<?php

/**
 * Kolab calendar storage class
 *
 * @version @package_version@
 * @author Thomas Bruederli <bruederli@kolabsys.com>
 * @author Aleksander Machniak <machniak@kolabsys.com>
 *
 * Copyright (C) 2012-2015, Kolab Systems AG <contact@kolabsys.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */


class kolab_calendar extends kolab_storage_folder_api
{
  public $ready = false;
  public $rights = 'lrs';
  public $editable = false;
  public $attachments = true;
  public $alarms = false;
  public $history = false;
  public $subscriptions = true;
  public $categories = array();
  public $storage;

  public $type = 'event';

  protected $cal;
  protected $events = array();
  protected $search_fields = array('title', 'description', 'location', 'attendees');

  /**
   * Factory method to instantiate a kolab_calendar object
   *
   * @param string  Calendar ID (encoded IMAP folder name)
   * @param object  calendar plugin object
   * @return object kolab_calendar instance
   */
  public static function factory($id, $calendar)
  {
    $imap = $calendar->rc->get_storage();
    $imap_folder = kolab_storage::id_decode($id);
    $info = $imap->folder_info($imap_folder, true);
    if (empty($info) || $info['noselect'] || strpos(kolab_storage::folder_type($imap_folder), 'event') !== 0) {
      return new kolab_user_calendar($imap_folder, $calendar);
    }
    else {
      return new kolab_calendar($imap_folder, $calendar);
    }
  }

  /**
   * Default constructor
   */
  public function __construct($imap_folder, $calendar)
  {
    $this->cal = $calendar;
    $this->imap = $calendar->rc->get_storage();
    $this->name = $imap_folder;

    // ID is derrived from folder name
    $this->id = kolab_storage::folder_id($this->name, true);
    $old_id   = kolab_storage::folder_id($this->name, false);

    // fetch objects from the given IMAP folder
    $this->storage = kolab_storage::get_folder($this->name);
    $this->ready = $this->storage && $this->storage->valid;

    // Set writeable and alarms flags according to folder permissions
    if ($this->ready) {
      if ($this->storage->get_namespace() == 'personal') {
        $this->editable = true;
        $this->rights = 'lrswikxteav';
        $this->alarms = true;
      }
      else {
        $rights = $this->storage->get_myrights();
        if ($rights && !PEAR::isError($rights)) {
          $this->rights = $rights;
          if (strpos($rights, 't') !== false || strpos($rights, 'd') !== false)
            $this->editable = strpos($rights, 'i');;
        }
      }
      
      // user-specific alarms settings win
      $prefs = $this->cal->rc->config->get('kolab_calendars', array());
      if (isset($prefs[$this->id]['showalarms']))
        $this->alarms = $prefs[$this->id]['showalarms'];
      else if (isset($prefs[$old_id]['showalarms']))
        $this->alarms = $prefs[$old_id]['showalarms'];
    }

    $this->default = $this->storage->default;
    $this->subtype = $this->storage->subtype;
  }


  /**
   * Getter for the IMAP folder name
   *
   * @return string Name of the IMAP folder
   */
  public function get_realname()
  {
    return $this->name;
  }

  /**
   *
   */
  public function get_title()
  {
    return null;
  }


  /**
   * Return color to display this calendar
   */
  public function get_color($default = null)
  {
    // color is defined in folder METADATA
    if ($color = $this->storage->get_color()) {
      return $color;
    }

    // calendar color is stored in user prefs (temporary solution)
    $prefs = $this->cal->rc->config->get('kolab_calendars', array());

    if (!empty($prefs[$this->id]) && !empty($prefs[$this->id]['color']))
      return $prefs[$this->id]['color'];

    return $default ?: 'cc0000';
  }

  /**
   * Compose an URL for CalDAV access to this calendar (if configured)
   */
  public function get_caldav_url()
  {
    if ($template = $this->cal->rc->config->get('calendar_caldav_url', null)) {
      return strtr($template, array(
        '%h' => $_SERVER['HTTP_HOST'],
        '%u' => urlencode($this->cal->rc->get_user_name()),
        '%i' => urlencode($this->storage->get_uid()),
        '%n' => urlencode($this->name),
      ));
    }

    return false;
  }


  /**
   * Update properties of this calendar folder
   *
   * @see calendar_driver::edit_calendar()
   */
  public function update(&$prop)
  {
    $prop['oldname'] = $this->get_realname();
    $newfolder = kolab_storage::folder_update($prop);

    if ($newfolder === false) {
      $this->cal->last_error = $this->cal->gettext(kolab_storage::$last_error);
      return false;
    }

    // create ID
    return kolab_storage::folder_id($newfolder);
  }

  /**
   * Getter for a single event object
   */
  public function get_event($id)
  {
    // remove our occurrence identifier if it's there
    $master_id = preg_replace('/-\d{8}(T\d{6})?$/', '', $id);

    // directly access storage object
    if (!$this->events[$id] && $master_id == $id && ($record = $this->storage->get_object($id))) {
      $this->events[$id] = $this->_to_driver_event($record, true);
    }

    // maybe a recurring instance is requested
    if (!$this->events[$id] && $master_id != $id) {
      $instance_id = substr($id, strlen($master_id) + 1);

      if ($record = $this->storage->get_object($master_id)) {
        $master = $this->_to_driver_event($record);
      }

      if ($master) {
        // check for match in top-level exceptions (aka loose single occurrences)
        if ($master['_formatobj'] && ($instance = $master['_formatobj']->get_instance($instance_id))) {
          $this->events[$id] = $this->_to_driver_event($instance, false, true, $master);
        }
        // check for match on the first instance already
        else if ($master['_instance'] && $master['_instance'] == $instance_id) {
          $this->events[$id] = $master;
        }
        else if (is_array($master['recurrence'])) {
          $this->get_recurring_events($record, $master['start'], null, $id);
        }
      }
    }

    return $this->events[$id];
  }

  /**
   * Get attachment body
   * @see calendar_driver::get_attachment_body()
   */
  public function get_attachment_body($id, $event)
  {
    if (!$this->ready)
        return false;

    $data = $this->storage->get_attachment($event['id'], $id);

    if ($data == null) {
        // try again with master UID
        $uid = preg_replace('/-\d+(T\d{6})?$/', '', $event['id']);
        if ($uid != $event['id']) {
            $data = $this->storage->get_attachment($uid, $id);
        }
    }

    return $data;
  }

  /**
   * @param  integer Event's new start (unix timestamp)
   * @param  integer Event's new end (unix timestamp)
   * @param  string  Search query (optional)
   * @param  boolean Include virtual events (optional)
   * @param  array   Additional parameters to query storage
   * @param  array   Additional query to filter events
   * @return array A list of event records
   */
  public function list_events($start, $end, $search = null, $virtual = 1, $query = array(), $filter_query = null)
  {
    // convert to DateTime for comparisons
    // #5190: make the range a little bit wider
    // to workaround possible timezone differences
    try {
      $start = new DateTime('@' . ($start - 12 * 3600));
    }
    catch (Exception $e) {
      $start = new DateTime('@0');
    }
    try {
      $end = new DateTime('@' . ($end + 12 * 3600));
    }
    catch (Exception $e) {
      $end = new DateTime('today +10 years');
    }

    // get email addresses of the current user
    $user_emails = $this->cal->get_user_emails();

    // query Kolab storage
    $query[] = array('dtstart', '<=', $end);
    $query[] = array('dtend',   '>=', $start);

    if (is_array($filter_query)) {
      $query = array_merge($query, $filter_query);
    }

    if (!empty($search)) {
        $search = mb_strtolower($search);
        $words = rcube_utils::tokenize_string($search, 1);
        foreach (rcube_utils::normalize_string($search, true) as $word) {
            $query[] = array('words', 'LIKE', $word);
        }
    }
    else {
      $words = array();
    }

    // set partstat filter to skip pending and declined invitations
    if (empty($filter_query) && $this->cal->rc->config->get('kolab_invitation_calendars')
      && $this->get_namespace() != 'other'
    ) {
      $partstat_exclude = array('NEEDS-ACTION','DECLINED');
    }
    else {
      $partstat_exclude = array();
    }

    $events = array();
    foreach ($this->storage->select($query) as $record) {
      $event = $this->_to_driver_event($record, !$virtual, false);

      // remember seen categories
      if ($event['categories']) {
        $cat = is_array($event['categories']) ? $event['categories'][0] : $event['categories'];
        $this->categories[$cat]++;
      }

      // list events in requested time window
      if ($event['start'] <= $end && $event['end'] >= $start) {
        unset($event['_attendees']);
        $add = true;

        // skip the first instance of a recurring event if listed in exdate
        if ($virtual && !empty($event['recurrence']['EXDATE'])) {
          $event_date = $event['start']->format('Ymd');
          $exdates = (array)$event['recurrence']['EXDATE'];

          foreach ($exdates as $exdate) {
            if ($exdate->format('Ymd') == $event_date) {
              $add = false;
              break;
            }
          }
        }

        // find and merge exception for the first instance
        if ($virtual && !empty($event['recurrence']) && is_array($event['recurrence']['EXCEPTIONS'])) {
          foreach ($event['recurrence']['EXCEPTIONS'] as $exception) {
            if ($event['_instance'] == $exception['_instance']) {
              // clone date objects from main event before adjusting them with exception data
              if (is_object($event['start'])) $event['start'] = clone $record['start'];
              if (is_object($event['end']))   $event['end']   = clone $record['end'];
              kolab_driver::merge_exception_data($event, $exception);
            }
          }
        }

        if ($add)
          $events[] = $event;
      }

      // resolve recurring events
      if ($record['recurrence'] && $virtual == 1) {
        $events = array_merge($events, $this->get_recurring_events($record, $start, $end));
      }
      // add top-level exceptions (aka loose single occurrences)
      else if (is_array($record['exceptions'])) {
        foreach ($record['exceptions'] as $ex) {
          $component = $this->_to_driver_event($ex, false, false, $record);
          if ($component['start'] <= $end && $component['end'] >= $start) {
            $events[] = $component;
          }
        }
      }
    }

    // post-filter all events by fulltext search and partstat values
    $me = $this;
    $events = array_filter($events, function($event) use ($words, $partstat_exclude, $user_emails, $me) {
      // fulltext search
      if (count($words)) {
        $hits = 0;
        foreach ($words as $word) {
          $hits += $me->fulltext_match($event, $word, false);
        }
        if ($hits < count($words)) {
          return false;
        }
      }

      // partstat filter
      if (count($partstat_exclude) && is_array($event['attendees'])) {
        foreach ($event['attendees'] as $attendee) {
          if (in_array($attendee['email'], $user_emails) && in_array($attendee['status'], $partstat_exclude)) {
            return false;
          }
        }
      }

      return true;
    });

    // Apply event-to-mail relations
    $config = kolab_storage_config::get_instance();
    $config->apply_links($events);

    // avoid session race conditions that will loose temporary subscriptions
    $this->cal->rc->session->nowrite = true;

    return $events;
  }

  /**
   *
   * @param  integer Date range start (unix timestamp)
   * @param  integer Date range end (unix timestamp)
   * @param  array   Additional query to filter events
   * @return integer Count
   */
  public function count_events($start, $end = null, $filter_query = null)
  {
    // convert to DateTime for comparisons
    try {
      $start = new DateTime('@'.$start);
    }
    catch (Exception $e) {
      $start = new DateTime('@0');
    }
    if ($end) {
      try {
        $end = new DateTime('@'.$end);
      }
      catch (Exception $e) {
        $end = null;
      }
    }

    // query Kolab storage
    $query[] = array('dtend',   '>=', $start);
    
    if ($end)
      $query[] = array('dtstart', '<=', $end);

    // add query to exclude pending/declined invitations
    if (empty($filter_query)) {
      foreach ($this->cal->get_user_emails() as $email) {
        $query[] = array('tags', '!=', 'x-partstat:' . $email . ':needs-action');
        $query[] = array('tags', '!=', 'x-partstat:' . $email . ':declined');
      }
    }
    else if (is_array($filter_query)) {
      $query = array_merge($query, $filter_query);
    }

    // we rely the Kolab storage query (no post-filtering)
    return $this->storage->count($query);
  }

  /**
   * Create a new event record
   *
   * @see calendar_driver::new_event()
   * 
   * @return mixed The created record ID on success, False on error
   */
  public function insert_event($event)
  {
    if (!is_array($event))
      return false;

    // email links are stored separately
    $links = $event['links'];
    unset($event['links']);

    //generate new event from RC input
    $object = $this->_from_driver_event($event);
    $saved  = $this->storage->save($object, 'event');

    if (!$saved) {
      rcube::raise_error(array(
        'code' => 600, 'type' => 'php',
        'file' => __FILE__, 'line' => __LINE__,
        'message' => "Error saving event object to Kolab server"),
        true, false);
      $saved = false;
    }
    else {
      // save links in configuration.relation object
      if ($this->save_links($event['uid'], $links)) {
        $object['links'] = $links;
      }

      $this->events = array($event['uid'] => $this->_to_driver_event($object, true));
    }

    return $saved;
  }

  /**
   * Update a specific event record
   *
   * @see calendar_driver::new_event()
   * @return boolean True on success, False on error
   */

  public function update_event($event, $exception_id = null)
  {
    $updated = false;
    $old = $this->storage->get_object($event['uid'] ?: $event['id']);
    if (!$old || PEAR::isError($old))
      return false;

    // email links are stored separately
    $links = $event['links'];
    unset($event['links']);

    $object = $this->_from_driver_event($event, $old);
    $saved  = $this->storage->save($object, 'event', $old['uid']);

    if (!$saved) {
      rcube::raise_error(array(
        'code' => 600, 'type' => 'php',
        'file' => __FILE__, 'line' => __LINE__,
        'message' => "Error saving event object to Kolab server"),
        true, false);
    }
    else {
      // save links in configuration.relation object
      if ($this->save_links($event['uid'], $links)) {
        $object['links'] = $links;
      }

      $updated = true;
      $this->events = array($event['uid'] => $this->_to_driver_event($object, true));

      // refresh local cache with recurring instances
      if ($exception_id) {
        $this->get_recurring_events($object, $event['start'], $event['end'], $exception_id);
      }
    }

    return $updated;
  }

  /**
   * Delete an event record
   *
   * @see calendar_driver::remove_event()
   * @return boolean True on success, False on error
   */
  public function delete_event($event, $force = true)
  {
    $deleted = $this->storage->delete($event['uid'] ?: $event['id'], $force);

    if (!$deleted) {
      rcube::raise_error(array(
        'code' => 600, 'type' => 'php',
        'file' => __FILE__, 'line' => __LINE__,
        'message' => sprintf("Error deleting event object '%s' from Kolab server", $event['id'])),
        true, false);
    }

    return $deleted;
  }

  /**
   * Restore deleted event record
   *
   * @see calendar_driver::undelete_event()
   * @return boolean True on success, False on error
   */
  public function restore_event($event)
  {
    if ($this->storage->undelete($event['id'])) {
        return true;
    }
    else {
        rcube::raise_error(array(
          'code' => 600, 'type' => 'php',
          'file' => __FILE__, 'line' => __LINE__,
          'message' => "Error undeleting the event object $event[id] from the Kolab server"),
        true, false);
    }

    return false;
  }

  /**
   * Find messages linked with an event
   */
  protected function get_links($uid)
  {
    $storage = kolab_storage_config::get_instance();
    return $storage->get_object_links($uid);
  }

  /**
   *
   */
  protected function save_links($uid, $links)
  {
    $storage = kolab_storage_config::get_instance();
    return $storage->save_object_links($uid, (array) $links);
  }

  /**
   * Create instances of a recurring event
   *
   * @param array  Hash array with event properties
   * @param object DateTime Start date of the recurrence window
   * @param object DateTime End date of the recurrence window
   * @param string ID of a specific recurring event instance
   * @return array List of recurring event instances
   */
  public function get_recurring_events($event, $start, $end = null, $event_id = null)
  {
    $object = $event['_formatobj'];
    if (!$object) {
      $rec = $this->storage->get_object($event['id']);
      $object = $rec['_formatobj'];
    }
    if (!is_object($object))
      return array();

    // determine a reasonable end date if none given
    if (!$end) {
      $end = clone $event['start'];
      $end->add(new DateInterval('P100Y'));
    }

    // copy the recurrence rule from the master event (to be used in the UI)
    $recurrence_rule = $event['recurrence'];
    unset($recurrence_rule['EXCEPTIONS'], $recurrence_rule['EXDATE']);

    // read recurrence exceptions first
    $events = array();
    $exdata = array();
    $futuredata = array();
    $recurrence_id_format = libcalendaring::recurrence_id_format($event);

    if (is_array($event['recurrence']['EXCEPTIONS'])) {
      foreach ($event['recurrence']['EXCEPTIONS'] as $exception) {
        if (!$exception['_instance'])
          $exception['_instance'] = libcalendaring::recurrence_instance_identifier($exception, $event['allday']);

        $rec_event = $this->_to_driver_event($exception, false, false, $event);
        $rec_event['id'] = $event['uid'] . '-' . $exception['_instance'];
        $rec_event['isexception'] = 1;

        // found the specifically requested instance: register exception (single occurrence wins)
        if ($rec_event['id'] == $event_id && (!$this->events[$event_id] || $this->events[$event_id]['thisandfuture'])) {
          $rec_event['recurrence'] = $recurrence_rule;
          $rec_event['recurrence_id'] = $event['uid'];
          $this->events[$rec_event['id']] = $rec_event;
        }

        // remember this exception's date
        $exdate = substr($exception['_instance'], 0, 8);
        if (!$exdata[$exdate] || $exdata[$exdate]['thisandfuture']) {
          $exdata[$exdate] = $rec_event;
        }
        if ($rec_event['thisandfuture']) {
          $futuredata[$exdate] = $rec_event;
        }
      }
    }

    // found the specifically requested instance, exiting...
    if ($event_id && !empty($this->events[$event_id])) {
      return array($this->events[$event_id]);
    }

    // use libkolab to compute recurring events
    if (class_exists('kolabcalendaring')) {
        $recurrence = new kolab_date_recurrence($object);
    }
    else {
      // fallback to local recurrence implementation
      require_once($this->cal->home . '/lib/calendar_recurrence.php');
      $recurrence = new calendar_recurrence($this->cal, $event);
    }

    $i = 0;
    while ($next_event = $recurrence->next_instance()) {
      $datestr     = $next_event['start']->format('Ymd');
      $instance_id = $next_event['start']->format($recurrence_id_format);

      // use this event data for future recurring instances
      if ($futuredata[$datestr])
        $overlay_data = $futuredata[$datestr];

      $rec_id      = $event['uid'] . '-' . $instance_id;
      $exception   = $exdata[$datestr] ?: $overlay_data;
      $event_start = $next_event['start'];
      $event_end   = $next_event['end'];

      // copy some event from exception to get proper start/end dates
      if ($exception) {
        $event_copy = $next_event;
        kolab_driver::merge_exception_dates($event_copy, $exception);
        $event_start = $event_copy['start'];
        $event_end   = $event_copy['end'];
      }

      // add to output if in range
      if (($event_start <= $end && $event_end >= $start) || ($event_id && $rec_id == $event_id)) {
        $rec_event = $this->_to_driver_event($next_event, false, false, $event);
        $rec_event['_instance'] = $instance_id;
        $rec_event['_count'] = $i + 1;

        if ($exception)  // copy data from exception
          kolab_driver::merge_exception_data($rec_event, $exception);

        $rec_event['id'] = $rec_id;
        $rec_event['recurrence_id'] = $event['uid'];
        $rec_event['recurrence'] = $recurrence_rule;
        unset($rec_event['_attendees']);
        $events[] = $rec_event;

        if ($rec_id == $event_id) {
          $this->events[$rec_id] = $rec_event;
          break;
        }
      }
      else if ($next_event['start'] > $end)  // stop loop if out of range
        break;

      // avoid endless recursion loops
      if (++$i > 100000)
          break;
    }
    
    return $events;
  }

  /**
   * Convert from Kolab_Format to internal representation
   */
  private function _to_driver_event($record, $noinst = false, $links = true, $master_event = null)
  {
    $record['calendar'] = $this->id;

    if ($links && !array_key_exists('links', $record)) {
      $record['links'] = $this->get_links($record['uid']);
    }

    if ($this->get_namespace() == 'other') {
      $record['className'] = 'fc-event-ns-other';
      $record = kolab_driver::add_partstat_class($record, array('NEEDS-ACTION','DECLINED'), $this->get_owner());
    }

    // add instance identifier to first occurrence (master event)
    $recurrence_id_format = libcalendaring::recurrence_id_format($master_event ? $master_event : $record);
    if (!$noinst && $record['recurrence'] && !$record['recurrence_id'] && !$record['_instance']) {
      $record['_instance'] = $record['start']->format($recurrence_id_format);
    }
    else if (is_a($record['recurrence_date'], 'DateTime')) {
      $record['_instance'] = $record['recurrence_date']->format($recurrence_id_format);
    }

    // clean up exception data
    if ($record['recurrence'] && is_array($record['recurrence']['EXCEPTIONS'])) {
      array_walk($record['recurrence']['EXCEPTIONS'], function(&$exception) {
        unset($exception['_mailbox'], $exception['_msguid'], $exception['_formatobj'], $exception['_attachments']);
      });
    }

    return $record;
  }

   /**
   * Convert the given event record into a data structure that can be passed to Kolab_Storage backend for saving
   * (opposite of self::_to_driver_event())
   */
  private function _from_driver_event($event, $old = array())
  {
    // set current user as ORGANIZER
    if ($identity = $this->cal->rc->user->list_emails(true)) {
      $event['attendees'] = (array) $event['attendees'];
      $found = false;

      // there can be only resources on attendees list (T1484)
      // let's check the existence of an organizer
      foreach ($event['attendees'] as $attendee) {
        if ($attendee['role'] == 'ORGANIZER') {
          $found = true;
          break;
        }
      }

      if (!$found) {
        $event['attendees'][] = array('role' => 'ORGANIZER', 'name' => $identity['name'], 'email' => $identity['email']);
      }

      $event['_owner'] = $identity['email'];
    }

    // remove EXDATE values if RDATE is given
    if (!empty($event['recurrence']['RDATE'])) {
      $event['recurrence']['EXDATE'] = array();
    }

    // remove recurrence information (e.g. EXDATES and EXCEPTIONS) entirely
    if ($event['recurrence'] && empty($event['recurrence']['FREQ']) && empty($event['recurrence']['RDATE'])) {
      $event['recurrence'] = array();
    }

    // keep 'comment' from initial itip invitation
    if (!empty($old['comment'])) {
      $event['comment'] = $old['comment'];
    }

    // clean up exception data
    if (is_array($event['exceptions'])) {
      array_walk($event['exceptions'], function(&$exception) {
        unset($exception['_mailbox'], $exception['_msguid'], $exception['_formatobj'], $exception['_attachments'],
          $event['attachments'], $event['deleted_attachments'], $event['recurrence_id']);
      });
    }

    // remove some internal properties which should not be saved
    unset($event['_savemode'], $event['_fromcalendar'], $event['_identity'], $event['_folder_id'],
      $event['recurrence_id'], $event['attachments'], $event['deleted_attachments'], $event['className']);

    // copy meta data (starting with _) from old object
    foreach ((array)$old as $key => $val) {
      if (!isset($event[$key]) && $key[0] == '_')
        $event[$key] = $val;
    }

    return $event;
  }

  /**
   * Match the given word in the event contents
   */
  public function fulltext_match($event, $word, $recursive = true)
  {
    $hits = 0;
    foreach ($this->search_fields as $col) {
      $sval = is_array($event[$col]) ? self::_complex2string($event[$col]) : $event[$col];
      if (empty($sval))
        continue;

      // do a simple substring matching (to be improved)
      $val = mb_strtolower($sval);
      if (strpos($val, $word) !== false) {
        $hits++;
        break;
      }
    }

    return $hits;
  }

  /**
   * Convert a complex event attribute to a string value
   */
  private static function _complex2string($prop)
  {
      static $ignorekeys = array('role','status','rsvp');

      $out = '';
      if (is_array($prop)) {
          foreach ($prop as $key => $val) {
              if (is_numeric($key)) {
                  $out .= self::_complex2string($val);
              }
              else if (!in_array($key, $ignorekeys)) {
                $out .= $val . ' ';
            }
          }
      }
      else if (is_string($prop) || is_numeric($prop)) {
          $out .= $prop . ' ';
      }

      return rtrim($out);
  }

}