<?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\Component\EventDispatcher;

/**

 * The EventDispatcherInterface is the central point of Symfony's event listener system.

 *

 * Listeners are registered on the manager and events are dispatched through the

 * manager.

 *

 * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>

 * @author  Jonathan Wage <jonwage@gmail.com>

 * @author  Roman Borschel <roman@code-factory.org>

 * @author  Bernhard Schussek <bschussek@gmail.com>

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

 * @author  Jordi Boggiano <j.boggiano@seld.be>

 *

 * @api

 */

class EventDispatcher implements EventDispatcherInterface

{

    private $listeners = array();

    private $sorted = array();

    /**

     * @see EventDispatcherInterface::dispatch

     *

     * @api

     */

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

    {

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

            return;

        }

        if (null === $event) {

            $event = new Event();

        }

        $this->doDispatch($this->getListeners($eventName), $eventName, $event);

    }

    /**

     * @see EventDispatcherInterface::getListeners

     */

    public function getListeners($eventName = null)

    {

        if (null !== $eventName) {

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

                $this->sortListeners($eventName);

            }

            return $this->sorted[$eventName];

        }

        foreach (array_keys($this->listeners) as $eventName) {

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

                $this->sortListeners($eventName);

            }

        }

        return $this->sorted;

    }

    /**

     * @see EventDispatcherInterface::hasListeners

     */

    public function hasListeners($eventName = null)

    {

        return (Boolean) count($this->getListeners($eventName));

    }

    /**

     * @see EventDispatcherInterface::addListener

     *

     * @api

     */

    public function addListener($eventName, $listener, $priority = 0)

    {

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

        unset($this->sorted[$eventName]);

    }

    /**

     * @see EventDispatcherInterface::removeListener

     */

    public function removeListener($eventName, $listener)

    {

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

            return;

        }

        foreach ($this->listeners[$eventName] as $priority => $listeners) {

            if (false !== ($key = array_search($listener, $listeners))) {

                unset($this->listeners[$eventName][$priority][$key], $this->sorted[$eventName]);

            }

        }

    }

    /**

     * @see EventDispatcherInterface::addSubscriber

     *

     * @api

     */

    public function addSubscriber(EventSubscriberInterface $subscriber)

    {

        foreach ($subscriber->getSubscribedEvents() as $eventName => $params) {

            if (is_string($params)) {

                $this->addListener($eventName, array($subscriber, $params));

            } else {

                $this->addListener($eventName, array($subscriber, $params[0]), $params[1]);

            }

        }

    }

    /**

     * @see EventDispatcherInterface::removeSubscriber

     */

    public function removeSubscriber(EventSubscriberInterface $subscriber)

    {

        foreach ($subscriber->getSubscribedEvents() as $eventName => $params) {

            $this->removeListener($eventName, array($subscriber, is_string($params) ? $params : $params[0]));

        }

    }

    /**

     * Triggers the listeners of an event.

     *

     * This method can be overridden to add functionality that is executed

     * for each listener.

     *

     * @param array[callback] $listeners The event listeners.

     * @param string $eventName The name of the event to dispatch.

     * @param Event $event The event object to pass to the event handlers/listeners.

     */

    protected function doDispatch($listeners, $eventName, Event $event)

    {

        foreach ($listeners as $listener) {

            call_user_func($listener, $event);

            if ($event->isPropagationStopped()) {

                break;

            }

        }

    }

    /**

     * Sorts the internal list of listeners for the given event by priority.

     *

     * @param string $eventName The name of the event.

     */

    private function sortListeners($eventName)

    {

        $this->sorted[$eventName] = array();

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

            krsort($this->listeners[$eventName]);

            $this->sorted[$eventName] = call_user_func_array('array_merge', $this->listeners[$eventName]);

        }

    }

}