Fix querying for maxFileSize of uploaded files

Improve retrieving max. file size upload information, inspired by Drupal core.

Also, the previous assertion of 'maxFilesize' => 2097152 in ManagedFileTest was incorrect, given we set the maxfilesize to be 80 kb in this test.

Closes #3478477

src/Plugin/GraphQL/SchemaExtension/WebformExtension.php

@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace Drupal\graphql_webform\Plugin\GraphQL\SchemaExtension;
 
 use Drupal\Component\Utility\Bytes;
+use Drupal\Component\Utility\Environment;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\graphql\GraphQL\ResolverBuilder;
@@ -288,19 +289,33 @@ class WebformExtension extends SdlSchemaExtensionPluginBase {
 
     // Resolve the max filesize of managed file elements.
     $registry->addFieldResolver('WebformElementManagedFileBase', 'maxFilesize',
-      $builder->callback(function (array $value): ?int {
+      $builder->callback(function (array $value): int {
+        // Check if the webform element has a max filesize set. If set this is
+        // representing the size in MB.
         $size = $value['#max_filesize'] ?? NULL;
-        if ($size && is_numeric($size)) {
-          return (int) $size * 1024 * 1024;
-        }
-        $size = $this->getWebformSetting('file.default_max_filesize');
         if (!empty($size)) {
-          $size = Bytes::toNumber($size);
-          if (!empty($size)) {
-            return (int) $size;
-          }
+          $size .= 'MB';
         }
-        return NULL;
+
+        // Consider the other possible sources for the max filesize: the PHP
+        // limit and the default webform setting.
+        $sizes = array_filter([
+          $size,
+          // Ignore the PHP limit if a default max filesize is set on the form.
+          // This follows the functionality of the Webform module, but in case
+          // the PHP limit is lower than the default max filesize, the reported
+          // value will be incorrect.
+          // @todo Change this behavior when the bug is fixed in the Webform
+          //   module.
+          // @see https://www.drupal.org/project/webform/issues/3482402
+          $this->getWebformSetting('file.default_max_filesize') ?: Environment::getUploadMaxSize(),
+        ]);
+
+        // Convert to bytes.
+        $sizes = array_map(fn ($size): int => (int) Bytes::toNumber($size), $sizes);
+
+        // Return the smallest value.
+        return min($sizes);
       })
     );