<?php
abstract class user {
  private $fails = 0;
  protected $password;
  protected $username;

  abstract public function setPassword($password);
  abstract public function setUsername($username);
  abstract protected function checkLogin($username, $password);
  final public function login($username, $password){
    if($this->fails < 3){
      if(!$this->checkLogin($username, $password)){
        $this->fails++;
      } else {
        $this->fails = 0;
        echo "Acc logged in\n";
      }
    } else {
      echo "Acc blocked\n";
    }
  }
}

class admin extends user {
  public function setPassword($password){
    if(strlen($password)>=10){
      echo "Pass: ok\n";
    } else {
      echo "Pass: not ok\n";
    }
    $this->password = $password;
  }
  public function setUsername($username){$this->username = $username;}
  protected function checkLogin($username, $password){
    return ($this->username == $username && $this->password == $password);
  }
}

class client extends user {
  public function setPassword($password){
    if(strlen($password)>=8){
      echo "Pass: ok\n";
    } else {
      echo "Pass: not ok\n";
    }
    $this->password = $password;
  }
  public function setUsername($username){$this->username = $username;}

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

  protected function checkLogin($username, $password){
    return ($this->username == $username && $this->password == $password);
  }
}

class UserSet implements Iterator{
  private $position = 0;
  private $userSet;

  public function __construct() {
      $this->position = 0;
  }

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

  public function current() {
      return $this->userSet[$this->position];
  }

  public function key() {
      return $this->position;
  }

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

  public function valid() {
      return isset($this->userSet[$this->position]);
  }

  public function add(Client $obj){
    $this->userSet[] = $obj;
  }
}

function checkLogin($password, UserSet $set){
  foreach($set as $obj){
    if($obj->getPassword() == $password){
      echo $obj->getUsername() . "\n";
    }
  }
}

$obj1 = new client();

$obj1->setUsername('Admin');
$obj1->setPassword('1234');

$obj2 = new client();

$obj2->setUsername('Client1');
$obj2->setPassword('1234');

$obj3 = new client();

$obj3->setUsername('Client2');
$obj3->setPassword('12345');

$obj4 = new client();

$obj4->setUsername('Client3');
$obj4->setPassword('12345');

$objSet =  new UserSet();

$objSet->add($obj1);
$objSet->add($obj2);
$objSet->add($obj3);
$objSet->add($obj4);

checkLogin('12345', $objSet);