Attendance book creation UX improvements

modules/attendance/enums.php

@@ -0,0 +1,63 @@
+<?php
+
+/*
+ *  ========================================================================
+ *  * Open eClass
+ *  * E-learning and Course Management System
+ *  * ========================================================================
+ *  * Copyright 2003-2025, Greek Universities Network - GUnet
+ *  *
+ *  * Open eClass is an open platform distributed in the hope that it will
+ *  * be useful (without any warranty), under the terms of the GNU (General
+ *  * Public License) as published by the Free Software Foundation.
+ *  * The full license can be read in "/info/license/license_gpl.txt".
+ *  *
+ *  * Contact address: GUnet Asynchronous eLearning Group
+ *  *                  e-mail: info@openeclass.org
+ *  * ========================================================================
+ *
+ */
+
+interface IEnumSemester
+{
+    public function str(): string;
+    public function month_start(): int;
+    // Used to calculate the academic year
+    public function year_offset() : DateInterval;
+    public static function fromMonth(int $month) : self;
+}
+
+enum Semester: int implements IEnumSemester
+{
+    case WINTER = 1;
+    case SPRING = 2;
+    public function str(): string
+    {
+        return match($this) {
+            Semester::WINTER => 'winter',
+            Semester::SPRING => 'spring',
+        };
+    }
+
+    public function month_start(): int
+    {
+        return match($this) {
+            Semester::WINTER => 9,
+            Semester::SPRING => 3,
+        };
+    }
+
+    public function year_offset(): DateInterval
+    {
+        return match($this) {
+            Semester::WINTER => DateInterval::createFromDateString('0 days'),
+            Semester::SPRING => DateInterval::createFromDateString('-1 year'),
+        };
+    }
+
+    public static function fromMonth(int $month): self
+    {
+        return ($month >= self::SPRING->month_start() && $month < self::WINTER->month_start() ? self::SPRING : self::WINTER);
+    }
+}
+?>