<?php
require_once ROGUE_DIR . '/types/Observer.php';

/**
 * keeps track of object changes, similar to property change listener, however
 * this is not ment to be extended and does not create member variables on changeValue
 * 
 * @author Cory Marsh
 * @license http://www.opensource.org/licenses/bsd-license.php BSD License
 */
class ChangeTracker
{
    protected $_oldValues;
    protected $_newValues;
    protected $_listeners;
    protected $_observed;
    
    /**
     * Calls parent constructor to create array for listeners. Creates
     * arrays to hold old and new values.
     */
    public function __construct($observed)
    {
        $this->_oldValues = array();
        $this->_newValues = array();
        $this->_listeners = array();
        $this->_observed = $observed;
    }
       
    /**
     * @return array $oldValues Old values of properties listened to.
     */
    public function getOldValues()
    {
        return $this->_oldValues;
    }
    
    /**
     * @return array $newValues New values of properties listened to.
     */
    public function getNewValues()
    {
        return $this->_newValues;
    }
    
    /**
     * Notifies each listener that the value of a property has changed.
     * @param string $name The name of the property that changed.
     * @param string $oldValue The old value of the property.
     * @param string $newValue The new value of the property.
     * @return mixed $newValue the new property value is returned
     */
    public function changeValue($name, $oldValue, $newValue)
    {
		//Logger::getLogger('boom')->warn("2 changeValue() called");
        if ($oldValue !== $newValue)
        {
			// we want to save just the original value, not intermediates
			if (!isset($this->_oldValues[$name]))
				$this->_oldValues[$name] = $oldValue;
            $this->_newValues[$name] = $newValue;

            foreach ($this->_listeners as $listener)
            {
                $listener->notify($this->_observed, array($name, $oldValue, $newValue));
            }
        }
        return $newValue;
    }
    
    /**
     * clear all state changes in the listener, but NOT the observers
     * @return PropertyChangeListener the class reference
     */
    public function clearChanges()
    {
        $this->_oldValues = array();
        $this->_newValues = array();
        return $this;
    }

    /**
     * @param observer $obs An object that will be listening to this object.
     */
    public function addListener(iObserver $observer)
    {
        $this->_listeners[] = $observer;
    }
}