f32>(0., 1.) + j as f32) / ny as f32;
                let r = cam.get_ray(u, v);
                col = col + color(r, &world, 0);
            }
            col = col / ns as f32;
            // Gamma correct, use gamma 2 correction, which is 1/gamma where gamma=2 which is 1/2
            // or sqrt.
            col = Vec3::new(col[0].sqrt(), col[1].sqrt(), col[2].sqrt());
            let ir = (255.99 * col[0]) as u32;
            let ig = (255.99 * col[1]) as u32;
            let ib = (255.99 * col[2]) as u32;
            println!("{} {} {}", ir, ig, ib);
        }
    }
    Ok(())
}