<?php

namespace Drupal\Core\Cache;

/**
 * Trait for \Drupal\Core\Cache\RefinableCacheableDependencyInterface.
 */
trait RefinableCacheableDependencyTrait {

  /**
   * Cache contexts.
   *
   * @var string[]
   */
  protected $cacheContexts = [];

  /**
   * Cache tags.
   *
   * @var string[]
   */
  protected $cacheTags = [];

  /**
   * Cache max-age.
   *
   * @var int
   */
  protected $cacheMaxAge = Cache::PERMANENT;

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

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

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

  /**
   * {@inheritdoc}
   */
  public function addCacheableDependency($other_object) {
    if ($other_object instanceof CacheableDependencyInterface) {
      $this->addCacheContexts($other_object->getCacheContexts());
      $this->addCacheTags($other_object->getCacheTags());
      $this->mergeCacheMaxAge($other_object->getCacheMaxAge());
    }
    else {
      // Not a cacheable dependency, this can not be cached.
      $this->cacheMaxAge = 0;
    }
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function addCacheContexts(array $cache_contexts) {
    if ($cache_contexts) {
      $this->cacheContexts = Cache::mergeContexts($this->cacheContexts, $cache_contexts);
    }
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function addCacheTags(array $cache_tags) {
    if ($cache_tags) {
      $this->cacheTags = Cache::mergeTags($this->cacheTags, $cache_tags);
    }
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function mergeCacheMaxAge($max_age) {
    $this->cacheMaxAge = Cache::mergeMaxAges($this->cacheMaxAge, $max_age);
    return $this;
  }

}