// Not all functions are used by all tests.
#![allow(dead_code)]

use std::io::{self, Read, Write};
use std::net::SocketAddr;
use std::sync::Once;
use std::time::Duration;

use bytes::{Buf, BufMut};
use mio::{Events, Poll};

pub fn init() {
    static INIT: Once = Once::new();

    INIT.call_once(|| {
        env_logger::try_init().expect("unable to initialise logger");
    })
}

pub fn assert_sync<T: Sync>() {}
pub fn assert_send<T: Send>() {}

pub trait TryRead {
    fn try_read_buf<B: BufMut>(&mut self, buf: &mut B) -> io::Result<Option<usize>>
    where
        Self: Sized,
    {
        // Reads the length of the slice supplied by buf.mut_bytes into the buffer
        // This is not guaranteed to consume an entire datagram or segment.
        // If your protocol is msg based (instead of continuous stream) you should
        // ensure that your buffer is large enough to hold an entire segment (1532 bytes if not jumbo
        // frames)
        let res = self.try_read(unsafe { buf.bytes_mut() });

        if let Ok(Some(cnt)) = res {
            unsafe {
                buf.advance_mut(cnt);
            }
        }

        res
    }

    fn try_read(&mut self, buf: &mut [u8]) -> io::Result<Option<usize>>;
}

pub trait TryWrite {
    fn try_write_buf<B: Buf>(&mut self, buf: &mut B) -> io::Result<Option<usize>>
    where
        Self: Sized,
    {
        let res = self.try_write(buf.bytes());

        if let Ok(Some(cnt)) = res {
            buf.advance(cnt);
        }

        res
    }

    fn try_write(&mut self, buf: &[u8]) -> io::Result<Option<usize>>;
}

impl<T: Read> TryRead for T {
    fn try_read(&mut self, dst: &mut [u8]) -> io::Result<Option<usize>> {
        self.read(dst).map_non_block()
    }
}

impl<T: Write> TryWrite for T {
    fn try_write(&mut self, src: &[u8]) -> io::Result<Option<usize>> {
        self.write(src).map_non_block()
    }
}

/*
 *
 * ===== Helpers =====
 *
 */

/// A helper trait to provide the map_non_block function on Results.
trait MapNonBlock<T> {
    /// Maps a `Result<T>` to a `Result<Option<T>>` by converting
    /// operation-would-block errors into `Ok(None)`.
    fn map_non_block(self) -> io::Result<Option<T>>;
}

impl<T> MapNonBlock<T> for io::Result<T> {
    fn map_non_block(self) -> io::Result<Option<T>> {
        use std::io::ErrorKind::WouldBlock;

        match self {
            Ok(value) => Ok(Some(value)),
            Err(err) => {
                if let WouldBlock = err.kind() {
                    Ok(None)
                } else {
                    Err(err)
                }
            }
        }
    }
}

pub fn expect_no_events(poll: &mut Poll, events: &mut Events) {
    poll.poll(events, Some(Duration::from_millis(50)))
        .expect("unable to poll");
    assert!(events.is_empty(), "received events, but didn't expect any");
}

/// Bind to any port on localhost.
pub fn any_local_address() -> SocketAddr {
    "127.0.0.1:0".parse().unwrap()
}

/// Bind to any port on localhost, using a IPv6 address.
pub fn any_local_ipv6_address() -> SocketAddr {
    "[::1]:0".parse().unwrap()
}