<?php

namespace Sabre\CalDAV;

use
    Sabre\DAV,
    Sabre\HTTP\RequestInterface,
    Sabre\HTTP\ResponseInterface;

/**
 * This plugin implements support for caldav sharing.
 *
 * This spec is defined at:
 * http://svn.calendarserver.org/repository/calendarserver/CalendarServer/trunk/doc/Extensions/caldav-sharing.txt
 *
 * See:
 * Sabre\CalDAV\Backend\SharingSupport for all the documentation.
 *
 * Note: This feature is experimental, and may change in between different
 * SabreDAV versions.
 *
 * @copyright Copyright (C) fruux GmbH (https://fruux.com/)
 * @author Evert Pot (http://evertpot.com/)
 * @license http://sabre.io/license/ Modified BSD License
 */
class SharingPlugin extends DAV\ServerPlugin {

    /**
     * These are the various status constants used by sharing-messages.
     */
    const STATUS_ACCEPTED = 1;
    const STATUS_DECLINED = 2;
    const STATUS_DELETED = 3;
    const STATUS_NORESPONSE = 4;
    const STATUS_INVALID = 5;

    /**
     * Reference to SabreDAV server object.
     *
     * @var Sabre\DAV\Server
     */
    protected $server;

    /**
     * This method should return a list of server-features.
     *
     * This is for example 'versioning' and is added to the DAV: header
     * in an OPTIONS response.
     *
     * @return array
     */
    function getFeatures() {

        return ['calendarserver-sharing'];

    }

    /**
     * Returns a plugin name.
     *
     * Using this name other plugins will be able to access other plugins
     * using Sabre\DAV\Server::getPlugin
     *
     * @return string
     */
    function getPluginName() {

        return 'caldav-sharing';

    }

    /**
     * This initializes the plugin.
     *
     * This function is called by Sabre\DAV\Server, after
     * addPlugin is called.
     *
     * This method should set up the required event subscriptions.
     *
     * @param DAV\Server $server
     * @return void
     */
    function initialize(DAV\Server $server) {

        $this->server = $server;
        $server->resourceTypeMapping['Sabre\\CalDAV\\ISharedCalendar'] = '{' . Plugin::NS_CALENDARSERVER . '}shared';

        array_push(
            $this->server->protectedProperties,
            '{' . Plugin::NS_CALENDARSERVER . '}invite',
            '{' . Plugin::NS_CALENDARSERVER . '}allowed-sharing-modes',
            '{' . Plugin::NS_CALENDARSERVER . '}shared-url'
        );

        $this->server->on('propFind',     [$this,'propFindEarly']);
        $this->server->on('propFind',     [$this,'propFindLate'], 150);
        $this->server->on('propPatch',    [$this, 'propPatch'], 40);
        $this->server->on('method:POST',  [$this, 'httpPost']);

    }

    /**
     * This event is triggered when properties are requested for a certain
     * node.
     *
     * This allows us to inject any properties early.
     *
     * @param DAV\PropFind $propFind
     * @param DAV\INode $node
     * @return void
     */
    function propFindEarly(DAV\PropFind $propFind, DAV\INode $node) {

        if ($node instanceof IShareableCalendar) {

            $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}invite', function() use ($node) {
                return new Property\Invite(
                    $node->getShares()
                );
            });

        }

        if ($node instanceof ISharedCalendar) {

            $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}shared-url', function() use ($node) {
                return new DAV\Property\Href(
                    $node->getSharedUrl()
                );
            });

            $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}invite', function() use ($node) {

                // Fetching owner information
                $props = $this->server->getPropertiesForPath($node->getOwner(), [
                    '{http://sabredav.org/ns}email-address',
                    '{DAV:}displayname',
                ], 0);

                $ownerInfo = [
                    'href' => $node->getOwner(),
                ];

                if (isset($props[0][200])) {

                    // We're mapping the internal webdav properties to the
                    // elements caldav-sharing expects.
                    if (isset($props[0][200]['{http://sabredav.org/ns}email-address'])) {
                        $ownerInfo['href'] = 'mailto:' . $props[0][200]['{http://sabredav.org/ns}email-address'];
                    }
                    if (isset($props[0][200]['{DAV:}displayname'])) {
                        $ownerInfo['commonName'] = $props[0][200]['{DAV:}displayname'];
                    }

                }

                return new Property\Invite(
                    $node->getShares(),
                    $ownerInfo
                );

            });

        }

    }

    /**
     * This method is triggered *after* all properties have been retrieved.
     * This allows us to inject the correct resourcetype for calendars that
     * have been shared.
     *
     * @param DAV\PropFind $propFind
     * @param DAV\INode $node
     * @return void
     */
    function propFindLate(DAV\PropFind $propFind, DAV\INode $node) {

        if ($node instanceof IShareableCalendar) {
            if ($rt = $propFind->get('{DAV:}resourcetype')) {
                if (count($node->getShares()) > 0) {
                    $rt->add('{' . Plugin::NS_CALENDARSERVER . '}shared-owner');
                }
            }
            $propFind->handle('{' . Plugin::NS_CALENDARSERVER . '}allowed-sharing-modes', function() {
                return new Property\AllowedSharingModes(true,false);
            });

        }

    }

    /**
     * This method is trigged when a user attempts to update a node's
     * properties.
     *
     * A previous draft of the sharing spec stated that it was possible to use
     * PROPPATCH to remove 'shared-owner' from the resourcetype, thus unsharing
     * the calendar.
     *
     * Even though this is no longer in the current spec, we keep this around
     * because OS X 10.7 may still make use of this feature.
     *
     * @param string $path
     * @param DAV\PropPatch $propPatch
     * @return void
     */
    function propPatch($path, DAV\PropPatch $propPatch) {

        $node = $this->server->tree->getNodeForPath($path);
        if (!$node instanceof IShareableCalendar)
            return;

        $propPatch->handle('{DAV:}resourcetype', function($value) use ($node) {
            if($value->is('{' . Plugin::NS_CALENDARSERVER . '}shared-owner')) return false;
            $shares = $node->getShares();
            $remove = [];
            foreach($shares as $share) {
                $remove[] = $share['href'];
            }
            $node->updateShares([], $remove);

            return true;

        });

    }

    /**
     * We intercept this to handle POST requests on calendars.
     *
     * @param RequestInterface $request
     * @param ResponseInterface $response
     * @return null|bool
     */
    function httpPost(RequestInterface $request, ResponseInterface $response) {

        $path = $request->getPath();

        // Only handling xml
        $contentType = $request->getHeader('Content-Type');
        if (strpos($contentType,'application/xml')===false && strpos($contentType,'text/xml')===false)
            return;

        // Making sure the node exists
        try {
            $node = $this->server->tree->getNodeForPath($path);
        } catch (DAV\Exception\NotFound $e) {
            return;
        }

        $requestBody = $request->getBodyAsString();

        // If this request handler could not deal with this POST request, it
        // will return 'null' and other plugins get a chance to handle the
        // request.
        //
        // However, we already requested the full body. This is a problem,
        // because a body can only be read once. This is why we preemptively
        // re-populated the request body with the existing data.
        $request->setBody($requestBody);

        $dom = DAV\XMLUtil::loadDOMDocument($requestBody);

        $documentType = DAV\XMLUtil::toClarkNotation($dom->firstChild);

        switch($documentType) {

            // Dealing with the 'share' document, which modified invitees on a
            // calendar.
            case '{' . Plugin::NS_CALENDARSERVER . '}share' :

                // We can only deal with IShareableCalendar objects
                if (!$node instanceof IShareableCalendar) {
                    return;
                }

                $this->server->transactionType = 'post-calendar-share';

                // Getting ACL info
                $acl = $this->server->getPlugin('acl');

                // If there's no ACL support, we allow everything
                if ($acl) {
                    $acl->checkPrivileges($path, '{DAV:}write');
                }

                $mutations = $this->parseShareRequest($dom);

                $node->updateShares($mutations[0], $mutations[1]);

                $response->setStatus(200);
                // Adding this because sending a response body may cause issues,
                // and I wanted some type of indicator the response was handled.
                $response->setHeader('X-Sabre-Status', 'everything-went-well');

                // Breaking the event chain
                return false;

            // The invite-reply document is sent when the user replies to an
            // invitation of a calendar share.
            case '{'. Plugin::NS_CALENDARSERVER.'}invite-reply' :

                // This only works on the calendar-home-root node.
                if (!$node instanceof CalendarHome) {
                    return;
                }
                $this->server->transactionType = 'post-invite-reply';

                // Getting ACL info
                $acl = $this->server->getPlugin('acl');

                // If there's no ACL support, we allow everything
                if ($acl) {
                    $acl->checkPrivileges($path, '{DAV:}write');
                }

                $message = $this->parseInviteReplyRequest($dom);

                $url = $node->shareReply(
                    $message['href'],
                    $message['status'],
                    $message['calendarUri'],
                    $message['inReplyTo'],
                    $message['summary']
                );

                $response->setStatus(200);
                // Adding this because sending a response body may cause issues,
                // and I wanted some type of indicator the response was handled.
                $response->setHeader('X-Sabre-Status', 'everything-went-well');

                if ($url) {
                    $dom = new \DOMDocument('1.0', 'UTF-8');
                    $dom->formatOutput = true;

                    $root = $dom->createElement('cs:shared-as');
                    foreach($this->server->xmlNamespaces as $namespace => $prefix) {
                        $root->setAttribute('xmlns:' . $prefix, $namespace);
                    }

                    $dom->appendChild($root);
                    $href = new DAV\Property\Href($url);

                    $href->serialize($this->server, $root);
                    $response->setHeader('Content-Type','application/xml');
                    $response->setBody($dom->saveXML());

                }

                // Breaking the event chain
                return false;

            case '{' . Plugin::NS_CALENDARSERVER . '}publish-calendar' :

                // We can only deal with IShareableCalendar objects
                if (!$node instanceof IShareableCalendar) {
                    return;
                }
                $this->server->transactionType = 'post-publish-calendar';

                // Getting ACL info
                $acl = $this->server->getPlugin('acl');

                // If there's no ACL support, we allow everything
                if ($acl) {
                    $acl->checkPrivileges($path, '{DAV:}write');
                }

                $node->setPublishStatus(true);

                // iCloud sends back the 202, so we will too.
                $response->setStatus(202);

                // Adding this because sending a response body may cause issues,
                // and I wanted some type of indicator the response was handled.
                $response->setHeader('X-Sabre-Status', 'everything-went-well');

                // Breaking the event chain
                return false;

            case '{' . Plugin::NS_CALENDARSERVER . '}unpublish-calendar' :

                // We can only deal with IShareableCalendar objects
                if (!$node instanceof IShareableCalendar) {
                    return;
                }
                $this->server->transactionType = 'post-unpublish-calendar';

                // Getting ACL info
                $acl = $this->server->getPlugin('acl');

                // If there's no ACL support, we allow everything
                if ($acl) {
                    $acl->checkPrivileges($path, '{DAV:}write');
                }

                $node->setPublishStatus(false);

                $response->setStatus(200);

                // Adding this because sending a response body may cause issues,
                // and I wanted some type of indicator the response was handled.
                $response->setHeader('X-Sabre-Status', 'everything-went-well');

                // Breaking the event chain
                return false;

        }



    }

    /**
     * Parses the 'share' POST request.
     *
     * This method returns an array, containing two arrays.
     * The first array is a list of new sharees. Every element is a struct
     * containing a:
     *   * href element. (usually a mailto: address)
     *   * commonName element (often a first and lastname, but can also be
     *     false)
     *   * readOnly (true or false)
     *   * summary (A description of the share, can also be false)
     *
     * The second array is a list of sharees that are to be removed. This is
     * just a simple array with 'hrefs'.
     *
     * @param \DOMDocument $dom
     * @return array
     */
    function parseShareRequest(\DOMDocument $dom) {

        $xpath = new \DOMXPath($dom);
        $xpath->registerNamespace('cs', Plugin::NS_CALENDARSERVER);
        $xpath->registerNamespace('d', 'urn:DAV');

        $set = [];
        $elems = $xpath->query('cs:set');

        for($i=0; $i < $elems->length; $i++) {

            $xset = $elems->item($i);
            $set[] = [
                'href' => $xpath->evaluate('string(d:href)', $xset),
                'commonName' => $xpath->evaluate('string(cs:common-name)', $xset),
                'summary' => $xpath->evaluate('string(cs:summary)', $xset),
                'readOnly' => $xpath->evaluate('boolean(cs:read)', $xset)!==false
            ];

        }

        $remove = [];
        $elems = $xpath->query('cs:remove');

        for($i=0; $i < $elems->length; $i++) {

            $xremove = $elems->item($i);
            $remove[] = $xpath->evaluate('string(d:href)', $xremove);

        }

        return [$set, $remove];

    }

    /**
     * Parses the 'invite-reply' POST request.
     *
     * This method returns an array, containing the following properties:
     *   * href - The sharee who is replying
     *   * status - One of the self::STATUS_* constants
     *   * calendarUri - The url of the shared calendar
     *   * inReplyTo - The unique id of the share invitation.
     *   * summary - Optional description of the reply.
     *
     * @param \DOMDocument $dom
     * @return array
     */
    function parseInviteReplyRequest(\DOMDocument $dom) {

        $xpath = new \DOMXPath($dom);
        $xpath->registerNamespace('cs', Plugin::NS_CALENDARSERVER);
        $xpath->registerNamespace('d', 'urn:DAV');

        $hostHref = $xpath->evaluate('string(cs:hosturl/d:href)');
        if (!$hostHref) {
            throw new DAV\Exception\BadRequest('The {' . Plugin::NS_CALENDARSERVER . '}hosturl/{DAV:}href element is required');
        }

        return [
            'href' => $xpath->evaluate('string(d:href)'),
            'calendarUri' => $this->server->calculateUri($hostHref),
            'inReplyTo' => $xpath->evaluate('string(cs:in-reply-to)'),
            'summary' => $xpath->evaluate('string(cs:summary)'),
            'status' => $xpath->evaluate('boolean(cs:invite-accepted)')?self::STATUS_ACCEPTED:self::STATUS_DECLINED
        ];

    }

}
