reduce config complexity by converting php format to js format (#734)

src/Utils/MomentFormatConverter.php

@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Utils;
+
+/**
+ * This class is used to convert PHP date format to moment.js format.
+ *
+ * @author Yonel Ceruto <yonelceruto@gmail.com>
+ */
+class MomentFormatConverter
+{
+    /**
+     * This defines the mapping between PHP ICU date format (key) and moment.js date format (value)
+     * For ICU formats see http://userguide.icu-project.org/formatparse/datetime#TOC-Date-Time-Format-Syntax
+     * For Moment formats see http://momentjs.com/docs/#/displaying/format/.
+     *
+     * @var array
+     */
+    private static $formatConvertRules = [
+        // year
+        'yyyy' => 'YYYY', 'yy' => 'YY', 'y' => 'YYYY',
+        // day
+        'dd' => 'DD', 'd' => 'D',
+        // day of week
+        'EE' => 'ddd', 'EEEEEE' => 'dd',
+        // timezone
+        'ZZZZZ' => 'Z', 'ZZZ' => 'ZZ',
+        // letter 'T'
+        '\'T\'' => 'T',
+    ];
+
+    /**
+     * Returns associated moment.js format.
+     *
+     * @param string $format
+     * @return string
+     */
+    public function convert(string $format): string
+    {
+        return strtr($format, self::$formatConvertRules);
+    }
+}