Resolve #3403816 "Simplify dark options"

Closes #3403816

src/HookHandler/PreprocessPatternNavbar.php

-<?php
-
-declare(strict_types=1);
-
-namespace Drupal\ui_suite_bootstrap\HookHandler;
-
-use Drupal\Core\Render\Element;
-
-/**
- * Handle variables needed for the pattern.
- */
-class PreprocessPatternNavbar {
-
-  /**
-   * Length of the word dark.
-   */
-  public const DARK_LENGTH = 4;
-
-  /**
-   * Pattern fields where render elements will be injected.
-   */
-  public const REGIONS_FIELDS = [
-    'navigation',
-    'navigation_collapsible',
-  ];
-
-  /**
-   * Handle variables needed for the pattern.
-   *
-   * @param array $variables
-   *   The preprocessed variables.
-   */
-  public function preprocess(array &$variables): void {
-    if (\substr($variables['variant'], 0, self::DARK_LENGTH) === 'dark') {
-      foreach (self::REGIONS_FIELDS as $region) {
-        if (isset($variables[$region])) {
-          $this->addDarkSetting($variables[$region]);
-        }
-      }
-    }
-  }
-
-  /**
-   * Add dark setting to navbar_nav pattern.
-   *
-   * @param array $item
-   *   The render element to parse.
-   */
-  protected function addDarkSetting(array &$item): void {
-    if (isset($item['#type'])
-      && \in_array($item['#type'], ['pattern', 'pattern_preview'], TRUE)
-      && $item['#id'] == 'navbar_nav'
-    ) {
-      $item['#dark'] = TRUE;
-      // Stop recursion when a navbar_nav is found, no need to enter in it.
-      return;
-    }
-
-    $children = Element::children($item);
-    foreach ($children as $key) {
-      $this->addDarkSetting($item[$key]);
-    }
-  }
-
-}