use std::{fs::File, io::Write, path::PathBuf};

use nalgebra::Point2;
use crate::algebra::{Scalar, N};
use crate::renderer::Camera;
use crate::particle_system::Particle;

pub struct PPM<const WIDTH: usize, const HEIGHT: usize> {
    pub prefix: PathBuf,

    buffer: [[bool; WIDTH]; HEIGHT],
    // pixels_per_unit: usize,
}

impl<const WIDTH: usize, const HEIGHT: usize> PPM<WIDTH, HEIGHT> {
    pub fn new(prefix: PathBuf) -> Self {
        Self {
            prefix,
            buffer: [[false; WIDTH]; HEIGHT],
        }
    }

    pub fn clear_buffer(&mut self) {
        self.buffer = [[false; WIDTH]; HEIGHT]
    }

    pub fn draw_circle(&mut self, center: Point2<Scalar>, radius: Scalar) {
        let screen_center = Point2::new((WIDTH / 2) as Scalar, (HEIGHT / 2) as Scalar);

        for pixel_row in 0..HEIGHT {
            for pixel_col in 0..WIDTH {
                let point = Point2::new(pixel_col as Scalar, pixel_row as Scalar);

                if (point - center - screen_center.coords).norm() <= radius {
                    self.buffer[HEIGHT - pixel_row - 1][pixel_col] = true
                }
            }
        }
    }

    pub fn render_particles(&mut self, particles: &Vec<Particle>, camera: &Camera) {
        for p in particles {
            let point = camera.world_to_screen_space(p.position);
            self.draw_circle(point, p.mass.powf(1.0 / N as Scalar));
        }
    }

    pub fn save_frame(&self, time: Scalar) {
        let file_name = format!("frame-{:08.3}", time);
        let path = self.prefix.join(file_name);
        let mut file = File::create(path).unwrap();

        let mut s = format!("P3\n{} {}\n255\n", WIDTH, HEIGHT);
        let white = "255 255 255 ";
        let black = "0 0 0 ";

        for row in self.buffer {
            for pixel in row {
                let color = if pixel { black } else { white };
                s += color
            }
            s += "\n";
        }

        file.write(s.as_bytes()).unwrap();
    }
}