move supported languages logic to service (#2701)

src/Utils/LanguageService.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;
+
+use App\Constants;
+
+final class LanguageService
+{
+    /**
+     * @var string[]|string
+     */
+    private $locales;
+
+    public function __construct(string $locales)
+    {
+        $this->locales = $locales;
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getAllLanguages(): array
+    {
+        if (!\is_array($this->locales)) {
+            // no further checks, because the list of languages is hard coded and we can be sure that
+            // it is well formatted and contains the default langauge english
+            $this->locales = array_unique(explode('|', trim($this->locales)));
+        }
+
+        return $this->locales;
+    }
+
+    public function isKnownLanguage(string $language): bool
+    {
+        return \in_array($language, $this->getAllLanguages());
+    }
+
+    public function getDefaultLanguage(): string
+    {
+        return Constants::DEFAULT_LOCALE;
+    }
+}