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use std;
use std::result::Result;
use std::convert::From;

#[derive(Debug)]
pub struct BytesRead(pub usize);
#[derive(Debug)]
pub struct BytesWritten(pub usize);

#[derive(Debug)]
pub enum DecodingError {
  ProtocolError,
  IncompleteFrame
}

#[derive(Debug)]
pub enum EncodingError {
  ProtocolError,
  InsufficientBuffer
}

impl From<std::io::Error> for EncodingError {
    fn from(error: std::io::Error) -> EncodingError {
        use std::io::ErrorKind::*;
        match error.kind() {
            WriteZero => return EncodingError::InsufficientBuffer,
            _ => {}
        }
        panic!("IO Error occurred while encoding: {:?}", error);
    }
}

pub struct DecodedFrame<F> {
  pub frame: F,
  pub bytes_read: BytesRead
}

impl <F> DecodedFrame<F> {
  pub fn new(frame: F, bytes_read: BytesRead) -> DecodedFrame<F> {
    DecodedFrame {
      frame: frame,
      bytes_read: bytes_read
    }
  }
}

// No need for EncodedFrame type yet (ever?)

pub type DecodingResult<F> = Result<DecodedFrame<F>, DecodingError>;
pub type EncodingResult = Result<BytesWritten, EncodingError>;

pub trait Codec<F> {
  fn new() -> Self;
  fn encode(&mut self, frame: &F, &mut [u8]) -> EncodingResult;
  fn decode(&mut self, &[u8]) -> DecodingResult<F>;
}