End date must not exceed one year ahead of the session date

add_form.php

@@ -195,6 +195,9 @@ class mod_attendance_add_form extends moodleform {
                 $errors['sdays'] = get_string('checkweekdays', 'attendance');
             }
         }
+        if ($addmulti && ceil(($data['sessionenddate'] - $data['sessiondate']) / YEARSECS) > 1) {
+            $errors['sessionenddate'] = get_string('timeahead', 'attendance');
+        }
         return $errors;
     }
 

lang/en/attendance.php

@@ -308,3 +308,5 @@ $string['notmember'] = 'not member';
 $string['deletehiddensessions'] = 'Delete all hidden sessions';
 $string['confirmdeletehiddensessions'] = 'Are you sure you want to delete {$a->count} sessions scheduled before the course start date ({$a->date})?';
 $string['hiddensessionsdeleted'] = 'All hidden sessions were delete';
+
+$string['timeahead'] = 'Must not exceed one year ahead of the session date';