Extracted some private functions ase helper global functions

module/Core/functions/functions.php

@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core;
 
+use Cake\Chronos\Chronos;
+use DateTimeInterface;
 use PUGX\Shortid\Factory as ShortIdFactory;
 
 function generateRandomShortCode(int $length = 5): string
@@ -16,3 +18,24 @@ function generateRandomShortCode(int $length = 5): string
     $alphabet = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
     return $shortIdFactory->generate($length, $alphabet)->serialize();
 }
+
+function parseDateFromQuery(array $query, string $dateName): ?Chronos
+{
+    return ! isset($query[$dateName]) || empty($query[$dateName]) ? null : Chronos::parse($query[$dateName]);
+}
+
+/**
+ * @param string|DateTimeInterface|Chronos|null $date
+ */
+function parseDateField($date): ?Chronos
+{
+    if ($date === null || $date instanceof Chronos) {
+        return $date;
+    }
+
+    if ($date instanceof DateTimeInterface) {
+        return Chronos::instance($date);
+    }
+
+    return Chronos::parse($date);
+}