From a48c19f8c933291a3e65a3143eabda03e8bf1ede Mon Sep 17 00:00:00 2001
From: Owen Jacobson <owen@grimoire.ca>
Date: Sun, 15 Sep 2024 22:39:23 -0400
Subject: Annotate channel events with channel ID at the router, not
 intrinsically.

This bugged me aesthetically. At `app.channel().events(channel)`, the caller knows the channel ID; they don't need to be told. Having the same info come back out in the returned events felt bad.
---
 src/events.rs | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

(limited to 'src/events.rs')

diff --git a/src/events.rs b/src/events.rs
index 2d1e1f8..51f06b4 100644
--- a/src/events.rs
+++ b/src/events.rs
@@ -49,21 +49,33 @@ async fn on_events(
     let streams = stream::iter(query.channels)
         .then(|channel| {
             let app = app.clone();
-            async move { app.channels().events(&channel, resume_at.as_ref()).await }
+            async move {
+                let events = app
+                    .channels()
+                    .events(&channel, resume_at.as_ref())
+                    .await?
+                    .map_ok(move |message| ChannelEvent {
+                        channel: channel.clone(),
+                        message,
+                    });
+
+                Ok::<_, BoxedError>(events)
+            }
         })
         .try_collect::<Vec<_>>()
         .await?;
 
-    let stream = stream::select_all(streams).and_then(|msg| future::ready(to_event(msg)));
+    let stream = stream::select_all(streams).and_then(|msg| future::ready(to_sse_event(msg)));
     let sse = Sse::new(stream).keep_alive(sse::KeepAlive::default());
 
     Ok(sse)
 }
 
-fn to_event(msg: BroadcastMessage) -> Result<sse::Event, BoxedError> {
-    let data = serde_json::to_string(&msg)?;
+fn to_sse_event(event: ChannelEvent<BroadcastMessage>) -> Result<sse::Event, BoxedError> {
+    let data = serde_json::to_string(&event)?;
     let event = sse::Event::default()
-        .id(msg
+        .id(event
+            .message
             .sent_at
             .to_rfc3339_opts(SecondsFormat::AutoSi, /* use_z */ true))
         .data(&data);
@@ -71,6 +83,13 @@ fn to_event(msg: BroadcastMessage) -> Result<sse::Event, BoxedError> {
     Ok(event)
 }
 
+#[derive(serde::Serialize)]
+struct ChannelEvent<M> {
+    channel: ChannelId,
+    #[serde(flatten)]
+    message: M,
+}
+
 pub struct LastEventId(pub String);
 
 static LAST_EVENT_ID: HeaderName = HeaderName::from_static("last-event-id");
-- 
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