#include <iostream>

#include "color.h"
#include "vec3.h"
#include "ray.h"
#include "util.h"

#include "hittable_list.h"
#include "sphere.h"

Color ray_color(const Ray& r, const Hittable& world) {
    hit_record rec;
    if (world.hit(r, 0, infinity, rec)) {
        return 0.5 * (rec.normal + Color(1,1,1));
    }
    Vec3 unit_direction = unit_vector(r.direction());
    auto t = 0.5 * (unit_direction.y() + 1.0);
    return (1.0 - t) * Color(1.0, 1.0, 1.0) + t * Color(0.5, 0.7, 1.0);
}

int main() {
    const auto aspect_ratio = 16.0 / 9.0;
    const int image_width = 1280;
    const int image_height = static_cast<int>(image_width / aspect_ratio);

    std::cout << "P3\n" << image_width << " " << image_height << "\n255\n";

    auto viewport_height = 2.0;
    auto viewport_width = aspect_ratio * viewport_height;
    auto focal_length = 1.0;

    auto origin = Point3(0, 0, 0);
    auto horizontal = Vec3(viewport_width, 0, 0);
    auto vertical = Vec3(0, viewport_height, 0);
    auto lower_left_corner = origin - horizontal/2 - vertical/2 - Vec3(0, 0, focal_length);

    Hittable_list world;
    world.add(std::make_shared<Sphere>(Point3(0, 0, -1), 0.5));
    world.add(std::make_shared<Sphere>(Point3(0, -100.5, -1), 100));

    for (int j = image_height - 1; j >= 0; --j) {
        std::cerr << "\rScanlines remaining: " << j << " " << std::flush;
        for (int i = 0; i < image_width; ++i) {
            auto u = double(i) / (image_width - 1);
            auto v = double(j) / (image_height - 1);
            Ray r(origin, lower_left_corner + u*horizontal + v*vertical - origin);
            Color pixel_color = ray_color(r, world);
            write_color(std::cout, pixel_color);
        }
    }
    std::cerr << "\nDone.\n";
}