use std::io::{Result, Write};

use nalgebra::Vector3;

/// A pixel color represented by a red, green, and blue value in the range 0-1.
pub type Color = Vector3<f64>;

/// A representation of an image
pub struct Image {
  /// Width in pixels
  pub width: usize,

  /// Height in pixels
  pub height: usize,

  /// Pixel data in row-major form.
  pub data: Vec<Color>,
}

impl Image {
  /// Write the image in PPM format to a file.
  pub fn write(&self, mut w: impl Write) -> Result<()> {
    // Header
    let header = format!("P3 {} {} 255\n", self.width, self.height);
    w.write_all(header.as_bytes())?;

    // Pixel data
    assert_eq!(self.data.len(), self.width * self.height);

    for pixel in self.data.iter() {
      let pixel = pixel * 256.0;
      let red = pixel.x as u8;
      let green = pixel.y as u8;
      let blue = pixel.z as u8;
      let pixel = format!("{red} {green} {blue}\n");
      w.write_all(pixel.as_bytes())?;
    }

    Ok(())
  }
}