import { Injectable } from '@angular/core';
   import { HttpClient } from '@angular/common/http';
   import { map } from 'rxjs/operators';

 @Injectable()
 export class AuthenticationService {
   constructor(private http: HttpClient) { }

   login(username: string, password: string) {
     return this.http.post<any>(`${config.apiUrl}/users/authenticate`, {
     username: username, password: password })
       .pipe(map(user => {
    // login successful if there's a jwt token in the response
    if (user && user.token) {
      // store user details and jwt token in local storage to keep user logged in between page refreshes
      localStorage.setItem('currentUser', JSON.stringify(user));
    }

    return user;
    }));
  }

   logout() {
     // remove user from local storage to log user out
    localStorage.removeItem('currentUser');
   }
 }