JetSmartFilters Hierarchical Filter Not Working for Brand and Model

/**
 * BoostMyCroco: one-time migration from two flat taxonomies (brand + model)
 * into one hierarchical taxonomy (brand = parent term, model = child term).
 *
 * 1. Fill in the settings and the $map below, using OLD taxonomy term slugs.
 * 2. As an administrator, open /wp-admin/?bmc_migrate_vehicle=1
 * 3. Click "Start migration", then "Next batch" until you see "Done".
 * 4. Remove this snippet.
 *
 * The old taxonomies are never changed or deleted.
 */
add_action( 'admin_init', 'bmc_migrate_vehicle_taxonomy' );

function bmc_migrate_vehicle_taxonomy() {
	if ( ! isset( $_GET['bmc_migrate_vehicle'] ) ) {
		return;
	}

	if ( ! current_user_can( 'manage_options' ) ) {
		wp_die( 'You are not allowed to run this migration.' );
	}

	// ---- Settings -------------------------------------------------------
	$new_tax        = 'vehicle'; // New JetEngine taxonomy with Hierarchical enabled.
	$old_brand_tax  = 'brand';   // Old flat brand taxonomy.
	$old_model_tax  = 'model';   // Old flat model taxonomy.
	$post_type      = 'product'; // Or your JetEngine CPT slug.
	$batch_size     = 100;
	$assign_parents = true;      // Also add the brand (parent) term with each model.

	// Old brand term slug => old model term slugs. Take them from the old taxonomies'
	// term lists, not from relation posts. Use your JetEngine relation only as a guide.
	$map = array(
		'brand-a' => array( 'model-a1', 'model-a2' ),
		'brand-b' => array( 'model-b1', 'model-b2' ),
	);
	// ---------------------------------------------------------------------

	$nonce = isset( $_GET['_wpnonce'] ) ? sanitize_text_field( wp_unslash( $_GET['_wpnonce'] ) ) : '';

	if ( ! wp_verify_nonce( $nonce, 'bmc_migrate_vehicle' ) ) {
		$start = wp_nonce_url(
			add_query_arg( array( 'bmc_migrate_vehicle' => 1, 'bmc_offset' => 0 ), admin_url() ),
			'bmc_migrate_vehicle'
		);
		wp_die(
			'<p>Export your database, empty or restore the product trash, and move products out of custom statuses before you start.</p><p><a href="' . esc_url( $start ) . '">Start migration</a></p>',
			'Vehicle taxonomy migration',
			array( 'response' => 200 )
		);
	}

	foreach ( array( $new_tax, $old_brand_tax, $old_model_tax ) as $tax ) {
		if ( ! taxonomy_exists( $tax ) ) {
			wp_die( 'Taxonomy not found: ' . esc_html( $tax ) );
		}
	}

	if ( ! is_taxonomy_hierarchical( $new_tax ) ) {
		wp_die( 'Enable Hierarchical for the new taxonomy in JetEngine first.' );
	}

	if ( ! is_object_in_taxonomy( $post_type, $new_tax ) ) {
		wp_die( 'Attach the new taxonomy to ' . esc_html( $post_type ) . ' first.' );
	}

	$offset = isset( $_GET['bmc_offset'] ) ? absint( $_GET['bmc_offset'] ) : 0;
	$errors = array();

	// Step 1: build the Brand > Model tree on the first batch and keep it in a transient.
	// Existing terms under the same parent are reused, so rebuilding is safe.
	$tree = ( $offset > 0 ) ? get_transient( 'bmc_vehicle_tree' ) : false;

	if ( ! is_array( $tree ) || ! isset( $tree['models'], $tree['brands'], $tree['parent_of'] ) ) {
		$tree = array(
			'models'    => array(), // Old model slug => new model term IDs.
			'brands'    => array(), // Old brand slug => new brand term ID.
			'parent_of' => array(), // New model term ID => new brand term ID.
		);

		foreach ( $map as $brand_slug => $model_slugs ) {
			$brand_slug = sanitize_title( $brand_slug );
			$brand_id   = bmc_get_or_create_term( $brand_slug, $old_brand_tax, $new_tax, 0, $errors );

			if ( ! $brand_id ) {
				$errors[] = 'All models of ' . $brand_slug . ' were skipped because its brand term could not be set up.';
				continue;
			}

			$tree['brands'][ $brand_slug ] = $brand_id;

			foreach ( (array) $model_slugs as $model_slug ) {
				$model_slug = sanitize_title( $model_slug );
				$model_id   = bmc_get_or_create_term( $model_slug, $old_model_tax, $new_tax, $brand_id, $errors );

				if ( ! $model_id ) {
					continue;
				}

				$tree['models'][ $model_slug ][] = $model_id;
				$tree['parent_of'][ $model_id ]  = $brand_id;
			}
		}

		// Keep setup problems so every batch screen and the Done screen show them.
		$tree['errors'] = $errors;
		set_transient( 'bmc_vehicle_tree', $tree, HOUR_IN_SECONDS );
	} elseif ( $offset > 0 && ! empty( $tree['errors'] ) ) {
		$errors = array_merge( $tree['errors'], $errors );
	}

	// Unmapped slug totals for the whole run, kept between batches.
	$missing_totals = ( $offset > 0 ) ? get_transient( 'bmc_vehicle_missing' ) : array();

	if ( ! is_array( $missing_totals ) ) {
		$missing_totals = array();
	}

	// Step 2: add the new terms to one batch of products.
	$product_ids = get_posts(
		array(
			'post_type'        => $post_type,
			'post_status'      => 'any', // Excludes trash, auto-draft and custom statuses hidden from search.
			'posts_per_page'   => $batch_size,
			'offset'           => $offset,
			'orderby'          => 'ID',
			'order'            => 'ASC',
			'fields'           => 'ids',
			'no_found_rows'    => true,
			'suppress_filters' => true,
		)
	);

	$updated     = 0;
	$brand_added = 0;
	$missing     = array(); // 'taxonomy: slug' => product IDs in this batch with no new term.

	foreach ( $product_ids as $product_id ) {
		$old_models = wp_get_object_terms( $product_id, $old_model_tax, array( 'fields' => 'slugs' ) );
		$old_brands = wp_get_object_terms( $product_id, $old_brand_tax, array( 'fields' => 'slugs' ) );
		$old_models = is_wp_error( $old_models ) ? array() : $old_models;
		$old_brands = is_wp_error( $old_brands ) ? array() : $old_brands;

		$new_ids = array();
		$covered = array(); // Brand term IDs already represented by one of this product's models.

		foreach ( $old_models as $old_slug ) {
			if ( ! isset( $tree['models'][ $old_slug ] ) ) {
				$missing[ $old_model_tax . ': ' . $old_slug ][] = $product_id;
				continue;
			}

			foreach ( $tree['models'][ $old_slug ] as $model_id ) {
				$new_ids[] = (int) $model_id;
				$brand_id  = isset( $tree['parent_of'][ $model_id ] ) ? (int) $tree['parent_of'][ $model_id ] : 0;

				if ( $brand_id ) {
					$covered[] = $brand_id;

					if ( $assign_parents ) {
						$new_ids[] = $brand_id;
					}
				}
			}
		}

		// An old brand with no mapped model on this product (for example a part that fits
		// every model of that brand): add the brand term so it stays in that brand's results.
		$added = false;

		foreach ( $old_brands as $old_slug ) {
			if ( ! isset( $tree['brands'][ $old_slug ] ) ) {
				$missing[ $old_brand_tax . ': ' . $old_slug ][] = $product_id;
				continue;
			}

			$brand_id = (int) $tree['brands'][ $old_slug ];

			if ( ! in_array( $brand_id, $covered, true ) ) {
				$new_ids[] = $brand_id;
				$covered[] = $brand_id;
				$added     = true;
			}
		}

		if ( $added ) {
			$brand_added++;
		}

		if ( empty( $new_ids ) ) {
			continue;
		}

		// Append = true keeps any Vehicle terms the product already has.
		$result = wp_set_object_terms( $product_id, array_values( array_unique( array_map( 'intval', $new_ids ) ) ), $new_tax, true );

		if ( is_wp_error( $result ) ) {
			$errors[] = 'Item ' . $product_id . ': ' . $result->get_error_message();
			continue;
		}

		$updated++;
	}

	// One line per slug with no new term in this batch, and add it to the run totals.
	foreach ( $missing as $label => $ids ) {
		$errors[] = 'No new term for ' . $label . ' (not in $map, or skipped by a problem above; ' . count( $ids ) . ' items in this batch, e.g. IDs ' . implode( ', ', array_slice( $ids, 0, 5 ) ) . ')';

		$missing_totals[ $label ] = ( isset( $missing_totals[ $label ] ) ? (int) $missing_totals[ $label ] : 0 ) + count( $ids );
	}

	$html = '<p>Offset ' . (int) $offset . ': ' . count( $product_ids ) . ' items checked, ' . (int) $updated . ' updated, ' . (int) $brand_added . ' given a brand term with no mapped model of that brand.</p>';

	if ( $errors ) {
		$html .= '<ul><li>' . implode( '</li><li>', array_map( 'esc_html', $errors ) ) . '</li></ul>';
	}

	if ( count( $product_ids ) < $batch_size ) {
		delete_transient( 'bmc_vehicle_tree' );
		delete_transient( 'bmc_vehicle_missing' );
		$html .= '<p><strong>Done.</strong> Remove this snippet now.</p>';

		if ( $missing_totals ) {
			$lines = array();

			foreach ( $missing_totals as $label => $count ) {
				$lines[] = $label . ': ' . (int) $count . ' items in total';
			}

			$html .= '<p>Slugs with no new term across the whole run:</p><ul><li>' . implode( '</li><li>', array_map( 'esc_html', $lines ) ) . '</li></ul>';
		}
	} else {
		set_transient( 'bmc_vehicle_missing', $missing_totals, HOUR_IN_SECONDS );

		$next = wp_nonce_url(
			add_query_arg( array( 'bmc_migrate_vehicle' => 1, 'bmc_offset' => $offset + $batch_size ), admin_url() ),
			'bmc_migrate_vehicle'
		);
		$html .= '<p><a href="' . esc_url( $next ) . '">Next batch</a></p>';
	}

	wp_die( $html, 'Vehicle taxonomy migration', array( 'response' => 200 ) );
}

/**
 * Lowercases text, multibyte-safe when mbstring is available.
 */
function bmc_lower( $text ) {
	return function_exists( 'mb_strtolower' ) ? mb_strtolower( $text, 'UTF-8' ) : strtolower( $text );
}

/**
 * Returns the ID of a term with this slug (or name) under $parent_id in $target_tax,
 * creating it if needed with the name of the old term.
 * A slug missing from the old taxonomy, or already used under another parent, is reported.
 */
function bmc_get_or_create_term( $slug, $source_tax, $target_tax, $parent_id, &$errors ) {
	$slug      = sanitize_title( $slug );
	$parent_id = (int) $parent_id;
	$source    = get_term_by( 'slug', $slug, $source_tax );

	// The slug must exist in the old taxonomy, so products can be matched and the real name copied.
	if ( ! ( $source instanceof WP_Term ) ) {
		$errors[] = $slug . ': not found in ' . $source_tax . ', check the slug in $map.';
		return 0;
	}

	$name = $source->name;

	// 1. Reuse a term with the same slug or name under the same parent.
	$siblings = get_terms(
		array(
			'taxonomy'   => $target_tax,
			'hide_empty' => false,
			'parent'     => $parent_id,
		)
	);

	if ( ! is_wp_error( $siblings ) ) {
		foreach ( $siblings as $sibling ) {
			if ( $sibling->slug === $slug || bmc_lower( $sibling->name ) === bmc_lower( $name ) ) {
				return (int) $sibling->term_id;
			}
		}
	}

	// 2. The slug exists under a different parent: report it instead of creating a near-duplicate.
	$existing = get_term_by( 'slug', $slug, $target_tax );

	if ( $existing instanceof WP_Term ) {
		$errors[] = $slug . ': already exists in ' . $target_tax . ' under another parent (term ID ' . (int) $existing->term_id . '). Move or delete it, then start again.';
		return 0;
	}

	$result = wp_insert_term( $name, $target_tax, array( 'slug' => $slug, 'parent' => $parent_id ) );

	if ( is_wp_error( $result ) ) {
		// WordPress refuses a duplicate name under the same parent and returns the existing ID.
		if ( 'term_exists' === $result->get_error_code() && $result->get_error_data() ) {
			return (int) $result->get_error_data();
		}

		$errors[] = $slug . ': ' . $result->get_error_message();
		return 0;
	}

	return (int) $result['term_id'];
}