diff options
Diffstat (limited to 'packages/merchant-backend-ui/src/hooks/listener.ts')
-rw-r--r-- | packages/merchant-backend-ui/src/hooks/listener.ts | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/packages/merchant-backend-ui/src/hooks/listener.ts b/packages/merchant-backend-ui/src/hooks/listener.ts new file mode 100644 index 000000000..231ed6c87 --- /dev/null +++ b/packages/merchant-backend-ui/src/hooks/listener.ts @@ -0,0 +1,68 @@ +/* + 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]; +} |