//  [python]
def edit_list_user(param):
    vals = request.form.to_dict(flat=False)
    all_user = ub.session.query(ub.User)
    if not config.config_anonbrowse:
        all_user = all_user.filter(ub.User.role.op('&')(constants.ROLE_ANONYMOUS) != constants.ROLE_ANONYMOUS)
    # only one user is posted
    if "pk" in vals:
        users = [all_user.filter(ub.User.id == vals['pk'][0]).one_or_none()]
    else:
        if "pk[]" in vals:
            users = all_user.filter(ub.User.id.in_(vals['pk[]'])).all()
        else:
            return _("Malformed request"), 400
    if 'field_index' in vals:
        vals['field_index'] = vals['field_index'][0]
    if 'value' in vals:
        vals['value'] = vals['value'][0]
    elif not ('value[]' in vals):
        return _("Malformed request"), 400
    for user in users:
        try:
            if param in ['denied_tags', 'allowed_tags', 'allowed_column_value', 'denied_column_value']:
                if 'value[]' in vals:
                    setattr(user, param, prepare_tags(user, vals['action'][0], param, vals['value[]']))
                else:
                    setattr(user, param, vals['value'].strip())
            else:
                vals['value'] = vals['value'].strip()
                if param == 'name':
                    if user.name == "Guest":
                        raise Exception(_("Guest Name can't be changed"))
                    user.name = check_username(vals['value'])
                elif param == 'email':
                    user.email = check_email(vals['value'])
                elif param == 'kobo_only_shelves_sync':
                    user.kobo_only_shelves_sync = int(vals['value'] == 'true')
                elif param == 'kindle_mail':
                    user.kindle_mail = valid_email(vals['value']) if vals['value'] else ""
                elif param.endswith('role'):
                    value = int(vals['field_index'])
                    if user.name == "Guest" and value in \
                            [constants.ROLE_ADMIN, constants.ROLE_PASSWD, constants.ROLE_EDIT_SHELFS]:
                        raise Exception(_("Guest can't have this role"))
                    # check for valid value, last on checks for power of 2 value
                    if value > 0 and value <= constants.ROLE_VIEWER and (value & value-1 == 0 or value == 1):
                        if vals['value'] == 'true':
                            user.role |= value
                        elif vals['value'] == 'false':
                            if value == constants.ROLE_ADMIN:
                                if not ub.session.query(ub.User).\
                                       filter(ub.User.role.op('&')(constants.ROLE_ADMIN) == constants.ROLE_ADMIN,
                                              ub.User.id != user.id).count():
                                    return Response(
                                        json.dumps([{'type': "danger",
                                                     'message': _(u"No admin user remaining, can't remove admin role",
                                                                  nick=user.name)}]), mimetype='application/json')
                            user.role &= ~value
                        else:
                            raise Exception(_("Value has to be true or false"))
                    else:
                        raise Exception(_("Invalid role"))
                elif param.startswith('sidebar'):
                    value = int(vals['field_index'])
                    if user.name == "Guest" and value == constants.SIDEBAR_READ_AND_UNREAD:
                        raise Exception(_("Guest can't have this view"))
                    # check for valid value, last on checks for power of 2 value
                    if value > 0 and value <= constants.SIDEBAR_LIST and (value & value-1 == 0 or value == 1):
                        if vals['value'] == 'true':
                            user.sidebar_view |= value
                        elif vals['value'] == 'false':
                            user.sidebar_view &= ~value
                        else:
                            raise Exception(_("Value has to be true or false"))
                    else:
                        raise Exception(_("Invalid view"))
                elif param == 'locale':
                    if user.name == "Guest":
                        raise Exception(_("Guest's Locale is determined automatically and can't be set"))
                    if vals['value'] in _BABEL_TRANSLATIONS:
                        user.locale = vals['value']
                    else:
                        raise Exception(_("No Valid Locale Given"))
                elif param == 'default_language':
                    languages = calibre_db.session.query(db.Languages) \
                        .join(db.books_languages_link) \
                        .join(db.Books) \
                        .filter(calibre_db.common_filters()) \
                        .group_by(text('books_languages_link.lang_code')).all()
                    lang_codes = [lang.lang_code for lang in languages] + ["all"]
                    if vals['value'] in lang_codes:
                        user.default_language = vals['value']
                    else:
                        raise Exception(_("No Valid Book Language Given"))
                else:
                    return _("Parameter not found"), 400
        except Exception as ex:
            log.error_or_exception(ex)
            return str(ex), 400
    ub.session_commit()
    return ""