// @flow

import { _SET_APP_STATE_LISTENER, APP_STATE_CHANGED } from './actionTypes';

/**
 * Sets the listener to be used with React Native's AppState API.
 *
 * @param {Function} listener - Function to be set as the change event listener.
 * @protected
 * @returns {{
 *     type: _SET_APP_STATE_LISTENER,
 *     listener: Function
 * }}
 */
export function _setAppStateListener(listener: ?Function) {
    return {
        type: _SET_APP_STATE_LISTENER,
        listener
    };
}

/**
 * Signals that the App state has changed (in terms of execution state). The
 * application can be in 3 states: 'active', 'inactive' and 'background'.
 *
 * @param {string} appState - The new App state.
 * @public
 * @returns {{
 *     type: APP_STATE_CHANGED,
 *     appState: string
 * }}
 * @see {@link https://facebook.github.io/react-native/docs/appstate.html}
 */
export function appStateChanged(appState: string) {
    return {
        type: APP_STATE_CHANGED,
        appState
    };
}