extern crate image;

mod camera;
mod color;
mod hittable;
mod hittable_list;
mod material;
mod ray;
mod utility;
mod vec3;

use camera::Camera;
use hittable::{HitRecord, Hittable, Sphere, Triangle};
use hittable_list::HittableList;
use image::{Rgb, RgbImage};
use material::{Dielectric, Lambertian, Material, Metal};
use ray::Ray;
use rayon::prelude::*;
use std::env;
use std::fs::File;
use std::io::{self, BufRead};
use std::path::Path;
use std::sync::atomic::{AtomicU32, Ordering};
use std::sync::Arc;
use tobj;
use vec3::{Color, Point3, Vec3};

fn ray_color(r: &Ray, world: &HittableList, depth: u32) -> Color {
    let mut rec = HitRecord::empty();

    if depth <= 0 {
        return Color::null();
    }

    if world.hit(r, 0.001, f64::INFINITY, &mut rec) {
        let mut scattered = Ray::new(Point3::null(), Vec3::null());
        let mut attenuation = Color::null();
        if rec
            .mat_ptr
            .scatter(r, &rec, &mut attenuation, &mut scattered)
        {
            return attenuation * ray_color(&scattered, world, depth - 1);
        }
        return Color::null();

        //let target = rec.p + rec.normal + Vec3::random_unit_vector(); // rec.p + rec.normal.random_in_hemisphere();
        //return 0.5 * ray_color(&Ray::new(rec.p, target - rec.p), world, depth - 1);
    }
    let unit_direction = r.direction();
    let t = 0.5 * (unit_direction.y() + 1.0);
    return (1.0 - t) * Color::new(1.0, 1.0, 1.0) + t * Color::new(0.5, 0.7, 1.0);
}

fn random_world() -> HittableList {
    let mut world = HittableList::new();

    let material_ground = Arc::new(Lambertian::new(&Color::new(0.05, 0.05, 0.05)));
    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(0.0, -50000.0, 0.0),
        50000.0,
        material_ground.clone(),
    )));

    (-6..5).into_iter().for_each(|a| {
        (-6..5).into_iter().for_each(|b| {
            let choose_mat = utility::random_f64();
            let rad = utility::random_rng(0.1, 0.5);
            let center = Point3::new(
                1.5 * a as f64 + 1.3 * utility::random_f64(),
                rad,
                1.5 * b as f64 + 1.3 * utility::random_f64(),
            );
            if (center - Point3::new(4.0, rad, 0.0)).length() > 0.9 {
                if choose_mat < 0.8 {
                    // diffuse
                    let sphere_material = Arc::new(Lambertian::new(
                        &(Color::random_f64() * Color::random_f64()),
                    ));
                    world.add(Box::<Sphere>::new(Sphere::new(
                        center,
                        rad,
                        sphere_material.clone(),
                    )));
                } else if choose_mat < 0.95 {
                    // metal
                    let sphere_material = Arc::new(Metal::new(
                        &Color::random_rng(0.5, 1.0),
                        utility::random_rng(0.0, 0.5),
                    ));
                    world.add(Box::<Sphere>::new(Sphere::new(
                        center,
                        0.2,
                        sphere_material.clone(),
                    )));
                } else {
                    // glass
                    let sphere_material = Arc::new(Dielectric::new(1.5));
                    world.add(Box::<Sphere>::new(Sphere::new(
                        center,
                        0.2,
                        sphere_material.clone(),
                    )));
                }
            }
        });
    });

    let material1 = Arc::new(Dielectric::new(1.5));
    let material2 = Arc::new(Lambertian::new(&Color::new(0.4, 0.2, 0.1)));
    let material3 = Arc::new(Metal::new(&Color::new(0.7, 0.6, 0.5), 0.0));
    let material4 = Arc::new(Dielectric::new(2.0));
    let material5 = Arc::new(Metal::new(&Color::new(0.9, 0.9, 0.7), 0.0));

    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(0.0, 1.0, 0.0),
        1.0,
        material2.clone(),
    )));

    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(-4.0, 1.0, 0.0),
        1.0,
        material1.clone(),
    )));

    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(4.0, 1.0, 0.0),
        1.0,
        material3.clone(),
    )));

    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(-2.0, 2.0, -5.0),
        2.0,
        material4.clone(),
    )));

    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(-3.6, 2.0, -2.0),
        0.6,
        material5.clone(),
    )));

    world.add(Box::<Triangle>::new(Triangle::new(
        Point3::new(0.0, 1.0, 5.0),
        Point3::new(3.0, 2.0, 0.0),
        Point3::new(0.0, 4.0, 0.0),
        material2.clone(),
    )));

    world.add(Box::<Triangle>::new(Triangle::new(
        Point3::new(5.0, 1.0, -6.0),
        Point3::new(1.0, 3.0, -5.0),
        Point3::new(6.0, 4.0, -6.0),
        material5.clone(),
    )));
    world.add(Box::<Triangle>::new(Triangle::new(
        Point3::new(5.0, 1.0, -6.0),
        Point3::new(8.0, 1.0, -7.0),
        Point3::new(6.0, 4.0, -6.0),
        material5.clone(),
    )));
    world.add(Box::<Triangle>::new(Triangle::new(
        Point3::new(8.0, 4.0, -5.0),
        Point3::new(8.0, 1.0, -7.0),
        Point3::new(6.0, 4.0, -6.0),
        material5.clone(),
    )));

    return world;
}

fn from_obj(path: &str) -> HittableList {

    let mut world = HittableList::new();

    let material_ground = Arc::new(Lambertian::new(&Color::new(0.05, 0.05, 0.05)));
    world.add(Box::<Sphere>::new(Sphere::new(
        Point3::new(0.0, -50000.0, 0.0),
        50000.0,
        material_ground.clone(),
    )));

    /*
    if let Ok(lines) = read_lines(path) {
        for line in lines {
            if let Ok(text) = line {
                dbg!(text);
            }
        }
    }*/

    let material = Arc::new(Lambertian::new(&Color::new(0.4, 0.2, 0.1)));

    let cornell_box = tobj::load_obj(path, &tobj::GPU_LOAD_OPTIONS);
    let (models, materials) = cornell_box.expect("Failed to load OBJ file");
    let materials = materials.expect("Failed to load MTL file");

    for (i, m) in models.iter().enumerate() {
        let mesh = &m.mesh;

        let mut next_face = 0;
        for f in 0..mesh.face_arities.len() {
            let end = next_face + mesh.face_arities[f] as usize;
            let face_indices: Vec<_> = mesh.indices[next_face..end].iter().collect();
            println!("    face[{}] = {:?}", f, face_indices);
            next_face = end;
        }

        // todo!("find out how to get triangular faces and build world"); // https://docs.rs/tobj/3.2.3/tobj/struct.Mesh.html

        for v in 0..mesh.indices.len() / 3 {
            let indexA = mesh.indices[3 * v];
            let indexB = mesh.indices[3 * v + 1];
            let indexC = mesh.indices[3 * v + 2];

            world.add(Box::<Triangle>::new(Triangle::new(
                Point3::new(
                    mesh.positions[3 * indexA] as f64,
                    mesh.positions[3 * indexA + 1] as f64,
                    mesh.positions[3 * indexA + 2] as f64
                ),
                Point3::new(
                    mesh.positions[3 * indexB] as f64,
                    mesh.positions[3 * indexB + 1] as f64,
                    mesh.positions[3 * indexB + 2] as f64
                ),
                Point3::new(
                    mesh.positions[3 * indexC] as f64,
                    mesh.positions[3 * indexC + 1] as f64,
                    mesh.positions[3 * indexC + 2] as f64
                ),
                material
            )));

        for v in 0..mesh.positions.len() / 3 {
            println!(
                "    v[{}] = ({}, {}, {})",
                v,
                mesh.positions[3 * v],
                mesh.positions[3 * v + 1],
                mesh.positions[3 * v + 2]
            );
        }
    }

    

    return world;
    
}

// The output is wrapped in a Result to allow matching on errors
// Returns an Iterator to the Reader of the lines of the file.
fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
where P: AsRef<Path>, {
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}

/*
Current world view:

            I y
            I
            I
            I
          /   \
        /       \
      /           \
    / z             \ x

*/

fn main() {
    // File
    let mut default_file = "image.ppm";

    // Image
    let aspect_ratio = 16.0 / 9.0;
    let image_width = 200;
    let image_height = (image_width as f64 / aspect_ratio) as u32;
    let samples_per_pixel = 100_u32;
    let max_depth = 50;

    let vfov = 40.0;
    let lookfrom = Point3::new(10.0, 4.0, 13.0);
    let lookat = Point3::new(0.0, 0.0, 0.0);
    let vup = Vec3::new(0.0, 1.0, 0.0);
    let dist_to_focus = 17.0;
    let aperture = 0.1;

    let world = from_obj("obj/baum.obj");

    // World
    let world = random_world();

    // Camera
    let cam = Camera::new(
        lookfrom,
        lookat,
        vup,
        vfov,
        aspect_ratio,
        aperture,
        dist_to_focus,
    );

    // Render
    let args: Vec<String> = env::args().collect();
    if args.len() > 1 && args[1] != "" {
        default_file = &args[1];
    }

    let mut image = RgbImage::new(image_width, image_height);

    let atomic_counter = Arc::new(AtomicU32::new(0));
    let color_lines: Vec<_> = (0..image_height)
        .into_par_iter() // threadded/parallel variant
        //.into_iter()  // iterative variant
        .rev()
        .map(|j| {
            let v = atomic_counter.fetch_add(1, Ordering::Relaxed);
            eprint!("\rScanlines remaining: {:5}", image_height - v);

            let mut colors = Vec::new();
            for i in 0..image_width {
                let mut pixel_color = Color::new(0.0, 0.0, 0.0);
                for _ in 0..samples_per_pixel {
                    let u = (i as f64 + utility::random_f64()) / (image_width - 1) as f64;
                    let v = (j as f64 + utility::random_f64()) / (image_height - 1) as f64;
                    let r = cam.get_ray(u, v);
                    pixel_color += ray_color(&r, &world, max_depth);
                }
                colors.push(pixel_color);
            }
            return colors;
        })
        .collect();
    eprint!("\rScanlines remaining: {:5}", 0);

    (0..image_height).into_iter().rev().for_each(|j| {
        (0..image_width).into_iter().for_each(|i| {
            color::put_color(
                &mut image,
                &color_lines[(image_height - j - 1) as usize][i as usize],
                i,
                image_height - j - 1,
                samples_per_pixel,
            );
        })
    });

    image.save(default_file).unwrap();
    eprintln!("\nDone!");
}