Jet Smart Filters JSF Complex Query (meta field, taxonomy)

jsf_custom_search.php

/**
 * Filter for searching publications by post_title, meta field 'authors', and taxonomy 'conference' in JetSmartFilters.
 * Uses the _search_publications query variable.
 */
add_filter( 'jet-smart-filters/query/final-query', function( $query ) {
    global $wpdb;

    // Loop through meta_query to check for _search_publications
    foreach ( $query['meta_query'] as $index => $meta_query_item ) {
        if ( isset( $meta_query_item['key'] ) && $meta_query_item['key'] === '_search_publications' ) {
            // Get the search term from the value
            $search_term = sanitize_text_field( $meta_query_item['value'] );
            
            // Restrict the query to the 'publications' post type
            $query['post_type'] = 'publications';

            // Query the wp_posts table for post_title matches
            $post_title_ids = $wpdb->get_col(
                $wpdb->prepare(
                    "SELECT ID FROM {$wpdb->posts} WHERE post_title LIKE %s AND post_type = %s AND post_status = 'publish'",
                    '%' . $wpdb->esc_like( $search_term ) . '%',
                    'publications'
                )
            );

            // Query the wp_postmeta table for meta_key 'authors' matches
            $author_ids = $wpdb->get_col(
                $wpdb->prepare(
                    "SELECT DISTINCT post_id FROM {$wpdb->postmeta} WHERE meta_key = %s AND meta_value LIKE %s",
                    'authors',
                    '%' . $wpdb->esc_like( $search_term ) . '%'
                )
            );

            // Query the wp_terms and wp_term_relationships table for matching taxonomy 'conference'
            $conference_ids = $wpdb->get_col(
                $wpdb->prepare(
                    "SELECT DISTINCT tr.object_id FROM {$wpdb->term_relationships} tr
                     INNER JOIN {$wpdb->term_taxonomy} tt ON tr.term_taxonomy_id = tt.term_taxonomy_id
                     INNER JOIN {$wpdb->terms} t ON tt.term_id = t.term_id
                     WHERE tt.taxonomy = %s AND t.name LIKE %s",
                    'conference',
                    '%' . $wpdb->esc_like( $search_term ) . '%'
                )
            );

            // Combine the results from post_title, authors, and conference
            $matching_ids = array_unique( array_merge( $post_title_ids, $author_ids, $conference_ids ) );

            // If matching IDs are found, adjust the query to include those IDs
            if ( ! empty( $matching_ids ) ) {
                $query['post__in'] = ! empty( $query['post__in'] )
                    ? array_intersect( $query['post__in'], $matching_ids ) // Narrow down existing IDs
                    : $matching_ids; // Start with matching IDs
            } else {
                // No matches found, prevent any results
                $query['post__in'] = [ 0 ]; // Impossible condition
            }

            // Remove the original _search_publications meta_query to prevent conflicts
            unset( $query['meta_query'][$index] );

            // Stop processing further meta queries
            break;
        }
    }

    return $query;
});