login.component.ts

import { Component, OnInit } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
import { Router } from '@angular/router';
import { AuthenticationService } from '../services/authentication.service';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.css']
})

export class LoginComponent implements OnInit {

  loginForm = new FormGroup({
    username: new FormControl('', Validators.required),
    password: new FormControl('', Validators.required)
  });

  constructor(
    private router: Router,
    private auth: AuthenticationService) { }

  ngOnInit(): void {
    if (this.auth.isLoggedIn())
      this.router.navigateByUrl("/");
  }

  onSubmit():void {
    const username = this.loginForm.get('username')!.value;
    const password = this.loginForm.get('password')!.value;

    this.auth.login(username, password);
    this.router.navigateByUrl("/");
  }
}