class BigPipeTestController

class BigPipeTestController implements TrustedCallbackInterface {

  /**
   * Returns all BigPipe placeholder test case render arrays.
   *
   * @return array
   */
  public function test() {
    $has_session = \Drupal::service('session_configuration')
      ->hasSession(\Drupal::requestStack()
      ->getMainRequest());
    $build = [];
    $cases = BigPipePlaceholderTestCases::cases(\Drupal::getContainer());

    // 1. HTML placeholder: status messages. Drupal renders those automatically,
    // so all that we need to do in this controller is set a message.
    if ($has_session) {

      // Only set a message if a session already exists, otherwise we always
      // trigger a session, which means we can't test no-session requests.
      \Drupal::messenger()
        ->addStatus('Hello from BigPipe!');
    }
    $build['html'] = $cases['html']->renderArray;

    // 2. HTML attribute value placeholder: form action.
    $build['html_attribute_value'] = $cases['html_attribute_value']->renderArray;

    // 3. HTML attribute value subset placeholder: CSRF token in link.
    $build['html_attribute_value_subset'] = $cases['html_attribute_value_subset']->renderArray;

    // 4. Edge case: custom string to be considered as a placeholder that
    // happens to not be valid HTML.
    $build['edge_case__invalid_html'] = $cases['edge_case__invalid_html']->renderArray;

    // 5. Edge case: non-#lazy_builder placeholder that suspends.
    $build['edge_case__html_non_lazy_builder_suspend'] = $cases['edge_case__html_non_lazy_builder_suspend']->renderArray;

    // 6. Edge case: non-#lazy_builder placeholder.
    $build['edge_case__html_non_lazy_builder'] = $cases['edge_case__html_non_lazy_builder']->renderArray;

    // 7. Exception: #lazy_builder that throws an exception.
    $build['exception__lazy_builder'] = $cases['exception__lazy_builder']->renderArray;

    // 8. Exception: placeholder that causes response filter to throw exception.
    $build['exception__embedded_response'] = $cases['exception__embedded_response']->renderArray;
    return $build;
  }

  /**
   * @return array
   */
  public static function nope() {
    return [
      '#markup' => '<p>Nope.</p>',
    ];
  }

  /**
   * A page with multiple occurrences of the same placeholder.
   *
   * @see \Drupal\Tests\big_pipe\Functional\BigPipeTest::testBigPipeMultiOccurrencePlaceholders()
   *
   * @return array
   */
  public function multiOccurrence() {
    return [
      'item1' => [
        '#lazy_builder' => [
          static::class . '::counter',
          [],
        ],
        '#create_placeholder' => TRUE,
      ],
      'item2' => [
        '#lazy_builder' => [
          static::class . '::counter',
          [],
        ],
        '#create_placeholder' => TRUE,
      ],
      'item3' => [
        '#lazy_builder' => [
          static::class . '::counter',
          [],
        ],
        '#create_placeholder' => TRUE,
      ],
    ];
  }

  /**
   * A page with placeholder preview.
   *
   * @return array[]
   */
  public function placeholderPreview() {
    return [
      'user_container' => [
        '#type' => 'container',
        '#attributes' => [
          'id' => 'placeholder-preview-twig-container',
        ],
        'user' => [
          '#lazy_builder' => [
            'user.toolbar_link_builder:renderDisplayName',
            [],
          ],
          '#create_placeholder' => TRUE,
        ],
      ],
      'user_links_container' => [
        '#type' => 'container',
        '#attributes' => [
          'id' => 'placeholder-render-array-container',
        ],
        'user_links' => [
          '#lazy_builder' => [
            static::class . '::helloOrYarhar',
            [],
          ],
          '#create_placeholder' => TRUE,
          '#lazy_builder_preview' => [
            '#attributes' => [
              'id' => 'render-array-preview',
            ],
            '#type' => 'container',
            '#markup' => 'There is a lamb and there is a puppy',
          ],
        ],
      ],
    ];
  }

  /**
   * #lazy_builder callback; builds <time> markup with current time.
   *
   * Note: does not actually use current time, that would complicate testing.
   *
   * @return array
   */
  public static function currentTime() {
    return [
      '#markup' => '<time datetime="' . date('Y-m-d', 668948400) . '"></time>',
      '#cache' => [
        'max-age' => 0,
      ],
    ];
  }

  /**
   * #lazy_builder callback; suspends its own execution then returns markup.
   *
   * @return array
   */
  public static function piggy() : array {

    // Immediately call Fiber::suspend(), so that other placeholders are
    // executed next. When this is resumed, it will immediately return the
    // render array.
    if (\Fiber::getCurrent() !== NULL) {
      \Fiber::suspend();
    }
    return [
      '#markup' => '<span>This 🐷 little 🐽 piggy 🐖 stayed 🐽 at 🐷 home.</span>',
      '#cache' => [
        'max-age' => 0,
      ],
    ];
  }

  /**
   * #lazy_builder callback; says "hello" or "yarhar".
   *
   * @return array
   */
  public static function helloOrYarhar() {
    return [
      '#markup' => BigPipeMarkup::create('<marquee>Yarhar llamas forever!</marquee>'),
      '#cache' => [
        'max-age' => 0,
        'tags' => [
          'cache_tag_set_in_lazy_builder',
        ],
      ],
    ];
  }

  /**
   * #lazy_builder callback; throws exception.
   *
   * @throws \Exception
   */
  public static function exception() {
    throw new \Exception('You are not allowed to say llamas are not cool!');
  }

  /**
   * #lazy_builder callback; returns content that will trigger an exception.
   *
   * @see \Drupal\big_pipe_test\EventSubscriber\BigPipeTestSubscriber::onRespondTriggerException()
   *
   * @return array
   */
  public static function responseException() {
    return [
      '#plain_text' => BigPipeTestSubscriber::CONTENT_TRIGGER_EXCEPTION,
    ];
  }

  /**
   * #lazy_builder callback; returns the current count.
   *
   * @see \Drupal\Tests\big_pipe\Functional\BigPipeTest::testBigPipeMultiOccurrencePlaceholders()
   *
   * @return array
   *   The render array.
   */
  public static function counter() {

    // Lazy builders are not allowed to build their own state like this function
    // does, but in this case we're intentionally doing that for testing
    // purposes: so we can ensure that each lazy builder is only ever called
    // once with the same parameters.
    static $count;
    if (!isset($count)) {
      $count = 0;
    }
    $count++;
    return [
      '#markup' => BigPipeMarkup::create("<p>The count is {$count}.</p>"),
      '#cache' => [
        'max-age' => 0,
      ],
    ];
  }

  /**
   * {@inheritdoc}
   */
  public static function trustedCallbacks() {
    return [
      'currentTime',
      'piggy',
      'helloOrYarhar',
      'exception',
      'responseException',
      'counter',
    ];
  }

}