From 4c7bc1f2989bbc6082706555558ca2e250cafbad Mon Sep 17 00:00:00 2001
From: Brad Stein <brad.stein@gmail.com>
Date: Mon, 2 Jun 2025 20:41:36 -0500
Subject: [PATCH] updates

---
 server/src/main.rs | 69 +++++++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 31 deletions(-)

diff --git a/server/src/main.rs b/server/src/main.rs
index bbfc761..0959765 100644
--- a/server/src/main.rs
+++ b/server/src/main.rs
@@ -1,60 +1,67 @@
-//! navka-server – echoes HID reports back to every client
+//! navka-server — receive HidReport and write to /dev/hidg0
 #![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 std::{pin::Pin, sync::Arc};
+use tokio::{fs::OpenOptions, io::AsyncWriteExt};
+use tokio_stream::{wrappers::ReceiverStream, Stream, StreamExt};
+use tonic::{transport::Server, Request, Response, Status};
 
 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>,
+struct Handler {
+    /// shared async handle to /dev/hidg0
+    hid: Arc<tokio::sync::Mutex<tokio::fs::File>>,
 }
 
-#[async_trait]
-impl Relay for RelaySvc {
-    type StreamStream = ReceiverStream<Result<HidReport, Status>>;
+#[tonic::async_trait]
+impl Relay for Handler {
+    type StreamStream =
+        Pin<Box<dyn Stream<Item = Result<HidReport, Status>> + Send + 'static>>;
 
     async fn stream(
         &self,
         request: Request<tonic::Streaming<HidReport>>,
     ) -> Result<Response<Self::StreamStream>, Status> {
-        let mut inbound = request.into_inner();
+        let mut in_stream = request.into_inner();
+        let hid = self.hid.clone();
 
-        // each connected client gets its own outbound channel
-        let (tx, rx) = mpsc::channel::<Result<HidReport, Status>>(32);
-        let outbound = ReceiverStream::new(rx);
+        // echo everything back to caller & push down USB
+        let (tx, rx) = tokio::sync::mpsc::channel(32);
 
-        // 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;
-                }
+        tokio::spawn(async move {
+            while let Some(msg) = in_stream.next().await.transpose()? {
+                // 1) write to /dev/hidg0
+                let mut file = hid.lock().await;
+                file.write_all(&msg.data).await.map_err(|e| Status::internal(e.to_string()))?;
+                file.flush().await.ok();
+
+                // 2) echo back
+                tx.send(Ok(msg)).await.ok();
             }
-            Ok::<(), Status>(())
+            Ok::<_, Status>(())
         });
 
-        Ok(Response::new(outbound))
+        Ok(Response::new(Box::pin(ReceiverStream::new(rx))))
     }
 }
 
 #[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);
+async fn main() -> anyhow::Result<()> {
+    let file = OpenOptions::new()
+        .write(true)
+        .open("/dev/hidg0")
+        .await?;
+    let hid = Arc::new(tokio::sync::Mutex::new(file));
 
-    println!("🌀 navka-server listening on 0.0.0.0:50051");
+    let handler = Handler { hid };
+
+    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())
+        .add_service(RelayServer::new(handler))
+        .serve(([0, 0, 0, 0], 50051).into())
         .await?;
     Ok(())
 }