Manually disconnect & reconnect the livekit call if our focus changes

Without breaking the 'disconnected' screen

src/livekit/useECConnectionState.ts

@@ -0,0 +1,90 @@
+/*
+Copyright 2023 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { ConnectionState, Room, RoomEvent } from "livekit-client";
+import { useCallback, useEffect, useRef, useState } from "react";
+import { logger } from "matrix-js-sdk/src/logger";
+
+import { SFUConfig, sfuConfigEquals } from "./openIDSFU";
+
+/*
+ * Additional values for states that a call can be in, beyond what livekit
+ * provides in ConnectionState. Also reconnects the call if the SFU Config
+ * changes.
+ */
+export enum ECAddonConnectionState {
+  // We are switching from one focus to another (or between livekit room aliases on the same focus)
+  ECSwitchingFocus = "ec_switching_focus",
+  // The call has just been initialised and is waiting for credentials to arrive before attempting
+  // to connect. This distinguishes from the 'Disconected' state which is now just for when livekit
+  // gives up on connectivity and we consider the call to have failed.
+  ECWaiting = "ec_waiting",
+}
+
+export type ECConnectionState = ConnectionState | ECAddonConnectionState;
+
+export function useECConnectionState(
+  livekitRoom?: Room,
+  sfuConfig?: SFUConfig
+): ECConnectionState {
+  const [connState, setConnState] = useState(
+    sfuConfig && livekitRoom
+      ? livekitRoom.state
+      : ECAddonConnectionState.ECWaiting
+  );
+
+  const [isSwitchingFocus, setSwitchingFocus] = useState(false);
+
+  const onConnStateChanged = useCallback((state: ConnectionState) => {
+    if (state == ConnectionState.Connected) setSwitchingFocus(false);
+    setConnState(state);
+  }, []);
+
+  useEffect(() => {
+    const oldRoom = livekitRoom;
+
+    if (livekitRoom) {
+      livekitRoom.on(RoomEvent.ConnectionStateChanged, onConnStateChanged);
+    }
+
+    return () => {
+      if (oldRoom)
+        oldRoom.off(RoomEvent.ConnectionStateChanged, onConnStateChanged);
+    };
+  }, [livekitRoom, onConnStateChanged]);
+
+  const currentSFUConfig = useRef(Object.assign({}, sfuConfig));
+
+  useEffect(() => {
+    if (
+      sfuConfig &&
+      currentSFUConfig.current &&
+      !sfuConfigEquals(currentSFUConfig.current, sfuConfig)
+    ) {
+      logger.info("JWT changed!");
+
+      (async () => {
+        setSwitchingFocus(true);
+        await livekitRoom?.disconnect();
+        await livekitRoom?.connect(sfuConfig.url, sfuConfig.jwt);
+      })();
+    }
+
+    currentSFUConfig.current = Object.assign({}, sfuConfig);
+  }, [sfuConfig, livekitRoom]);
+
+  return isSwitchingFocus ? ECAddonConnectionState.ECSwitchingFocus : connState;
+}