<?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\Debug;

use Symfony\Component\EventDispatcher\EventDispatcherInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\EventDispatcher\Event;
use Symfony\Component\Stopwatch\Stopwatch;
use Psr\Log\LoggerInterface;

/**
 * Collects some data about event listeners.
 *
 * This event dispatcher delegates the dispatching to another one.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class TraceableEventDispatcher implements TraceableEventDispatcherInterface
{
    protected $logger;
    protected $stopwatch;

    private $called;
    private $dispatcher;
    private $wrappedListeners;

    /**
     * @param EventDispatcherInterface $dispatcher An EventDispatcherInterface instance
     * @param Stopwatch                $stopwatch  A Stopwatch instance
     * @param LoggerInterface          $logger     A LoggerInterface instance
     */
    public function __construct(EventDispatcherInterface $dispatcher, Stopwatch $stopwatch, LoggerInterface $logger = null)
    {
        $this->dispatcher = $dispatcher;
        $this->stopwatch = $stopwatch;
        $this->logger = $logger;
        $this->called = array();
        $this->wrappedListeners = array();
    }

    /**
     * {@inheritdoc}
     */
    public function addListener($eventName, $listener, $priority = 0)
    {
        $this->dispatcher->addListener($eventName, $listener, $priority);
    }

    /**
     * {@inheritdoc}
     */
    public function addSubscriber(EventSubscriberInterface $subscriber)
    {
        $this->dispatcher->addSubscriber($subscriber);
    }

    /**
     * {@inheritdoc}
     */
    public function removeListener($eventName, $listener)
    {
        if (isset($this->wrappedListeners[$eventName])) {
            foreach ($this->wrappedListeners[$eventName] as $index => $wrappedListener) {
                if ($wrappedListener->getWrappedListener() === $listener) {
                    $listener = $wrappedListener;
                    unset($this->wrappedListeners[$eventName][$index]);
                    break;
                }
            }
        }

        return $this->dispatcher->removeListener($eventName, $listener);
    }

    /**
     * {@inheritdoc}
     */
    public function removeSubscriber(EventSubscriberInterface $subscriber)
    {
        return $this->dispatcher->removeSubscriber($subscriber);
    }

    /**
     * {@inheritdoc}
     */
    public function getListeners($eventName = null)
    {
        return $this->dispatcher->getListeners($eventName);
    }

    /**
     * {@inheritdoc}
     */
    public function getListenerPriority($eventName, $listener)
    {
        // we might have wrapped listeners for the event (if called while dispatching)
        // in that case get the priority by wrapper
        if (isset($this->wrappedListeners[$eventName])) {
            foreach ($this->wrappedListeners[$eventName] as $index => $wrappedListener) {
                if ($wrappedListener->getWrappedListener() === $listener) {
                    return $this->dispatcher->getListenerPriority($eventName, $wrappedListener);
                }
            }
        }

        return $this->dispatcher->getListenerPriority($eventName, $listener);
    }

    /**
     * {@inheritdoc}
     */
    public function hasListeners($eventName = null)
    {
        return $this->dispatcher->hasListeners($eventName);
    }

    /**
     * {@inheritdoc}
     */
    public function dispatch($eventName, Event $event = null)
    {
        if (null === $event) {
            $event = new Event();
        }

        if (null !== $this->logger && $event->isPropagationStopped()) {
            $this->logger->debug(sprintf('The "%s" event is already stopped. No listeners have been called.', $eventName));
        }

        $this->preProcess($eventName);
        $this->preDispatch($eventName, $event);

        $e = $this->stopwatch->start($eventName, 'section');

        $this->dispatcher->dispatch($eventName, $event);

        if ($e->isStarted()) {
            $e->stop();
        }

        $this->postDispatch($eventName, $event);
        $this->postProcess($eventName);

        return $event;
    }

    /**
     * {@inheritdoc}
     */
    public function getCalledListeners()
    {
        $called = array();
        foreach ($this->called as $eventName => $listeners) {
            foreach ($listeners as $listener) {
                $called[$eventName.'.'.$listener->getPretty()] = $listener->getInfo($eventName);
            }
        }

        return $called;
    }

    /**
     * {@inheritdoc}
     */
    public function getNotCalledListeners()
    {
        try {
            $allListeners = $this->getListeners();
        } catch (\Exception $e) {
            if (null !== $this->logger) {
                $this->logger->info('An exception was thrown while getting the uncalled listeners.', array('exception' => $e));
            }

            // unable to retrieve the uncalled listeners
            return array();
        }

        $notCalled = array();
        foreach ($allListeners as $eventName => $listeners) {
            foreach ($listeners as $listener) {
                $called = false;
                if (isset($this->called[$eventName])) {
                    foreach ($this->called[$eventName] as $l) {
                        if ($l->getWrappedListener() === $listener) {
                            $called = true;

                            break;
                        }
                    }
                }

                if (!$called) {
                    if (!$listener instanceof WrappedListener) {
                        $listener = new WrappedListener($listener, null, $this->stopwatch, $this);
                    }
                    $notCalled[$eventName.'.'.$listener->getPretty()] = $listener->getInfo($eventName);
                }
            }
        }

        uasort($notCalled, array($this, 'sortListenersByPriority'));

        return $notCalled;
    }

    /**
     * Proxies all method calls to the original event dispatcher.
     *
     * @param string $method    The method name
     * @param array  $arguments The method arguments
     *
     * @return mixed
     */
    public function __call($method, $arguments)
    {
        return call_user_func_array(array($this->dispatcher, $method), $arguments);
    }

    /**
     * Called before dispatching the event.
     *
     * @param string $eventName The event name
     * @param Event  $event     The event
     */
    protected function preDispatch($eventName, Event $event)
    {
    }

    /**
     * Called after dispatching the event.
     *
     * @param string $eventName The event name
     * @param Event  $event     The event
     */
    protected function postDispatch($eventName, Event $event)
    {
    }

    private function preProcess($eventName)
    {
        foreach ($this->dispatcher->getListeners($eventName) as $listener) {
            $priority = $this->getListenerPriority($eventName, $listener);
            $wrappedListener = new WrappedListener($listener, null, $this->stopwatch, $this);
            $this->wrappedListeners[$eventName][] = $wrappedListener;
            $this->dispatcher->removeListener($eventName, $listener);
            $this->dispatcher->addListener($eventName, $wrappedListener, $priority);
        }
    }

    private function postProcess($eventName)
    {
        unset($this->wrappedListeners[$eventName]);
        $skipped = false;
        foreach ($this->dispatcher->getListeners($eventName) as $listener) {
            if (!$listener instanceof WrappedListener) { // #12845: a new listener was added during dispatch.
                continue;
            }
            // Unwrap listener
            $priority = $this->getListenerPriority($eventName, $listener);
            $this->dispatcher->removeListener($eventName, $listener);
            $this->dispatcher->addListener($eventName, $listener->getWrappedListener(), $priority);

            if (null !== $this->logger) {
                $context = array('event' => $eventName, 'listener' => $listener->getPretty());
            }

            if ($listener->wasCalled()) {
                if (null !== $this->logger) {
                    $this->logger->debug('Notified event "{event}" to listener "{listener}".', $context);
                }

                if (!isset($this->called[$eventName])) {
                    $this->called[$eventName] = new \SplObjectStorage();
                }

                $this->called[$eventName]->attach($listener);
            }

            if (null !== $this->logger && $skipped) {
                $this->logger->debug('Listener "{listener}" was not called for event "{event}".', $context);
            }

            if ($listener->stoppedPropagation()) {
                if (null !== $this->logger) {
                    $this->logger->debug('Listener "{listener}" stopped propagation of the event "{event}".', $context);
                }

                $skipped = true;
            }
        }
    }

    private function sortListenersByPriority($a, $b)
    {
        if (is_int($a['priority']) && !is_int($b['priority'])) {
            return 1;
        }

        if (!is_int($a['priority']) && is_int($b['priority'])) {
            return -1;
        }

        if ($a['priority'] === $b['priority']) {
            return 0;
        }

        if ($a['priority'] > $b['priority']) {
            return -1;
        }

        return 1;
    }
}
