class CheckProvider

class CheckProvider implements CheckProviderInterface, ContainerAwareInterface {
  use ContainerAwareTrait;

  /**
   * Array of registered access check service ids.
   *
   * @var array
   */
  protected $checkIds = [];

  /**
   * Array of access check objects keyed by service id.
   *
   * @var \Drupal\Core\Routing\Access\AccessInterface[]
   */
  protected $checks;

  /**
   * Array of access check method names keyed by service ID.
   *
   * @var array
   */
  protected $checkMethods = [];

  /**
   * Array of access checks which only will be run on the incoming request.
   */
  protected $checksNeedsRequest = [];

  /**
   * An array to map static requirement keys to service IDs.
   *
   * @var array
   */
  protected $staticRequirementMap;

  /**
   * An array to map dynamic requirement keys to service IDs.
   *
   * @var array
   */
  protected $dynamicRequirementMap;

  /**
   * {@inheritdoc}
   */
  public function addCheckService($service_id, $service_method, array $applies_checks = [], $needs_incoming_request = FALSE) {
    $this->checkIds[] = $service_id;
    $this->checkMethods[$service_id] = $service_method;
    if ($needs_incoming_request) {
      $this->checksNeedsRequest[$service_id] = $service_id;
    }
    foreach ($applies_checks as $applies_check) {
      $this->staticRequirementMap[$applies_check][] = $service_id;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getChecksNeedRequest() {
    return $this->checksNeedsRequest;
  }

  /**
   * {@inheritdoc}
   */
  public function setChecks(RouteCollection $routes) {
    $this
      ->loadDynamicRequirementMap();
    foreach ($routes as $route) {
      if ($checks = $this
        ->applies($route)) {
        $route
          ->setOption('_access_checks', $checks);
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  public function loadCheck($service_id) {
    if (empty($this->checks[$service_id])) {
      if (!in_array($service_id, $this->checkIds)) {
        throw new \InvalidArgumentException(sprintf('No check has been registered for %s', $service_id));
      }
      $check = $this->container
        ->get($service_id);
      if (!$check instanceof AccessInterface) {
        throw new AccessException('All access checks must implement AccessInterface.');
      }
      if (!is_callable([
        $check,
        $this->checkMethods[$service_id],
      ])) {
        throw new AccessException(sprintf('Access check method %s in service %s must be callable.', $this->checkMethods[$service_id], $service_id));
      }
      $this->checks[$service_id] = $check;
    }
    return [
      $this->checks[$service_id],
      $this->checkMethods[$service_id],
    ];
  }

  /**
   * Determine which registered access checks apply to a route.
   *
   * @param \Symfony\Component\Routing\Route $route
   *   The route to get list of access checks for.
   *
   * @return array
   *   An array of service ids for the access checks that apply to passed
   *   route.
   */
  protected function applies(Route $route) {
    $checks = [];

    // Iterate through map requirements from appliesTo() on access checkers.
    // Only iterate through all checkIds if this is not used.
    foreach ($route
      ->getRequirements() as $key => $value) {
      if (isset($this->staticRequirementMap[$key])) {
        foreach ($this->staticRequirementMap[$key] as $service_id) {
          $checks[] = $service_id;
        }
      }
    }

    // Finally, see if any dynamic access checkers apply.
    foreach ($this->dynamicRequirementMap as $service_id) {
      if ($this->checks[$service_id]
        ->applies($route)) {
        $checks[] = $service_id;
      }
    }
    return $checks;
  }

  /**
   * Compiles a mapping of requirement keys to access checker service IDs.
   */
  protected function loadDynamicRequirementMap() {
    if (isset($this->dynamicRequirementMap)) {
      return;
    }

    // Set them here, so we can use the isset() check above.
    $this->dynamicRequirementMap = [];
    foreach ($this->checkIds as $service_id) {
      if (empty($this->checks[$service_id])) {
        $this
          ->loadCheck($service_id);
      }

      // Add the service ID to an array that will be iterated over.
      if ($this->checks[$service_id] instanceof AccessCheckInterface) {
        $this->dynamicRequirementMap[] = $service_id;
      }
    }
  }

}