ModuleRequiredByThemesUninstallValidator.php

<?php

namespace Drupal\Core\Extension;

use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\Core\StringTranslation\TranslationInterface;

/**
 * Ensures modules cannot be uninstalled if enabled themes depend on them.
 */
class ModuleRequiredByThemesUninstallValidator implements ModuleUninstallValidatorInterface {
    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;
    }
    
    /**
     * 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 $module.
     */
    protected function getThemesDependingOnModule($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);
    }

}