base91le 0.1.0

little-endian base91 encoding format that supports padding
Documentation 
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use std::io::{self, Error, ErrorKind, Read};

use crate::{copier::Copier, ring::RingBuf};

#[derive(Debug)]
pub struct DecodeReader<R: Read> {
    nth_chunk: usize,
    reader: R,
    copier: Copier,
    ring: RingBuf<1024>,
}

impl<R: Read> DecodeReader<R> {
    pub const fn new(reader: R) -> Self {
        Self {
            nth_chunk: 0,
            reader,
            copier: Copier::new_decode(),
            ring: RingBuf::new(),
        }
    }
}

impl<R: Read> Read for DecodeReader<R> {
    fn read(&mut self, mut buf: &mut [u8]) -> io::Result<usize> {
        while self.ring.is_empty() {
            if !self.copier.write() && self.copier.copy_encoded(&mut self.reader, self.nth_chunk)? {
                if self.copier.is_empty() {
                    break;
                }
                self.copier.decode().map_err(|err| {
                    Error::new(ErrorKind::InvalidData, err.nth_chunk(self.nth_chunk))
                })?;
                self.nth_chunk += 1;
            }

            if self.copier.write() && self.copier.copy_to(&mut self.ring)? {
                self.copier = Copier::new_decode();
            }
        }
        self.ring.copy_to_writer(&mut buf)
    }
}