[WordPress] Determine not only if a WordPress post has a term applied to it, but determine if the term is actively applied to it.

1-define-the-function.php

<?php

function acme_stocked_artifacts( $post_id ) {
  
  // More to come...
  
}

2-define-the-array.php

<?php

function acme_stocked_artifacts( $post_id ) {

	$stocked_artifacts = array(
		'applied'     => array(),
		'not_applied' => array()
	);
	
	// More to come...
	
}

3-get-all-artifacts.php

<?php

function acme_stocked_artifacts( $post_id ) {

	$stocked_artifacts = array(
		'applied'     => array(),
		'not_applied' => array()
	);
	
	// Get all of the artifacts for the post
	$artifacts = wp_get_post_terms( $post_id, 'acme_artifacts' );

  // More to come...
	
}

4-loop-through-artifacts.php

<?php

function acme_stocked_artifacts( $post_id ) {

	$stocked_artifacts = array(
		'applied'     => array(),
		'not_applied' => array()
	);
	
	// Get all of the artifacts for the post
	$artifacts = wp_get_post_terms( $post_id, 'acme_artifacts' );

	/* For each of the materials, determine which are applied and which are not
	 * and put them in the appropriate index of the array
	 */
	foreach ( $artifacts as $artifact ) {

		// Check to see if the current term has children
		$children = get_term_children( $artifact->term_id, 'acme_artifacts' );
		if ( 0 < count( $children ) ) {

			// If the first index of the children array isn't set, then we don't have any that are applied
			if ( has_term( $children[0], 'acme_artifacts', $post_id ) ) {
				array_push( $stocked_artifacts['not_applied'], $artifact );
			} else {
				array_push( $stocked_artifacts['applied'], $artifact );
			}

		// If there aren't any children, then we know it's applied.
		} else {
			if ( 'name of child' !== strtolower( $artifact->name ) ) {
				array_push( $stocked_artifacts['applied'], $artifact );
			}
		}

	}
	
}