47 lines
1.5 KiB
TypeScript
47 lines
1.5 KiB
TypeScript
/*
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Copyright 2024 New Vector Ltd.
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Copyright 2021 The Matrix.org Foundation C.I.C.
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SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
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Please see LICENSE files in the repository root for full details.
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*/
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import { useCallback, useEffect, useRef, useState } from "react";
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import { Room, RoomState, RoomStateEvent } from "matrix-js-sdk/src/matrix";
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import { useTypedEventEmitter } from "./useEventEmitter";
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type Mapper<T> = (roomState: RoomState) => T;
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const defaultMapper: Mapper<RoomState> = (roomState: RoomState) => roomState;
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// Hook to simplify watching Matrix Room state
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// eslint-disable-next-line @typescript-eslint/no-unnecessary-type-constraint
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export const useRoomState = <T extends any = RoomState>(
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room?: Room,
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mapper: Mapper<T> = defaultMapper as Mapper<T>,
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): T => {
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// Create a ref that stores mapper
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const savedMapper = useRef(mapper);
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// Update ref.current value if mapper changes.
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useEffect(() => {
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savedMapper.current = mapper;
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}, [mapper]);
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const [value, setValue] = useState<T>(room ? mapper(room.currentState) : (undefined as T));
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const update = useCallback(() => {
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if (!room) return;
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setValue(savedMapper.current(room.currentState));
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}, [room]);
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useTypedEventEmitter(room?.currentState, RoomStateEvent.Update, update);
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useEffect(() => {
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update();
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return () => {
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setValue(room ? savedMapper.current(room.currentState) : (undefined as T));
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};
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}, [room, update]);
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return value;
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};
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