verdnatura-chat/app/lib/appStateMiddleware.js

// https://github.com/bamlab/redux-enhancer-react-native-appstate
import { AppState } from 'react-native';

import { APP_STATE } from '../actions/actionsTypes';

export default () =>
	createStore =>
	(...args) => {
		const store = createStore(...args);

		let currentState = '';

		const handleAppStateChange = nextAppState => {
			if (nextAppState !== 'inactive') {
				if (currentState !== nextAppState) {
					let type;
					if (nextAppState === 'active') {
						type = APP_STATE.FOREGROUND;
					} else if (nextAppState === 'background') {
						type = APP_STATE.BACKGROUND;
					}
					if (type) {
						store.dispatch({
							type
						});
					}
				}
				currentState = nextAppState;
			}
		};

		AppState.addEventListener('change', handleAppStateChange);

		// setTimeout to allow redux-saga to catch the initial state fired by redux-enhancer-react-native-appstate library
		setTimeout(() => handleAppStateChange(AppState.currentState));
		return store;
	};