public function login($username, $password){
    $this->db->query("SELECT * FROM users WHERE username = :username AND status = :status LIMIT 1");
    $this->db->bind(':username', $username);
    $this->db->bind(':status', 1);
    $row = $this->db->single();
    $count = $this->db->rowCount();
        if ($count > 0) {
            if (password_verify($password, $row['password'])) {
                $_SESSION['session'] = [
                    'id' => $row['id'],
                    'username' => $row['username'],
                    'email' => $row['email'],
                    ];
                return true;
            } else {
                return false;
            }
        }
}

public function isLoggedIn() {
    if (isset($_SESSION['session'])) {
    return true;
    }
}

if ($user->isLoggedIn()) {
    header('Location: index.php');
    exit();
}

if(isset($_POST['login'])){

    //Retrieve the field values from our login form.
    $username = !empty($_POST['username']) ? trim($_POST['username']) : null;
    $password = !empty($_POST['password']) ? trim($_POST['password']) : null;

    if($user->login($username, $password)) {
        header('Location: index.php');
        exit();
    } else {
        $message[] = 'We found problems with the login, please try again.';
    }
}