Added helper file, replaced size file for human version as a helper method, next prev buttons for chapters.

app/helpers.php

@@ -0,0 +1,22 @@
+<?php
+
+if (!function_exists('formatFileSize')) {
+    function formatFileSize($fileSizeInBytes): string
+    {
+        $base = log($fileSizeInBytes) / log(1024);
+        $suffix = ["", "k", "M", "G", "T"][floor($base)];
+        $size = round(pow(1024, $base - floor($base)), 2);
+        return !is_nan($size) ? $size . $suffix : '0B';
+    }
+}
+
+if (!function_exists('folderSize')) {
+    function folderSize($dir): int
+    {
+        $size = 0;
+        foreach (glob(rtrim($dir, '/') . '/*', GLOB_NOSORT) as $each) {
+            $size += is_file($each) ? filesize($each) : folderSize($each);
+        }
+        return $size;
+    }
+}