added API for handling work contract times (#4016)

src/Model/Month.php

@@ -0,0 +1,54 @@
+<?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\Model;
+
+use DateTimeInterface;
+
+class Month
+{
+    /**
+     * @var Day[]
+     */
+    private array $days = [];
+
+    public function __construct(private \DateTimeInterface $month)
+    {
+        $date = new \DateTimeImmutable($this->month->format('Y-m-01 00:00:00'));
+        $start = $date->format('m');
+        while ($start === $date->format('m')) {
+            $day = $this->createDay($date);
+            $this->setDay($day);
+            $date = $date->add(new \DateInterval('P1D'));
+        }
+    }
+
+    protected function createDay(\DateTimeInterface $day): Day
+    {
+        return new Day($day);
+    }
+
+    public function getMonth(): DateTimeInterface
+    {
+        return $this->month;
+    }
+
+    protected function setDay(Day $day): void
+    {
+        $this->days['_' . $day->getDay()->format('d')] = $day;
+    }
+
+    /**
+     * @return Day[]
+     */
+    public function getDays(): array
+    {
+        return array_values($this->days);
+    }
+}