From bc03902a463af339e19aa49e4148c4e26765490b Mon Sep 17 00:00:00 2001
From: "antonio.c.mariani" <antonio.c.mariani@ufsc.br>
Date: Sat, 7 Nov 2015 19:35:11 -0200
Subject: [PATCH] Alert if session date is prior to the course start date

---
 add_form.php           | 12 ++++++++++++
 lang/en/attendance.php |  1 +
 2 files changed, 13 insertions(+)

diff --git a/add_form.php b/add_form.php
index 0953b56..5755187 100644
--- a/add_form.php
+++ b/add_form.php
@@ -165,6 +165,12 @@ class mod_attendance_add_form extends moodleform {
                            null, array('maxfiles'=>EDITOR_UNLIMITED_FILES, 'noclean'=>true, 'context'=>$modcontext));
         $mform->setType('sdescription', PARAM_RAW);
 
+        $mform->addElement('hidden', 'coursestartdate', $course->startdate);
+        $mform->setType('coursestartdate', PARAM_INT);
+
+        $mform->addElement('hidden', 'previoussessiondate', 0);
+        $mform->setType('previoussessiondate', PARAM_INT);
+
         $submit_string = get_string('addsession', 'attendance');
         $this->add_action_buttons(false, $submit_string);
     }
@@ -198,6 +204,12 @@ class mod_attendance_add_form extends moodleform {
         if ($addmulti && ceil(($data['sessionenddate'] - $data['sessiondate']) / YEARSECS) > 1) {
             $errors['sessionenddate'] = get_string('timeahead', 'attendance');
         }
+
+        if ($data['sessiondate'] < $data['coursestartdate'] && $data['sessiondate'] != $data['previoussessiondate']) {
+            $errors['sessiondate'] = get_string('priorto', 'attendance', userdate($data['coursestartdate'], get_string('strftimedmy', 'attendance')));
+            $this->_form->setConstant('previoussessiondate', $data['sessiondate']);
+        }
+
         return $errors;
     }
 
diff --git a/lang/en/attendance.php b/lang/en/attendance.php
index 336b5a4..160b535 100644
--- a/lang/en/attendance.php
+++ b/lang/en/attendance.php
@@ -310,3 +310,4 @@ $string['confirmdeletehiddensessions'] = 'Are you sure you want to delete {$a->c
 $string['hiddensessionsdeleted'] = 'All hidden sessions were delete';
 
 $string['timeahead'] = 'Multiple sessions that exceed one year cannot be created, please adjust the start and end dates.';
+$string['priorto'] = 'The session date is prior to the course start date ({$a}) so that the new sessions scheduled before this date will be hidden (not accessible). You can change the course start date at any time (see course settings) in order to have access to earlier sessions.<br><br>Please change the session date or just click the "Add session" button again to confirm?';