#pragma once

#include "rtweekend.h"
#include "image.h"

class camera
{
    public:
        camera(
            point3  lookfrom,
            point3  lookat,
            vec3    vup,
            double  vfov,   // vertical field of view in degrees
            double  aspect_ratio,
            double  aperture,
            double  focus_dist)
        {
            auto theta = degrees_to_radians(vfov);
            auto h = tan(theta/2);
            auto viewport_height = 2.0 * h;
            auto viewport_width = aspect_ratio * viewport_height;

            w_ = unit_vector(lookfrom - lookat);
            u_ = unit_vector(cross(vup, w_));
            v_ = cross(w_, u_);

            origin_ = lookfrom;
            horizontal_ = focus_dist * viewport_width * u_;
            vertical_ = focus_dist * viewport_height * v_;
            lower_left_corner_ = origin_ - horizontal_/2 - vertical_/2 - focus_dist * w_;

            lens_radius_ = aperture / 2;
        }

        ray get_ray(double s, double t) const 
        {
            vec3 rd = lens_radius_ * random_in_unit_disk();
            vec3 offset = (u_ * rd.x()) + (v_ * rd.y());

            return ray(
                origin_ + offset,
                lower_left_corner_ + s*horizontal_ + t*vertical_ - origin_ - offset);
        }

    private:
        point3  origin_;
        point3  lower_left_corner_;
        vec3    horizontal_;
        vec3    vertical_;
        vec3    u_, v_, w_;
        double  lens_radius_;
};