// Copyright 2020 Parity Technologies (UK) Ltd.
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pub use libp2p_core::ProtocolName;

use async_trait::async_trait;
use futures::prelude::*;
use std::io;

/// A `RequestResponseCodec` defines the request and response types
/// for a [`RequestResponse`](crate::RequestResponse) protocol or
/// protocol family and how they are encoded / decoded on an I/O stream.
#[async_trait]
pub trait RequestResponseCodec {
    /// The type of protocol(s) or protocol versions being negotiated.
    type Protocol: ProtocolName + Send + Clone;
    /// The type of inbound and outbound requests.
    type Request: Send;
    /// The type of inbound and outbound responses.
    type Response: Send;

    /// Reads a request from the given I/O stream according to the
    /// negotiated protocol.
    async fn read_request<T>(&mut self, protocol: &Self::Protocol, io: &mut T)
        -> io::Result<Self::Request>
    where
        T: AsyncRead + Unpin + Send;

    /// Reads a response from the given I/O stream according to the
    /// negotiated protocol.
    async fn read_response<T>(&mut self, protocol: &Self::Protocol, io: &mut T)
        -> io::Result<Self::Response>
    where
        T: AsyncRead + Unpin + Send;

    /// Writes a request to the given I/O stream according to the
    /// negotiated protocol.
    async fn write_request<T>(&mut self, protocol: &Self::Protocol, io: &mut T, req: Self::Request)
        -> io::Result<()>
    where
        T: AsyncWrite + Unpin + Send;

    /// Writes a response to the given I/O stream according to the
    /// negotiated protocol.
    async fn write_response<T>(&mut self, protocol: &Self::Protocol, io: &mut T, res: Self::Response)
        -> io::Result<()>
    where
        T: AsyncWrite + Unpin + Send;
}
