extern crate mat4;
extern crate vec3;

use crate::object::Object;
use crate::ray::Ray;
use crate::sphere::Sphere;
use sdl2::pixels::Color;

fn put_pixel(data: &mut [u8], x: usize, y: usize, color: Color) {
    data[y * 3 * 800 + x * 3] = color.r;
    data[y * 3 * 800 + x * 3 + 1] = color.g;
    data[y * 3 * 800 + x * 3 + 2] = color.b;
}

pub fn render(data: &mut [u8]) {
    let sphere = Sphere {};
    let projection_matrix: [f64; 16] = *mat4::perspective(
        &mut mat4::new_zero(),
        &(45. * 3.141592 / 180.),
        &(800. / 600.),
        &(0.1),
        &(1000.),
    );
    let view_matrix: [f64; 16] = *mat4::translate(
        &mut mat4::new_identity(),
        &mat4::new_identity(),
        &vec3::new(0., 0., -10.),
    );
    let model_matrix: [f64; 16] = *mat4::translate(
        &mut mat4::new_identity(),
        &mat4::new_identity(),
        &vec3::new(1., 1., 0.),
    );
    for x in 0..800 {
        for y in 0..600 {
            let mut ray = Ray {
                origin: [0., 0., 0.],
                direction: [0., 0., 1.],
            };
            ray.direction[0] += (x as f64 - 400.) / 800.;
            ray.direction[1] += (y as f64 - 300.) / 800.;
            let mut n =
                ray.direction[0].powi(2) + ray.direction[1].powi(2) + ray.direction[2].powi(2);
            n = n.sqrt();
            ray.direction[0] /= n;
            ray.direction[1] /= n;
            ray.direction[2] /= n;
            // let ray2 = Box::clone(&Box::new(ray));
            // vec3::transform_mat4(&mut ray.direction, &ray2.direction, &projection_matrix);
            let ray2 = Box::clone(&Box::new(ray));
            vec3::transform_mat4(&mut ray.origin, &ray2.origin, &view_matrix);
            let ray2 = Box::clone(&Box::new(ray));
            vec3::transform_mat4(&mut ray.origin, &ray2.origin, &model_matrix);
            match sphere.get_intersection(ray) {
                Some(dist) => {
                    let n = [
                        ray.origin[0] + ray.direction[0] * dist,
                        ray.origin[1] + ray.direction[1] * dist,
                        ray.origin[2] + ray.direction[2] * dist,
                    ];
                    let normal = sphere.get_normal(n);
                    let light = [n[0] - 10., n[1] - 10., n[2] - 10.];
                    let scalar = (light[0].powi(2) + light[1].powi(2) + light[2].powi(2)).sqrt();
                    let light_d = [light[0] / scalar, light[1] / scalar, light[2] / scalar];
                    let mut diffuse =
                        normal[0] * light_d[0] + normal[1] * light_d[1] + normal[2] * light_d[2];
                    if diffuse < 0. {
                        diffuse = 0.;
                    }
                    put_pixel(
                        &mut *data,
                        x,
                        y,
                        Color {
                            r: (diffuse * 255.) as u8,
                            g: (diffuse * 255.) as u8,
                            b: (diffuse * 255.) as u8,
                            a: 0,
                        },
                    );
                }
                None => {
                    put_pixel(
                        &mut *data,
                        x,
                        y,
                        Color {
                            r: 0,
                            g: 0,
                            b: 0,
                            a: 0,
                        },
                    );
                }
            }
        }
    }
}