huskies: merge 616_story_extract_notifications_service

server/src/service/notifications/route.rs

@@ -0,0 +1,42 @@
+//! Room-routing decisions for notifications.
+//!
+//! Pure functions that determine which destination room IDs should receive
+//! a given notification.  Currently all notification kinds are broadcast to
+//! all registered rooms; this module is the single location to change that
+//! policy if per-event routing is needed in the future.
+
+/// Return the rooms that should receive a notification.
+///
+/// `get_room_ids` is called once per notification to obtain the current list
+/// of destination room IDs.  Passing a closure (rather than a static slice)
+/// allows callers to use a runtime-mutable set, e.g. WhatsApp ambient senders.
+///
+/// All currently supported event kinds are broadcast to every room returned
+/// by the closure.
+pub fn rooms_for_notification(get_room_ids: &impl Fn() -> Vec<String>) -> Vec<String> {
+    get_room_ids()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn returns_all_rooms_from_closure() {
+        let rooms = rooms_for_notification(&|| vec!["room1".to_string(), "room2".to_string()]);
+        assert_eq!(rooms, vec!["room1".to_string(), "room2".to_string()]);
+    }
+
+    #[test]
+    fn returns_empty_when_no_rooms_registered() {
+        let rooms = rooms_for_notification(&Vec::new);
+        assert!(rooms.is_empty());
+    }
+
+    #[test]
+    fn returns_single_room() {
+        let rooms = rooms_for_notification(&|| vec!["!abc:example.org".to_string()]);
+        assert_eq!(rooms.len(), 1);
+        assert_eq!(rooms[0], "!abc:example.org");
+    }
+}