def session(request):
    """
    Get the information about the current session or modify the current session.

    GET parameters:
      html
        turn on the HTML version of the API

    POST parameters:
      locale:
        client's locale
      time_zone:
        client's time zone
      display_width:
        width of the client's display
      display_height
        height of the client's display
    """

    if request.user.id is None:  # Google Bot
        return render_json(request, {
            'error': _('There is no user available to create a session.'),
            'error_type': 'user_undefined'
        }, status=400, template='user_json.html')

    if request.method == 'GET':
        return render_json(
            request,
            Session.objects.get_current_session(),
            template='user_session.html', help_text=session.__doc__)
    elif request.method == 'POST':
        current_session = Session.objects.get_current_session()
        if current_session is None:
            return HttpResponseBadRequest("there is no current session to modify")
        data = json_body(request.body.decode("utf-8"))
        locale = data.get('locale', None)
        time_zone = data.get('time_zone', None)
        display_width = data.get('display_width', None)
        display_height = data.get('display_height', None)
        if locale:
            current_session.locale = locale
        if time_zone:
            current_session.time_zone = TimeZone.objects.from_content(time_zone)
        if display_width:
            current_session.display_width = display_width
        if display_height:
            current_session.display_height = display_height
        current_session.save()
        return HttpResponse('ok', status=202)
    else:
        return HttpResponseBadRequest("method %s is not allowed".format(request.method))