use ractor::{cast, Actor, ActorProcessingErr, ActorRef};

/// [PingPong] is a basic actor that will print
/// ping..pong.. repeatedly until some exit
/// condition is met (a counter hits 10). Then
/// it will exit
pub struct PingPong;

/// This is the types of message [PingPong] supports
#[derive(Debug, Clone)]
pub enum Message {
    Ping,
    Pong,
}

impl Message {
    // retrieve the next message in the sequence
    fn next(&self) -> Self {
        match self {
            Self::Ping => Self::Pong,
            Self::Pong => Self::Ping,
        }
    }
    // print out this message
    fn print(&self) {
        match self {
            Self::Ping => print!("ping.."),
            Self::Pong => print!("pong.."),
        }
    }
}

// the implementation of our actor's "logic"
#[async_trait::async_trait]
impl Actor for PingPong {
    // An actor has a message type
    type Msg = Message;
    // and (optionally) internal state
    type State = u8;
    // Startup initialization args
    type Arguments = ();

    // Initially we need to create our state, and potentially
    // start some internal processing (by posting a message for
    // example)
    async fn pre_start(
        &self,
        myself: ActorRef<Self>,
        _: (),
    ) -> Result<Self::State, ActorProcessingErr> {
        // startup the event processing
        cast!(myself, Message::Ping)?;
        // create the initial state
        Ok(0u8)
    }

    // This is our main message handler
    async fn handle(
        &self,
        myself: ActorRef<Self>,
        message: Self::Msg,
        state: &mut Self::State,
    ) -> Result<(), ActorProcessingErr> {
        if *state < 10u8 {
            message.print();
            cast!(myself, message.next())?;
            *state += 1;
        } else {
            println!();
            myself.stop(None);
            // don't send another message, rather stop the agent after 10 iterations
        }
        Ok(())
    }
}

#[tokio::main]
async fn main() {
    let (_actor, handle) = Actor::spawn(None, PingPong, ())
        .await
        .expect("Failed to start ping-pong actor");
    handle
        .await
        .expect("Ping-pong actor failed to exit properly");
}