use std::sync::Arc;

use anyhow::Error;
use messagebus::{Builder, Bus, Context, Handler, IntoMessages, Message};

#[derive(Debug, Clone)]
pub struct Msg(pub i32);
impl Message for Msg {}

pub struct Processor {
    _state: i32,
}

impl Handler<Msg> for Processor {
    type Result = ();
    type Error = Error;

    async fn handle(
        &mut self,
        _msg: Msg,
        _ctx: Context,
        _bus: Bus,
    ) -> Result<impl IntoMessages<Self::Result, Self::Error>, Self::Error> {
        Ok(())
    }

    async fn handle_error(
        &mut self,
        _err: messagebus::Error,
        _ctx: Context,
        _bus: messagebus::Bus,
    ) -> Result<impl IntoMessages<Self::Result, Self::Error> + Send + '_, Self::Error> {
        Ok(None)
    }

    async fn finalize(self, _bus: Bus) -> Result<(), Self::Error> {
        Ok(())
    }
}

struct ProcSpawner;
impl Builder<Msg> for ProcSpawner {
    type Context = Processor;

    async fn build(
        &self,
        stream_id: u32,
        _task_id: u32,
    ) -> Result<Self::Context, messagebus::Error> {
        Ok(Processor {
            _state: stream_id as _,
        })
    }
}

impl Processor {
    pub async fn spawn(_sid: u32) -> Result<(usize, Self), Error> {
        Ok((4, Self { _state: 0 }))
    }

    pub async fn handler_msg(
        self: Arc<Self>,
        _sid: u32,
        _tid: u32,
        _msg: Msg,
    ) -> Result<(), Error> {
        Ok(())
    }

    pub async fn finalize_msg_handler(self: Arc<Self>, _sid: u32) -> Result<(), Error> {
        Ok(())
    }
}

async fn run() {
    let bus = Bus::new();
    bus.register(ProcSpawner).await;
}

#[tokio::main]
async fn main() {
    run().await
}