Gets a product's category, sort terms by category hierarchy and add term description to product content.

woocommerce-sorted-category-descriptions.php

<?php 

function msp_maybe_category_description( $content ){
    /**
     * Gets current product category, sorts terms in hierarchy order
     * 
     * @param string $content
     * @return string $content
     */

    if( is_product() ){
        global $product;
    
        $terms = get_terms( array(
            'object_ids' => $product->get_id(), 
            'taxonomy' => 'product_cat',
        ));

        // sort into Hierarchys
        $sorted_terms = msp_sort_terms_to_hierarchy( $terms );

        foreach( $sorted_terms as $terms ){

            // do children
            if( isset( $terms->children ) ){
                foreach( $terms->children as $term ){
                    $content .= msp_get_term_description( $term );
                }
            }

            // do parent;
            $content .= msp_get_term_description( $terms );

        }
    }

    // must always return content (leave outside if ^^)
    return $content;
}

function msp_get_term_description( $term ){
    /**
     * Extracts term description if there is one and returns html
     * @param WP_Term $term
     * @return string $html
     */
    $html = '';

    if( ! is_wp_error( $term ) && ! empty( $term->description ) ){
        $html .= sprintf( "<h5>%s</h5>%s", $term->name, $term->description );
    }

    return $html;
}


function msp_sort_terms_to_hierarchy($terms){
    /**
     * Sorts taxonomies into set hierarchy
     * @param array $terms
     * @return array $terms
     */

    if( empty( $terms ) ) return false;

    foreach($terms as $key => $term){
        if($term->parent != 0){
            $terms[$term->parent]->children[] = $term;
            unset($terms[$key]);
        }
    }

    return array_reverse( $terms );
}


/**
 * Allow HTML in term (category, tag) descriptions
 */
foreach ( array( 'pre_term_description' ) as $filter ) {
	remove_filter( $filter, 'wp_filter_kses' );
	if ( ! current_user_can( 'unfiltered_html' ) ) {
		add_filter( $filter, 'wp_filter_post_kses' );
	}
}
 
foreach ( array( 'term_description' ) as $filter ) {
	remove_filter( $filter, 'wp_kses_data' );
}
/**
 * ===================================================
 */