Feature Toogle model generator

toogle-model-generator.ts

import { forEach } from 'lodash';

/**
 * @author    Marco Turi <marco.turi@hotmail.it>
 * @author    Stefano Tedeschi <stefano.tedeschi@protechstudio.it>
 * This function generates an object composed by N elements (states). 
 * Every element is a boolean and only one of them could be true.
 * This is usefull if you want to implement for example a TAB menager
 * where the user can active only one tab/page/component.
 * @example 
 *  const tab = generateToggleModel(['home', 'contacts']);
 *  tab.home = true; // now tab.contacts is false
 *  tab.contacts = true; // now tab.home is false
 *  tab.currentStateKey(); // -> contacts
 * @param states
 * @returns {...states: boolean}
 */
export const generateToggleModel = (states: Array<string>) => {
    const result: any = {};

    result.currentStateKey = () => {
        let trueKey = '';
        forEach(result, (value, key) => {
            if (key !== 'currentStateKey' && value === true) {
                trueKey = key;
            }
        });
        trueKey = trueKey.substr(1);
        return trueKey;
    };

    states.forEach(state => {
        const privateM = '_' + state;
        result[privateM] = false;
        Object.defineProperty(result, state, {
            get: () => {
                return result[privateM];
            },
            set: (val) => {
                forEach(result, (localState, key) => {
                    if (key[0] === '_') {
                        result[key] = false;
                    }
                });
                result[privateM] = true;
            },
        });
    });
    return result;
};