<?php
/**
 * ---------------------------------------------------------------------
 * GLPI - Gestionnaire Libre de Parc Informatique
 * Copyright (C) 2015-2021 Teclib' and contributors.
 *
 * http://glpi-project.org
 *
 * based on GLPI - Gestionnaire Libre de Parc Informatique
 * Copyright (C) 2003-2014 by the INDEPNET Development Team.
 *
 * ---------------------------------------------------------------------
 *
 * LICENSE
 *
 * This file is part of GLPI.
 *
 * GLPI is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * GLPI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GLPI. If not, see <http://www.gnu.org/licenses/>.
 * ---------------------------------------------------------------------
 */

namespace Glpi\CalDAV\Backend;

if (!defined('GLPI_ROOT')) {
   die("Sorry. You can't access this file directly");
}

use Glpi\CalDAV\Contracts\CalDAVCompatibleItemInterface;
use Glpi\CalDAV\Node\Property;
use Glpi\CalDAV\Traits\CalDAVUriUtilTrait;
use Ramsey\Uuid\Uuid;
use Sabre\CalDAV\Backend\AbstractBackend;
use Sabre\CalDAV\Xml\Property\SupportedCalendarComponentSet;
use Sabre\DAV\Xml\Property\ResourceType;
use Sabre\VObject\Component\VCalendar;
use Sabre\VObject\Property\FlatText;
use Sabre\VObject\Property\ICalendar\DateTime;
use Sabre\VObject\Reader;

/**
 * Calendar backend for CalDAV server.
 *
 * @since 9.5.0
 *
 * @TODO Implement SyncSupport, SubscriptionSupport, SchedulingSupport, SharingSupport
 * @TODO Implement read/write of VALARM to define reminders.
 */
class Calendar extends AbstractBackend {

   use CalDAVUriUtilTrait;

   const BASE_CALENDAR_URI = 'calendar';
   const CALENDAR_ROOT     = 'calendars';
   const PREFIX_GROUPS     = self::CALENDAR_ROOT . '/groups';
   const PREFIX_USERS      = self::CALENDAR_ROOT . '/users';

   public function getCalendarsForUser($principalPath) {
      global $CFG_GLPI;

      $principal_item = $this->getPrincipalItemFromUri($principalPath);

      if (null === $principal_item) {
         return [];
      }

      $principal_calendar_key = \Planning::getPlanningKeyForActor(
         $principal_item->getType(),
         $principal_item->fields['id']
      );

      $calendars_params = [
         // Calendar of current principal
         $principal_calendar_key => [
            'key'          => $principal_calendar_key,
            'uri'          => self::BASE_CALENDAR_URI,
            'principaluri' => $principalPath,
            'name'         => $principal_item->getName(),
            'desc'         => sprintf(__('Calendar of %s'), $principal_item->getFriendlyName()),
            'color'        => null,
         ]
      ];

      if ($principal_item instanceof \User) {
         $user_params = importArrayFromDB($principal_item->fields['plannings']);
         $user_calendars = is_array($user_params) && array_key_exists('plannings', $user_params)
            ? $user_params['plannings']
            : [];
         foreach ($user_calendars as $key => $calendar_params) {
            if ($principal_calendar_key === $key) {
               $calendars_params[$principal_calendar_key]['color'] = $calendar_params['color'];
               continue;
            }

            if ('group_users' === $calendar_params['type']) {
               continue; // Ignore 'group_users' plannings
            }

            $item_type = \Planning::getActorTypeFromPlanningKey($key);
            $item_id   = \Planning::getActorIdFromPlanningKey($key);

            if (null === $item_type || !is_a($item_type, \CommonDBTM::class, true) || null === $item_id) {
               continue;
            }
            $calendar_principal = new $item_type();
            if (!$calendar_principal->getFromDB($item_id)) {
               continue;
            }

            $calendars_params[$key] = [
               'key'          => $key,
               'uri'          => \User::class === get_class($calendar_principal)
                  ? $calendar_principal->fields['name']
                  : $key,
               'principaluri' => $this->getPrincipalUri($calendar_principal),
               'name'         => $calendar_principal->getName(),
               'desc'         => sprintf(__('Calendar of %s'), $calendar_principal->getFriendlyName()),
               'color'        => $calendar_params['color'],
            ];
         }
      }

      $calendars = [];
      foreach ($calendars_params as $key => $calendar_data) {
         $calendars[] = [
             'id'                               => $key,
             'uri'                              => $calendar_data['uri'],
             'principaluri'                     => $calendar_data['principaluri'],
             Property::DISPLAY_NAME             => $calendar_data['name'],
             Property::CAL_COLOR                => $calendar_data['color'],
             Property::CAL_DESCRIPTION          => $calendar_data['desc'],
             Property::CAL_SUPPORTED_COMPONENTS => new SupportedCalendarComponentSet(
                $CFG_GLPI['caldav_supported_components']
             ),
             Property::RESOURCE_TYPE            => new ResourceType(
                ['{DAV:}collection', '{urn:ietf:params:xml:ns:caldav}calendar']
             ),
         ];
      }

      return $calendars;
   }

   public function createCalendar($principalPath, $calendarPath, array $properties) {
      throw new \Sabre\DAV\Exception\NotImplemented('Calendar creation is not implemented');
   }

   public function deleteCalendar($calendarId) {
      throw new \Sabre\DAV\Exception\NotImplemented('Calendar deletion is not implemented');
   }

   public function getCalendarObjects($calendarId) {

      global $CFG_GLPI;

      $principal_type = \Planning::getActorTypeFromPlanningKey($calendarId);
      $principal_id   = \Planning::getActorIdFromPlanningKey($calendarId);
      if (null !== $principal_type && is_a($principal_type, \CommonDBTM::class, true) && null !== $principal_id) {
         $item = new $principal_type();
         $exists = $item->getFromDB($principal_id);
      }

      if (!$exists) {
         throw new \Sabre\DAV\Exception\NotFound(sprintf('Calendar "%s" not found', $calendarId));
      }

      $objects = [];

      foreach ($CFG_GLPI['planning_types'] as $itemtype) {
         if (!is_a($itemtype, CalDAVCompatibleItemInterface::class, true)) {
            continue;
         }

         $vcalendars = [];
         switch ($principal_type) {
            case \Group::class:
               $vcalendars = $itemtype::getGroupItemsAsVCalendars($item->fields['id']);
               break;
            case \User::class:
               $vcalendars = $itemtype::getUserItemsAsVCalendars($item->fields['id']);
               break;
         }
         foreach ($vcalendars as $vcalendar) {
            $objects[] = $this->convertVCalendarToCalendarObject($vcalendar);
         }
      }

      return $objects;
   }

   public function getCalendarObject($calendarId, $objectPath) {

      $item = $this->getCalendarItemForPath($objectPath);
      if (null === $item) {
         return null;
      }

      $vcalendar = $item->getAsVCalendar();

      return null !== $vcalendar ? $this->convertVCalendarToCalendarObject($vcalendar) : null;
   }

   public function createCalendarObject($calendarId, $objectPath, $calendarData) {

      if (!$this->storeCalendarObject($calendarId, $calendarData)) {
         throw new \Sabre\DAV\Exception('Error during object creation');
      }

      return null;
   }

   public function updateCalendarObject($calendarId, $objectPath, $calendarData) {

      $item = $this->getCalendarItemForPath($objectPath);
      if (null === $item) {
         throw new \Sabre\DAV\Exception\NotFound(sprintf('Object "%s" not found', $objectPath));
      }

      if (!$this->storeCalendarObject($calendarId, $calendarData, $item)) {
         throw new \Sabre\DAV\Exception('Error during object creation');
      }

      return null;
   }

   public function deleteCalendarObject($calendarId, $objectPath) {

      $item = $this->getCalendarItemForPath($objectPath);
      if (null === $item) {
         throw new \Sabre\DAV\Exception\NotFound(sprintf('Object "%s" not found', $objectPath));
      }

      if (!$item->deleteFromDB()) {
         throw new \Sabre\DAV\Exception('Error during object deletion');
      }
   }

   /**
    * Convert a VCalendar object to an object served by CalDAV server.
    *
    * @param VCalendar $vcalendar
    *
    * @return array
    */
   private function convertVCalendarToCalendarObject(VCalendar $vcalendar) {

      $vcalendar->PRODID = '-//glpi-project.org//GLPI CalDAV server//EN';

      $calendardata  = $vcalendar->serialize();
      $vcomponent    = $vcalendar->getBaseComponent();
      /* @var \DateTimeInterface $last_modified */
      $last_modified = $vcomponent->{'LAST-MODIFIED'} instanceof DateTime
         ? $vcomponent->{'LAST-MODIFIED'}->getDateTime()
         : new \DateTime();

      return  [
         'uri'          => $vcomponent->UID . '.ics',
         'lastmodified' => (new \DateTime('@' . $last_modified->getTimestamp())),
         'size'         => strlen($calendardata),
         'calendardata' => $calendardata
      ];
   }

   /**
    * Store calendar object into given item.
    * If no item is specified, a new one (PlanningExternalEvent) will be created.
    *
    * @param string                             $calendarId    Calendar identifier
    * @param string                             $calendarData  Seialized VCalendar object
    * @param CalDAVCompatibleItemInterface|null $item          Item on which input will be stored
    *
    * @return boolean
    */
   private function storeCalendarObject($calendarId, $calendarData, CalDAVCompatibleItemInterface $item = null) {

      global $CFG_GLPI;

      /* @var \Sabre\VObject\Component\VCalendar $vcalendar */
      $vcalendar = Reader::read($calendarData);
      $vcomponent = $vcalendar->getBaseComponent();

      if (!in_array($vcomponent->name, $CFG_GLPI['caldav_supported_components'])) {
         throw new \Sabre\DAV\Exception\UnsupportedMediaType('Component "%s" is not supported');
      }

      $input = [];

      if (null === $item) {
         // $item is null when a new calendar item is created
         // New objects are handled as PlanningExternalEvent
         $item = new \PlanningExternalEvent();

         $principal_id   = \Planning::getActorIdFromPlanningKey($calendarId);
         $principal_type = \Planning::getActorTypeFromPlanningKey($calendarId);

         switch ($principal_type) {
            case \Group::class:
               $input['users_id'] = \Session::getLoginUserID();  // Owner is current logged user
               $input['groups_id'] = $principal_id;
               break;
            case \User::class:
               $input['users_id'] = $principal_id;
               break;
         }
      }

      $input += $item->getInputFromVCalendar($vcalendar);

      if ($vcomponent->UID instanceof FlatText) {
         $input['uuid'] = $vcomponent->UID->getValue();
      } else {
         // Generate a new UUID if none exists.
         $input['uuid'] = Uuid::uuid4();
      }

      $input = \Html::entities_deep($input);
      $input = \Toolbox::addslashes_deep($input);

      if ($item->isNewItem()) {
         // Auto set entities_id if exists and not set
         if (!array_key_exists('entities_id', $input)
             && $item->isField('entities_id')
             && array_key_exists('glpiactive_entity', $_SESSION)) {
            $input['entities_id'] = $_SESSION['glpiactive_entity'];
         }
         if (!$item->can(-1, CREATE, $input)) {
            throw new \Sabre\DAV\Exception\Forbidden();
         }
         $items_id = $item->add($input);
         if (false === $items_id) {
            return false;
         }
         return $this->storeVCalendarData($calendarData, $items_id, $item->getType());
      }

      $input['id'] = $item->fields['id'];
      if (!$item->can($item->fields['id'], UPDATE, $input)) {
         throw new \Sabre\DAV\Exception\Forbidden();
      }
      if (array_key_exists('date_creation', $input)) {
         unset($input['date_creation']); // Prevent date creation override
      }
      $update = $item->update($input);
      if (false === $update) {
         return false;
      }
      return $this->storeVCalendarData($calendarData, $item->fields['id'], $item->getType());
   }

   /**
    * Store raw VCalendar data and attach it to given item.
    *
    * @param string  $calendarData
    * @param integer $items_id
    * @param string  $itemtype
    *
    * @return boolean
    */
   private function storeVCalendarData($calendarData, $items_id, $itemtype) {

      $vobject = new \VObject();

      // Load existing object if exists.
      $vobject->getFromDBByCrit(
         [
            'itemtype' => $itemtype,
            'items_id' => $items_id,
         ]
      );

      $input = [
         'itemtype' => $itemtype,
         'items_id' => $items_id,
         'data'     => $calendarData,
      ];

      $input = \Toolbox::addslashes_deep($input);

      if ($vobject->isNewItem()) {
         return $vobject->add($input);
      }

      $input['id'] = $vobject->fields['id'];
      return $vobject->update($input);
   }
}
