refactor: extract shared validation metadata normalizer

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

lib/Service/File/ValidationMetadataNormalizer.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 LibreCode coop and contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Libresign\Service\File;
+
+final class ValidationMetadataNormalizer {
+	/**
+	 * @param array<string, mixed> $metadata
+	 * @return array<string, mixed>
+	 */
+	public static function normalize(array $metadata, string $fileName, int $totalPages): array {
+		$metadata['p'] = $totalPages;
+
+		$extension = pathinfo($fileName, PATHINFO_EXTENSION);
+		if (!isset($metadata['extension']) || !is_string($metadata['extension']) || trim($metadata['extension']) === '') {
+			$metadata['extension'] = is_string($extension) && $extension !== '' ? strtolower($extension) : 'pdf';
+		}
+
+		return $metadata;
+	}
+}