<?php

/**
 * This is a proxy class of entity object, it will be used for the lazyload in the X-to-X relations
 * The real entity object will be instanced when the user call the corresponding property.
 * Be careful about the array, anEntityProxy->arrayProperty[] = $newElement dont work. 
 * The user should define the array insert operation as a function, like: anEntityProxy->addItem($newElement)
 * 
 * @package		com.freeorm
 * @author		Yide Zou
 * @link		http://www.freeorm.com
 * @copyright	Copyright (c) 2010 Yide Zou <hide@address.com>. 
 * 				All Rights Reserved.
 * @license		This software is released under the terms of the GNU Lesser General Public License
 * 				A copy of which is available from http://www.gnu.org/copyleft/lesser.html
 */


class EntityProxy 
{
	// the class name of the linked entity
	public $classname;
	// the id of the linked entity
	public $id;
	// true if $instance !== null
	public $loaded = false;
	// the session object
	private $session;
	// the instance of the proxied object
	private $instance = null;
	
	
	public function __construct(Session $session, $classname, $id)
	{
		$this->session = $session;
		$this->classname = $classname;
		$this->id = $id;
	}
	
	/**
	 * Lazy load
	 */
	private function createInstance()
	{
		if ($this->instance === null)
		{
			$this->instance = $this->session->get($this->classname, $this->id);
			$this->loaded = true;
		}
	}
	
	
	/**
	 * The compare two Entity, if they are both EntityProxy then just compare classname and id
	 * if the $obj is a real object, then compare its class and id
	 * @param $obj
	 * @return true if they are same
	 */
	public function equals($obj)
	{
		if ($obj === null)
			return false;
		if ($obj instanceof EntityProxy)
			return ($this->classname == $obj->classname) &&
				($this->id == $obj->id);
		else
		{
			return ($this->classname == get_class($obj)) &&
				($this->id == $this->session->getObjId($obj));
		}
	}
	
	
	/**
	 * Compare two unloaded EntityProxy, in order to prevent the useless database hit during dirtycheck
	 * @param $objcache
	 * @param $objwatcher
	 * @return true if the both EntityProxy still not be loaded and with the same classname and id, that means they are real same
	 */
	public function equalsAndUnloaded(EntityProxy $obj)
	{
		if ($this->loaded || $obj->loaded)
			return false;
		return $this->equals($obj);
	}
	
	
	/*
	 * Proxy functions
	 */
	
	public function __get($name)
	{
		$this->createInstance();
		return $this->instance->$name;
	}
	
	public function __set($name, $value)
	{
		$this->createInstance();
		$this->instance->$name = $value;
	}
	
	public function __call($name, $arguments)
	{
		$this->createInstance();
		return call_user_func_array(array($this->instance, $name), $arguments);
	}
	
	public function __callStatic($name, $arguments)
	{
		$this->createInstance();
		return call_user_func_array(array($this->classname, $name), $arguments);
	}
	
}