//! Image and color representations.

use crate::durandal::err::*;
use std::io;

/// Creates a RGB8 color from a R5G5B5 format color.
pub fn r5g5b5_to_rgb8(rgb: u16) -> Color8
{
   let r = rgb >> 10 & 0x1f;
   let g = rgb >> 5  & 0x1f;
   let b = rgb       & 0x1f;
   Color8::new((r << 3 | r >> 2) as u8,
               (g << 3 | g >> 2) as u8,
               (b << 3 | b >> 2) as u8)
}

/// Creates a RGB16 color from a R5G5B5 format color.
pub fn r5g5b5_to_rgb16(rgb: u16) -> Color16
{
   let r = rgb >> 10 & 0x1f;
   let g = rgb >> 5  & 0x1f;
   let b = rgb       & 0x1f;
   Color16::new(r << 11, g << 11, b << 11)
}

/// Creates a RGB16 color from a RGB8 format color.
pub fn rgb8_to_rgb16(r: u8, g: u8, b: u8) -> Color16
{
   Color16::new(u16::from(r) << 8, u16::from(g) << 8, u16::from(b) << 8)
}

/// Writes a PPM file from an image.
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(())
}

/// Writes a TGA file from an image.
pub fn write_tga(out: &mut impl io::Write, im: &impl Image) -> ResultS<()>
{
   out.write_all(&[0, 0, 2])?; // id len, color map type, image type
   out.write_all(&[0, 0, 0, 0, 0])?; // color map spec
   out.write_all(&[0, 0])?; // x origin
   out.write_all(&[0, 0])?; // y origin
   out.write_all(&(im.w() as u16).to_le_bytes())?; // width
   out.write_all(&(im.h() as u16).to_le_bytes())?; // height
   out.write_all(&[32, 0])?; // depth, descriptor

   for y in (0..im.h()).rev() {
      for x in 0..im.w() {
         let cr = im.index(x, y);
         out.write_all(&[(cr.b() >> 8) as u8,
                         (cr.g() >> 8) as u8,
                         (cr.r() >> 8) as u8,
                         (cr.a() >> 8) as u8])?;
      }
   }

   Ok(())
}

pub trait Image
{
   type Output: Color;

   fn w(&self) -> usize;
   fn h(&self) -> usize;
   fn index(&self, x: usize, y: usize) -> &Self::Output;

   fn get(&self, x: usize, y: usize) -> Option<&Self::Output>
   {
      if x < self.w() && y < self.h() {
         Some(&self.index(x, y))
      } else {
         None
      }
   }
}

pub trait Color
{
   fn r(&self) -> u16;
   fn g(&self) -> u16;
   fn b(&self) -> u16;
   fn a(&self) -> u16;
}

impl Image16
{
   /// Creates a new Image16.
   pub fn new(w: usize, h: usize) -> Image16
   {
      Image16{w, h, cr: Vec::with_capacity(w * h)}
   }
}

impl Image for Image16
{
   type Output = Color16;

   fn w(&self) -> usize {self.w}
   fn h(&self) -> usize {self.h}

   fn index(&self, x: usize, y: usize) -> &Self::Output
   {
      &self.cr[x + y * self.w]
   }
}

impl Image8
{
   /// Creates a new Image8.
   pub fn new(w: usize, h: usize) -> Image8
   {
      Image8{w, h, cr: Vec::with_capacity(w * h)}
   }
}

impl Image for Image8
{
   type Output = Color8;

   fn w(&self) -> usize {self.w}
   fn h(&self) -> usize {self.h}

   fn index(&self, x: usize, y: usize) -> &Self::Output
   {
      &self.cr[x + y * self.w]
   }
}

impl Color16
{
   pub const fn new(r: u16, g: u16, b: u16) -> Color16
   {
      Color16(r, g, b)
   }
}

impl Color for Color16
{
   fn r(&self) -> u16 {self.0}
   fn g(&self) -> u16 {self.1}
   fn b(&self) -> u16 {self.2}
   fn a(&self) -> u16 {u16::max_value()}
}

impl Color8
{
   pub const fn new(r: u8, g: u8, b: u8) -> Color8
   {
      Color8(r, g, b)
   }
}

impl Color for Color8
{
   fn r(&self) -> u16 {u16::from(self.0) << 8}
   fn g(&self) -> u16 {u16::from(self.1) << 8}
   fn b(&self) -> u16 {u16::from(self.2) << 8}
   fn a(&self) -> u16 {u16::max_value()}
}

/// A RGB16 color.
#[derive(Clone, Debug, PartialEq)]
pub struct Color16(u16, u16, u16);

/// A RGB8 color.
#[derive(Clone, Debug, PartialEq)]
pub struct Color8(u8, u8, u8);

/// RGB16 image.
pub struct Image16
{
   w:      usize,
   h:      usize,
   pub cr: Vec<Color16>,
}

/// RGB16 image.
pub struct Image8
{
   w:      usize,
   h:      usize,
   pub cr: Vec<Color8>,
}

// EOF