<?php

/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2005 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\CMS\Application;

use Joomla\CMS\Event\CoreEventAware;
use Joomla\Event\DispatcherInterface;
use Joomla\Event\Event;
use Psr\Log\LoggerInterface;

// phpcs:disable PSR1.Files.SideEffects
\defined('JPATH_PLATFORM') or die;
// phpcs:enable PSR1.Files.SideEffects

/**
 * Trait for application classes which dispatch events
 *
 * @since  4.0.0
 */
trait EventAware
{
    use CoreEventAware;

    /**
     * Get the event dispatcher.
     *
     * @return  DispatcherInterface
     *
     * @since   4.0.0
     * @throws  \UnexpectedValueException May be thrown if the dispatcher has not been set.
     */
    abstract public function getDispatcher();

    /**
     * Get the logger.
     *
     * @return  LoggerInterface
     *
     * @since   4.0.0
     */
    abstract public function getLogger();

    /**
     * Registers a handler to a particular event group.
     *
     * @param   string    $event    The event name.
     * @param   callable  $handler  The handler, a function or an instance of an event object.
     *
     * @return  $this
     *
     * @since   4.0.0
     */
    public function registerEvent($event, callable $handler)
    {
        try {
            $this->getDispatcher()->addListener($event, $handler);
        } catch (\UnexpectedValueException $e) {
            // No dispatcher is registered, don't throw an error (mimics old behavior)
        }

        return $this;
    }

    /**
     * Calls all handlers associated with an event group.
     *
     * This is a legacy method, implementing old-style (Joomla! 3.x) plugin calls. It's best to go directly through the
     * Dispatcher and handle the returned EventInterface object instead of going through this method. This method is
     * deprecated and will be removed in Joomla! 5.x.
     *
     * This method will only return the 'result' argument of the event
     *
     * @param   string       $eventName  The event name.
     * @param   array|Event  $args       An array of arguments or an Event object (optional).
     *
     * @return  array  An array of results from each function call. Note this will be an empty array if no dispatcher is set.
     *
     * @since       4.0.0
     * @throws      \InvalidArgumentException
     * @deprecated  5.0
     */
    public function triggerEvent($eventName, $args = [])
    {
        try {
            $dispatcher = $this->getDispatcher();
        } catch (\UnexpectedValueException $exception) {
            $this->getLogger()->error(sprintf('Dispatcher not set in %s, cannot trigger events.', \get_class($this)));

            return [];
        }

        if ($args instanceof Event) {
            $event = $args;
        } elseif (\is_array($args)) {
            $className = self::getEventClassByEventName($eventName);
            $event     = new $className($eventName, $args);
        } else {
            throw new \InvalidArgumentException('The arguments must either be an event or an array');
        }

        $result = $dispatcher->dispatch($eventName, $event);

        // @todo - There are still test cases where the result isn't defined, temporarily leave the isset check in place
        return !isset($result['result']) || \is_null($result['result']) ? [] : $result['result'];
    }
}