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    use crate::io::{Interest, PollEvented};
    use crate::net::tcp::TcpStream;
    use crate::net::{to_socket_addrs, ToSocketAddrs};

    use std::convert::TryFrom;
    use std::fmt;
    use std::io;
    use std::net::{self, SocketAddr};
    use std::task::{Context, Poll};

    cfg_net! {
        /// A TCP socket server, listening for connections.
        ///
        /// You can accept a new connection by using the [`accept`](`TcpListener::accept`)
        /// method.
        ///
        /// # Errors
        ///
        /// Note that accepting a connection can lead to various errors and not all
        /// of them are necessarily fatal ‒ for example having too many open file
        /// descriptors or the other side closing the connection while it waits in
        /// an accept queue. These would terminate the stream if not handled in any
        /// way.
        ///
        /// # Examples
        ///
        /// Using `accept`:
        /// ```no_run
        /// use tokio::net::TcpListener;
        ///
        /// use std::io;
        ///
        /// async fn process_socket<T>(socket: T) {
        ///     # drop(socket);
        ///     // do work with socket here
        /// }
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
        ///
        ///     loop {
        ///         let (socket, _) = listener.accept().await?;
        ///         process_socket(socket).await;
        ///     }
        /// }
        /// ```
        pub struct TcpListener {
            io: PollEvented<mio::net::TcpListener>,
        }
    }

    impl TcpListener {
        /// Creates a new TcpListener, which will be bound to the specified address.
        ///
        /// The returned listener is ready for accepting connections.
        ///
        /// Binding with a port number of 0 will request that the OS assigns a port
        /// to this listener. The port allocated can be queried via the `local_addr`
        /// method.
        ///
        /// The address type can be any implementor of the [`ToSocketAddrs`] trait.
        /// Note that strings only implement this trait when the **`net`** feature
        /// is enabled, as strings may contain domain names that need to be resolved.
        ///
        /// If `addr` yields multiple addresses, bind will be attempted with each of
        /// the addresses until one succeeds and returns the listener. If none of
        /// the addresses succeed in creating a listener, the error returned from
        /// the last attempt (the last address) is returned.
        ///
        /// This function sets the `SO_REUSEADDR` option on the socket.
        ///
        /// [`ToSocketAddrs`]: trait@crate::net::ToSocketAddrs
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use tokio::net::TcpListener;
        ///
        /// use std::io;
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///     let listener = TcpListener::bind("127.0.0.1:2345").await?;
        ///
        ///     // use the listener
        ///
        ///     # let _ = listener;
        ///     Ok(())
        /// }
        /// ```
        pub async fn bind<A: ToSocketAddrs>(addr: A) -> io::Result<TcpListener> {
            let addrs = to_socket_addrs(addr).await?;

            let mut last_err = None;

            for addr in addrs {
                match TcpListener::bind_addr(addr) {
                    Ok(listener) => return Ok(listener),
                    Err(e) => last_err = Some(e),
                }
            }

            Err(last_err.unwrap_or_else(|| {
                io::Error::new(
                    io::ErrorKind::InvalidInput,
                    "could not resolve to any address",
                )
            }))
        }

        fn bind_addr(addr: SocketAddr) -> io::Result<TcpListener> {
            let listener = mio::net::TcpListener::bind(addr)?;
            TcpListener::new(listener)
        }

        /// Accepts a new incoming connection from this listener.
        ///
        /// This function will yield once a new TCP connection is established. When
        /// established, the corresponding [`TcpStream`] and the remote peer's
        /// address will be returned.
        ///
        /// [`TcpStream`]: struct@crate::net::TcpStream
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use tokio::net::TcpListener;
        ///
        /// use std::io;
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
        ///
        ///     match listener.accept().await {
        ///         Ok((_socket, addr)) => println!("new client: {:?}", addr),
        ///         Err(e) => println!("couldn't get client: {:?}", e),
        ///     }
        ///
        ///     Ok(())
        /// }
        /// ```
        pub async fn accept(&self) -> io::Result<(TcpStream, SocketAddr)> {
            let (mio, addr) = self
                .io
                .registration()
                .async_io(Interest::READABLE, || self.io.accept())
                .await?;

            let stream = TcpStream::new(mio)?;
            Ok((stream, addr))
        }

        /// Polls to accept a new incoming connection to this listener.
        ///
        /// If there is no connection to accept, `Poll::Pending` is returned and the
        /// current task will be notified by a waker.  Note that on multiple calls
        /// to `poll_accept`, only the `Waker` from the `Context` passed to the most
        /// recent call is scheduled to receive a wakeup.
        pub fn poll_accept(&self, cx: &mut Context<'_>) -> Poll<io::Result<(TcpStream, SocketAddr)>> {
            loop {
                let ev = ready!(self.io.registration().poll_read_ready(cx))?;

                match self.io.accept() {
                    Ok((io, addr)) => {
                        let io = TcpStream::new(io)?;
                        return Poll::Ready(Ok((io, addr)));
                    }
                    Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
                        self.io.registration().clear_readiness(ev);
                    }
                    Err(e) => return Poll::Ready(Err(e)),
                }
            }
        }

        /// Creates new `TcpListener` from a `std::net::TcpListener`.
        ///
        /// This function is intended to be used to wrap a TCP listener from the
        /// standard library in the Tokio equivalent. The conversion assumes nothing
        /// about the underlying listener; it is left up to the user to set it in
        /// non-blocking mode.
        ///
        /// This API is typically paired with the `socket2` crate and the `Socket`
        /// type to build up and customize a listener before it's shipped off to the
        /// backing event loop. This allows configuration of options like
        /// `SO_REUSEPORT`, binding to multiple addresses, etc.
        ///
        ///
        /// # Examples
        ///
        /// ```rust,no_run
        /// use std::error::Error;
        /// use tokio::net::TcpListener;
        ///
        /// #[tokio::main]
        /// async fn main() -> Result<(), Box<dyn Error>> {
        ///     let std_listener = std::net::TcpListener::bind("127.0.0.1:0")?;
        ///     std_listener.set_nonblocking(true)?;
        ///     let listener = TcpListener::from_std(std_listener)?;
        ///     Ok(())
        /// }
        /// ```
        ///
        /// # Panics
        ///
        /// This function panics if thread-local runtime is not set.
        ///
        /// The runtime is usually set implicitly when this function is called
        /// from a future driven by a tokio runtime, otherwise runtime can be set
        /// explicitly with [`Runtime::enter`](crate::runtime::Runtime::enter) function.
        pub fn from_std(listener: net::TcpListener) -> io::Result<TcpListener> {
            let io = mio::net::TcpListener::from_std(listener);
            let io = PollEvented::new(io)?;
            Ok(TcpListener { io })
        }

        pub(crate) fn new(listener: mio::net::TcpListener) -> io::Result<TcpListener> {
            let io = PollEvented::new(listener)?;
            Ok(TcpListener { io })
        }

        /// Returns the local address that this listener is bound to.
        ///
        /// This can be useful, for example, when binding to port 0 to figure out
        /// which port was actually bound.
        ///
        /// # Examples
        ///
        /// ```rust,no_run
        /// use tokio::net::TcpListener;
        ///
        /// use std::io;
        /// use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
        ///
        ///     assert_eq!(listener.local_addr()?,
        ///                SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080)));
        ///
        ///     Ok(())
        /// }
        /// ```
        pub fn local_addr(&self) -> io::Result<SocketAddr> {
            self.io.local_addr()
        }

        /// Gets the value of the `IP_TTL` option for this socket.
        ///
        /// For more information about this option, see [`set_ttl`].
        ///
        /// [`set_ttl`]: method@Self::set_ttl
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use tokio::net::TcpListener;
        ///
        /// use std::io;
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///    let listener = TcpListener::bind("127.0.0.1:0").await?;
        ///
        ///    listener.set_ttl(100).expect("could not set TTL");
        ///    assert_eq!(listener.ttl()?, 100);
        ///
        ///    Ok(())
        /// }
        /// ```
        pub fn ttl(&self) -> io::Result<u32> {
            self.io.ttl()
        }

        /// Sets the value for the `IP_TTL` option on this socket.
        ///
        /// This value sets the time-to-live field that is used in every packet sent
        /// from this socket.
        ///
        /// # Examples
        ///
        /// ```no_run
        /// use tokio::net::TcpListener;
        ///
        /// use std::io;
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///     let listener = TcpListener::bind("127.0.0.1:0").await?;
        ///
        ///     listener.set_ttl(100).expect("could not set TTL");
        ///
        ///     Ok(())
        /// }
        /// ```
        pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
            self.io.set_ttl(ttl)
        }
    }

    impl TryFrom<net::TcpListener> for TcpListener {
        type Error = io::Error;

        /// Consumes stream, returning the tokio I/O object.
        ///
        /// This is equivalent to
        /// [`TcpListener::from_std(stream)`](TcpListener::from_std).
        fn try_from(stream: net::TcpListener) -> Result<Self, Self::Error> {
            Self::from_std(stream)
        }
    }

    impl fmt::Debug for TcpListener {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            self.io.fmt(f)
        }
    }

    #[cfg(unix)]
    mod sys {
        use super::TcpListener;
        use std::os::unix::prelude::*;

        impl AsRawFd for TcpListener {
            fn as_raw_fd(&self) -> RawFd {
                self.io.as_raw_fd()
            }
        }
    }

    #[cfg(windows)]
    mod sys {
        use super::TcpListener;
        use std::os::windows::prelude::*;

        impl AsRawSocket for TcpListener {
            fn as_raw_socket(&self) -> RawSocket {
                self.io.as_raw_socket()
            }
        }
    }