use std::os::fd::OwnedFd;

use rustix::net::{AddressFamily, SocketFlags, SocketType, socketpair};

/// # Errors
/// Returns an error when the private sequenced-packet pair cannot be created.
pub fn private_seqpacket_pair() -> std::io::Result<(OwnedFd, OwnedFd)> {
    socketpair(
        AddressFamily::UNIX,
        SocketType::SEQPACKET,
        SocketFlags::CLOEXEC,
        None,
    )
    .map_err(Into::into)
}

/// # Errors
/// Returns an error when the private stream pair cannot be created.
pub fn private_stream_pair() -> std::io::Result<(OwnedFd, OwnedFd)> {
    socketpair(
        AddressFamily::UNIX,
        SocketType::STREAM,
        SocketFlags::CLOEXEC,
        None,
    )
    .map_err(Into::into)
}

#[cfg(test)]
mod tests {
    use std::os::fd::AsFd;

    use rustix::net::{RecvFlags, SendFlags, recv, send};

    use super::private_seqpacket_pair;

    #[test]
    fn preserves_message_boundaries() {
        let (left, right) = private_seqpacket_pair().unwrap();
        send(left.as_fd(), b"first", SendFlags::empty()).unwrap();
        send(left.as_fd(), b"second", SendFlags::empty()).unwrap();
        let mut buffer = [0_u8; 16];
        let (_, first) = recv(right.as_fd(), &mut buffer, RecvFlags::empty()).unwrap();
        assert_eq!(&buffer[..first], b"first");
        let (_, second) = recv(right.as_fd(), &mut buffer, RecvFlags::empty()).unwrap();
        assert_eq!(&buffer[..second], b"second");
    }
}