60 lines
1.7 KiB
TypeScript
60 lines
1.7 KiB
TypeScript
/*
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Copyright 2020 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import {
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Schema,
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} from 'zod';
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import React from 'react';
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/*
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* Initialises local storage to initial value if
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* a value matching the schema is not in storage.
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*/
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export function persistReducer<T, A>(
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stateKey: string,
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initialState: T,
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schema: Schema<T>,
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reducer: React.Reducer<T, A>,
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): [T, React.Reducer<T, A>] {
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let currentState = initialState;
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// Try to load state from local storage
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const stateInStorage = localStorage.getItem(stateKey);
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if (stateInStorage) {
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try {
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// Validate state type
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const parsedState = JSON.parse(stateInStorage);
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if (parsedState as T) {
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currentState = schema.parse(parsedState);
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}
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} catch (e) {
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// if invalid delete state
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localStorage.setItem(stateKey, JSON.stringify(initialState));
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}
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} else {
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localStorage.setItem(stateKey, JSON.stringify(initialState));
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}
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return [
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currentState,
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(state: T, action: A) => {
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// state passed to this reducer is the source of truth
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const newState = reducer(state, action);
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localStorage.setItem(stateKey, JSON.stringify(newState));
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return newState;
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},
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];
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}
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