//! Portable Pixel Map format images.

use crate::{err::*, fixed::FixedLong, image::*};
use std::io;

/// Writes a PPM file from an image.
///
/// # Errors
///
/// Errors if `out` cannot be written to.
pub fn write_ppm(out: &mut impl io::Write, im: &impl Image) -> ResultS<()>
{
   write!(out, "P3\n{} {}\n{}\n", im.w(), im.h(), u16::max_value())?;

   for y in 0..im.h() {
      for x in 0..im.w() {
         let cr = im.index(x, y);
         write!(out, "{} {} {} ", cr.r(), cr.g(), cr.b())?;
      }

      out.write_all(b"\n")?;
   }

   Ok(())
}

/// Reads a PPM file into an image.
pub fn read_ppm(inp: &[u8]) -> ResultS<Image16>
{
   let mut it = inp.split(|&n| n == b'\n' || n == b'\r' || n == b' ');

   if ok!(it.next(), "no magic number")? != b"P3" {
      bail!("not P3 format");
   }

   let mut get_num = move || -> ResultS<u16> {
      let st = loop {
         match ok!(it.next(), "no more strings")? {
            b"" => {}
            st  => break st
         }
      };
      let st = unsafe {std::str::from_utf8_unchecked(st)};
      let nu = u16::from_str_radix(st, 10)?;
      Ok(nu)
   };

   let width  = get_num()?;
   let height = get_num()?;
   let depth  = i64::from(get_num()?);

   let mut im = Image16::new(usize::from(width), usize::from(height));

   for _ in 0..height * width {
      let r = FixedLong::from_int(get_num()?.into());
      let g = FixedLong::from_int(get_num()?.into());
      let b = FixedLong::from_int(get_num()?.into());

      let r = (r / depth * 0xFFFF).integ() as u16;
      let g = (g / depth * 0xFFFF).integ() as u16;
      let b = (b / depth * 0xFFFF).integ() as u16;

      im.cr.push(Color16::new(r, g, b));
   }

   Ok(im)
}

// EOF