use std::{
	cmp::{Eq, Ord, Ordering, PartialEq, PartialOrd},
	hash::{Hash, Hasher},
};

use crate::{dialer::Dialer, listener::Listener};

/// An NNG communication pipe.
///
/// A pipe can be thought of as a single connection and are associated with
/// either the listener or dialer that created them. Therefore, they are
/// automatically associated with a single socket.
///
/// Most applications should never concern themselves with individual pipes.
/// However, it is possible to access a pipe when more information about the
/// source of the message is needed or when more control is required over
/// message delivery.
///
/// See the [NNG documentation][1] for more information.
///
/// [1]: https://nanomsg.github.io/nng/man/v1.2.2/nng_pipe.5
#[derive(Clone, Copy, Debug)]
pub struct Pipe
{
	/// The underlying NNG pipe.
	handle: nng_sys::nng_pipe,
}
impl Pipe
{
	/// Returns the dialer associated with this pipe, if any.
	pub fn dialer(self) -> Option<Dialer>
	{
		let (dialer, id) = unsafe {
			let dialer = nng_sys::nng_pipe_dialer(self.handle);
			let id = nng_sys::nng_dialer_id(dialer);
			(dialer, id)
		};

		if id > 0 { Some(Dialer::from_nng_sys(dialer)) } else { None }
	}

	/// Returns the listener associated with this pipe, if any.
	pub fn listener(self) -> Option<Listener>
	{
		let (listener, id) = unsafe {
			let listener = nng_sys::nng_pipe_listener(self.handle);
			let id = nng_sys::nng_listener_id(listener);
			(listener, id)
		};

		if id > 0 { Some(Listener::from_nng_sys(listener)) } else { None }
	}

	/// Closes the pipe.
	///
	/// Messages that have been submitted for sending may be flushed or
	/// delivered, depending upon the transport and the linger option. Pipe are
	/// automatically closed when their creator closes or when the remote peer
	/// closes the underlying connection.
	#[allow(clippy::missing_panics_doc)]
	pub fn close(self)
	{
		// The pipe either closes succesfully, was already closed, or was never open. In
		// any of those scenarios, the pipe is in the desired state. As such, we don't
		// care about the return value.
		let rv = unsafe { nng_sys::nng_pipe_close(self.handle) };
		assert!(
			rv == 0 || rv == nng_sys::NNG_ECLOSED as i32,
			"Unexpected error code while closing pipe ({})",
			rv
		);
	}

	/// Returns the underlying NNG handle for the pipe.
	pub(crate) const fn handle(self) -> nng_sys::nng_pipe { self.handle }

	/// Create a new Pipe handle from a NNG handle.
	///
	/// This function will panic if the handle is not valid.
	pub(crate) fn from_nng_sys(handle: nng_sys::nng_pipe) -> Self
	{
		assert!(unsafe { nng_sys::nng_pipe_id(handle) > 0 }, "Pipe handle is not initialized");
		Pipe { handle }
	}
}

#[cfg(feature = "ffi-module")]
impl Pipe
{
	/// Returns the handle to the underlying `nng_pipe` object.
	pub fn nng_pipe(self) -> nng_sys::nng_pipe { self.handle() }
}

impl PartialEq for Pipe
{
	fn eq(&self, other: &Pipe) -> bool
	{
		unsafe { nng_sys::nng_pipe_id(self.handle) == nng_sys::nng_pipe_id(other.handle) }
	}
}

impl Eq for Pipe {}

impl PartialOrd for Pipe
{
	fn partial_cmp(&self, other: &Pipe) -> Option<Ordering> { Some(self.cmp(other)) }
}

impl Ord for Pipe
{
	fn cmp(&self, other: &Pipe) -> Ordering
	{
		unsafe {
			let us = nng_sys::nng_pipe_id(self.handle);
			let them = nng_sys::nng_pipe_id(other.handle);
			us.cmp(&them)
		}
	}
}

impl Hash for Pipe
{
	fn hash<H: Hasher>(&self, state: &mut H)
	{
		let id = unsafe { nng_sys::nng_pipe_id(self.handle) };
		id.hash(state);
	}
}

#[rustfmt::skip]
expose_options!{
	Pipe :: handle -> nng_sys::nng_pipe;

	GETOPT_BOOL = nng_sys::nng_pipe_get_bool;
	GETOPT_INT = nng_sys::nng_pipe_get_int;
	GETOPT_MS = nng_sys::nng_pipe_get_ms;
	GETOPT_SIZE = nng_sys::nng_pipe_get_size;
	GETOPT_SOCKADDR = nng_sys::nng_pipe_get_addr;
	GETOPT_STRING = nng_sys::nng_pipe_get_string;
	GETOPT_UINT64 = nng_sys::nng_pipe_get_uint64;

	SETOPT = crate::util::fake_genopt;
	SETOPT_BOOL = crate::util::fake_opt;
	SETOPT_INT = crate::util::fake_opt;
	SETOPT_MS = crate::util::fake_opt;
	SETOPT_PTR = crate::util::fake_opt;
	SETOPT_SIZE = crate::util::fake_opt;
	SETOPT_STRING =crate::util::fake_opt;

	Gets -> [LocalAddr, RemAddr, RecvMaxSize,
	         transport::ipc::PeerPid,
	         transport::tcp::NoDelay,
	         transport::tcp::KeepAlive,
	         transport::tls::Verified,
	         transport::websocket::RequestHeaders,
	         transport::websocket::ResponseHeaders];
	Sets -> [];
}

#[cfg(unix)]
mod unix_impls
{
	use super::*;
	use crate::options::{transport::ipc, SetOpt};

	impl SetOpt<ipc::PeerUid> for Pipe {}
	impl SetOpt<ipc::PeerGid> for Pipe {}
}

/// An event that happens on a [`Pipe`] instance.
///
///
/// [`Pipe`]: struct.Pipe.html
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum PipeEvent
{
	/// Occurs after a connection and negotiation has completed but before the
	/// pipe is added to the socket.
	///
	/// If the pipe is closed at this point, the socket will never see the pipe
	/// and no further events will occur for the given pipe.
	AddPre,

	/// This event occurs after the pipe is fully added to the socket.
	///
	/// Prior to this time, it is not possible to communicate over the pipe with
	/// the socket.
	AddPost,

	/// Occurs after the pipe has been removed from the socket.
	///
	/// The underlying transport may be closed at this point and it is not
	/// possible to communicate with this pipe.
	RemovePost,

	/// An unknown event.
	///
	/// Should never happen - used for forward compatibility.
	#[doc(hidden)]
	Unknown(u32),
}
impl PipeEvent
{
	/// Converts the NNG code into a `PipeEvent`.
	pub(crate) fn from_code(event: u32) -> Self
	{
		match event {
			nng_sys::NNG_PIPE_EV_ADD_PRE => PipeEvent::AddPre,
			nng_sys::NNG_PIPE_EV_ADD_POST => PipeEvent::AddPost,
			nng_sys::NNG_PIPE_EV_REM_POST => PipeEvent::RemovePost,
			_ => PipeEvent::Unknown(event),
		}
	}
}