--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plugins/libcalendaring/lib/Sabre/VObject/Component/VCalendar.php	Sat Jan 13 08:57:56 2018 -0500
@@ -0,0 +1,244 @@
+<?php
+
+namespace Sabre\VObject\Component;
+
+use Sabre\VObject;
+
+/**
+ * The VCalendar component
+ *
+ * This component adds functionality to a component, specific for a VCALENDAR.
+ *
+ * @copyright Copyright (C) 2007-2013 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://code.google.com/p/sabredav/wiki/License Modified BSD License
+ */
+class VCalendar extends VObject\Document {
+
+    static $defaultName = 'VCALENDAR';
+
+    /**
+     * Returns a list of all 'base components'. For instance, if an Event has
+     * a recurrence rule, and one instance is overridden, the overridden event
+     * will have the same UID, but will be excluded from this list.
+     *
+     * VTIMEZONE components will always be excluded.
+     *
+     * @param string $componentName filter by component name
+     * @return array
+     */
+    public function getBaseComponents($componentName = null) {
+
+        $components = array();
+        foreach($this->children as $component) {
+
+            if (!$component instanceof VObject\Component)
+                continue;
+
+            if (isset($component->{'RECURRENCE-ID'}))
+                continue;
+
+            if ($componentName && $component->name !== strtoupper($componentName))
+                continue;
+
+            if ($component->name === 'VTIMEZONE')
+                continue;
+
+            $components[] = $component;
+
+        }
+
+        return $components;
+
+    }
+
+    /**
+     * If this calendar object, has events with recurrence rules, this method
+     * can be used to expand the event into multiple sub-events.
+     *
+     * Each event will be stripped from it's recurrence information, and only
+     * the instances of the event in the specified timerange will be left
+     * alone.
+     *
+     * In addition, this method will cause timezone information to be stripped,
+     * and normalized to UTC.
+     *
+     * This method will alter the VCalendar. This cannot be reversed.
+     *
+     * This functionality is specifically used by the CalDAV standard. It is
+     * possible for clients to request expand events, if they are rather simple
+     * clients and do not have the possibility to calculate recurrences.
+     *
+     * @param DateTime $start
+     * @param DateTime $end
+     * @return void
+     */
+    public function expand(\DateTime $start, \DateTime $end) {
+
+        $newEvents = array();
+
+        foreach($this->select('VEVENT') as $key=>$vevent) {
+
+            if (isset($vevent->{'RECURRENCE-ID'})) {
+                unset($this->children[$key]);
+                continue;
+            }
+
+
+            if (!$vevent->rrule) {
+                unset($this->children[$key]);
+                if ($vevent->isInTimeRange($start, $end)) {
+                    $newEvents[] = $vevent;
+                }
+                continue;
+            }
+
+            $uid = (string)$vevent->uid;
+            if (!$uid) {
+                throw new \LogicException('Event did not have a UID!');
+            }
+
+            $it = new VObject\RecurrenceIterator($this, $vevent->uid);
+            $it->fastForward($start);
+
+            while($it->valid() && $it->getDTStart() < $end) {
+
+                if ($it->getDTEnd() > $start) {
+
+                    $newEvents[] = $it->getEventObject();
+
+                }
+                $it->next();
+
+            }
+            unset($this->children[$key]);
+
+        }
+
+        foreach($newEvents as $newEvent) {
+
+            foreach($newEvent->children as $child) {
+                if ($child instanceof VObject\Property\DateTime &&
+                    $child->getDateType() == VObject\Property\DateTime::LOCALTZ) {
+                        $child->setDateTime($child->getDateTime(),VObject\Property\DateTime::UTC);
+                    }
+            }
+
+            $this->add($newEvent);
+
+        }
+
+        // Removing all VTIMEZONE components
+        unset($this->VTIMEZONE);
+
+    }
+
+    /**
+     * Validates the node for correctness.
+     * An array is returned with warnings.
+     *
+     * Every item in the array has the following properties:
+     *    * level - (number between 1 and 3 with severity information)
+     *    * message - (human readable message)
+     *    * node - (reference to the offending node)
+     *
+     * @return array
+     */
+    /*
+    public function validate() {
+
+        $warnings = array();
+
+        $version = $this->select('VERSION');
+        if (count($version)!==1) {
+            $warnings[] = array(
+                'level' => 1,
+                'message' => 'The VERSION property must appear in the VCALENDAR component exactly 1 time',
+                'node' => $this,
+            );
+        } else {
+            if ((string)$this->VERSION !== '2.0') {
+                $warnings[] = array(
+                    'level' => 1,
+                    'message' => 'Only iCalendar version 2.0 as defined in rfc5545 is supported.',
+                    'node' => $this,
+                );
+            }
+        }
+        $version = $this->select('PRODID');
+        if (count($version)!==1) {
+            $warnings[] = array(
+                'level' => 2,
+                'message' => 'The PRODID property must appear in the VCALENDAR component exactly 1 time',
+                'node' => $this,
+            );
+        }
+        if (count($this->CALSCALE) > 1) {
+            $warnings[] = array(
+                'level' => 2,
+                'message' => 'The CALSCALE property must not be specified more than once.',
+                'node' => $this,
+            );
+        }
+        if (count($this->METHOD) > 1) {
+            $warnings[] = array(
+                'level' => 2,
+                'message' => 'The METHOD property must not be specified more than once.',
+                'node' => $this,
+            );
+        }
+
+        $allowedComponents = array(
+            'VEVENT',
+            'VTODO',
+            'VJOURNAL',
+            'VFREEBUSY',
+            'VTIMEZONE',
+        );
+        $allowedProperties = array(
+            'PRODID',
+            'VERSION',
+            'CALSCALE',
+            'METHOD',
+        );
+        $componentsFound = 0;
+        foreach($this->children as $child) {
+            if($child instanceof Component) {
+                $componentsFound++;
+                if (!in_array($child->name, $allowedComponents)) {
+                    $warnings[] = array(
+                        'level' => 1,
+                        'message' => 'The ' . $child->name . " component is not allowed in the VCALENDAR component",
+                        'node' => $this,
+                    );
+                }
+            }
+            if ($child instanceof Property) {
+                if (!in_array($child->name, $allowedProperties)) {
+                    $warnings[] = array(
+                        'level' => 2,
+                        'message' => 'The ' . $child->name . " property is not allowed in the VCALENDAR component",
+                        'node' => $this,
+                    );
+                }
+            }
+        }
+
+        if ($componentsFound===0) {
+            $warnings[] = array(
+                'level' => 1,
+                'message' => 'An iCalendar object must have at least 1 component.',
+                'node' => $this,
+            );
+        }
+
+        return array_merge(
+            $warnings,
+            parent::validate()
+        );
+
+    }
+     */
+
+}
+