Make coupons invalid at product level & Set the product discount amount to zero

gistfile1.txt

// Make coupons invalid at product level
add_filter('woocommerce_coupon_is_valid_for_product', 'set_coupon_validity_for_excluded_products', 12, 4);
function set_coupon_validity_for_excluded_products($valid, $product, $coupon, $values ){
    if( ! count(get_option( '_products_disabled_for_coupons' )) > 0 ) return $valid;

    $disabled_products = get_option( '_products_disabled_for_coupons' );
    if( in_array( $product->get_id(), $disabled_products ) )
        $valid = false;

    return $valid;
}

// Set the product discount amount to zero
add_filter( 'woocommerce_coupon_get_discount_amount', 'zero_discount_for_excluded_products', 12, 5 );
function zero_discount_for_excluded_products($discount, $discounting_amount, $cart_item, $single, $coupon ){
    if( ! count(get_option( '_products_disabled_for_coupons' )) > 0 ) return $discount;

    $disabled_products = get_option( '_products_disabled_for_coupons' );
    if( in_array( $cart_item['product_id'], $disabled_products ) )
        $discount = 0;

    return $discount;
}