ping.service.js

/*@ngInject*/
export default function pingService($http, endpoint) {
    return {
        ping: () => $http.get(`${endpoint}ping`).then(response => response.data)
    };
}

session.service.js

import sha256 from 'jssha/src/sha256';

/*@ngInject*/
export default function sessionService($rootScope, $http, $q, $window, localStorageService, endpoint, pingService) {
    const USER_SESSION = 'userSession',
        USERS = 'users',
        CREDENTIALS = 'credentials';
    let idSurveyLastVisited = null;

    function setSession(user) {
        $rootScope.isLoggedIn = !!user;
        let auth = null;
        if (user) {
            auth = `Basic ${$window.btoa(user._id + ':' + user.password)}`;
        } else {
            idSurveyLastVisited = null;
        }
        $http.defaults.headers.common.Authorization = auth;
    }

    function loginLocally(username, password) {
        let users = localStorageService.get(USERS);
        if (!users) {
            return;
        }
        let user = users[username];
        if (!user) {
            return;
        }
        if (user.password != sha256(password)) {
            return null;
        }
        localStorageService.set(USER_SESSION, user);
        setSession(user);
        return user;
    }

    function loginOnServer(username, password) {
        return $http.post(`${endpoint}sign-in`, {username: username, password: password}).then(
            response => {
                let users = localStorageService.get(USERS);
                users = users || {};
                users[response.data._id] = response.data;
                localStorageService.set(USERS, users);
                localStorageService.set(USER_SESSION, response.data);
                setSession(response.data);
                return response.data;
            },
            response => {
                if (response.status == 403) {
                    localStorageService.remove(username);
                }
                return response.error;
            });
    }

    setSession(localStorageService.get(USER_SESSION));

    return {
        getCurrent: () => localStorageService.get(USER_SESSION),
        login: (username, password) => pingService.ping().then(
            () => loginOnServer(username, password),
            () => loginLocally(username, password)
        ),
        logout: () => {
            let user = localStorageService.get(USER_SESSION);
            localStorageService.set(CREDENTIALS, {username: user._id});
            localStorageService.remove(USER_SESSION);
            setSession();
        },
        getLastCredentials: () => localStorageService.get(CREDENTIALS),
        setLastVisited: idSurvey => idSurveyLastVisited = idSurvey,
        getLastVisited: () => idSurveyLastVisited
    };
}

signIn.controller.js

/*@ngInject*/
export default class SignInController {
    constructor($window, $state, sessionService, surveyService, messagesService) {
        this.$window = $window;
        this.$state = $state;
        this.sessionService = sessionService;
        this.surveyService = surveyService;
        this.messagesService = messagesService;
        this.login = () => {
            return sessionService.login(this.username, this.password).then(
                user => {
                    this.working = false;
                    if (user) {
                        this.$state.go('survey.areas');
                        return true;
                    }
                    this.invalidLogin = true;
                    return false;
                },
                () => {
                    this.invalidLogin = true;
                    this.working = false;
                }
            );
        };
    }

    $onInit() {
        let user = this.sessionService.getCurrent();
        if (user) {
            return this.$state.go('survey.areas');
        }
        let credentials = this.sessionService.getLastCredentials();
        if (credentials) {
            this.lastUser = this.username = credentials.username;
            this.$window.document.getElementById('password').focus();
        } else {
            this.$window.document.getElementById('username').focus();
        }
    }

    signIn() {
        this.working = true;
        this.errorMessage = '';

        if (!this.username && !this.password) {
            return;
        }

        if (this.lastUser && this.lastUser != this.username) {
            return this.changeUserWarning = true;
        }

        this.invalidLogin = false;
        this.login().then(
            loggedIn => {
                if (loggedIn) {
                    this.messagesService.fetchMessages();
                }
            }
        );
    }

    continueChangeUser() {
        this.login().then(
            loggedIn => {
                if (loggedIn) {
                    this.surveyService.clear();
                    this.messagesService.clear().then(
                        () => this.messagesService.fetchMessages()
                    );
                }
            }
        );
    }

    cancelChangeUser() {
        this.username = this.lastUser;
        this.password = null;
        this.changeUserWarning = false;
        this.$window.document.getElementById('password').focus();
    }
}