element-web/src/contexts/ToastContext.tsx
David Langley 491f0cd08a
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2024-09-09 13:57:16 +00:00

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TypeScript

/*
Copyright 2024 New Vector Ltd.
Copyright 2024 The Matrix.org Foundation C.I.C.
SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only
Please see LICENSE files in the repository root for full details.
*/
import { ReactNode, createContext, useCallback, useContext, useEffect, useRef, useState } from "react";
/**
* A ToastContext helps components display any kind of toast message and can be provided
* by a parent component such that their children can display toasts, eg. a settings dialog
* can provide a ToastContext such that controls within it can display toasts at the bottom
* of the dialog.
*
* It is not (at time of writing) used by the *other* toasts that appear in the top right
* corner of the app, however the name 'toast' as used in this class refers to the component
* of the same name in compound that it is written to manage.
*/
export const ToastContext = createContext(null as any);
ToastContext.displayName = "ToastContext";
/**
* Returns the ToastRack in context in order to display toasts
*/
export function useToastContext(): ToastRack {
return useContext(ToastContext);
}
/**
* For components that wish to display toasts, return the currently active toast and
* the ToastRack object that should be provided to the context
*/
export function useActiveToast(): [ReactNode | undefined, ToastRack] {
const toastRack = useRef(new ToastRack());
const [activeToast, setActiveToast] = useState<ReactNode | undefined>(toastRack.current.getActiveToast());
const updateCallback = useCallback(() => {
setActiveToast(toastRack.current.getActiveToast());
}, [setActiveToast, toastRack]);
useEffect(() => {
toastRack.current.setCallback(updateCallback);
}, [toastRack, updateCallback]);
return [activeToast, toastRack.current];
}
interface DisplayedToast {
id: number;
contents: ReactNode;
}
type RemoveCallback = () => void;
export class ToastRack {
private currentToast: DisplayedToast | undefined;
private updateCallback?: () => void;
private idSeq = 0;
public setCallback(cb: () => void): void {
this.updateCallback = cb;
}
public displayToast(contents: ReactNode): RemoveCallback {
const newToastId = ++this.idSeq;
this.currentToast = { id: newToastId, contents: contents };
this.updateCallback?.();
const removeFn = (): void => {
if (this.currentToast?.id === newToastId) {
this.currentToast = undefined;
this.updateCallback?.();
}
};
return removeFn;
}
public getActiveToast(): ReactNode | undefined {
return this.currentToast?.contents;
}
}