login(username: string, password: string): Observable<boolean> {

        return this.http.post(environment.baseUrl + '/api/authenticate', JSON.stringify({ username: username, password: password }))
            .map((response: Response, error: any) => {

                console.log('mapping response...', response.status.toString());

                // login successful if there's a jwt token in the response
                const token = response.json() && response.json().token;
                if (token) {
                    // set token property
                    this.token = token;

                    // store username and jwt token in local storage to keep user logged in between page refreshes
                    localStorage.setItem('currentUser', JSON.stringify({ username: username, token: token }));

                    // return true to indicate successful login
                    return true;
                } else {
                    // return false to indicate failed login
                    return false;
                }
            });

    }