AuthService.js

var buffer = require('buffer');
var AsyncStorage = require('react-native').AsyncStorage;
var _ = require('lodash');

const authKey = 'auth';
const userKey = 'user';

class AuthService {
	getAuthInfo(cb){
		AsyncStorage.multiGet([authKey, userKey], (err, val) => {
			if(err) {
				return cb(err);
			}

			if(!val){
				return cb();
			}

			var zippedObj = _.zipObject(val);

			if(!zippedObj[authKey]){
				return cb();
			}

			var authInfo = {
				header: {
					Authorization: 'Basic ' + zippedObj[authKey]  
				},
				user: JSON.parse(zippedObj[userKey])
			}

			return cb(null, authInfo);

		});
	}
	login(creds, cb){
		var b = new buffer.Buffer(creds.username +
			':' + creds.password);

		var encodedAuth = b.toString('base64');
		
		fetch('https://api.github.com/user', {
			headers: {
				'Authorization' : 'Basic ' + encodedAuth
			}
		})
		.then((response) => {
			if(response.status >= 200 && response.status < 300){
				return response;
			}
			
			throw {
				badCredentials: response.status == 401,
				unknownError: response.status != 401
			}
				
		})
		.then((response) => {
			return response.json();
		})
		.then((results) => {
			AsyncStorage.multiSet([
				[authKey, encodedAuth],
				[userKey, JSON.stringify(results)]
			], (err) => {
				if(err){
					throw err;
				}
				return cb({success: true})
			})
		})
		.catch((err) => {
			return cb(err)
		})
	}
}

module.exports = new AuthService();