use event_imp::{Ready, ready_from_usize};

use std::ops;

/// Unix specific extensions to `Ready`
///
/// Provides additional readiness event kinds that are available on unix
/// platforms. Unix platforms are able to provide readiness events for
/// additional socket events, such as HUP and error.
///
/// HUP events occur when the remote end of a socket hangs up. In the TCP case,
/// this occurs when the remote end of a TCP socket shuts down writes.
///
/// Error events occur when the socket enters an error state. In this case, the
/// socket will also receive a readable or writable event. Reading or writing to
/// the socket will result in an error.
///
/// Conversion traits are implemented between `Ready` and `UnixReady`. See the
/// examples.
///
/// For high level documentation on polling and readiness, see [`Poll`].
///
/// # Examples
///
/// Most of the time, all that is needed is using bit operations
///
/// ```
/// use mio::Ready;
/// use mio::unix::UnixReady;
///
/// let ready = Ready::readable() | UnixReady::hup();
///
/// assert!(ready.is_readable());
/// assert!(UnixReady::from(ready).is_hup());
/// ```
///
/// Basic conversion between ready types.
///
/// ```
/// use mio::Ready;
/// use mio::unix::UnixReady;
///
/// // Start with a portable ready
/// let ready = Ready::readable();
///
/// // Convert to a unix ready, adding HUP
/// let mut unix_ready = UnixReady::from(ready) | UnixReady::hup();
///
/// unix_ready.insert(UnixReady::error());
///
/// // `unix_ready` maintains readable interest
/// assert!(unix_ready.is_readable());
/// assert!(unix_ready.is_hup());
/// assert!(unix_ready.is_error());
///
/// // Convert back to `Ready`
/// let ready = Ready::from(unix_ready);
///
/// // Readable is maintained
/// assert!(ready.is_readable());
/// ```
///
/// Registering readable and error interest on a socket
///
/// ```
/// use mio::{Ready, Poll, PollOpt, Token};
/// use mio::tcp::TcpStream;
/// use mio::unix::UnixReady;
///
/// let addr = "216.58.193.68:80".parse().unwrap();
/// let socket = TcpStream::connect(&addr).unwrap();
///
/// let poll = Poll::new().unwrap();
///
/// poll.register(&socket,
///               Token(0),
///               Ready::readable() | UnixReady::error(),
///               PollOpt::edge()).unwrap();
///
/// ```
///
/// [`Poll`]: struct.Poll.html
/// [readiness]: struct.Poll.html#readiness-operations
#[derive(Debug, Copy, PartialEq, Eq, Clone, PartialOrd, Ord)]
pub struct UnixReady(Ready);

const ERROR: usize = 0b0100;
const HUP: usize   = 0b1000;

impl UnixReady {
    /// Returns a `Ready` representing error readiness.
    ///
    /// **Note that only readable and writable readiness is guaranteed to be
    /// supported on all platforms**. This means that `error` readiness
    /// should be treated as a hint. For more details, see [readiness] in the
    /// poll documentation.
    ///
    /// See [`Poll`] for more documentation on polling.
    ///
    /// # Examples
    ///
    /// ```
    /// use mio::Ready;
    ///
    /// let ready = Ready::error();
    ///
    /// assert!(ready.is_error());
    /// ```
    ///
    /// [`Poll`]: struct.Poll.html
    /// [readiness]: struct.Poll.html#readiness-operations
    #[inline]
    pub fn error() -> UnixReady {
        UnixReady(ready_from_usize(ERROR))
    }

    /// Returns a `Ready` representing HUP readiness.
    ///
    /// A HUP (or hang-up) signifies that a stream socket **peer** closed the
    /// connection, or shut down the writing half of the connection.
    ///
    /// **Note that only readable and writable readiness is guaranteed to be
    /// supported on all platforms**. This means that `hup` readiness
    /// should be treated as a hint. For more details, see [readiness] in the
    /// poll documentation.
    ///
    /// See [`Poll`] for more documentation on polling.
    ///
    /// # Examples
    ///
    /// ```
    /// use mio::Ready;
    ///
    /// let ready = Ready::hup();
    ///
    /// assert!(ready.is_hup());
    /// ```
    ///
    /// [`Poll`]: struct.Poll.html
    /// [readiness]: struct.Poll.html#readiness-operations
    #[inline]
    pub fn hup() -> UnixReady {
        UnixReady(ready_from_usize(HUP))
    }

    /// Returns true if the value includes error readiness
    ///
    /// **Note that only readable and writable readiness is guaranteed to be
    /// supported on all platforms**. This means that `error` readiness should
    /// be treated as a hint. For more details, see [readiness] in the poll
    /// documentation.
    ///
    /// See [`Poll`] for more documentation on polling.
    ///
    /// # Examples
    ///
    /// ```
    /// use mio::Ready;
    ///
    /// let ready = Ready::error();
    ///
    /// assert!(ready.is_error());
    /// ```
    ///
    /// [`Poll`]: struct.Poll.html
    #[inline]
    pub fn is_error(&self) -> bool {
        self.contains(ready_from_usize(ERROR))
    }

    /// Returns true if the value includes HUP readiness
    ///
    /// A HUP (or hang-up) signifies that a stream socket **peer** closed the
    /// connection, or shut down the writing half of the connection.
    ///
    /// **Note that only readable and writable readiness is guaranteed to be
    /// supported on all platforms**. This means that `hup` readiness
    /// should be treated as a hint. For more details, see [readiness] in the
    /// poll documentation.
    ///
    /// See [`Poll`] for more documentation on polling.
    ///
    /// # Examples
    ///
    /// ```
    /// use mio::Ready;
    ///
    /// let ready = Ready::hup();
    ///
    /// assert!(ready.is_hup());
    /// ```
    ///
    /// [`Poll`]: struct.Poll.html
    #[inline]
    pub fn is_hup(&self) -> bool {
        self.contains(ready_from_usize(HUP))
    }
}

impl From<Ready> for UnixReady {
    fn from(src: Ready) -> UnixReady {
        UnixReady(src)
    }
}

impl From<UnixReady> for Ready {
    fn from(src: UnixReady) -> Ready {
        src.0
    }
}

impl ops::Deref for UnixReady {
    type Target = Ready;

    fn deref(&self) -> &Ready {
        &self.0
    }
}

impl ops::DerefMut for UnixReady {
    fn deref_mut(&mut self) -> &mut Ready {
        &mut self.0
    }
}

impl ops::BitOr for UnixReady {
    type Output = UnixReady;

    #[inline]
    fn bitor(self, other: UnixReady) -> UnixReady {
        (self.0 | other.0).into()
    }
}

impl ops::BitXor for UnixReady {
    type Output = UnixReady;

    #[inline]
    fn bitxor(self, other: UnixReady) -> UnixReady {
        (self.0 ^ other.0).into()
    }
}

impl ops::BitAnd for UnixReady {
    type Output = UnixReady;

    #[inline]
    fn bitand(self, other: UnixReady) -> UnixReady {
        (self.0 & other.0).into()
    }
}

impl ops::Sub for UnixReady {
    type Output = UnixReady;

    #[inline]
    fn sub(self, other: UnixReady) -> UnixReady {
        (self.0 & !other.0).into()
    }
}

impl ops::Not for UnixReady {
    type Output = UnixReady;

    #[inline]
    fn not(self) -> UnixReady {
        (!self.0).into()
    }
}
