MDL-62960 calendar: Implementing course events validity check callback

course/lib.php

@@ -3710,6 +3710,41 @@ function core_course_inplace_editable($itemtype, $itemid, $newvalue) {
     }
 }
 
+/**
+ * This function calculates the minimum and maximum cutoff values for the timestart of
+ * the given event.
+ *
+ * It will return an array with two values, the first being the minimum cutoff value and
+ * the second being the maximum cutoff value. Either or both values can be null, which
+ * indicates there is no minimum or maximum, respectively.
+ *
+ * If a cutoff is required then the function must return an array containing the cutoff
+ * timestamp and error string to display to the user if the cutoff value is violated.
+ *
+ * A minimum and maximum cutoff return value will look like:
+ * [
+ *     [1505704373, 'The date must be after this date'],
+ *     [1506741172, 'The date must be before this date']
+ * ]
+ *
+ * @param calendar_event $event The calendar event to get the time range for
+ * @param stdClass $course The course object to get the range from
+ * @return array Returns an array with min and max date.
+ */
+function core_course_core_calendar_get_valid_event_timestart_range(\calendar_event $event, $course) {
+    $mindate = null;
+    $maxdate = null;
+
+    if ($course->startdate) {
+        $mindate = [
+            $course->startdate,
+            get_string('errorbeforecoursestart', 'calendar')
+        ];
+    }
+
+    return [$mindate, $maxdate];
+}
+
 /**
  * Returns course modules tagged with a specified tag ready for output on tag/index.php page
  *