class ModuleRequiredByThemesUninstallValidator

class ModuleRequiredByThemesUninstallValidator implements ConfigImportModuleUninstallValidatorInterface {
    use StringTranslationTrait;
    
    /**
     * The module extension list.
     *
     * @var \Drupal\Core\Extension\ModuleExtensionList
     */
    protected $moduleExtensionList;
    
    /**
     * The theme extension list.
     *
     * @var \Drupal\Core\Extension\ThemeExtensionList
     */
    protected $themeExtensionList;
    
    /**
     * Constructs a new ModuleRequiredByThemesUninstallValidator.
     *
     * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
     *   The string translation service.
     * @param \Drupal\Core\Extension\ModuleExtensionList $extension_list_module
     *   The module extension list.
     * @param \Drupal\Core\Extension\ThemeExtensionList $extension_list_theme
     *   The theme extension list.
     */
    public function __construct(TranslationInterface $string_translation, ModuleExtensionList $extension_list_module, ThemeExtensionList $extension_list_theme) {
        $this->stringTranslation = $string_translation;
        $this->moduleExtensionList = $extension_list_module;
        $this->themeExtensionList = $extension_list_theme;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validate($module) {
        $reasons = [];
        $themes_depending_on_module = $this->getThemesDependingOnModule($module);
        if (!empty($themes_depending_on_module)) {
            $module_name = $this->moduleExtensionList
                ->get($module)->info['name'];
            $theme_names = implode(', ', $themes_depending_on_module);
            $reasons[] = $this->formatPlural(count($themes_depending_on_module), 'Required by the theme: @theme_names', 'Required by the themes: @theme_names', [
                '@module_name' => $module_name,
                '@theme_names' => $theme_names,
            ]);
        }
        return $reasons;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateConfigImport(string $module, StorageInterface $source_storage) : array {
        $reasons = [];
        $themes_depending_on_module = $this->getThemesDependingOnModule($module);
        if (!empty($themes_depending_on_module)) {
            $installed_themes_after_import = $source_storage->read('core.extension')['theme'];
            $themes_depending_on_module_still_installed = array_intersect_key($themes_depending_on_module, $installed_themes_after_import);
            // Ensure that any dependent themes will be uninstalled by the module.
            if (!empty($themes_depending_on_module_still_installed)) {
                $reasons[] = $this->formatPlural(count($themes_depending_on_module_still_installed), 'Required by the theme: @theme_names', 'Required by the themes: @theme_names', [
                    '@theme_names' => implode(', ', $themes_depending_on_module_still_installed),
                ]);
            }
        }
        return $reasons;
    }
    
    /**
     * Returns themes that depend on a module.
     *
     * @param string $module
     *   The module machine name.
     *
     * @return string[]
     *   An array of the names of themes that depend on $module keyed by the
     *   theme's machine name.
     */
    protected function getThemesDependingOnModule($module) {
        $installed_themes = $this->themeExtensionList
            ->getAllInstalledInfo();
        $themes_depending_on_module = array_map(function ($theme) use ($module) {
            if (in_array($module, $theme['dependencies'])) {
                return $theme['name'];
            }
        }, $installed_themes);
        return array_filter($themes_depending_on_module);
    }

}