Add account and room-account data hooks

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/hooks/useAccountData.ts

@@ -0,0 +1,50 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+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 {useCallback, useState} from "react";
+import {MatrixClient} from "matrix-js-sdk/src/client";
+import {MatrixEvent} from "matrix-js-sdk/src/models/event";
+import {Room} from "matrix-js-sdk/src/models/room";
+
+import {useEventEmitter} from "./useEventEmitter";
+
+const tryGetContent = (ev?: MatrixEvent) => ev ? ev.getContent() : undefined;
+
+// Hook to simplify listening to Matrix account data
+export const useAccountData = <T extends {}>(cli: MatrixClient, eventType: string) => {
+    const [value, setValue] = useState<T>(() => tryGetContent(cli.getAccountData(eventType)));
+
+    const handler = useCallback((event) => {
+        if (event.getType() !== eventType) return;
+        setValue(event.getContent());
+    }, [cli, eventType]);
+    useEventEmitter(cli, "accountData", handler);
+
+    return value || {};
+};
+
+// Hook to simplify listening to Matrix room account data
+export const useRoomAccountData = <T extends {}>(room: Room, eventType: string) => {
+    const [value, setValue] = useState<T>(() => tryGetContent(room.getAccountData(eventType)));
+
+    const handler = useCallback((event) => {
+        if (event.getType() !== eventType) return;
+        setValue(event.getContent());
+    }, [room, eventType]);
+    useEventEmitter(room, "Room.accountData", handler);
+
+    return value || {};
+};