$sanitized[ $allowed_var ] = (bool) $vars[ $allowed_var ];
                        break;

                    case 'mixed':
                        $sanitized[ $allowed_var ] = $vars[ $allowed_var ];
                        break;
                }
            }
        }

        return $sanitized;
    }

    /**
     * @param array        $lang
     * @param WPML_LS_Slot $slot
     *
     * @return array
     */
    private function add_backward_compatibility_to_languages( $lang, $slot ) {

        if ( $this->needs_backward_compatibility() ) {

            $is_current_language = isset( $lang['is_current'] ) && $lang['is_current'];

            if ( $slot->is_menu() ) {

                if ( $is_current_language ) {
                    array_unshift( $lang['css_classes'], 'menu-item-language-current' );
                }

                array_unshift( $lang['css_classes'], 'menu-item-language' );
            }

            if ( $slot->is_sidebar() || $slot->is_shortcode_actions() ) {

                if ( $this->is_legacy_template( $slot->template(), 'list-vertical' )
                    || $this->is_legacy_template( $slot->template(), 'list-horizontal' )
                ){
                    array_unshift( $lang['css_classes'], 'icl-' . $lang['code'] );
                    $lang['backward_compatibility']['css_classes_a'] = $is_current_language ?
                        'lang_sel_sel' : 'lang_sel_other';
                }

                if ( $this->is_legacy_template( $slot->template(), 'dropdown' )
					|| $this->is_legacy_template( $slot->template(), 'dropdown-click' )
				){

                    if ( $is_current_language ) {
                        $lang['backward_compatibility']['css_classes_a'] = 'lang_sel_sel icl-' . $lang['code'];
                    } else {
                        array_unshift( $lang['css_classes'], 'icl-' . $lang['code'] );
                    }
                }
            }
        }

        return $lang;
    }

    /**
     * @param array        $vars
     * @param WPML_LS_Slot $slot
     *
     * @return mixed
     */
    private function add_backward_compatibility_to_wrapper( $vars, $slot ) {

        if ( $this->needs_backward_compatibility() ) {

            if ( $slot->is_sidebar() || $slot->is_shortcode_actions() ) {

                if ( $this->is_legacy_template( $slot->template(), 'list-vertical' )
                    || $this->is_legacy_template( $slot->template(), 'list-horizontal' )
                ){
                    $vars['backward_compatibility']['css_id'] = 'lang_sel_list';

                    if ( $this->is_legacy_template( $slot->template(), 'list-horizontal' ) ) {
                        $vars['css_classes'] = 'lang_sel_list_horizontal ' . $vars['css_classes'];
                    } else {
                        $vars['css_classes'] = 'lang_sel_list_vertical ' . $vars['css_classes'];
                    }
                }

                if ( $this->is_legacy_template( $slot->template(), 'dropdown' ) ) {
                    $vars['backward_compatibility']['css_id'] = 'lang_sel';
                }

                if ( $this->is_legacy_template( $slot->template(), 'dropdown-click' ) ) {
                    $vars['backward_compatibility']['css_id'] = 'lang_sel_click';
                }
            }

            if ( $slot->is_post_translations() ) {
                $vars['css_classes'] = 'icl_post_in_other_langs ' . $vars['css_classes'];
            }

            if ( $slot->is_footer() ) {
                $vars['backward_compatibility']['css_id'] = 'lang_sel_footer';
            }

            $vars['backward_compatibility']['css_classes_flag']    = 'iclflag';
            $vars['backward_compatibility']['css_classes_native']  = 'icl_lang_sel_native';
            $vars['backward_compatibility']['css_classes_display'] = 'icl_lang_sel_translated';
            $vars['backward_compatibility']['css_classes_bracket'] = 'icl_lang_sel_bracket';
        }

        return $vars;
    }

    /**
     * @param $template_slug
     * @param mixed|string|null $type
     *
     * @return bool
     */
    private function is_legacy_template( $template_slug, $type = null ) {
        $templates = $this->settings->get_core_templates();
        $ret = in_array( $template_slug, $templates, true);

        if ( $ret && array_key_exists( $type, $templates ) ) {
            $ret = $templates[ $type ] === $template_slug;
        }

        return $ret;
    }
}