Add basic status page

apps/backend/src/mtp_server.rs

@@ -0,0 +1,96 @@
+use std::{net::IpAddr, sync::Arc};
+
+use mtp::{
+    codec::{CommunicationType, CommunicationValue, DataType, DataValue, TypeMap},
+    host::{HostConfig, Policy, SendMode},
+    webserver::{MTPWebServer, WebMTPConnection, WebServerConfig},
+};
+use tokio::sync::watch;
+
+pub async fn serve(
+    address: IpAddr,
+    port: u16,
+    certificate: Vec<u8>,
+    private_key: Vec<u8>,
+    state: Arc<crate::AppState>,
+) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
+    let policy = Policy::default().with_send_mode(SendMode::SingleStreamPerMessage);
+    let host = HostConfig::new(address, port, certificate, private_key).with_policy(policy);
+    let web = WebServerConfig::new()
+        .mtp_path("/mtp")
+        .serve_tcp_https(false);
+    let mut server = MTPWebServer::new(host, web).await?;
+    tracing::info!(address = %server.local_addr(), "MTP WebTransport listening");
+
+    let mut next_connection_id = 1_u64;
+    while let Some(connection) = server.accept().await? {
+        let connection_id = next_connection_id;
+        next_connection_id += 1;
+        tracing::info!(connection_id, "MTP client connected");
+        let updates = state.updates.subscribe();
+        let state = Arc::clone(&state);
+        tokio::spawn(
+            async move { serve_connection(connection_id, connection, updates, state).await },
+        );
+    }
+    Ok(())
+}
+
+async fn serve_connection(
+    connection_id: u64,
+    connection: WebMTPConnection,
+    mut updates: watch::Receiver<String>,
+    state: Arc<crate::AppState>,
+) {
+    let sender = connection.sender.clone();
+    let type_map = connection.codec.type_map().clone();
+    loop {
+        tokio::select! {
+            request = connection.receiver.receive() => {
+                let request = match request {
+                    Ok(request) => request,
+                    Err(error) => {
+                        tracing::warn!(connection_id, %error, "failed to receive MTP request");
+                        break;
+                    }
+                };
+                if request.is_type(CommunicationType::GetStatus) {
+                    let payload = state.snapshot_json().await;
+                    let bytes = payload.len();
+                    let response = snapshot(&type_map, payload).with_id(request.get_id());
+                    tracing::info!(connection_id, request_id = request.get_id(), bytes, "received status request");
+                    if let Err(error) = sender.send(&response).await {
+                        tracing::warn!(connection_id, request_id = request.get_id(), %error, "failed to send status response");
+                        break;
+                    }
+                    tracing::info!(connection_id, request_id = request.get_id(), "sent status response");
+                } else {
+                    tracing::warn!(connection_id, "received unsupported MTP request");
+                }
+            }
+            changed = updates.changed() => {
+                if changed.is_err() {
+                    tracing::info!(connection_id, "status update channel closed");
+                    break;
+                }
+                let payload = updates.borrow_and_update().clone();
+                let bytes = payload.len();
+                let response = snapshot(&type_map, payload);
+                if let Err(error) = sender.send(&response).await {
+                    tracing::warn!(connection_id, %error, "failed to push status update");
+                    break;
+                }
+                tracing::info!(connection_id, bytes, "pushed status update");
+            }
+        }
+    }
+    tracing::info!(connection_id, "MTP client disconnected");
+}
+
+fn snapshot(type_map: &TypeMap, payload: String) -> CommunicationValue {
+    CommunicationValue::from_comm(CommunicationType::StatusSnapshot, type_map).add_typed(
+        DataType::Payload,
+        type_map,
+        DataValue::Str(payload),
+    )
+}