CurrentPathContext.php

<?php

namespace Drupal\rules\ContextProvider;

use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Path\CurrentPathStack;
use Drupal\Core\Plugin\Context\Context;
use Drupal\Core\Plugin\Context\ContextDefinition;
use Drupal\Core\Plugin\Context\ContextProviderInterface;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\Core\Url;

/**
 * Makes the current path available as a context variable.
 */
class CurrentPathContext implements ContextProviderInterface {
  use StringTranslationTrait;
  
  /**
   * The current path service.
   *
   * @var \Drupal\Core\Path\CurrentPathStack
   */
  protected $currentPathStack;
  
  /**
   * Constructs a new CurrentPathContext.
   *
   * @param \Drupal\Core\Path\CurrentPathStack $current_path_stack
   *   The current path stack service.
   */
  public function __construct(CurrentPathStack $current_path_stack) {
    $this->currentPathStack = $current_path_stack;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getRuntimeContexts(array $unqualified_context_ids) {
    $values = [
      'path' => $this->currentPathStack
        ->getPath(),
      'url' => Url::fromRoute('<current>', [], [
        'absolute' => TRUE,
      ])->toString(),
    ];
    $context_definition = new ContextDefinition('current_path', $this->t('Current path'));
    $context = new Context($context_definition, $values);
    $cacheability = new CacheableMetadata();
    $cacheability->setCacheContexts([
      'url.path',
    ]);
    $context->addCacheableDependency($cacheability);
    $result = [
      'current_path' => $context,
    ];
    return $result;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getAvailableContexts() {
    return $this->getRuntimeContexts([]);
  }

}