use crossbeam_channel::Receiver;

use crossbeam_channel::SendError;

/// A [`Responder`] returns results after processing a service [`Command`].

///

/// To construct a [`Responder`], use [`Responder::new`], which also returns its

/// corresponding [`Receiver`].

///

/// To send results, use either:

/// - [`Responder::send`]

/// - [`Responder::ok`]

/// - [`Responder::err`]

pub struct Responder<T> {

    channel: Sender<Result<T>>,

}

impl<T> Responder<T> {

    /// Construct a new [`Responder`] and its corresponding [`Receiver`].

    pub fn new() -> (Self, Receiver<Result<T>>) {

        let (sender, receiver) = crossbeam_channel::bounded(1);

        (Self { channel: sender }, receiver)

    }

    /// Send a [`Result`] to the receiver.

    pub fn send(&self, result: Result<T>) -> std::result::Result<(), SendError<Result<T>>> {

        self.channel.send(result)

    }

    /// Send a [`Result::Ok`] to the receiver.

    pub fn ok(&self, value: T) -> std::result::Result<(), SendError<Result<T>>> {

        self.send(Ok(value))

    }

    /// Send a [`Result::Err`] to the receiver.

    pub fn err<E>(&self, error: E) -> std::result::Result<(), SendError<Result<T>>>

    where

        E: std::error::Error + Send + Sync + 'static,

    {

        self.send(Err(Error::other(error)))

    }

}