class NavigationTestHooks

class NavigationTestHooks {
    
    /**
     * NavigationTestHooks constructor.
     *
     * @param \Drupal\Core\State\StateInterface $state
     *   The state service.
     */
    public function __construct(StateInterface $state) {
    }
    
    /**
     * Implements hook_block_alter().
     */
    public function blockAlter(&$definitions) : void {
        if ($this->state
            ->get('navigation_safe_alter')) {
            $definitions['navigation_link']['allow_in_navigation'] = TRUE;
            $definitions['navigation_shortcuts']['allow_in_navigation'] = FALSE;
        }
    }
    
    /**
     * Implements hook_navigation_content_top().
     */
    public function navigationContentTop() : array {
        if (\Drupal::keyValue('navigation_test')->get('content_top')) {
            $items = [
                'navigation_foo' => [
                    '#markup' => 'foo',
                ],
                'navigation_bar' => [
                    '#markup' => 'bar',
                ],
                'navigation_baz' => [
                    '#markup' => 'baz',
                ],
            ];
        }
        else {
            $items = [
                'navigation_foo' => [],
                'navigation_bar' => [],
                'navigation_baz' => [],
            ];
        }
        // Add cache tags to our items to express a made up dependency to test
        // cacheability. Note that as we're always returning the same items,
        // sometimes only with cacheability metadata. By doing this we're testing
        // conditional rendering of content_top items.
        foreach ($items as &$element) {
            CacheableMetadata::createFromRenderArray($element)->addCacheTags([
                'navigation_test',
            ])
                ->applyTo($element);
        }
        return $items;
    }
    
    /**
     * Implements hook_navigation_content_top_alter().
     */
    public function navigationContentTopAlter(&$content_top) : void {
        if (\Drupal::keyValue('navigation_test')->get('content_top_alter')) {
            unset($content_top['navigation_foo']);
            $content_top['navigation_bar']['#markup'] = 'new bar';
            $content_top['navigation_baz']['#weight'] = '-100';
        }
    }

}