session.class.php

<?php
class Session {
    private array $messages;
    public function __construct() {
      session_start();
      $this->messages = isset($_SESSION['messages']) ? $_SESSION['messages'] : array();
      unset($_SESSION['messages']);
    }

    public static function login() : bool {
      return isset($_SESSION['id']);    
    }

    public static function logout() {
      session_destroy();
    }

    public static function getId() : ?int {
      return isset($_SESSION['id']) ? $_SESSION['id'] : null;    
    }

    public static function getUsername() : ?string {
      return isset($_SESSION['username']) ? $_SESSION['username'] : null;
    }

    public function setId(int $id) {
      $_SESSION['id'] = $id;
    }

    public function setUsername(string $username) {
      $_SESSION['username'] = $username;
    }

    public function addMessage(string $type, string $text) {
      $_SESSION['messages'][] = array('type' => $type, 'text' => $text);
    }

    public function getMessages() {
      return $this->messages;
    }
  }
?>