timesheet lockdown with grace period (#1644)

src/Validator/Constraints/TimesheetLockdown.php

@@ -0,0 +1,30 @@
+<?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\Validator\Constraints;
+
+final class TimesheetLockdown extends TimesheetConstraint
+{
+    public const PERIOD_LOCKED = 'kimai-timesheet-lockdown-01';
+
+    protected static $errorNames = [
+        self::PERIOD_LOCKED => 'This period is locked, please choose a later date.',
+    ];
+
+    public $message = 'This period is locked, please choose a later date.';
+    /**
+     * @var \DateTime|string|null
+     */
+    public $now;
+
+    public function getTargets()
+    {
+        return self::CLASS_CONSTRAINT;
+    }
+}