lesavka/server/src/main.rs

//! navka-server – echoes HID reports back to every client
#![forbid(unsafe_code)]

use anyhow::Result;
use tokio::{sync::mpsc, task};
use tokio_stream::wrappers::ReceiverStream;
use tonic::{Request, Response, Status, transport::Server};
use tonic::async_trait;

use navka_common::navka::{
    relay_server::{Relay, RelayServer},
    HidReport,
};

struct RelaySvc {
    // shared broadcast channel (unused for now, but kept for future fan-out)
    _hub_tx: mpsc::Sender<HidReport>,
}

#[async_trait]
impl Relay for RelaySvc {
    type StreamStream = ReceiverStream<Result<HidReport, Status>>;

    async fn stream(
        &self,
        request: Request<tonic::Streaming<HidReport>>,
    ) -> Result<Response<Pin<Box<dyn Stream<Item = Result<HidReport, Status>> + Send>>>, Status> {
        let mut inbound = request.into_inner();

        // each connected client gets its own outbound channel
        let (tx, rx) = mpsc::channel::<Result<HidReport, Status>>(32);
        let outbound = ReceiverStream::new(rx);

        // task: read → echo
        task::spawn(async move {
            while let Some(report) = inbound.message().await? {
                // errors here just mean the client hung up – stop the loop
                if tx.send(Ok(report)).await.is_err() {
                    break;
                }
            }
            Ok::<(), Status>(())
        });

        Ok(Response::new(outbound))
    }
}

#[tokio::main]
async fn main() -> Result<()> {
    // placeholder hub – you’ll reuse this when you forward to the OTG gadget
    let (hub_tx, _hub_rx) = mpsc::channel::<HidReport>(32);

    println!("🌀 navka-server listening on 0.0.0.0:50051");
    Server::builder()
        .add_service(RelayServer::new(RelaySvc { _hub_tx: hub_tx }))
        .serve("0.0.0.0:50051".parse().unwrap())
        .await?;
    Ok(())
}