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

/// A 24-bit pixel represented by a red, green, and blue value.
#[derive(Clone, Copy, Default, Debug)]
pub struct Color {
  pub red: u8,
  pub green: u8,
  pub blue: u8,
}

impl Color {
  pub fn new(r: u8, g: u8, b: u8) -> Self {
    Color {
      red: r,
      green: g,
      blue: b,
    }
  }

  pub fn from_01_float(r: f64, g: f64, b: f64) -> Self {
    Color::new((r * 256.0) as u8, (g * 256.0) as u8, (b * 256.0) as u8)
  }
}

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

  /// Height in pixels
  pub(crate) height: usize,

  /// Pixel data in row-major form.
  pub(crate) 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 Color { red, green, blue } = pixel;
      let pixel = format!("{red} {green} {blue}\n");
      w.write_all(pixel.as_bytes())?;
    }

    Ok(())
  }
}