altcolor-1.0.0-beta1/src/Theme/ColorPreviewThemeNegotiator.php

<?php

namespace Drupal\altcolor\Theme;

use Drupal\Core\Extension\ThemeHandlerInterface;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Session\AccountProxyInterface;
use Drupal\Core\TempStore\PrivateTempStoreFactory;
use Drupal\Core\Theme\ThemeNegotiatorInterface;
use Symfony\Component\HttpFoundation\RequestStack;

/**
 * Allows rendering of the front page in a different theme for color previews.
 */
class ColorPreviewThemeNegotiator implements ThemeNegotiatorInterface {

  /**
   * The temp store.
   *
   * @var \Drupal\Core\TempStore\PrivateTempStore
   */
  protected $tempStore;

  /**
   * Constructs a ColorPreviewThemeNegotiator.
   *
   * @param \Drupal\Core\Extension\ThemeHandlerInterface $themeHandler
   *   The theme handler.
   * @param \Symfony\Component\HttpFoundation\RequestStack $requestStack
   *   The request stack.
   * @param \Drupal\Core\Session\AccountProxyInterface $currentUser
   *   The current user.
   * @param \Drupal\Core\TempStore\PrivateTempStoreFactory $temp_store_factory
   *   The temp store factory.
   */
  public function __construct(
    protected ThemeHandlerInterface $themeHandler,
    protected RequestStack $requestStack,
    protected AccountProxyInterface $currentUser,
    PrivateTempStoreFactory $temp_store_factory,
  ) {
    $this->tempStore = $temp_store_factory->get('altcolor');
  }

  /**
   * Gets the theme.
   *
   * @return string
   *   The theme system name if found, or NULL otherwise.
   */
  protected function getTheme() {
    $altcolor_preview_theme = $this->tempStore->get($this->currentUser->id() . ':preview_theme');
    // Check if this is an existing theme and if it is enabled.
    if ($this->themeHandler->themeExists($altcolor_preview_theme)) {
      return $altcolor_preview_theme;
    }
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function applies(RouteMatchInterface $route_match) {
    // This negotiator should only work for the form preview page. We use
    // several methods to check this. We do not check for an administration
    // permission here because it is assumed that this was already checked on
    // the page where the iframe is being rendered.
    if (
        // First, check if the query parameter is set.
        $this->requestStack->getCurrentRequest()->query->get('altcolor_preview') == '1'
        // Then check if the request is coming from our own site...
        && $this->requestStack->getCurrentRequest()->headers->get('Sec-Fetch-Site') == 'same-origin'
        // ...and the request is coming from an iframe...
        && $this->requestStack->getCurrentRequest()->headers->get('Sec-Fetch-Dest') == 'iframe'
        // ...and the theme resolves.
        && $this->getTheme()
    ) {
      return TRUE;
    }
    return FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function determineActiveTheme(RouteMatchInterface $route_match) {
    return $this->getTheme();
  }

}