Add a custom class to variation options displaying “Out Of Stock” in Woocommerce

// Function that will check the stock status and display the corresponding additional text
function get_stock_status_text( $product, $name, $term_slug ){
    foreach ( $product->get_available_variations() as $variation ){
        if($variation['attributes'][$name] == $term_slug )
            $stock = $variation['is_in_stock'];
    }

    return $stock == 1 ? ' - (In Stock)' : ' - (Out of Stock)';
}

// The hooked function that will add the stock status to the dropdown options elements.
add_filter( 'woocommerce_dropdown_variation_attribute_options_html', 'show_stock_status_in_dropdown', 10, 2);
function show_stock_status_in_dropdown( $html, $args ) {
    // Only if there is a unique variation attribute (one dropdown)
    if( sizeof($args['product']->get_variation_attributes()) == 1 ) :

    $options               = $args['options'];
    $product               = $args['product'];
    $attribute             = $args['attribute']; // The product attribute taxonomy
    $name                  = $args['name'] ? $args['name'] : 'attribute_' . sanitize_title( $attribute );
    $id                    = $args['id'] ? $args['id'] : sanitize_title( $attribute );
    $class                 = $args['class'];
    $show_option_none      = $args['show_option_none'] ? true : false;
    $show_option_none_text = $args['show_option_none'] ? $args['show_option_none'] : __( 'Choose an option', 'woocommerce' );

    if ( empty( $options ) && ! empty( $product ) && ! empty( $attribute ) ) {
        $attributes = $product->get_variation_attributes();
        $options    = $attributes[ $attribute ];
    }

    $html = '<select id="' . esc_attr( $id ) . '" class="' . esc_attr( $class ) . '" name="' . esc_attr( $name ) . '" data-attribute_name="attribute_' . esc_attr( sanitize_title( $attribute ) ) . '" data-show_option_none="' . ( $show_option_none ? 'yes' : 'no' ) . '">';
    $html .= '<option value="">' . esc_html( $show_option_none_text ) . '</option>';

    if ( ! empty( $options ) ) {
        if ( $product && taxonomy_exists( $attribute ) ) {
            $terms = wc_get_product_terms( $product->get_id(), $attribute, array( 'fields' => 'all' ) );

            foreach ( $terms as $term ) {
                if ( in_array( $term->slug, $options ) ) {
                    // HERE Added the function to get the text status
                    $stock_status = get_stock_status_text( $product, $name, $term->slug );

                    // HERE we add a custom class to <option> that are "Out of stock"
                    $option_class = $stock_status === ' - (Out of Stock)' ? ' class="outofstock"' : '';

                    $html .= '<option value="' . esc_attr( $term->slug ) . '" ' . selected( sanitize_title( $args['selected'] ), $term->slug, false ) . $option_class . '>' . esc_html( apply_filters( 'woocommerce_variation_option_name', $term->name ) . $stock_status ) . '</option>';
                }
            }
        } else {
            foreach ( $options as $option ) {
                $selected = sanitize_title( $args['selected'] ) === $args['selected'] ? selected( $args['selected'], sanitize_title( $option ), false ) : selected( $args['selected'], $option, false );
                // HERE Added the function to get the text status
                $stock_status = get_stock_status_text( $product, $name, $option );

                // HERE we add a custom class to <option> that are "Out of stock"
                $option_class = $stock_status === ' - (Out of Stock)' ? ' class="outofstock"' : '';

                $html .= '<option value="' . esc_attr( $option ) . '" ' . $selected . $option_class . '>' .
                esc_html( apply_filters( 'woocommerce_variation_option_name', $option ) . $stock_status ) . '</option>';
            }
        }
    }
    $html .= '</select>';

    endif;

    return $html;
}

#My Modified version to disable the out of stock product

// Function that will check the stock status and display the corresponding additional text
function get_stock_status_text( $product, $name, $term_slug ){
    foreach ( $product->get_available_variations() as $variation ){
        if($variation['attributes'][$name] == $term_slug )
            $stock = $variation['is_in_stock'];
    }

    return $stock == 1 ? ' - (In Stock)' : ' - (Out of Stock)';
}

// The hooked function that will add the stock status to the dropdown options elements.
add_filter( 'woocommerce_dropdown_variation_attribute_options_html', 'show_stock_status_in_dropdown', 10, 2);
function show_stock_status_in_dropdown( $html, $args ) {
    // Only if there is a unique variation attribute (one dropdown)
    if( sizeof($args['product']->get_variation_attributes()) == 1 ) :

    $options               = $args['options'];
    $product               = $args['product'];
    $attribute             = $args['attribute']; // The product attribute taxonomy
    $name                  = $args['name'] ? $args['name'] : 'attribute_' . sanitize_title( $attribute );
    $id                    = $args['id'] ? $args['id'] : sanitize_title( $attribute );
    $class                 = $args['class'];
    $show_option_none      = $args['show_option_none'] ? true : false;
    $show_option_none_text = $args['show_option_none'] ? $args['show_option_none'] : __( 'Choose an option', 'woocommerce' );

    if ( empty( $options ) && ! empty( $product ) && ! empty( $attribute ) ) {
        $attributes = $product->get_variation_attributes();
        $options    = $attributes[ $attribute ];
    }

    $html = '<select id="' . esc_attr( $id ) . '" class="' . esc_attr( $class ) . '" name="' . esc_attr( $name ) . '" data-attribute_name="attribute_' . esc_attr( sanitize_title( $attribute ) ) . '" data-show_option_none="' . ( $show_option_none ? 'yes' : 'no' ) . '">';
    $html .= '<option value="">' . esc_html( $show_option_none_text ) . '</option>';

    if ( ! empty( $options ) ) {
        if ( $product && taxonomy_exists( $attribute ) ) {
            $terms = wc_get_product_terms( $product->get_id(), $attribute, array( 'fields' => 'all' ) );

            foreach ( $terms as $term ) {
                if ( in_array( $term->slug, $options ) ) {
                    // HERE Added the function to get the text status
                    $stock_status = get_stock_status_text( $product, $name, $term->slug );

                    // HERE we add a custom class to <option> that are "Out of stock"
                    $option_class = $stock_status === ' - (Out of Stock)' ? ' class="outofstock"' : '';
                    
                    if( $stock_status === ' - (Out of Stock)' ){
                        $disable = 'disabled';
                    }else{
                        $disable = '';
                    }

                    $html .= '<option value="' . esc_attr( $term->slug ) . '" ' . selected( sanitize_title( $args['selected'] ), $term->slug, false ) . $option_class . ' '.$disable.'>' . esc_html( apply_filters( 'woocommerce_variation_option_name', $term->name ) . $stock_status ) . '</option>';
                }
            }
        } else {
            foreach ( $options as $option ) {
                $selected = sanitize_title( $args['selected'] ) === $args['selected'] ? selected( $args['selected'], sanitize_title( $option ), false ) : selected( $args['selected'], $option, false );
                // HERE Added the function to get the text status
                $stock_status = get_stock_status_text( $product, $name, $option );

                // HERE we add a custom class to <option> that are "Out of stock"
                $option_class = $stock_status === ' - (Out of Stock)' ? ' class="outofstock"' : '';

                $html .= '<option value="' . esc_attr( $option ) . '" ' . $selected . $option_class . '>' .
                esc_html( apply_filters( 'woocommerce_variation_option_name', $option ) . $stock_status ) . '</option>';
            }
        }
    }
    $html .= '</select>';

    endif;

    return $html;
}

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