src/app/auth/auth.guard.ts

import { Injectable } from '@angular/core';
import { CanActivate, Router, UrlTree } from '@angular/router';
import { AuthService } from './auth.service';
import { AuthUiService } from './auth-ui.service';

@Injectable({ providedIn: 'root' })
export class AuthGuard implements CanActivate {
  constructor(private auth: AuthService, private authUi: AuthUiService, private router: Router) {}

  canActivate(): boolean | UrlTree {
    if (this.auth.isAuthenticated()) return true;
    this.authUi.openSignin();
    return this.router.parseUrl('/'); // redirect home; modal is open
  }
}