refreshless-8.x-1.x-dev/modules/refreshless_turbo/src/PageCache/AdditiveLibrariesRequestPolicy.php

<?php

declare(strict_types=1);

namespace Drupal\refreshless_turbo\PageCache;

use Drupal\Core\PageCache\RequestPolicyInterface;
use Drupal\refreshless\Service\RequestWrapperFactoryInterface;
use Symfony\Component\HttpFoundation\Request;

/**
 * Request policy to prevent serving page_cache responses for Turbo.
 *
 * This is necessary to ensure the page varies by the libraries that are
 * already loaded on a page for anonymous requests. Under normal conditions,
 * the page_cache module will cache and serve the entire response so whatever
 * state the libraries were in for the first response for a page is what all
 * subsequent responses for that page would be served, leading to an incorrect
 * combination of libraries.
 */
class AdditiveLibrariesRequestPolicy implements RequestPolicyInterface {

  /**
   * Service constructor; saves dependencies.
   *
   * @param \Drupal\refreshless\Service\RequestWrapperFactoryInterface $requestWrapperFactory
   *   The RefreshLess request wrapper factory.
   */
  public function __construct(
    protected readonly RequestWrapperFactoryInterface $requestWrapperFactory,
  ) {}

  /**
   * {@inheritdoc}
   */
  public function check(Request $request) {

    $requestWrapper = $this->requestWrapperFactory->fromRequest($request);

    if ($requestWrapper->isRefreshless()) {
      return static::DENY;
    }

  }

}