<?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\HttpKernel\EventListener;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\RequestMatcherInterface;
use Symfony\Component\HttpFoundation\RequestStack;
use Symfony\Component\HttpFoundation\Session\Session;
use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
use Symfony\Component\HttpKernel\Event\PostResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\HttpKernel\Profiler\Profiler;

/**
 * ProfilerListener collects data for the current request by listening to the kernel events.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 *
 * @final since Symfony 4.3
 */
class ProfilerListener implements EventSubscriberInterface
{
    protected $profiler;
    protected $matcher;
    protected $onlyException;
    protected $onlyMasterRequests;
    protected $exception;
    protected $profiles;
    protected $requestStack;
    protected $parents;

    /**
     * @param bool $onlyException      True if the profiler only collects data when an exception occurs, false otherwise
     * @param bool $onlyMasterRequests True if the profiler only collects data when the request is a master request, false otherwise
     */
    public function __construct(Profiler $profiler, RequestStack $requestStack, RequestMatcherInterface $matcher = null, bool $onlyException = false, bool $onlyMasterRequests = false)
    {
        $this->profiler = $profiler;
        $this->matcher = $matcher;
        $this->onlyException = $onlyException;
        $this->onlyMasterRequests = $onlyMasterRequests;
        $this->profiles = new \SplObjectStorage();
        $this->parents = new \SplObjectStorage();
        $this->requestStack = $requestStack;
    }

    /**
     * Handles the onKernelException event.
     */
    public function onKernelException(GetResponseForExceptionEvent $event)
    {
        if ($this->onlyMasterRequests && !$event->isMasterRequest()) {
            return;
        }

        $this->exception = $event->getThrowable();
    }

    /**
     * Handles the onKernelResponse event.
     */
    public function onKernelResponse(FilterResponseEvent $event)
    {
        $master = $event->isMasterRequest();
        if ($this->onlyMasterRequests && !$master) {
            return;
        }

        if ($this->onlyException && null === $this->exception) {
            return;
        }

        $request = $event->getRequest();
        $exception = $this->exception;
        $this->exception = null;

        if (null !== $this->matcher && !$this->matcher->matches($request)) {
            return;
        }

        $session = method_exists(Request::class, 'getPreferredFormat') && $request->hasPreviousSession() && $request->hasSession() ? $request->getSession() : null;

        if ($session instanceof Session) {
            $usageIndexValue = $usageIndexReference = &$session->getUsageIndex();
            $usageIndexReference = \PHP_INT_MIN;
        }

        try {
            if (!$profile = $this->profiler->collect($request, $event->getResponse(), $exception)) {
                return;
            }
        } finally {
            if ($session instanceof Session) {
                $usageIndexReference = $usageIndexValue;
            }
        }

        $this->profiles[$request] = $profile;

        $this->parents[$request] = $this->requestStack->getParentRequest();
    }

    public function onKernelTerminate(PostResponseEvent $event)
    {
        // attach children to parents
        foreach ($this->profiles as $request) {
            if (null !== $parentRequest = $this->parents[$request]) {
                if (isset($this->profiles[$parentRequest])) {
                    $this->profiles[$parentRequest]->addChild($this->profiles[$request]);
                }
            }
        }

        // save profiles
        foreach ($this->profiles as $request) {
            $this->profiler->saveProfile($this->profiles[$request]);
        }

        $this->profiles = new \SplObjectStorage();
        $this->parents = new \SplObjectStorage();
    }

    public static function getSubscribedEvents()
    {
        return [
            KernelEvents::RESPONSE => ['onKernelResponse', -100],
            KernelEvents::EXCEPTION => ['onKernelException', 0],
            KernelEvents::TERMINATE => ['onKernelTerminate', -1024],
        ];
    }
}
