import { Injectable } from '@angular/core';
import { Router,CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, UrlTree } from '@angular/router';
import { Observable } from 'rxjs';

import { AuthenticationService } from './../_services/authentication.service';

@Injectable({
  providedIn: 'root'
})
export class AuthGuard implements CanActivate {

  constructor(
    private router: Router,
    private authenticationService: AuthenticationService
) { }
  
  canActivate(
    next: ActivatedRouteSnapshot,
    state: RouterStateSnapshot): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree {
      const currentUser = this.authenticationService.currentUserValue;
    if (currentUser) {
        // authorised so return true
        return true;
    }

    // not logged in so redirect to login page

    this.router.navigate(['/login'], { queryParams: { returnUrl: state.url } });
    return false;
  }
  
}