#![feature(box_patterns)]
use anyhow::Context;
use clap::Parser;
use evc::{
    block::{Block, BlockInner},
    frame::Frame,
    header::Header,
    pixel::Pixel,
    ser::Source,
    view::View,
};
use std::io::{BufReader, BufWriter};

#[derive(Parser)]
#[clap(about, version)]
pub struct DecodeArgs {
    #[arg(long)]
    debug: bool,
}

fn main() -> anyhow::Result<()> {
    let args = DecodeArgs::parse();

    let mut input = BufReader::new(std::io::stdin());
    let mut output = BufWriter::new(std::io::stdout());

    let header = input.get::<Header>().context("reading header")?;
    eprintln!("{header:?}");
    let size = header.resolution;

    let mut prev = Frame::new(size);
    for i in 0.. {
        eprintln!("decode frame {i}");
        let block = Block::read(&mut input, size).context("reading encoded frame")?;
        let mut frame = Frame::new(size);

        blit_block(
            &block,
            frame.view_mut((0, 0), size),
            prev.view((0, 0), size),
        );

        if args.debug {
            let mut f2 = frame.clone();
            draw_debug(&block, f2.view_mut((0, 0), size));
            f2.write(&mut output).context("writing raw frame")?;
        } else {
            frame.write(&mut output).context("writing raw frame")?;
        }

        prev = frame;
    }
    drop(input);
    Ok(())
}

fn blit_block(block: &Block, mut target: View<&mut Frame>, prev: View<&Frame>) {
    match &block.inner {
        BlockInner::Literal(pixels) => target.set_pixels(pixels),
        BlockInner::Split(box [a, b]) => {
            let [at, bt] = target.split_mut_unsafe();
            let [ap, bp] = prev.split();
            blit_block(a, at, ap);
            blit_block(b, bt, bp);
        }
        BlockInner::Reference { translation: _ } => target.copy_from(&prev),
    }
}

fn draw_debug(block: &Block, mut target: View<&mut Frame>) {
    match &block.inner {
        BlockInner::Literal(_) => {
            target.draw_box(Pixel::GREEN);
        }
        BlockInner::Split(box [a, b]) => {
            let [at, bt] = target.split_mut_unsafe();
            draw_debug(a, at);
            draw_debug(b, bt);
        }
        BlockInner::Reference { translation: _ } => {
            target.draw_box(Pixel::BLUE);
        }
    }
}