<?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;

use Psr\EventDispatcher\StoppableEventInterface;
use Symfony\Component\EventDispatcher\Debug\WrappedListener;
use Symfony\Contracts\EventDispatcher\Event as ContractsEvent;

/**
 * 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>
 * @author Jordan Alliot <jordan.alliot@gmail.com>
 * @author Nicolas Grekas <p@tchwork.com>
 */
class EventDispatcher implements EventDispatcherInterface
{
    private $listeners = [];
    private $sorted = [];
    private $optimized;

    public function __construct()
    {
        if (__CLASS__ === \get_class($this)) {
            $this->optimized = [];
        }
    }

    /**
     * {@inheritdoc}
     *
     * @param string|null $eventName
     */
    public function dispatch($event/*, string $eventName = null*/)
    {
        $eventName = 1 < \func_num_args() ? func_get_arg(1) : null;

        if (\is_object($event)) {
            $eventName = $eventName ?? \get_class($event);
        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof Event)) {
            @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as the first argument is deprecated since Symfony 4.3, pass it as the second argument and provide the event object as the first argument instead.', EventDispatcherInterface::class), E_USER_DEPRECATED);
            $swap = $event;
            $event = $eventName ?? new Event();
            $eventName = $swap;
        } else {
            throw new \TypeError(sprintf('Argument 1 passed to "%s::dispatch()" must be an object, %s given.', EventDispatcherInterface::class, \is_object($event) ? \get_class($event) : \gettype($event)));
        }

        if (null !== $this->optimized && null !== $eventName) {
            $listeners = $this->optimized[$eventName] ?? (empty($this->listeners[$eventName]) ? [] : $this->optimizeListeners($eventName));
        } else {
            $listeners = $this->getListeners($eventName);
        }

        if ($listeners) {
            $this->callListeners($listeners, $eventName, $event);
        }

        return $event;
    }

    /**
     * {@inheritdoc}
     */
    public function getListeners($eventName = null)
    {
        if (null !== $eventName) {
            if (empty($this->listeners[$eventName])) {
                return [];
            }

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

            return $this->sorted[$eventName];
        }

        foreach ($this->listeners as $eventName => $eventListeners) {
            if (!isset($this->sorted[$eventName])) {
                $this->sortListeners($eventName);
            }
        }

        return array_filter($this->sorted);
    }

    /**
     * {@inheritdoc}
     */
    public function getListenerPriority($eventName, $listener)
    {
        if (empty($this->listeners[$eventName])) {
            return null;
        }

        if (\is_array($listener) && isset($listener[0]) && $listener[0] instanceof \Closure) {
            $listener[0] = $listener[0]();
        }

        foreach ($this->listeners[$eventName] as $priority => &$listeners) {
            foreach ($listeners as &$v) {
                if ($v !== $listener && \is_array($v) && isset($v[0]) && $v[0] instanceof \Closure) {
                    $v[0] = $v[0]();
                }
                if ($v === $listener) {
                    return $priority;
                }
            }
        }

        return null;
    }

    /**
     * {@inheritdoc}
     */
    public function hasListeners($eventName = null)
    {
        if (null !== $eventName) {
            return !empty($this->listeners[$eventName]);
        }

        foreach ($this->listeners as $eventListeners) {
            if ($eventListeners) {
                return true;
            }
        }

        return false;
    }

    /**
     * {@inheritdoc}
     */
    public function addListener($eventName, $listener, $priority = 0)
    {
        $this->listeners[$eventName][$priority][] = $listener;
        unset($this->sorted[$eventName], $this->optimized[$eventName]);
    }

    /**
     * {@inheritdoc}
     */
    public function removeListener($eventName, $listener)
    {
        if (empty($this->listeners[$eventName])) {
            return;
        }

        if (\is_array($listener) && isset($listener[0]) && $listener[0] instanceof \Closure) {
            $listener[0] = $listener[0]();
        }

        foreach ($this->listeners[$eventName] as $priority => &$listeners) {
            foreach ($listeners as $k => &$v) {
                if ($v !== $listener && \is_array($v) && isset($v[0]) && $v[0] instanceof \Closure) {
                    $v[0] = $v[0]();
                }
                if ($v === $listener) {
                    unset($listeners[$k], $this->sorted[$eventName], $this->optimized[$eventName]);
                }
            }

            if (!$listeners) {
                unset($this->listeners[$eventName][$priority]);
            }
        }
    }

    /**
     * {@inheritdoc}
     */
    public function addSubscriber(EventSubscriberInterface $subscriber)
    {
        foreach ($subscriber->getSubscribedEvents() as $eventName => $params) {
            if (\is_string($params)) {
                $this->addListener($eventName, [$subscriber, $params]);
            } elseif (\is_string($params[0])) {
                $this->addListener($eventName, [$subscriber, $params[0]], isset($params[1]) ? $params[1] : 0);
            } else {
                foreach ($params as $listener) {
                    $this->addListener($eventName, [$subscriber, $listener[0]], isset($listener[1]) ? $listener[1] : 0);
                }
            }
        }
    }

    /**
     * {@inheritdoc}
     */
    public function removeSubscriber(EventSubscriberInterface $subscriber)
    {
        foreach ($subscriber->getSubscribedEvents() as $eventName => $params) {
            if (\is_array($params) && \is_array($params[0])) {
                foreach ($params as $listener) {
                    $this->removeListener($eventName, [$subscriber, $listener[0]]);
                }
            } else {
                $this->removeListener($eventName, [$subscriber, \is_string($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 callable[] $listeners The event listeners
     * @param string     $eventName The name of the event to dispatch
     * @param object     $event     The event object to pass to the event handlers/listeners
     */
    protected function callListeners(iterable $listeners, string $eventName, $event)
    {
        if ($event instanceof Event) {
            $this->doDispatch($listeners, $eventName, $event);

            return;
        }

        $stoppable = $event instanceof ContractsEvent || $event instanceof StoppableEventInterface;

        foreach ($listeners as $listener) {
            if ($stoppable && $event->isPropagationStopped()) {
                break;
            }
            // @deprecated: the ternary operator is part of a BC layer and should be removed in 5.0
            $listener($listener instanceof WrappedListener ? new LegacyEventProxy($event) : $event, $eventName, $this);
        }
    }

    /**
     * @deprecated since Symfony 4.3, use callListeners() instead
     */
    protected function doDispatch($listeners, $eventName, Event $event)
    {
        foreach ($listeners as $listener) {
            if ($event->isPropagationStopped()) {
                break;
            }
            $listener($event, $eventName, $this);
        }
    }

    /**
     * Sorts the internal list of listeners for the given event by priority.
     */
    private function sortListeners(string $eventName)
    {
        krsort($this->listeners[$eventName]);
        $this->sorted[$eventName] = [];

        foreach ($this->listeners[$eventName] as &$listeners) {
            foreach ($listeners as $k => $listener) {
                if (\is_array($listener) && isset($listener[0]) && $listener[0] instanceof \Closure) {
                    $listener[0] = $listener[0]();
                }
                $this->sorted[$eventName][] = $listener;
            }
        }
    }

    /**
     * Optimizes the internal list of listeners for the given event by priority.
     */
    private function optimizeListeners(string $eventName): array
    {
        krsort($this->listeners[$eventName]);
        $this->optimized[$eventName] = [];

        foreach ($this->listeners[$eventName] as &$listeners) {
            foreach ($listeners as &$listener) {
                $closure = &$this->optimized[$eventName][];
                if (\is_array($listener) && isset($listener[0]) && $listener[0] instanceof \Closure) {
                    $closure = static function (...$args) use (&$listener, &$closure) {
                        if ($listener[0] instanceof \Closure) {
                            $listener[0] = $listener[0]();
                        }
                        ($closure = \Closure::fromCallable($listener))(...$args);
                    };
                } else {
                    $closure = $listener instanceof \Closure || $listener instanceof WrappedListener ? $listener : \Closure::fromCallable($listener);
                }
            }
        }

        return $this->optimized[$eventName];
    }
}
