<?php
/**
 * Resque event/plugin system class
 *
 * @package		Resque/Event
 * @author		Chris Boulton <chris.boulton@interspire.com>
 * @copyright	(c) 2010 Chris Boulton
 * @license		http://www.opensource.org/licenses/mit-license.php
 */
class Resque_Event
{
	/**
	 * @var array Array containing all registered callbacks, indexked by event name.
	 */
	private static $events = array();

	/**
	 * Raise a given event with the supplied data.
	 *
	 * @param string $event Name of event to be raised.
	 * @param mixed $data Optional, any data that should be passed to each callback.
	 * @return true
	 */
	public static function trigger($event, $data = null)
	{
		if (!is_array($data)) {
			$data = array($data);
		}

		if (empty(self::$events[$event])) {
			return true;
		}
		
		foreach (self::$events[$event] as $callback) {
			if (!is_callable($callback)) {
				continue;
			}
			call_user_func_array($callback, $data);
		}
		
		return true;
	}
	
	/**
	 * Listen in on a given event to have a specified callback fired.
	 *
	 * @param string $event Name of event to listen on.
	 * @param mixed $callback Any callback callable by call_user_func_array.
	 * @return true
	 */
	public static function listen($event, $callback)
	{
		if (!isset(self::$events[$event])) {
			self::$events[$event] = array();
		}
		
		self::$events[$event][] = $callback;
		return true;
	}
	
	/**
	 * Stop a given callback from listening on a specific event.
	 *
	 * @param string $event Name of event.
	 * @param mixed $callback The callback as defined when listen() was called.
	 * @return true
	 */
	public static function stopListening($event, $callback)
	{
		if (!isset(self::$events[$event])) {
			return true;
		}
		
		$key = array_search($callback, self::$events[$event]);
		if ($key !== false) {
			unset(self::$events[$event][$key]);
		}
		
		return true;
	}
	
	/**
	 * Call all registered listeners.
	 */
	public static function clearListeners()
	{
		self::$events = array();
	}
}