Get main parent categories for a product

Can someone please help me, I’m looking for a way to find the main parent product category of a WooCommerce product? Say, the product is marked under Gadgets, but the main parent of them all is Electronics.

I want this per post, as I want to add a class to each post signifying its main parent product_cat.

Please remember, product categories are custom taxonomy, and cannot be retrieved using get_category_parents(). They are listed as terms.

Thanks in advance.

// edit:

This is the code I have already, I’m calling this on each post and my posts are rendered similar to an archive page.

function all_cat_classes($post) {
    $cats = "";

    $terms = get_the_terms($post->ID, "product_cat");

    $count = 0;
    $count = count($terms);
    $key = 0;
    foreach ($terms as $cat) {

        $key++;
    }

    return $cats;
}

just to offer a alternative solution that might help somebody:

code

function wc_origin_trail_ancestor( $link = false, $trail = false ) {

    if (is_product_category()) {
        global $wp_query;
        $q_obj = $wp_query->get_queried_object();
        $cat_id = $q_obj->term_id;

        $descendant = get_term_by("id", $cat_id, "product_cat");
        $descendant_id = $descendant->term_id;

        $ancestors = get_ancestors($cat_id, 'product_cat');
        $ancestors = array_reverse($ancestors);

        $origin_ancestor = get_term_by("id", $ancestors[0], "product_cat");
        $origin_ancestor_id = $origin_ancestor->term_id;

        $ac = count($ancestors);

    } else if ( is_product() ) {

        $descendant = get_the_terms( $post->ID, 'product_cat' );
        $descendant = array_reverse($descendant);
        $descendant = $descendant[0];
        $descendant_id = $descendant->term_id;

        $ancestors = array_reverse(get_ancestors($descendant_id, 'product_cat'));
        $ac = count($ancestors);

    }


    $c = 1;
    if( $trail == false ){

        $origin_ancestor_term = get_term_by("id", $ancestors[0], "product_cat");
        $origin_ancestor_link = get_term_link( $origin_ancestor_term->slug, $origin_ancestor_term->taxonomy );

        if($link == true) 
            echo '<a href="'. $origin_ancestor_link .'">';
        echo $origin_ancestor_term->name;
        if($link == true) 
            echo '</a>';

    }else{

        foreach ($ancestors as $ancestor) {
            $ancestor_term = get_term_by("id", $ancestor, "product_cat");
            $ancestor_link = get_term_link( $ancestor_term->slug, $ancestor_term->taxonomy );

            if($c++ == 1) 
                echo '» '; 
            else if($c++ != 1 || $c++ != $ac) 
                echo ' » ';

            if($link == true) 
                echo '<a href="'. $ancestor_link .'">';
            echo  $ancestor_term->name;
            if($link == true) 
                echo '</a>';

        }

        $descendant_term = get_term_by("id", $descendant_id, "product_cat");
        $descendant_link = get_term_link( $descendant_term->slug, $descendant_term->taxonomy );

        echo ' » ';
        if($link == true) 
            echo '<a href="'. $descendant_link .'">';
        echo $descendant->name;
        if($link == true) 
            echo '</a>';

    }

}

how to use

• just toplevel, origin ancestor; without link
  wc_origin_trail_ancestor();
• just toplevel, origin ancestor; with link
  wc_origin_trail_ancestor(true);
• ancestor trail; without link
  wc_origin_trail_ancestor(false,true);
• ancestor trail; with link
  wc_origin_trail_ancestor(true,true);

notes

• won’t work if a product has multiple main-/toplevel-categories, or at least won’t show them all;
• same should be the case for multiple subcategories on the same level;
• I did no further tests concerning above points, because the function does all I wanted for that project;