class PhpExtensionsValidator

class PhpExtensionsValidator implements EventSubscriberInterface {
    use StringTranslationTrait;
    
    /**
     * Indicates if a particular PHP extension is loaded.
     *
     * @param string $name
     *   The name of the PHP extension to check for.
     *
     * @return bool
     *   TRUE if the given extension is loaded, FALSE otherwise.
     */
    protected final function isExtensionLoaded(string $name) : bool {
        // If and ONLY if we're currently running a test, allow the list of loaded
        // extensions to be overridden by a state variable.
        if (self::insideTest()) {
            // By default, assume OpenSSL is enabled and Xdebug isn't. This allows us
            // to run tests in environments that we might not support in production,
            // such as Drupal CI.
            $loaded_extensions = \Drupal::state()->get('package_manager_loaded_php_extensions', [
                'openssl',
            ]);
            return in_array($name, $loaded_extensions, TRUE);
        }
        return extension_loaded($name);
    }
    
    /**
     * Flags a warning if Xdebug is enabled.
     *
     * @param \Drupal\package_manager\Event\StatusCheckEvent $event
     *   The event object.
     */
    public function validateXdebug(StatusCheckEvent $event) : void {
        if ($this->isExtensionLoaded('xdebug')) {
            $event->addWarning([
                $this->t('Xdebug is enabled, which may have a negative performance impact on Package Manager and any modules that use it.'),
            ]);
        }
    }
    
    /**
     * Flags an error if the OpenSSL extension is not installed.
     *
     * @param \Drupal\package_manager\Event\PreOperationStageEvent $event
     *   The event object.
     */
    public function validateOpenSsl(PreOperationStageEvent $event) : void {
        if (!$this->isExtensionLoaded('openssl')) {
            $message = $this->t('The OpenSSL extension is not enabled, which is a security risk. See <a href=":url">the PHP documentation</a> for information on how to enable this extension.', [
                ':url' => 'https://www.php.net/manual/en/openssl.installation.php',
            ]);
            $event->addError([
                $message,
            ]);
        }
    }
    
    /**
     * Whether this validator is running inside a test.
     *
     * @return bool
     */
    private static function insideTest() : bool {
        // @see \Drupal\Core\CoreServiceProvider::registerTest()
        $in_functional_test = drupal_valid_test_ua();
        // @see \Drupal\Core\DependencyInjection\DependencySerializationTrait::__wakeup()
        $in_kernel_test = isset($GLOBALS['__PHPUNIT_BOOTSTRAP']);
        // @see \Drupal\BuildTests\Framework\BuildTestBase::setUp()
        $in_build_test = str_contains(__FILE__, DrupalFilesystem::getOsTemporaryDirectory() . '/build_workspace_');
        return $in_functional_test || $in_kernel_test || $in_build_test;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        return [
            StatusCheckEvent::class => [
                [
                    'validateXdebug',
                ],
                [
                    'validateOpenSsl',
                ],
            ],
            PreCreateEvent::class => [
                'validateOpenSsl',
            ],
            PreApplyEvent::class => [
                'validateOpenSsl',
            ],
        ];
    }

}