Zaawansowany PHP dzien 1

<?php

abstract class User
{
    protected $username;
    protected $password;

    abstract function checkLogin($username, $password);

    abstract function setLogin($username);

    abstract function setPassword($password);

    final public function login($username, $password){
        return $this->checkLogin($username,$password);
    }
}

class Client extends User {

    function checkLogin($username, $password)
    {
        if ($password != $this->password) return false;
        if ($username != $this->username) return false;
        return true;
    }

    function setLogin($username)
    {
        $this->username = $username;
    }

    function setPassword($password)
    {
        if ( strlen($password) < 8 ) return false;
        $this->password = $password;
    }

    function getPassword(){
        return $this->password;
    }

    public function getUsername()
    {
        return $this->username;
    }
}

class Admin extends User {

    private $ip;

    function checkLogin($username, $password)
    {
        $this->ip = "192.168.33.22";
        if ($password != $this->password) return false;
        if ($username != $this->username) return false;
        return true;
    }

    function setLogin($username)
    {
        $this->username = $username;
    }

    function setPassword($password)
    {
        if ( strlen($password) < 9 ) return false;
        $this->password = $password;
    }
}

class UserSet implements Iterator {
    private $users = array();
    private $index = 0;

    public function add($user){
        $this->users[] = $user;
    }

    public function current()
    {
        return $this->users[$this->index];
    }

    public function next()
    {
        $this->index++;
    }

    public function key()
    {
    }

    public function valid()
    {
        if ($this->index == count($this->users)) return false;
        return true;
    }

    public function rewind()
    {
        $this->index=0;
    }

    public function checkLogin($password){
        foreach ($this as $user){
            if ($password == $user->getPassword()) echo $user->getUserName()."\n";
        }
    }
}

$admin = new Admin();
$admin->setLogin("admin");
$admin->setPassword("testowiecsda");
if ($admin->login("admin","testowiecs")){
    echo "brawo";
}

$userSet = new UserSet();
$c1 = new Client();
$c1->setLogin("marek");
$c1->setPassword("zegarek");

$c2 = new Client();
$c2->setLogin("arek");
$c2->setPassword("figlarek");

$c3 = new Client();
$c3->setLogin("test");
$c3->setPassword("testowski");

$userSet->add($c1);
$userSet->add($c2);
$userSet->add($c3);

$userSet->checkLogin("figlarek");