Standardized ordering field handling and added validation for short URLs list

module/Core/src/Model/Ordering.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Model;
+
+final class Ordering
+{
+    private const DEFAULT_DIR = 'ASC';
+
+    private function __construct(private ?string $field, private string $dir)
+    {
+    }
+
+    public static function fromTuple(array $props): self
+    {
+        [$field, $dir] = $props;
+        return new self($field, $dir ?? self::DEFAULT_DIR);
+    }
+
+    public function orderField(): ?string
+    {
+        return $this->field;
+    }
+
+    public function orderDirection(): string
+    {
+        return $this->dir;
+    }
+
+    public function hasOrderField(): bool
+    {
+        return $this->field !== null;
+    }
+}