class RestExport

class RestExport extends PathPluginBase {

  /**
   * Overrides \Drupal\views\Plugin\views\display\DisplayPluginBase::$usesAJAX.
   */
  protected $usesAJAX = FALSE;

  /**
   * Overrides \Drupal\views\Plugin\views\display\DisplayPluginBase::$usesPager.
   */
  protected $usesPager = FALSE;

  /**
   * Overrides \Drupal\views\Plugin\views\display\DisplayPluginBase::$usesMore.
   */
  protected $usesMore = FALSE;

  /**
   * Overrides \Drupal\views\Plugin\views\display\DisplayPluginBase::$usesAreas.
   */
  protected $usesAreas = FALSE;

  /**
   * Overrides \Drupal\views\Plugin\views\display\DisplayPluginBase::$usesAreas.
   */
  protected $usesOptions = FALSE;

  /**
   * Overrides the content type of the data response, if needed.
   *
   * @var string
   */
  protected $contentType = 'json';

  /**
   * The mime type for the response.
   *
   * @var string
   */
  protected $mimeType;

  /**
   * {@inheritdoc}
   */
  public function initDisplay(ViewExecutable $view, array &$display, array &$options = NULL) {
    parent::initDisplay($view, $display, $options);
    $container = drupal_container();
    $negotiation = $container
      ->get('content_negotiation');
    $request = $container
      ->get('request');
    $request_content_type = $negotiation
      ->getContentType($request);

    // Only use the requested content type if it's not 'html'. If it is then
    // default to 'json' to aid debugging.
    // @todo Remove the need for this when we have better content negotiation.
    if ($request_content_type != 'html') {
      $this
        ->setContentType($request_content_type);
    }
    $this
      ->setMimeType($request
      ->getMimeType($this->contentType));
  }

  /**
   * {@inheritdoc}
   */
  protected function getType() {
    return 'data';
  }

  /**
   * {@inheritdoc}
   */
  public function usesExposed() {
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function displaysExposed() {
    return FALSE;
  }

  /**
   * Sets the request content type.
   *
   * @param string $mime_type
   *   The response mime type. E.g. 'application/json'.
   */
  public function setMimeType($mime_type) {
    $this->mimeType = $mime_type;
  }

  /**
   * Gets the mime type.
   *
   * This will return any overridden mime type, otherwise returns the mime type
   * from the request.
   *
   * @return string
   *   The response mime type. E.g. 'application/json'.
   */
  public function getMimeType() {
    return $this->mimeType;
  }

  /**
   * Sets the content type.
   *
   * @param string $content_type
   *   The content type machine name. E.g. 'json'.
   */
  public function setContentType($content_type) {
    $this->contentType = $content_type;
  }

  /**
   * Gets the content type.
   *
   * @return string
   *   The content type machine name. E.g. 'json'.
   */
  public function getContentType() {
    return $this->contentType;
  }

  /**
   * {@inheritdoc}
   */
  protected function defineOptions() {
    $options = parent::defineOptions();

    // Set the default style plugin to 'json'.
    $options['style']['contains']['type']['default'] = 'serializer';
    $options['row']['contains']['type']['default'] = 'data_entity';
    $options['defaults']['default']['style'] = FALSE;
    $options['defaults']['default']['row'] = FALSE;

    // Remove css/exposed form settings, as they are not used for the data display.
    unset($options['exposed_form']);
    unset($options['exposed_block']);
    unset($options['css_class']);
    return $options;
  }

  /**
   * {@inheritdoc}
   */
  public function optionsSummary(&$categories, &$options) {
    parent::optionsSummary($categories, $options);
    unset($categories['page'], $categories['exposed']);

    // Hide some settings, as they aren't useful for pure data output.
    unset($options['show_admin_links'], $options['analyze-theme']);
    $categories['path'] = array(
      'title' => t('Path settings'),
      'column' => 'second',
      'build' => array(
        '#weight' => -10,
      ),
    );
    $options['path']['category'] = 'path';
    $options['path']['title'] = t('Path');

    // Remove css/exposed form settings, as they are not used for the data
    // display.
    unset($options['exposed_form']);
    unset($options['exposed_block']);
    unset($options['css_class']);
  }

  /**
   * {@inheritdoc}
   */
  public function collectRoutes(RouteCollection $collection) {
    parent::collectRoutes($collection);
    $style_plugin = $this
      ->getPlugin('style');

    // REST exports should only respond to get methods.
    $requirements = array(
      '_method' => 'GET',
    );

    // Format as a string using pipes as a delimeter.
    $requirements['_format'] = implode('|', $style_plugin
      ->getFormats());

    // Add the new requirements to each route.
    foreach ($collection as $route) {
      $route
        ->addRequirements($requirements);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function execute() {
    parent::execute();
    $output = $this->view
      ->render();
    return new Response(drupal_render($output), 200, array(
      'Content-type' => $this
        ->getMimeType(),
    ));
  }

  /**
   * {@inheritdoc}
   */
  public function render() {
    $build = array();
    $build['#markup'] = $this->view->style_plugin
      ->render();

    // Wrap the output in a pre tag if this is for a live preview.
    if (!empty($this->view->live_preview)) {
      $build['#prefix'] = '<pre>';
      $build['#markup'] = check_plain($build['#markup']);
      $build['#suffix'] = '</pre>';
    }
    return $build;
  }

  /**
   * {@inheritdoc}
   *
   * The DisplayPluginBase preview method assumes we will be returning a render
   * array. The data plugin will already return the serialized string.
   */
  public function preview() {
    return $this->view
      ->render();
  }

}