Object oriented programming example in php

oop.php

<? php
class User {
  
  private $name;
  private $lastLoggedInAt;
  private $loggedIn;
  
  function __construct($name) {
    $this->name = $name;
    $this->loggedIn = false;
    $this->lastLoggedInAt = null;
  }

  function isLoggedIn() {
    return $this->loggedIn;
  }
  function getLastLoggedInAt() {
    return $this->lastLoggedInAt;
  }

  function logIn() {
    $this->lastLoggedInAt = date("Y-m-d H:i:s");
    $this->loggedIn = true;
  }
  
  function logOut() {
    $this->loggedIn = false;
  }

  function getName() {
    return $this->name;
  }
  
  function setName($name) {
    $this->name = $name;
  }

  function canEdit($comment) {
    if($comment->getAuthor() instanceof User and $comment->getAuthor() === $this){
      return true;
    }
    return false;
  }
  
  function canDelete($comment) {
    return false;
  }
}

class Moderator extends User{
  
  function __construct($name) { 
    parent::__construct($name);
  }
  
  function canEdit($comment) {
    if($comment->getAuthor() instanceof Moderator and $comment->getAuthor() === $this){
      return true;
    }
    return false;
  }
  
  function canDelete($comment) {
    if($comment instanceof Comment){
      return true;
    }
    return false;
  }
}

class Admin extends Moderator{
  function __construct($name) { 
    parent::__construct($name);
  }
  
  function canEdit($comment) {
    if($comment instanceof Comment){
      return true;
    }
    return false;
  }
  
  function canDelete($comment) {
    if($comment instanceof Comment){
      return true;
    }
    return false;
  }
}

class Comment {
  private $author;
  private $message;
  private $repliedTo;
  private $createdAt;
  
  
  function __construct($author, $message, $repliedTo=null) {
    $this->author = $author;
    $this->message = $message;
    $this->repliedTo = $repliedTo;
    $this->createdAt = date("Y-m-d H:i:s");
  }
  

  function getMessage() {
    return $this->message;
  }
  function setMessage($message) {
    $this->message = $message;
  }
  
  function getCreatedAt() {
    return $this->createdAt;
  }
  function getAuthor() {
    return $this->author;
  }
  function getRepliedTo() {
    return $this->repliedTo;
  }
  
  function __toString() {
    if (!is_null($this->repliedTo) and $this->repliedTo instanceof Comment){
      return "{$this->message} by {$this->author->getName()} (replied to {$this->repliedTo->getAuthor()->getName()})";
    }
    return "{$this->message} by {$this->author->getName()}";
  }
}

class OOPTest extends TestCase {
  public function testExample() {
    //should be set somewhere globally
    date_default_timezone_set("Europe/Helsinki");
    
    $user = new User("User 1");
    $this->assertEquals("User 1", $user->getName(), "User name is set correctly");
    $mod = new Moderator("Moderator");
    $this->assertInstanceOf(User::class, $mod, "Moderator is a User");
    
  }
  public function testComment() {
    //should be set somewhere globally
    date_default_timezone_set("Europe/Helsinki");
    
    $user = new User("User 1");
    $this->assertEquals("User 1", $user->getName(), "User name is set correctly");
    $mod = new Moderator("Moderator");
    $this->assertInstanceOf(User::class, $mod, "Moderator is a User");
    $admin = new Admin("Admin");
    
    $commentUser = new Comment($user, "My first comment!");
    $this->assertEquals(true, $user->canEdit($commentUser), "User can edit his comment");
    $this->assertEquals(false, $mod->canEdit($commentUser), "Moderator can't edit user comment");
    $this->assertEquals(true, $admin->canEdit($commentUser), "Admin can edit user comment");
    
    $commentModerator = new Comment($mod, "My first comment!", null);
    $this->assertEquals(false, $user->canEdit($commentModerator), "User can't edit moderator comment");
    $this->assertEquals(true, $mod->canEdit($commentModerator), "Moderator can edit his comment");
    $this->assertEquals(true, $admin->canEdit($commentModerator), "Admin can edit user comment");
    
  }
}