//! MaybeTlsStream.
//!
//! Represents a stream that may or may not be encrypted with TLS.
use crate::tls::{ChannelBinding, TlsStream};
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};

/// A stream that may or may not be encrypted with TLS.
pub enum MaybeTlsStream<S, T> {
    /// An unencrypted stream.
    Raw(S),
    /// An encrypted stream.
    Tls(T),
}

impl<S, T> AsyncRead for MaybeTlsStream<S, T>
where
    S: AsyncRead + Unpin,
    T: AsyncRead + Unpin,
{
    fn poll_read(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut ReadBuf<'_>,
    ) -> Poll<io::Result<()>> {
        match &mut *self {
            MaybeTlsStream::Raw(s) => Pin::new(s).poll_read(cx, buf),
            MaybeTlsStream::Tls(s) => Pin::new(s).poll_read(cx, buf),
        }
    }
}

impl<S, T> AsyncWrite for MaybeTlsStream<S, T>
where
    S: AsyncWrite + Unpin,
    T: AsyncWrite + Unpin,
{
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<io::Result<usize>> {
        match &mut *self {
            MaybeTlsStream::Raw(s) => Pin::new(s).poll_write(cx, buf),
            MaybeTlsStream::Tls(s) => Pin::new(s).poll_write(cx, buf),
        }
    }

    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        match &mut *self {
            MaybeTlsStream::Raw(s) => Pin::new(s).poll_flush(cx),
            MaybeTlsStream::Tls(s) => Pin::new(s).poll_flush(cx),
        }
    }

    fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
        match &mut *self {
            MaybeTlsStream::Raw(s) => Pin::new(s).poll_shutdown(cx),
            MaybeTlsStream::Tls(s) => Pin::new(s).poll_shutdown(cx),
        }
    }
}

impl<S, T> TlsStream for MaybeTlsStream<S, T>
where
    S: AsyncRead + AsyncWrite + Unpin,
    T: TlsStream + Unpin,
{
    fn channel_binding(&self) -> ChannelBinding {
        match self {
            MaybeTlsStream::Raw(_) => ChannelBinding::none(),
            MaybeTlsStream::Tls(s) => s.channel_binding(),
        }
    }
}