<?php

/*

 * This file is part of the Symfony package.

 *

 * (c) Fabien Potencier <fabien@symfony.com>

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

namespace Symfony\Bundle\FrameworkBundle;

use Symfony\Component\DependencyInjection\ContainerInterface;

use Symfony\Component\EventDispatcher\EventDispatcher;

use Symfony\Component\EventDispatcher\Event;

/**

 * Lazily loads listeners and subscribers from the dependency injection

 * container

 *

 * @author Fabien Potencier <fabien@symfony.com>

 * @author Bernhard Schussek <bernhard.schussek@symfony.com>

 */

class ContainerAwareEventDispatcher extends EventDispatcher

{

    /**

     * The container from where services are loaded

     * @var ContainerInterface

     */

    private $container;

    /**

     * The service IDs of the event listeners and subscribers

     * @var array

     */

    private $listenerIds = array();

    /**

     * The services registered as listeners

     * @var array

     */

    private $listeners = array();

    /**

     * Constructor.

     *

     * @param ContainerInterface $container A ContainerInterface instance

     */

    public function __construct(ContainerInterface $container)

    {

        $this->container = $container;

    }

    /**

     * Adds a service as event listener

     *

     * @param string   $eventName Event for which the listener is added

     * @param array    $callback  The service ID of the listener service & the method

     *                            name that has to be called

     * @param integer  $priority  The higher this value, the earlier an event listener

     *                            will be triggered in the chain.

     *                            Defaults to 0.

     */

    public function addListenerService($eventName, $callback, $priority = 0)

    {

        if (!is_array($callback) || 2 !== count($callback)) {

            throw new \InvalidArgumentException('Expected an array("service", "method") argument');

        }

        $this->listenerIds[$eventName][] = array($callback[0], $callback[1], $priority);

    }

    /**

     * {@inheritDoc}

     *

     * Lazily loads listeners for this event from the dependency injection

     * container.

     *

     * @throws \InvalidArgumentException if the service is not defined

     */

    public function dispatch($eventName, Event $event = null)

    {

        if (isset($this->listenerIds[$eventName])) {

            foreach ($this->listenerIds[$eventName] as $args) {

                list($serviceId, $method, $priority) = $args;

                $listener = $this->container->get($serviceId);

                $key = $serviceId.'.'.$method;

                if (!isset($this->listeners[$eventName][$key])) {

                    $this->addListener($eventName, array($listener, $method), $priority);

                } elseif ($listener !== $this->listeners[$eventName][$key]) {

                    $this->removeListener($eventName, array($this->listeners[$eventName][$key], $method));

                    $this->addListener($eventName, array($listener, $method), $priority);

                }

                $this->listeners[$eventName][$key] = $listener;

            }

        }

        parent::dispatch($eventName, $event);

    }

}