<?php
/**
 * ---------------------------------------------------------------------
 * GLPI - Gestionnaire Libre de Parc Informatique
 * Copyright (C) 2015-2020 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\Traits;

use Glpi\CalDAV\Backend\Principal;
use Glpi\CalDAV\Contracts\CalDAVCompatibleItemInterface;

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

/**
 * Trait used for CalDAV URI utilities, like generation and parsing.
 *
 * @since 9.5.0
 */
trait CalDAVUriUtilTrait {

   /**
    * Get principal URI, relative to CalDAV server root.
    *
    * @param \CommonDBTM $item
    *
    * @return string|null
    */
   protected function getPrincipalUri(\CommonDBTM $item) {

      $principal_uri = null;

      switch (get_class($item)) {
         case \Group::class:
            $principal_uri = $this->getGroupPrincipalUri($item->fields['id']);
            break;
         case \User::class:
            $principal_uri = $this->getUserPrincipalUri($item->fields['name']);
            break;
      }

      return $principal_uri;
   }

   /**
    * Get principal URI for a group, relative to CalDAV server root.
    *
    * @param integer $group_id
    *
    * @return string
    */
   protected function getGroupPrincipalUri($group_id) {
      return Principal::PREFIX_GROUPS . '/' . $group_id;
   }

   /**
    * Get principal URI for a user, relative to CalDAV server root.
    *
    * @param string $username
    *
    * @return string|null
    */
   protected function getUserPrincipalUri($username) {
      return Principal::PREFIX_USERS . '/' . $username;;
   }

   /**
    * Return item corresponding to given URI.
    *
    * @param string $uri
    *
    * @return \CommonDBTM|null
    */
   protected function getPrincipalItemFromUri($uri) {
      $principal_itemtype = $this->getPrincipalItemtypeFromUri($uri);

      if (null === $principal_itemtype || !class_exists($principal_itemtype)
          || !is_a($principal_itemtype, \CommonDBTM::class, true)) {
         return null;
      }

      $item  = new $principal_itemtype();
      switch ($principal_itemtype) {
         case \Group::class:
            $found = $item->getFromDB($this->getGroupIdFromPrincipalUri($uri));
            break;
         case \User::class:
            $found = $item->getFromDBbyName($this->getUsernameFromPrincipalUri($uri));
            break;
      }

      return $found ? $item : null;
   }

   /**
    * Return itemtype corresponding to given URI.
    *
    * @param string $uri
    *
    * @return string|null
    */
   protected function getPrincipalItemtypeFromUri($uri) {
      $uri_parts = \Sabre\Uri\split($uri);
      $prefix = $uri_parts[0];

      $itemtype = null;

      switch ($prefix) {
         case Principal::PREFIX_GROUPS:
            $itemtype = \Group::class;
            break;
         case Principal::PREFIX_USERS:
            $itemtype = \User::class;
            break;
      }

      return $itemtype;
   }

   /**
    * Return group id corresponding to given principal URI.
    *
    * @param string $uri
    *
    * @return string|null
    */
   protected function getGroupIdFromPrincipalUri($uri) {
      $uri_parts = \Sabre\Uri\split($uri);
      return \Group::class === $this->getPrincipalItemtypeFromUri($uri) ? $uri_parts[1] : null;
   }

   /**
    * Return user name corresponding to given principal URI.
    *
    * @param string $uri
    *
    * @return string|null
    */
   protected function getUsernameFromPrincipalUri($uri) {
      $uri_parts = \Sabre\Uri\split($uri);
      return \User::class === $this->getPrincipalItemtypeFromUri($uri) ? $uri_parts[1] : null;
   }

   /**
    * Returns calendar item for given UID.
    *
    * @param string  $uid
    *
    * @return CalDAVCompatibleItemInterface|null
    */
   protected function getCalendarItemForUid($uid) {

      global $CFG_GLPI, $DB;

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

         $union->addQuery(
            [
               'SELECT' => [
                  'id',
                  new \QueryExpression(
                     $DB->quoteValue($itemtype) . ' AS ' . $DB->quoteName('itemtype')
                  ),
               ],
               'FROM'   => getTableForItemType($itemtype),
               'WHERE'  => [
                  'uuid' => $uid,
               ]
            ]
         );
      }

      $items_iterator = $DB->request(
         [
            'SELECT'   => [
               'id',
               'itemtype'
            ],
            'DISTINCT' => true,
            'FROM'     => $union,
         ]
      );

      if ($items_iterator->count() !== 1) {
         if ($items_iterator->count() > 1) {
            // Ambiguous response, unable to return matching element.
            // Should never happens as UID has very very low probability to not be unique.
            \Toolbox::logError(
               sprintf(
                  'Multiple calendar items found with uuid %s. Unable to determine which item should be returned.',
                  $uid
               )
            );
         }
         return null;
      }

      $item_specs = $items_iterator->next();
      if (!is_a($item_specs['itemtype'], CalDAVCompatibleItemInterface::class, true)) {
         return null;
      }

      if (!$item = getItemForItemtype($item_specs['itemtype'])) {
         return null;
      }

      if (!$item->getFromDB($item_specs['id'])) {
         return null;
      }

      return $item;
   }

   /**
    * Returns calendar item for given path.
    *
    * @param string  $uid
    *
    * @return CalDAVCompatibleItemInterface|null
    */
   protected function getCalendarItemForPath($path) {
      return $this->getCalendarItemForUid(preg_replace('/\.ics$/', '', $path));
   }
}