import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { BehaviorSubject, Observable } from 'rxjs';
import { map } from 'rxjs/operators';
import { SERVER_API_URL } from 'app/app.constants';

@Injectable({ providedIn: 'root' })
export class AuthenticationService {
  private currentUserSubject: BehaviorSubject<any>;
  public currentUser: Observable<any>;

  constructor(private http: HttpClient) {
    this.currentUserSubject = new BehaviorSubject<any>(JSON.parse(sessionStorage.getItem('currentUser')));
    this.currentUser = this.currentUserSubject.asObservable();
  }

  public get currentUserValue() {
    return this.currentUserSubject.value;
  }

  login(email, password) {
    return this.http.post<any>(SERVER_API_URL + '/api/authenticate', { email, password }).pipe(
      map(user => {
        // store user details and jwt token in local storage to keep user logged in between page refreshes
        sessionStorage.setItem('currentUser', JSON.stringify(user));
        this.currentUserSubject.next(user);
        return user;
      })
    );
  }

  logout() {
    // remove user from local storage and set current user to null
    sessionStorage.removeItem('currentUser');
    this.currentUserSubject.next(null);
  }
}