/**
   * @param ownerIdentifier
   * @param model
   * @param fbo
   * @param bindingResult
   * @return
   * @throws NotAVisitorException
   * @throws OwnerNotFoundException
   * @throws SchedulingException
   */
  @RequestMapping(method = RequestMethod.POST)
  protected String createAppointment(
      final ModelMap model,
      @PathVariable("ownerIdentifier") final String ownerIdentifier,
      @Valid @ModelAttribute(COMMAND_ATTR_NAME) final CreateAppointmentFormBackingObject fbo,
      BindingResult bindingResult)
      throws NotAVisitorException, OwnerNotFoundException, SchedulingException {
    CalendarAccountUserDetailsImpl currentUser =
        (CalendarAccountUserDetailsImpl)
            SecurityContextHolder.getContext().getAuthentication().getPrincipal();
    IScheduleVisitor visitor = currentUser.getScheduleVisitor();

    if (bindingResult.hasErrors()) {
      return "visitor/create-appointment-form";
    }

    IScheduleOwner selectedOwner = null;
    if (StringUtils.isNumeric(ownerIdentifier)) {
      Long ownerId = Long.parseLong(ownerIdentifier);
      selectedOwner = findOwnerForVisitor(visitor, ownerId);
    } else {
      PublicProfile profile = publicProfileDao.locatePublicProfileByKey(ownerIdentifier);
      if (null != profile) {
        selectedOwner = ownerDao.locateOwnerByAvailableId(profile.getOwnerId());
      }
    }

    if (null == selectedOwner) {
      throw new OwnerNotFoundException("no owner found for " + ownerIdentifier);
    }

    validateChosenStartTime(
        selectedOwner.getPreferredVisibleWindow(), fbo.getTargetBlock().getStartTime());

    AvailableBlock finalAppointmentBlock = fbo.getTargetBlock();
    if (fbo.isDoubleLengthAvailable()) {
      // check if selected meeting duration matches meeting durations maxLength
      // if it's greater, then we need to look up the next block in the schedule and attempt to
      // combine
      if (fbo.getSelectedDuration() == fbo.getMeetingDurations().getMaxLength()) {
        finalAppointmentBlock =
            availableScheduleDao.retrieveTargetDoubleLengthBlock(
                selectedOwner, finalAppointmentBlock.getStartTime());
      }
    }
    if (null == finalAppointmentBlock) {
      throw new SchedulingException("requested time is not available");
    }

    VEvent event =
        schedulingAssistantService.scheduleAppointment(
            visitor, selectedOwner, finalAppointmentBlock, fbo.getReason());
    model.put("event", event);
    model.put("owner", selectedOwner);
    model.put("ownerRemindersPreference", selectedOwner.getRemindersPreference());
    return "visitor/create-appointment-success";
  }