Get main term from a sub term in Woocommerce

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() ) {

        $ancestors = get_the_terms( $post->ID, 'product_cat' );

        $i = 0;
        foreach($ancestors as $ancestor) {
            if( $i == 0 ) {
                $origin_ancestor = $ancestor;
                $origin_ancestor_id = $origin_ancestor->term_id;
            }
        }

        $ancestors = array_reverse($ancestors);

        $ac = count($ancestors);

        $descendant = $ancestors[0];
        $descendant_id = $descendant->term_id;

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

    }


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

        $origin_ancestor_term = get_term_by("id", $origin_ancestor_id, "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 $origin_ancestor->name;
        if($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;