initial sabre upgrade (needs lots of work - to wit: authentication, redo the browser interface, and rework event export/import)

21 files changed, 2610 insertions, 0 deletions

diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Filter/CalendarData.php b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/CalendarData.php
new file mode 100644
index 000000000..9babcf15c
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/CalendarData.php
@@ -0,0 +1,84 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Filter;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\CalDAV\Plugin;
+use Sabre\VObject\DateTimeParser;
+
+/**
+ * CalendarData parser.
+ *
+ * This class parses the {urn:ietf:params:xml:ns:caldav}calendar-data XML
+ * element, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-9.6
+ *
+ * This element is used in three distinct places in the caldav spec, but in
+ * this case, this element class only implements the calendar-data element as
+ * it appears in a DAV:prop element, in a calendar-query or calendar-multiget
+ * REPORT request.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class CalendarData implements XmlDeserializable {
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $result = [
+            'contentType' => $reader->getAttribute('content-type') ?: 'text/calendar',
+            'version'     => $reader->getAttribute('version') ?: '2.0',
+        ];
+
+        $elems = (array)$reader->parseInnerTree();
+        foreach ($elems as $elem) {
+
+            switch ($elem['name']) {
+                case '{' . Plugin::NS_CALDAV . '}expand' :
+
+                    $result['expand'] = [
+                        'start' => isset($elem['attributes']['start']) ? DateTimeParser::parseDateTime($elem['attributes']['start']) : null,
+                        'end'   => isset($elem['attributes']['end']) ? DateTimeParser::parseDateTime($elem['attributes']['end']) : null,
+                    ];
+
+                    if (!$result['expand']['start'] || !$result['expand']['end']) {
+                        throw new BadRequest('The "start" and "end" attributes are required when expanding calendar-data');
+                    }
+                    if ($result['expand']['end'] <= $result['expand']['start']) {
+                        throw new BadRequest('The end-date must be larger than the start-date when expanding calendar-data');
+                    }
+                    break;
+            }
+
+        }
+
+        return $result;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Filter/CompFilter.php b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/CompFilter.php
new file mode 100644
index 000000000..c9b27dbfd
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/CompFilter.php
@@ -0,0 +1,97 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Filter;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\CalDAV\Plugin;
+use Sabre\VObject\DateTimeParser;
+
+/**
+ * CompFilter parser.
+ *
+ * This class parses the {urn:ietf:params:xml:ns:caldav}comp-filter XML
+ * element, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-9.6
+ *
+ * The result will be spit out as an array.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class CompFilter implements XmlDeserializable {
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $result = [
+            'name'           => null,
+            'is-not-defined' => false,
+            'comp-filters'   => [],
+            'prop-filters'   => [],
+            'time-range'     => false,
+        ];
+
+        $att = $reader->parseAttributes();
+        $result['name'] = $att['name'];
+
+        $elems = $reader->parseInnerTree();
+
+        if (is_array($elems)) foreach ($elems as $elem) {
+
+            switch ($elem['name']) {
+
+                case '{' . Plugin::NS_CALDAV . '}comp-filter' :
+                    $result['comp-filters'][] = $elem['value'];
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}prop-filter' :
+                    $result['prop-filters'][] = $elem['value'];
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}is-not-defined' :
+                    $result['is-not-defined'] = true;
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}time-range' :
+                    if ($result['name'] === 'VCALENDAR') {
+                        throw new BadRequest('You cannot add time-range filters on the VCALENDAR component');
+                    }
+                    $result['time-range'] = [
+                        'start' => isset($elem['attributes']['start']) ? DateTimeParser::parseDateTime($elem['attributes']['start']) : null,
+                        'end'   => isset($elem['attributes']['end']) ? DateTimeParser::parseDateTime($elem['attributes']['end']) : null,
+                    ];
+                    if ($result['time-range']['start'] && $result['time-range']['end'] && $result['time-range']['end'] <= $result['time-range']['start']) {
+                        throw new BadRequest('The end-date must be larger than the start-date');
+                    }
+                    break;
+
+            }
+
+        }
+
+        return $result;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Filter/ParamFilter.php b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/ParamFilter.php
new file mode 100644
index 000000000..eb7f564df
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/ParamFilter.php
@@ -0,0 +1,82 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Filter;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * PropFilter parser.
+ *
+ * This class parses the {urn:ietf:params:xml:ns:caldav}param-filter XML
+ * element, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-9.7.3
+ *
+ * The result will be spit out as an array.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ParamFilter implements XmlDeserializable {
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * Important note 2: You are responsible for advancing the reader to the
+     * next element. Not doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $result = [
+            'name'           => null,
+            'is-not-defined' => false,
+            'text-match'     => null,
+        ];
+
+        $att = $reader->parseAttributes();
+        $result['name'] = $att['name'];
+
+        $elems = $reader->parseInnerTree();
+
+        if (is_array($elems)) foreach ($elems as $elem) {
+
+            switch ($elem['name']) {
+
+                case '{' . Plugin::NS_CALDAV . '}is-not-defined' :
+                    $result['is-not-defined'] = true;
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}text-match' :
+                    $result['text-match'] = [
+                        'negate-condition' => isset($elem['attributes']['negate-condition']) && $elem['attributes']['negate-condition'] === 'yes',
+                        'collation'        => isset($elem['attributes']['collation']) ? $elem['attributes']['collation'] : 'i;ascii-casemap',
+                        'value'            => $elem['value'],
+                    ];
+                    break;
+
+            }
+
+        }
+
+        return $result;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Filter/PropFilter.php b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/PropFilter.php
new file mode 100644
index 000000000..4c2e1b172
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Filter/PropFilter.php
@@ -0,0 +1,98 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Filter;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\CalDAV\Plugin;
+use Sabre\VObject\DateTimeParser;
+
+/**
+ * PropFilter parser.
+ *
+ * This class parses the {urn:ietf:params:xml:ns:caldav}prop-filter XML
+ * element, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-9.7.2
+ *
+ * The result will be spit out as an array.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class PropFilter implements XmlDeserializable {
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $result = [
+            'name'           => null,
+            'is-not-defined' => false,
+            'param-filters'  => [],
+            'text-match'     => null,
+            'time-range'     => false,
+        ];
+
+        $att = $reader->parseAttributes();
+        $result['name'] = $att['name'];
+
+        $elems = $reader->parseInnerTree();
+
+        if (is_array($elems)) foreach ($elems as $elem) {
+
+            switch ($elem['name']) {
+
+                case '{' . Plugin::NS_CALDAV . '}param-filter' :
+                    $result['param-filters'][] = $elem['value'];
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}is-not-defined' :
+                    $result['is-not-defined'] = true;
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}time-range' :
+                    $result['time-range'] = [
+                        'start' => isset($elem['attributes']['start']) ? DateTimeParser::parseDateTime($elem['attributes']['start']) : null,
+                        'end'   => isset($elem['attributes']['end']) ? DateTimeParser::parseDateTime($elem['attributes']['end']) : null,
+                    ];
+                    if ($result['time-range']['start'] && $result['time-range']['end'] && $result['time-range']['end'] <= $result['time-range']['start']) {
+                        throw new BadRequest('The end-date must be larger than the start-date');
+                    }
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}text-match' :
+                    $result['text-match'] = [
+                        'negate-condition' => isset($elem['attributes']['negate-condition']) && $elem['attributes']['negate-condition'] === 'yes',
+                        'collation'        => isset($elem['attributes']['collation']) ? $elem['attributes']['collation'] : 'i;ascii-casemap',
+                        'value'            => $elem['value'],
+                    ];
+                    break;
+
+            }
+
+        }
+
+        return $result;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php
new file mode 100644
index 000000000..7fb022e33
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/Invite.php
@@ -0,0 +1,307 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Notification;
+
+use Sabre\Xml\Writer;
+use Sabre\CalDAV\SharingPlugin as SharingPlugin;
+use Sabre\CalDAV;
+
+/**
+ * This class represents the cs:invite-notification notification element.
+ *
+ * This element is defined here:
+ * http://svn.calendarserver.org/repository/calendarserver/CalendarServer/trunk/doc/Extensions/caldav-sharing.txt
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Invite implements NotificationInterface {
+
+    /**
+     * A unique id for the message
+     *
+     * @var string
+     */
+    protected $id;
+
+    /**
+     * Timestamp of the notification
+     *
+     * @var DateTime
+     */
+    protected $dtStamp;
+
+    /**
+     * A url to the recipient of the notification. This can be an email
+     * address (mailto:), or a principal url.
+     *
+     * @var string
+     */
+    protected $href;
+
+    /**
+     * The type of message, see the SharingPlugin::STATUS_* constants.
+     *
+     * @var int
+     */
+    protected $type;
+
+    /**
+     * True if access to a calendar is read-only.
+     *
+     * @var bool
+     */
+    protected $readOnly;
+
+    /**
+     * A url to the shared calendar.
+     *
+     * @var string
+     */
+    protected $hostUrl;
+
+    /**
+     * Url to the sharer of the calendar
+     *
+     * @var string
+     */
+    protected $organizer;
+
+    /**
+     * The name of the sharer.
+     *
+     * @var string
+     */
+    protected $commonName;
+
+    /**
+     * The name of the sharer.
+     *
+     * @var string
+     */
+    protected $firstName;
+
+    /**
+     * The name of the sharer.
+     *
+     * @var string
+     */
+    protected $lastName;
+
+    /**
+     * A description of the share request
+     *
+     * @var string
+     */
+    protected $summary;
+
+    /**
+     * The Etag for the notification
+     *
+     * @var string
+     */
+    protected $etag;
+
+    /**
+     * The list of supported components
+     *
+     * @var Sabre\CalDAV\Property\SupportedCalendarComponentSet
+     */
+    protected $supportedComponents;
+
+    /**
+     * Creates the Invite notification.
+     *
+     * This constructor receives an array with the following elements:
+     *
+     *   * id           - A unique id
+     *   * etag         - The etag
+     *   * dtStamp      - A DateTime object with a timestamp for the notification.
+     *   * type         - The type of notification, see SharingPlugin::STATUS_*
+     *                    constants for details.
+     *   * readOnly     - This must be set to true, if this is an invite for
+     *                    read-only access to a calendar.
+     *   * hostUrl      - A url to the shared calendar.
+     *   * organizer    - Url to the sharer principal.
+     *   * commonName   - The real name of the sharer (optional).
+     *   * firstName    - The first name of the sharer (optional).
+     *   * lastName     - The last name of the sharer (optional).
+     *   * summary      - Description of the share, can be the same as the
+     *                    calendar, but may also be modified (optional).
+     *   * supportedComponents - An instance of
+     *                    Sabre\CalDAV\Property\SupportedCalendarComponentSet.
+     *                    This allows the client to determine which components
+     *                    will be supported in the shared calendar. This is
+     *                    also optional.
+     *
+     * @param array $values All the options
+     */
+    function __construct(array $values) {
+
+        $required = [
+            'id',
+            'etag',
+            'href',
+            'dtStamp',
+            'type',
+            'readOnly',
+            'hostUrl',
+            'organizer',
+        ];
+        foreach ($required as $item) {
+            if (!isset($values[$item])) {
+                throw new \InvalidArgumentException($item . ' is a required constructor option');
+            }
+        }
+
+        foreach ($values as $key => $value) {
+            if (!property_exists($this, $key)) {
+                throw new \InvalidArgumentException('Unknown option: ' . $key);
+            }
+            $this->$key = $value;
+        }
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        $writer->writeElement('{' . CalDAV\Plugin::NS_CALENDARSERVER . '}invite-notification');
+
+    }
+
+    /**
+     * This method serializes the entire notification, as it is used in the
+     * response body.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerializeFull(Writer $writer) {
+
+        $cs = '{' . CalDAV\Plugin::NS_CALENDARSERVER . '}';
+
+        $this->dtStamp->setTimezone(new \DateTimezone('GMT'));
+        $writer->writeElement($cs . 'dtstamp', $this->dtStamp->format('Ymd\\THis\\Z'));
+
+        $writer->startElement($cs . 'invite-notification');
+
+        $writer->writeElement($cs . 'uid', $this->id);
+        $writer->writeElement('{DAV:}href', $this->href);
+
+        switch ($this->type) {
+
+            case SharingPlugin::STATUS_ACCEPTED :
+                $writer->writeElement($cs . 'invite-accepted');
+                break;
+            case SharingPlugin::STATUS_DECLINED :
+                $writer->writeElement($cs . 'invite-declined');
+                break;
+            case SharingPlugin::STATUS_DELETED :
+                $writer->writeElement($cs . 'invite-deleted');
+                break;
+            case SharingPlugin::STATUS_NORESPONSE :
+                $writer->writeElement($cs . 'invite-noresponse');
+                break;
+
+        }
+
+        $writer->writeElement($cs . 'hosturl', [
+            '{DAV:}href' => $writer->contextUri . $this->hostUrl
+            ]);
+
+        if ($this->summary) {
+            $writer->writeElement($cs . 'summary', $this->summary);
+        }
+
+        $writer->startElement($cs . 'access');
+        if ($this->readOnly) {
+            $writer->writeElement($cs . 'read');
+        } else {
+            $writer->writeElement($cs . 'read-write');
+        }
+        $writer->endElement(); // access
+
+        $writer->startElement($cs . 'organizer');
+        // If the organizer contains a 'mailto:' part, it means it should be
+        // treated as absolute.
+        if (strtolower(substr($this->organizer, 0, 7)) === 'mailto:') {
+            $writer->writeElement('{DAV:}href', $this->organizer);
+        } else {
+            $writer->writeElement('{DAV:}href', $writer->contextUri . $this->organizer);
+        }
+        if ($this->commonName) {
+            $writer->writeElement($cs . 'common-name', $this->commonName);
+        }
+        if ($this->firstName) {
+            $writer->writeElement($cs . 'first-name', $this->firstName);
+        }
+        if ($this->lastName) {
+            $writer->writeElement($cs . 'last-name', $this->lastName);
+        }
+        $writer->endElement(); // organizer
+
+        if ($this->commonName) {
+            $writer->writeElement($cs . 'organizer-cn', $this->commonName);
+        }
+        if ($this->firstName) {
+            $writer->writeElement($cs . 'organizer-first', $this->firstName);
+        }
+        if ($this->lastName) {
+            $writer->writeElement($cs . 'organizer-last', $this->lastName);
+        }
+        if ($this->supportedComponents) {
+            $writer->writeElement('{' . CalDAV\Plugin::NS_CALDAV . '}supported-calendar-component-set', $this->supportedComponents);
+        }
+
+        $writer->endElement(); // invite-notification
+
+    }
+
+    /**
+     * Returns a unique id for this notification
+     *
+     * This is just the base url. This should generally be some kind of unique
+     * id.
+     *
+     * @return string
+     */
+    function getId() {
+
+        return $this->id;
+
+    }
+
+    /**
+     * Returns the ETag for this notification.
+     *
+     * The ETag must be surrounded by literal double-quotes.
+     *
+     * @return string
+     */
+    function getETag() {
+
+        return $this->etag;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php
new file mode 100644
index 000000000..945323fed
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/InviteReply.php
@@ -0,0 +1,212 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Notification;
+
+use Sabre\Xml\Writer;
+use Sabre\CalDAV;
+use Sabre\CalDAV\SharingPlugin;
+
+/**
+ * This class represents the cs:invite-reply notification element.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class InviteReply implements NotificationInterface {
+
+    /**
+     * A unique id for the message
+     *
+     * @var string
+     */
+    protected $id;
+
+    /**
+     * Timestamp of the notification
+     *
+     * @var DateTime
+     */
+    protected $dtStamp;
+
+    /**
+     * The unique id of the notification this was a reply to.
+     *
+     * @var string
+     */
+    protected $inReplyTo;
+
+    /**
+     * A url to the recipient of the original (!) notification.
+     *
+     * @var string
+     */
+    protected $href;
+
+    /**
+     * The type of message, see the SharingPlugin::STATUS_ constants.
+     *
+     * @var int
+     */
+    protected $type;
+
+    /**
+     * A url to the shared calendar.
+     *
+     * @var string
+     */
+    protected $hostUrl;
+
+    /**
+     * A description of the share request
+     *
+     * @var string
+     */
+    protected $summary;
+
+    /**
+     * Notification Etag
+     *
+     * @var string
+     */
+    protected $etag;
+
+    /**
+     * Creates the Invite Reply Notification.
+     *
+     * This constructor receives an array with the following elements:
+     *
+     *   * id           - A unique id
+     *   * etag         - The etag
+     *   * dtStamp      - A DateTime object with a timestamp for the notification.
+     *   * inReplyTo    - This should refer to the 'id' of the notification
+     *                    this is a reply to.
+     *   * type         - The type of notification, see SharingPlugin::STATUS_*
+     *                    constants for details.
+     *   * hostUrl      - A url to the shared calendar.
+     *   * summary      - Description of the share, can be the same as the
+     *                    calendar, but may also be modified (optional).
+     *
+     * @param array $values
+     */
+    function __construct(array $values) {
+
+        $required = [
+            'id',
+            'etag',
+            'href',
+            'dtStamp',
+            'inReplyTo',
+            'type',
+            'hostUrl',
+        ];
+        foreach ($required as $item) {
+            if (!isset($values[$item])) {
+                throw new \InvalidArgumentException($item . ' is a required constructor option');
+            }
+        }
+
+        foreach ($values as $key => $value) {
+            if (!property_exists($this, $key)) {
+                throw new \InvalidArgumentException('Unknown option: ' . $key);
+            }
+            $this->$key = $value;
+        }
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        $writer->writeElement('{' . CalDAV\Plugin::NS_CALENDARSERVER . '}invite-reply');
+
+    }
+
+    /**
+     * This method serializes the entire notification, as it is used in the
+     * response body.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerializeFull(Writer $writer) {
+
+        $cs = '{' . CalDAV\Plugin::NS_CALENDARSERVER . '}';
+
+        $this->dtStamp->setTimezone(new \DateTimezone('GMT'));
+        $writer->writeElement($cs . 'dtstamp', $this->dtStamp->format('Ymd\\THis\\Z'));
+
+        $writer->startElement($cs . 'invite-reply');
+
+        $writer->writeElement($cs . 'uid', $this->id);
+        $writer->writeElement($cs . 'in-reply-to', $this->inReplyTo);
+        $writer->writeElement('{DAV:}href', $this->href);
+
+        switch ($this->type) {
+
+            case SharingPlugin::STATUS_ACCEPTED :
+                $writer->writeElement($cs . 'invite-accepted');
+                break;
+            case SharingPlugin::STATUS_DECLINED :
+                $writer->writeElement($cs . 'invite-declined');
+                break;
+
+        }
+
+        $writer->writeElement($cs . 'hosturl', [
+            '{DAV:}href' => $writer->contextUri . $this->hostUrl
+            ]);
+
+        if ($this->summary) {
+            $writer->writeElement($cs . 'summary', $this->summary);
+        }
+        $writer->endElement(); // invite-reply
+
+    }
+
+    /**
+     * Returns a unique id for this notification
+     *
+     * This is just the base url. This should generally be some kind of unique
+     * id.
+     *
+     * @return string
+     */
+    function getId() {
+
+        return $this->id;
+
+    }
+
+    /**
+     * Returns the ETag for this notification.
+     *
+     * The ETag must be surrounded by literal double-quotes.
+     *
+     * @return string
+     */
+    function getETag() {
+
+        return $this->etag;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php
new file mode 100644
index 000000000..1c08f12fd
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/NotificationInterface.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Notification;
+
+use Sabre\Xml\XmlSerializable;
+use Sabre\Xml\Writer;
+
+/**
+ * This interface reflects a single notification type.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+interface NotificationInterface extends XmlSerializable {
+
+    /**
+     * This method serializes the entire notification, as it is used in the
+     * response body.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerializeFull(Writer $writer);
+
+    /**
+     * Returns a unique id for this notification
+     *
+     * This is just the base url. This should generally be some kind of unique
+     * id.
+     *
+     * @return string
+     */
+    function getId();
+
+    /**
+     * Returns the ETag for this notification.
+     *
+     * The ETag must be surrounded by literal double-quotes.
+     *
+     * @return string
+     */
+    function getETag();
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Notification/SystemStatus.php b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/SystemStatus.php
new file mode 100644
index 000000000..d41702e07
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Notification/SystemStatus.php
@@ -0,0 +1,182 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Notification;
+
+use Sabre\Xml\Writer;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * SystemStatus notification
+ *
+ * This notification can be used to indicate to the user that the system is
+ * down.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class SystemStatus implements NotificationInterface {
+
+    const TYPE_LOW = 1;
+    const TYPE_MEDIUM = 2;
+    const TYPE_HIGH = 3;
+
+    /**
+     * A unique id
+     *
+     * @var string
+     */
+    protected $id;
+
+    /**
+     * The type of alert. This should be one of the TYPE_ constants.
+     *
+     * @var int
+     */
+    protected $type;
+
+    /**
+     * A human-readable description of the problem.
+     *
+     * @var string
+     */
+    protected $description;
+
+    /**
+     * A url to a website with more information for the user.
+     *
+     * @var string
+     */
+    protected $href;
+
+    /**
+     * Notification Etag
+     *
+     * @var string
+     */
+    protected $etag;
+
+    /**
+     * Creates the notification.
+     *
+     * Some kind of unique id should be provided. This is used to generate a
+     * url.
+     *
+     * @param string $id
+     * @param string $etag
+     * @param int $type
+     * @param string $description
+     * @param string $href
+     */
+    function __construct($id, $etag, $type = self::TYPE_HIGH, $description = null, $href = null) {
+
+        $this->id = $id;
+        $this->type = $type;
+        $this->description = $description;
+        $this->href = $href;
+        $this->etag = $etag;
+
+    }
+
+    /**
+     * The serialize method is called during xml writing.
+     *
+     * It should use the $writer argument to encode this object into XML.
+     *
+     * Important note: it is not needed to create the parent element. The
+     * parent element is already created, and we only have to worry about
+     * attributes, child elements and text (if any).
+     *
+     * Important note 2: If you are writing any new elements, you are also
+     * responsible for closing them.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        switch ($this->type) {
+            case self::TYPE_LOW :
+                $type = 'low';
+                break;
+            case self::TYPE_MEDIUM :
+                $type = 'medium';
+                break;
+            default :
+            case self::TYPE_HIGH :
+                $type = 'high';
+                break;
+        }
+
+        $writer->startElement('{' . Plugin::NS_CALENDARSERVER . '}systemstatus');
+        $writer->writeAttribute('type', $type);
+        $writer->endElement();
+
+    }
+
+    /**
+     * This method serializes the entire notification, as it is used in the
+     * response body.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerializeFull(Writer $writer) {
+
+        $cs = '{' . Plugin::NS_CALENDARSERVER . '}';
+        switch ($this->type) {
+            case self::TYPE_LOW :
+                $type = 'low';
+                break;
+            case self::TYPE_MEDIUM :
+                $type = 'medium';
+                break;
+            default :
+            case self::TYPE_HIGH :
+                $type = 'high';
+                break;
+        }
+
+        $writer->startElement($cs . 'systemstatus');
+        $writer->writeAttribute('type', $type);
+
+
+        if ($this->description) {
+            $writer->writeElement($cs . 'description', $this->description);
+        }
+        if ($this->href) {
+            $writer->writeElement('{DAV:}href', $this->href);
+        }
+
+        $writer->endElement(); // systemstatus
+
+    }
+
+    /**
+     * Returns a unique id for this notification
+     *
+     * This is just the base url. This should generally be some kind of unique
+     * id.
+     *
+     * @return string
+     */
+    function getId() {
+
+        return $this->id;
+
+    }
+
+    /*
+     * Returns the ETag for this notification.
+     *
+     * The ETag must be surrounded by literal double-quotes.
+     *
+     * @return string
+     */
+    function getETag() {
+
+        return $this->etag;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/AllowedSharingModes.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/AllowedSharingModes.php
new file mode 100644
index 000000000..c2a2d565e
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/AllowedSharingModes.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\XmlSerializable;
+use Sabre\Xml\Writer;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * AllowedSharingModes
+ *
+ * This property encodes the 'allowed-sharing-modes' property, as defined by
+ * the 'caldav-sharing-02' spec, in the http://calendarserver.org/ns/
+ * namespace.
+ *
+ * This property is a representation of the supported-calendar_component-set
+ * property in the CalDAV namespace. It simply requires an array of components,
+ * such as VEVENT, VTODO
+ *
+ * @see https://trac.calendarserver.org/browser/CalendarServer/trunk/doc/Extensions/caldav-sharing-02.txt
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class AllowedSharingModes implements XmlSerializable {
+
+    /**
+     * Whether or not a calendar can be shared with another user
+     *
+     * @var bool
+     */
+    protected $canBeShared;
+
+    /**
+     * Whether or not the calendar can be placed on a public url.
+     *
+     * @var bool
+     */
+    protected $canBePublished;
+
+    /**
+     * Constructor
+     *
+     * @param bool $canBeShared
+     * @param bool $canBePublished
+     * @return void
+     */
+    function __construct($canBeShared, $canBePublished) {
+
+        $this->canBeShared = $canBeShared;
+        $this->canBePublished = $canBePublished;
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        if ($this->canBeShared) {
+            $writer->writeElement('{' . Plugin::NS_CALENDARSERVER . '}can-be-shared');
+        }
+        if ($this->canBePublished) {
+            $writer->writeElement('{' . Plugin::NS_CALENDARSERVER . '}can-be-published');
+        }
+
+    }
+
+
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/EmailAddressSet.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/EmailAddressSet.php
new file mode 100644
index 000000000..f577a9919
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/EmailAddressSet.php
@@ -0,0 +1,80 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\Writer;
+use Sabre\Xml\XmlSerializable;
+
+/**
+ * email-address-set property
+ *
+ * This property represents the email-address-set property in the
+ * http://calendarserver.org/ns/ namespace.
+ *
+ * It's a list of email addresses associated with a user.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class EmailAddressSet implements XmlSerializable {
+
+    /**
+     * emails
+     *
+     * @var array
+     */
+    private $emails;
+
+    /**
+     * __construct
+     *
+     * @param array $emails
+     */
+    function __construct(array $emails) {
+
+        $this->emails = $emails;
+
+    }
+
+    /**
+     * Returns the email addresses
+     *
+     * @return array
+     */
+    function getValue() {
+
+        return $this->emails;
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        foreach ($this->emails as $email) {
+
+            $writer->writeElement('{http://calendarserver.org/ns/}email-address', $email);
+
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php
new file mode 100644
index 000000000..3ee053214
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/Invite.php
@@ -0,0 +1,252 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\Element;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Writer;
+use Sabre\CalDAV\Plugin;
+use Sabre\CalDAV\SharingPlugin;
+
+/**
+ * Invite property
+ *
+ * This property encodes the 'invite' property, as defined by
+ * the 'caldav-sharing-02' spec, in the http://calendarserver.org/ns/
+ * namespace.
+ *
+ * @see https://trac.calendarserver.org/browser/CalendarServer/trunk/doc/Extensions/caldav-sharing-02.txt
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Invite implements Element {
+
+    /**
+     * The list of users a calendar has been shared to.
+     *
+     * @var array
+     */
+    protected $users;
+
+    /**
+     * The organizer contains information about the person who shared the
+     * object.
+     *
+     * @var array
+     */
+    protected $organizer;
+
+    /**
+     * Creates the property.
+     *
+     * Users is an array. Each element of the array has the following
+     * properties:
+     *
+     *   * href - Often a mailto: address
+     *   * commonName - Optional, for example a first and lastname for a user.
+     *   * status - One of the SharingPlugin::STATUS_* constants.
+     *   * readOnly - true or false
+     *   * summary - Optional, description of the share
+     *
+     * The organizer key is optional to specify. It's only useful when a
+     * 'sharee' requests the sharing information.
+     *
+     * The organizer may have the following properties:
+     *   * href - Often a mailto: address.
+     *   * commonName - Optional human-readable name.
+     *   * firstName - Optional first name.
+     *   * lastName - Optional last name.
+     *
+     * If you wonder why these two structures are so different, I guess a
+     * valid answer is that the current spec is still a draft.
+     *
+     * @param array $users
+     */
+    function __construct(array $users, array $organizer = null) {
+
+        $this->users = $users;
+        $this->organizer = $organizer;
+
+    }
+
+    /**
+     * Returns the list of users, as it was passed to the constructor.
+     *
+     * @return array
+     */
+    function getValue() {
+
+        return $this->users;
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        $cs = '{' . Plugin::NS_CALENDARSERVER . '}';
+
+        if (!is_null($this->organizer)) {
+
+            $writer->startElement($cs . 'organizer');
+            $writer->writeElement('{DAV:}href', $this->organizer['href']);
+
+            if (isset($this->organizer['commonName']) && $this->organizer['commonName']) {
+                $writer->writeElement($cs . 'common-name', $this->organizer['commonName']);
+            }
+            if (isset($this->organizer['firstName']) && $this->organizer['firstName']) {
+                $writer->writeElement($cs . 'first-name', $this->organizer['firstName']);
+            }
+            if (isset($this->organizer['lastName']) && $this->organizer['lastName']) {
+                $writer->writeElement($cs . 'last-name', $this->organizer['lastName']);
+            }
+            $writer->endElement(); // organizer
+
+        }
+
+        foreach ($this->users as $user) {
+
+            $writer->startElement($cs . 'user');
+            $writer->writeElement('{DAV:}href', $user['href']);
+            if (isset($user['commonName']) && $user['commonName']) {
+                $writer->writeElement($cs . 'common-name', $user['commonName']);
+            }
+            switch ($user['status']) {
+
+                case SharingPlugin::STATUS_ACCEPTED :
+                    $writer->writeElement($cs . 'invite-accepted');
+                    break;
+                case SharingPlugin::STATUS_DECLINED :
+                    $writer->writeElement($cs . 'invite-declined');
+                    break;
+                case SharingPlugin::STATUS_NORESPONSE :
+                    $writer->writeElement($cs . 'invite-noresponse');
+                    break;
+                case SharingPlugin::STATUS_INVALID :
+                    $writer->writeElement($cs . 'invite-invalid');
+                    break;
+            }
+
+            $writer->startElement($cs . 'access');
+            if ($user['readOnly']) {
+                $writer->writeElement($cs . 'read');
+            } else {
+                $writer->writeElement($cs . 'read-write');
+            }
+            $writer->endElement(); // access
+
+            if (isset($user['summary']) && $user['summary']) {
+                $writer->writeElement($cs . 'summary', $user['summary']);
+            }
+
+            $writer->endElement(); //user
+
+        }
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $cs = '{' . Plugin::NS_CALENDARSERVER . '}';
+
+        $users = [];
+
+        foreach ($reader->parseInnerTree() as $elem) {
+
+            if ($elem['name'] !== $cs . 'user')
+                continue;
+
+            $user = [
+                'href'       => null,
+                'commonName' => null,
+                'readOnly'   => null,
+                'summary'    => null,
+                'status'     => null,
+            ];
+
+            foreach ($elem['value'] as $userElem) {
+
+                switch ($userElem['name']) {
+                    case $cs . 'invite-accepted' :
+                        $user['status'] = SharingPlugin::STATUS_ACCEPTED;
+                        break;
+                    case $cs . 'invite-declined' :
+                        $user['status'] = SharingPlugin::STATUS_DECLINED;
+                        break;
+                    case $cs . 'invite-noresponse' :
+                        $user['status'] = SharingPlugin::STATUS_NORESPONSE;
+                        break;
+                    case $cs . 'invite-invalid' :
+                        $user['status'] = SharingPlugin::STATUS_INVALID;
+                        break;
+                    case '{DAV:}href' :
+                        $user['href'] = $userElem['value'];
+                        break;
+                    case $cs . 'common-name' :
+                        $user['commonName'] = $userElem['value'];
+                        break;
+                    case $cs . 'access' :
+                        foreach ($userElem['value'] as $accessHref) {
+                            if ($accessHref['name'] === $cs . 'read') {
+                                $user['readOnly'] = true;
+                            }
+                        }
+                        break;
+                    case $cs . 'summary' :
+                        $user['summary'] = $userElem['value'];
+                        break;
+
+                }
+
+            }
+            if (!$user['status']) {
+                throw new \InvalidArgumentException('Every user must have one of cs:invite-accepted, cs:invite-declined, cs:invite-noresponse or cs:invite-invalid');
+            }
+
+            $users[] = $user;
+
+        }
+
+        return new self($users);
+
+    }
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/ScheduleCalendarTransp.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/ScheduleCalendarTransp.php
new file mode 100644
index 000000000..4a253e008
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/ScheduleCalendarTransp.php
@@ -0,0 +1,140 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\Element;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Writer;
+use Sabre\Xml\Element\Elements;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * schedule-calendar-transp property.
+ *
+ * This property is a representation of the schedule-calendar-transp property.
+ * This property is defined in:
+ *
+ * http://tools.ietf.org/html/rfc6638#section-9.1
+ *
+ * Its values are either 'transparent' or 'opaque'. If it's transparent, it
+ * means that this calendar will not be taken into consideration when a
+ * different user queries for free-busy information. If it's 'opaque', it will.
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class ScheduleCalendarTransp implements Element {
+
+    const TRANSPARENT = 'transparent';
+    const OPAQUE = 'opaque';
+
+    /**
+     * value
+     *
+     * @var string
+     */
+    protected $value;
+
+    /**
+     * Creates the property
+     *
+     * @param string $value
+     */
+    function __construct($value) {
+
+        if ($value !== self::TRANSPARENT && $value !== self::OPAQUE) {
+            throw new \InvalidArgumentException('The value must either be specified as "transparent" or "opaque"');
+        }
+        $this->value = $value;
+
+    }
+
+    /**
+     * Returns the current value
+     *
+     * @return string
+     */
+    function getValue() {
+
+        return $this->value;
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        switch ($this->value) {
+            case self::TRANSPARENT :
+                $writer->writeElement('{' . Plugin::NS_CALDAV . '}transparent');
+                break;
+            case self::OPAQUE :
+                $writer->writeElement('{' . Plugin::NS_CALDAV . '}opaque');
+                break;
+        }
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = Elements::xmlDeserialize($reader);
+
+        $value = null;
+
+        foreach ($elems as $elem) {
+            switch ($elem) {
+                case '{' . Plugin::NS_CALDAV . '}opaque' :
+                    $value = self::OPAQUE;
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}transparent' :
+                    $value = self::TRANSPARENT;
+                    break;
+            }
+        }
+        if (is_null($value))
+           return null;
+
+        return new self($value);
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCalendarComponentSet.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCalendarComponentSet.php
new file mode 100644
index 000000000..7a26e767e
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCalendarComponentSet.php
@@ -0,0 +1,129 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\Element;
+use Sabre\Xml\ParseException;
+use Sabre\Xml\Reader;
+use Sabre\Xml\Writer;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * SupportedCalendarComponentSet property.
+ *
+ * This class represents the
+ * {urn:ietf:params:xml:ns:caldav}supported-calendar-component-set property, as
+ * defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-5.2.3
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class SupportedCalendarComponentSet implements Element {
+
+    /**
+     * List of supported components.
+     *
+     * This array will contain values such as VEVENT, VTODO and VJOURNAL.
+     *
+     * @var array
+     */
+    protected $components = [];
+
+    /**
+     * Creates the property.
+     *
+     * @param array $components
+     */
+    function __construct(array $components) {
+
+        $this->components = $components;
+
+    }
+
+    /**
+     * Returns the list of supported components
+     *
+     * @return array
+     */
+    function getValue() {
+
+        return $this->components;
+
+    }
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        foreach ($this->components as $component) {
+
+            $writer->startElement('{' . Plugin::NS_CALDAV . '}comp');
+            $writer->writeAttributes(['name' => $component]);
+            $writer->endElement();
+
+        }
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = $reader->parseInnerTree();
+
+        $components = [];
+
+        foreach ((array)$elems as $elem) {
+            if ($elem['name'] === '{' . Plugin::NS_CALDAV . '}comp') {
+                $components[] = $elem['attributes']['name'];
+            }
+        }
+
+        if (!$components) {
+            throw new ParseException('supported-calendar-component-set must have at least one CALDAV:comp element');
+        }
+
+        return new self($components);
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCalendarData.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCalendarData.php
new file mode 100644
index 000000000..b0c407fd6
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCalendarData.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\XmlSerializable;
+use Sabre\Xml\Writer;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * Supported-calendar-data property
+ *
+ * This property is a representation of the supported-calendar-data property
+ * in the CalDAV namespace. SabreDAV only has support for text/calendar;2.0
+ * so the value is currently hardcoded.
+ *
+ * This property is defined in:
+ * http://tools.ietf.org/html/rfc4791#section-5.2.4
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class SupportedCalendarData implements XmlSerializable {
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        $writer->startElement('{' . Plugin::NS_CALDAV . '}calendar-data');
+        $writer->writeAttributes([
+            'content-type' => 'text/calendar',
+            'version'      => '2.0',
+        ]);
+        $writer->endElement(); // calendar-data
+        $writer->startElement('{' . Plugin::NS_CALDAV . '}calendar-data');
+        $writer->writeAttributes([
+            'content-type' => 'application/calendar+json',
+        ]);
+        $writer->endElement(); // calendar-data
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCollationSet.php b/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCollationSet.php
new file mode 100644
index 000000000..71de25a62
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Property/SupportedCollationSet.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Property;
+
+use Sabre\Xml\Writer;
+use Sabre\Xml\XmlSerializable;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * supported-collation-set property
+ *
+ * This property is a representation of the supported-collation-set property
+ * in the CalDAV namespace.
+ *
+ * This property is defined in:
+ * http://tools.ietf.org/html/rfc4791#section-7.5.1
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class SupportedCollationSet implements XmlSerializable {
+
+    /**
+     * The xmlSerialize metod is called during xml writing.
+     *
+     * Use the $writer argument to write its own xml serialization.
+     *
+     * An important note: do _not_ create a parent element. Any element
+     * implementing XmlSerializble should only ever write what's considered
+     * its 'inner xml'.
+     *
+     * The parent of the current element is responsible for writing a
+     * containing element.
+     *
+     * This allows serializers to be re-used for different element names.
+     *
+     * If you are opening new elements, you must also close them again.
+     *
+     * @param Writer $writer
+     * @return void
+     */
+    function xmlSerialize(Writer $writer) {
+
+        $collations = [
+            'i;ascii-casemap',
+            'i;octet',
+            'i;unicode-casemap'
+        ];
+
+        foreach ($collations as $collation) {
+            $writer->writeElement('{' . Plugin::NS_CALDAV . '}supported-collation', $collation);
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/CalendarMultiGetReport.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/CalendarMultiGetReport.php
new file mode 100644
index 000000000..79b3bb3ac
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/CalendarMultiGetReport.php
@@ -0,0 +1,124 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Request;
+
+use Sabre\Xml\XmlDeserializable;
+use Sabre\Xml\Reader;
+use Sabre\CalDAV\Plugin;
+use Sabre\Uri;
+
+/**
+ * CalendarMultiGetReport request parser.
+ *
+ * This class parses the {urn:ietf:params:xml:ns:caldav}calendar-multiget
+ * REPORT, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-7.9
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class CalendarMultiGetReport implements XmlDeserializable {
+
+    /**
+     * An array with requested properties.
+     *
+     * @var array
+     */
+    public $properties;
+
+    /**
+     * This is an array with the urls that are being requested.
+     *
+     * @var array
+     */
+    public $hrefs;
+
+    /**
+     * If the calendar data must be expanded, this will contain an array with 2
+     * elements: start and end.
+     *
+     * Each may be a DateTime or null.
+     *
+     * @var array|null
+     */
+    public $expand = null;
+
+    /**
+     * The mimetype of the content that should be returend. Usually
+     * text/calendar.
+     *
+     * @var string
+     */
+    public $contentType = null;
+
+    /**
+     * The version of calendar-data that should be returned. Usually '2.0',
+     * referring to iCalendar 2.0.
+     *
+     * @var string
+     */
+    public $version = null;
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = $reader->parseInnerTree([
+            '{urn:ietf:params:xml:ns:caldav}calendar-data' => 'Sabre\\CalDAV\\Xml\\Filter\\CalendarData',
+            '{DAV:}prop'                                   => 'Sabre\\Xml\\Element\\KeyValue',
+        ]);
+
+        $newProps = [
+            'hrefs'      => [],
+            'properties' => [],
+        ];
+
+        foreach ($elems as $elem) {
+
+            switch ($elem['name']) {
+
+                case '{DAV:}prop' :
+                    $newProps['properties'] = array_keys($elem['value']);
+                    if (isset($elem['value']['{' . Plugin::NS_CALDAV . '}calendar-data'])) {
+                        $newProps += $elem['value']['{' . Plugin::NS_CALDAV . '}calendar-data'];
+                    }
+                    break;
+                case '{DAV:}href' :
+                    $newProps['hrefs'][] = Uri\resolve($reader->contextUri, $elem['value']);
+                    break;
+
+            }
+
+        }
+
+        $obj = new self();
+        foreach ($newProps as $key => $value) {
+            $obj->$key = $value;
+        }
+
+        return $obj;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/CalendarQueryReport.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/CalendarQueryReport.php
new file mode 100644
index 000000000..848a4dc46
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/CalendarQueryReport.php
@@ -0,0 +1,139 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Request;
+
+use Sabre\Xml\XmlDeserializable;
+use Sabre\Xml\Reader;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * CalendarQueryReport request parser.
+ *
+ * This class parses the {urn:ietf:params:xml:ns:caldav}calendar-query
+ * REPORT, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-7.9
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://www.rooftopsolutions.nl/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class CalendarQueryReport implements XmlDeserializable {
+
+    /**
+     * An array with requested properties.
+     *
+     * @var array
+     */
+    public $properties;
+
+    /**
+     * List of property/component filters.
+     *
+     * @var array
+     */
+    public $filters;
+
+    /**
+     * If the calendar data must be expanded, this will contain an array with 2
+     * elements: start and end.
+     *
+     * Each may be a DateTime or null.
+     *
+     * @var array|null
+     */
+    public $expand = null;
+
+    /**
+     * The mimetype of the content that should be returend. Usually
+     * text/calendar.
+     *
+     * @var string
+     */
+    public $contentType = null;
+
+    /**
+     * The version of calendar-data that should be returned. Usually '2.0',
+     * referring to iCalendar 2.0.
+     *
+     * @var string
+     */
+    public $version = null;
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = $reader->parseInnerTree([
+            '{urn:ietf:params:xml:ns:caldav}comp-filter'   => 'Sabre\\CalDAV\\Xml\\Filter\\CompFilter',
+            '{urn:ietf:params:xml:ns:caldav}prop-filter'   => 'Sabre\\CalDAV\\Xml\\Filter\\PropFilter',
+            '{urn:ietf:params:xml:ns:caldav}param-filter'  => 'Sabre\\CalDAV\\Xml\\Filter\\ParamFilter',
+            '{urn:ietf:params:xml:ns:caldav}calendar-data' => 'Sabre\\CalDAV\\Xml\\Filter\\CalendarData',
+            '{DAV:}prop'                                   => 'Sabre\\Xml\\Element\\KeyValue',
+        ]);
+
+        $newProps = [
+            'filters'    => null,
+            'properties' => [],
+        ];
+
+        if (!is_array($elems)) $elems = [];
+
+        foreach ($elems as $elem) {
+
+            switch ($elem['name']) {
+
+                case '{DAV:}prop' :
+                    $newProps['properties'] = array_keys($elem['value']);
+                    if (isset($elem['value']['{' . Plugin::NS_CALDAV . '}calendar-data'])) {
+                        $newProps += $elem['value']['{' . Plugin::NS_CALDAV . '}calendar-data'];
+                    }
+                    break;
+                case '{' . Plugin::NS_CALDAV . '}filter' :
+                    foreach ($elem['value'] as $subElem) {
+                        if ($subElem['name'] === '{' . Plugin::NS_CALDAV . '}comp-filter') {
+                            if (!is_null($newProps['filters'])) {
+                                throw new BadRequest('Only one top-level comp-filter may be defined');
+                            }
+                            $newProps['filters'] = $subElem['value'];
+                        }
+                    }
+                    break;
+
+            }
+
+        }
+
+        if (is_null($newProps['filters'])) {
+            throw new BadRequest('The {' . Plugin::NS_CALDAV . '}filter element is required for this request');
+        }
+
+        $obj = new self();
+        foreach ($newProps as $key => $value) {
+            $obj->$key = $value;
+        }
+        return $obj;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/FreeBusyQueryReport.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/FreeBusyQueryReport.php
new file mode 100644
index 000000000..e3b27d08e
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/FreeBusyQueryReport.php
@@ -0,0 +1,91 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Request;
+
+use Sabre\CalDAV\Plugin;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\VObject\DateTimeParser;
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+
+/**
+ * FreeBusyQueryReport
+ *
+ * This class parses the {DAV:}free-busy-query REPORT, as defined in:
+ *
+ * http://tools.ietf.org/html/rfc3253#section-3.8
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class FreeBusyQueryReport implements XmlDeserializable {
+
+    /**
+     * Starttime of report
+     *
+     * @var DateTime|null
+     */
+    public $start;
+
+    /**
+     * End time of report
+     *
+     * @var DateTime|null
+     */
+    public $end;
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $timeRange = '{' . Plugin::NS_CALDAV . '}time-range';
+
+        $start = null;
+        $end = null;
+
+        foreach ((array)$reader->parseInnerTree([]) as $elem) {
+
+            if ($elem['name'] !== $timeRange) continue;
+
+            $start = empty($elem['attributes']['start']) ?: $elem['attributes']['start'];
+            $end = empty($elem['attributes']['end']) ?: $elem['attributes']['end'];
+
+        }
+        if (!$start && !$end) {
+            throw new BadRequest('The freebusy report must have a time-range element');
+        }
+        if ($start) {
+            $start = DateTimeParser::parseDateTime($start);
+        }
+        if ($end) {
+            $end = DateTimeParser::parseDateTime($end);
+        }
+        $result = new self();
+        $result->start = $start;
+        $result->end = $end;
+
+        return $result;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php
new file mode 100644
index 000000000..ec627156f
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/InviteReply.php
@@ -0,0 +1,149 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Request;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\Xml\Element\KeyValue;
+use Sabre\DAV\Exception\BadRequest;
+use Sabre\CalDAV\Plugin;
+use Sabre\CalDAV\SharingPlugin;
+
+/**
+ * Invite-reply POST request parser
+ *
+ * This class parses the invite-reply POST request, as defined in:
+ *
+ * http://svn.calendarserver.org/repository/calendarserver/CalendarServer/trunk/doc/Extensions/caldav-sharing.txt
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class InviteReply implements XmlDeserializable {
+
+    /**
+     * The sharee calendar user address.
+     *
+     * This is the address that the original invite was set to
+     *
+     * @var string
+     */
+    public $href;
+
+    /**
+     * The uri to the calendar that was being shared.
+     *
+     * @var string
+     */
+    public $calendarUri;
+
+    /**
+     * The id of the invite message that's being responded to
+     *
+     * @var string
+     */
+    public $inReplyTo;
+
+    /**
+     * An optional message
+     *
+     * @var string
+     */
+    public $summary;
+
+    /**
+     * Either SharingPlugin::STATUS_ACCEPTED or SharingPlugin::STATUS_DECLINED.
+     *
+     * @var int
+     */
+    public $status;
+
+    /**
+     * Constructor
+     *
+     * @param string $href
+     * @param string $calendarUri
+     * @param string $inReplyTo
+     * @param string $summary
+     * @param int $status
+     */
+    function __construct($href, $calendarUri, $inReplyTo, $summary, $status) {
+
+        $this->href = $href;
+        $this->calendarUri = $calendarUri;
+        $this->inReplyTo = $inReplyTo;
+        $this->summary = $summary;
+        $this->status = $status;
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = KeyValue::xmlDeserialize($reader);
+
+        $href = null;
+        $calendarUri = null;
+        $inReplyTo = null;
+        $summary = null;
+        $status = null;
+
+        foreach ($elems as $name => $value) {
+
+            switch ($name) {
+
+                case '{' . Plugin::NS_CALENDARSERVER . '}hosturl' :
+                    foreach ($value as $bla) {
+                        if ($bla['name'] === '{DAV:}href') {
+                            $calendarUri = $bla['value'];
+                        }
+                    }
+                    break;
+                case '{' . Plugin::NS_CALENDARSERVER . '}invite-accepted' :
+                    $status = SharingPlugin::STATUS_ACCEPTED;
+                    break;
+                case '{' . Plugin::NS_CALENDARSERVER . '}invite-declined' :
+                    $status = SharingPlugin::STATUS_DECLINED;
+                    break;
+                case '{' . Plugin::NS_CALENDARSERVER . '}in-reply-to' :
+                    $inReplyTo = $value;
+                    break;
+                case '{' . Plugin::NS_CALENDARSERVER . '}summary' :
+                    $summary = $value;
+                    break;
+                case '{DAV:}href' :
+                    $href = $value;
+                    break;
+            }
+
+        }
+        if (is_null($calendarUri)) {
+            throw new BadRequest('The {http://calendarserver.org/ns/}hosturl/{DAV:}href element must exist');
+        }
+
+        return new self($href, $calendarUri, $inReplyTo, $summary, $status);
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/MkCalendar.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/MkCalendar.php
new file mode 100644
index 000000000..7b745db55
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/MkCalendar.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Request;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+
+/**
+ * MKCALENDAR parser.
+ *
+ * This class parses the MKCALENDAR request, as defined in:
+ *
+ * https://tools.ietf.org/html/rfc4791#section-5.3.1
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class MkCalendar implements XmlDeserializable {
+
+    /**
+     * The list of properties that will be set.
+     *
+     * @var array
+     */
+    public $properties = [];
+
+    /**
+     * Returns the list of properties the calendar will be initialized with.
+     *
+     * @return array
+     */
+    function getProperties() {
+
+        return $this->properties;
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $self = new self();
+
+        $elementMap = $reader->elementMap;
+        $elementMap['{DAV:}prop']   = 'Sabre\DAV\Xml\Element\Prop';
+        $elementMap['{DAV:}set']    = 'Sabre\Xml\Element\KeyValue';
+        $elems = $reader->parseInnerTree($elementMap);
+
+        foreach ($elems as $elem) {
+            if ($elem['name'] === '{DAV:}set') {
+                $self->properties = array_merge($self->properties, $elem['value']['{DAV:}prop']);
+            }
+        }
+
+        return $self;
+
+    }
+
+}
diff --git a/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php b/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php
new file mode 100644
index 000000000..dacc5dc94
--- /dev/null
+++ b/vendor/sabre/dav/lib/CalDAV/Xml/Request/Share.php
@@ -0,0 +1,116 @@
+<?php
+
+namespace Sabre\CalDAV\Xml\Request;
+
+use Sabre\Xml\Reader;
+use Sabre\Xml\XmlDeserializable;
+use Sabre\CalDAV\Plugin;
+
+/**
+ * Share POST request parser
+ *
+ * This class parses the share POST request, as defined in:
+ *
+ * http://svn.calendarserver.org/repository/calendarserver/CalendarServer/trunk/doc/Extensions/caldav-sharing.txt
+ *
+ * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Share implements XmlDeserializable {
+
+    /**
+     * The list of new people added or updated.
+     *
+     * Every element has the following keys:
+     * 1. href - An email address
+     * 2. commonName - Some name
+     * 3. summary - An optional description of the share
+     * 4. readOnly - true or false
+     *
+     * @var array
+     */
+    public $set = [];
+
+    /**
+     * List of people removed from the share list.
+     *
+     * The list is a flat list of email addresses (including mailto:).
+     *
+     * @var array
+     */
+    public $remove = [];
+
+    /**
+     * Constructor
+     *
+     * @param array $set
+     * @param array $remove
+     */
+    function __construct(array $set, array $remove) {
+
+        $this->set = $set;
+        $this->remove = $remove;
+
+    }
+
+    /**
+     * The deserialize method is called during xml parsing.
+     *
+     * This method is called statictly, this is because in theory this method
+     * may be used as a type of constructor, or factory method.
+     *
+     * Often you want to return an instance of the current class, but you are
+     * free to return other data as well.
+     *
+     * You are responsible for advancing the reader to the next element. Not
+     * doing anything will result in a never-ending loop.
+     *
+     * If you just want to skip parsing for this element altogether, you can
+     * just call $reader->next();
+     *
+     * $reader->parseInnerTree() will parse the entire sub-tree, and advance to
+     * the next element.
+     *
+     * @param Reader $reader
+     * @return mixed
+     */
+    static function xmlDeserialize(Reader $reader) {
+
+        $elems = $reader->parseInnerTree([
+            '{' . Plugin::NS_CALENDARSERVER . '}set'    => 'Sabre\\Xml\\Element\\KeyValue',
+            '{' . Plugin::NS_CALENDARSERVER . '}remove' => 'Sabre\\Xml\\Element\\KeyValue',
+        ]);
+
+        $set = [];
+        $remove = [];
+
+        foreach ($elems as $elem) {
+            switch ($elem['name']) {
+
+                case '{' . Plugin::NS_CALENDARSERVER . '}set' :
+                    $sharee = $elem['value'];
+
+                    $sumElem = '{' . Plugin::NS_CALENDARSERVER . '}summary';
+                    $commonName = '{' . Plugin::NS_CALENDARSERVER . '}common-name';
+
+                    $set[] = [
+                        'href'       => $sharee['{DAV:}href'],
+                        'commonName' => isset($sharee[$commonName]) ? $sharee[$commonName] : null,
+                        'summary'    => isset($sharee[$sumElem]) ? $sharee[$sumElem] : null,
+                        'readOnly'   => !array_key_exists('{' . Plugin::NS_CALENDARSERVER . '}read-write', $sharee),
+                    ];
+                    break;
+
+                case '{' . Plugin::NS_CALENDARSERVER . '}remove' :
+                    $remove[] = $elem['value']['{DAV:}href'];
+                    break;
+
+            }
+        }
+
+        return new self($set, $remove);
+
+    }
+
+}