From dbb49e8d48f2f10c6aee54dd0a6028156a86afdd Mon Sep 17 00:00:00 2001
From: Jun Pataleta <jun@moodle.com>
Date: Fri, 17 Mar 2017 13:27:20 +0800
Subject: [PATCH 1/2] MDL-57793 calendar: Add recursion to satisfy COUNT rule

* Add recursion to the creation of recurring calendar events to satisfy
  the COUNT rule, if necessary.
---
 calendar/classes/rrule_manager.php | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/calendar/classes/rrule_manager.php b/calendar/classes/rrule_manager.php
index 78cee59681d..ea8e1846375 100644
--- a/calendar/classes/rrule_manager.php
+++ b/calendar/classes/rrule_manager.php
@@ -721,6 +721,20 @@ class rrule_manager {
             unset($cloneevent->id);
             \calendar_event::create($cloneevent, false);
         }
+
+        // If COUNT rule is defined and the number of the generated event times is less than the the COUNT rule,
+        // repeat the processing until the COUNT rule is satisfied.
+        if ($count !== false && $count > 0) {
+            // Set count to the remaining counts.
+            $this->count = $count;
+            // Clone the original event, but set the timestart to the last generated event time.
+            $tmpevent = clone($event);
+            $tmpevent->timestart = end($eventtimes);
+            // Generate the additional event times.
+            $additionaleventtimes = $this->generate_recurring_event_times($tmpevent);
+            // Create the additional events.
+            $this->create_recurring_events($event, $additionaleventtimes);
+        }
     }
 
     /**

From 6d5661a9b3c72144e9766696c3b5ecce47bb0b60 Mon Sep 17 00:00:00 2001
From: Jun Pataleta <jun@moodle.com>
Date: Fri, 24 Mar 2017 12:29:49 +0800
Subject: [PATCH 2/2] MDL-57793 calendar: Additional edge-case tests

* Added leap year and 31th day of the month tests.
---
 calendar/tests/rrule_manager_test.php | 53 +++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/calendar/tests/rrule_manager_test.php b/calendar/tests/rrule_manager_test.php
index 2b0f315a953..9178329b81f 100644
--- a/calendar/tests/rrule_manager_test.php
+++ b/calendar/tests/rrule_manager_test.php
@@ -2691,6 +2691,59 @@ class core_calendar_rrule_manager_testcase extends advanced_testcase {
         }
     }
 
+    /*
+     * Other edge case tests.
+     */
+
+    /**
+     * Tests for MONTHLY RRULE with BYMONTHDAY set to 31.
+     * Should not include February, April, June, September and November.
+     */
+    public function test_monthly_bymonthday_31() {
+        global $DB;
+
+        $rrule = 'FREQ=MONTHLY;BYMONTHDAY=31;COUNT=20';
+        $mang = new rrule_manager($rrule);
+        $mang->parse_rrule();
+        $mang->create_events($this->event);
+
+        $records = $DB->get_records('event', ['repeatid' => $this->event->id], 'timestart ASC', 'id, repeatid, timestart');
+        $this->assertCount(20, $records);
+
+        $non31months = ['February', 'April', 'June', 'September', 'November'];
+
+        foreach ($records as $record) {
+            $month = date('F', $record->timestart);
+            $this->assertNotContains($month, $non31months);
+        }
+    }
+
+    /**
+     * Tests for the last day in February. (Leap year test)
+     */
+    public function test_yearly_on_the_last_day_of_february() {
+        global $DB;
+
+        $rrule = 'FREQ=YEARLY;BYMONTH=2;BYMONTHDAY=-1;COUNT=30';
+        $mang = new rrule_manager($rrule);
+        $mang->parse_rrule();
+        $mang->create_events($this->event);
+
+        $records = $DB->get_records('event', ['repeatid' => $this->event->id], 'timestart ASC', 'id, repeatid, timestart');
+        $this->assertCount(30, $records);
+
+        foreach ($records as $record) {
+            $date = new DateTime(date('Y-m-d H:i:s', $record->timestart));
+            $year = $date->format('Y');
+            $day = $date->format('d');
+            if ($year % 4 == 0) {
+                $this->assertEquals(29, $day);
+            } else {
+                $this->assertEquals(28, $day);
+            }
+        }
+    }
+
     /**
      * Change the event's timestart (DTSTART) based on the test's needs.
      *