added File Helper

lib/Helpers/FileHelper.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace OCA\GroupfolderFilesystemSnapshots\Helpers;
+
+class FileHelper {
+    private static function seperateFilesFromFolders($parentDir, $items) {
+        $files = [];
+        $folders = [];
+
+        foreach($items as $item) {
+            if(is_dir($parentDir . DIRECTORY_SEPARATOR . $item)) {
+                $folders[] = $item;
+            } else {
+                $files[] = $item;
+            }
+        }
+
+        return array($files, $folders);
+    }
+
+    public static function getFilesAndFolders($dir) {
+        $scan = array_diff(scandir($dir), array('..', '.'));
+
+        return self::seperateFilesFromFolders($dir, $scan);
+    }
+
+    public static function getFilesizesOfFiles($prefix, array $files) {
+        $result = array();
+
+        foreach($files as $index=>$file) {
+            $result[$index] = filesize($prefix . DIRECTORY_SEPARATOR . $file);
+        }
+
+        return $result;
+    }
+}