mattermost-mobile/app/store/utils.js

// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

function transformFromSet(incoming) {
    const state = {...incoming};

    for (const key in state) {
        if (state.hasOwnProperty(key)) {
            if (state[key] instanceof Set) {
                state[key] = Array.from([...state[key]]);
            }
        }
    }

    return state;
}

function transformToSet(incoming) {
    const state = {...incoming};

    for (const key in state) {
        if (state.hasOwnProperty(key)) {
            state[key] = new Set(state[key]);
        }
    }

    return state;
}

export function transformSet(incoming, setTransforms, toStorage = true) {
    const state = {...incoming};

    const transformer = toStorage ? transformFromSet : transformToSet;

    for (const key in state) {
        if (state.hasOwnProperty(key) && setTransforms.includes(key)) {
            state[key] = transformer(state[key]);
        }
    }

    return state;
}

export function waitForHydration(store, callback) {
    let unsubscribeFromStore;
    return new Promise((resolve) => {
        if (__DEV__) {
            // when in DEV mode resetting the app can get into a white screen
            resolve();
            return;
        }
        const subscription = () => {
            if (store.getState().views.root.hydrationComplete) {
                unsubscribeFromStore();
                if (callback && typeof callback === 'function') {
                    callback();
                }
                resolve();
            }
        };

        unsubscribeFromStore = store.subscribe(subscription);
    });
}