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/*
This file is part of GNU Taler
(C) 2021 Taler Systems S.A.
GNU Taler is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
/**
*
* @author Sebastian Javier Marchano (sebasjm)
*/
import { useState } from "preact/hooks";
/**
* returns subscriber and activator
* subscriber will receive a method (listener) that will be call when the activator runs.
* the result of calling the listener will be sent to @action
*
* @param action from <T> to <R>
* @returns activator and subscriber, undefined activator means that there is not subscriber
*/
export function useListener<T, R = any>(action: (r: T) => Promise<R>): [undefined | (() => Promise<R>), (listener?: () => T) => void] {
type RunnerHandler = { toBeRan?: () => Promise<R>; };
const [state, setState] = useState<RunnerHandler>({});
/**
* subscriber will receive a method that will be call when the activator runs
*
* @param listener function to be run when the activator runs
*/
const subscriber = (listener?: () => T) => {
if (listener) {
setState({
toBeRan: () => {
const whatWeGetFromTheListener = listener();
return action(whatWeGetFromTheListener);
}
});
} else {
setState({
toBeRan: undefined
})
}
};
/**
* activator will call runner if there is someone subscribed
*/
const activator = state.toBeRan ? async () => {
if (state.toBeRan) {
return state.toBeRan();
}
return Promise.reject();
} : undefined;
return [activator, subscriber];
}
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