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

use crate::particle_system::{Particle, Vector, N, Scalar};

pub struct PPM {
    pub prefix: PathBuf,
    pub width: usize,
    pub height: usize,
    // pixels_per_unit: usize,
}

impl PPM {
    fn render_particles(&self, particles: &Vec<Particle>) -> String {
        let mut s = format!("P3\n{} {}\n255\n", self.width, self.height);
        let white = "255 255 255 ";
        let black = "0 0 0 ";

        for pixel_row in 0..self.height {
            for pixel_col in 0..self.width {
                let point = Vector::new(pixel_col as Scalar, (pixel_row as Scalar) * -1.0)
                    + Vector::new(self.width as Scalar / -2.0, self.height as Scalar / 2.0);
                let color = match particles.iter().any(|p| {
                    (p.position - point).coords.norm() <= (p.mass).powf(1.0 / (N as f64))
                }) {
                    true => black,
                    false => white,
                };
                s += color;
            }
        }
        s
    }

    pub fn save_frame(&self, particles: &Vec<Particle>, 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 data = self.render_particles(particles);
        file.write(data.as_bytes()).unwrap();
    }
}