From 81a763f17f78a717f9198f444ff3538e71f08dcd Mon Sep 17 00:00:00 2001
From: Robert Long <robert@robertlong.me>
Date: Fri, 18 Feb 2022 16:23:37 -0800
Subject: [PATCH] Avoid duplicate sessions across devices/browsers

---
 src/ClientContext.jsx | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/ClientContext.jsx b/src/ClientContext.jsx
index 91d756a..69a4b64 100644
--- a/src/ClientContext.jsx
+++ b/src/ClientContext.jsx
@@ -182,12 +182,21 @@ export function ClientProvider({ children }) {
   }, [history]);
 
   useEffect(() => {
-    if ("BroadcastChannel" in window) {
+    if (client) {
       const loadTime = Date.now();
-      const broadcastChannel = new BroadcastChannel("matrix-video-chat");
 
-      function onMessage({ data }) {
-        if (data.load !== undefined && data.load > loadTime) {
+      const onToDeviceEvent = (event) => {
+        if (event.getType() !== "org.matrix.call_duplicate_session") {
+          return;
+        }
+
+        const content = event.getContent();
+
+        if (content.session_id === client.getSessionId()) {
+          return;
+        }
+
+        if (content.timestamp > loadTime) {
           if (client) {
             client.stopClient();
           }
@@ -199,13 +208,18 @@ export function ClientProvider({ children }) {
             ),
           }));
         }
-      }
+      };
 
-      broadcastChannel.addEventListener("message", onMessage);
-      broadcastChannel.postMessage({ load: loadTime });
+      client.on("toDeviceEvent", onToDeviceEvent);
+
+      client.sendToDevice("org.matrix.call_duplicate_session", {
+        [client.getUserId()]: {
+          "*": { session_id: client.getSessionId(), timestamp: loadTime },
+        },
+      });
 
       return () => {
-        broadcastChannel.removeEventListener("message", onMessage);
+        client.removeListener("toDeviceEvent", onToDeviceEvent);
       };
     }
   }, [client]);