Boost relevance for WooCommerce products with high total sales

searchwp-customisations.php

<?php

// Boost relevance for WooCommerce products with high total sales
add_filter( 'searchwp\query\mods', function( $mods, $query ) {
    global $wpdb;
    
    // Adjustable variables
    $min_total_sales = 100;     // Minimum sales required to qualify
    $bonus_weight    = 99999;    // Base relevance weight
    $sales_multiplier = 100;     // Extra relevance per sale
    
    $search_term = trim( $query->get_keywords() );
    if ( empty( $search_term ) ) {
        return $mods;
    }
    
    $mod = new \SearchWP\Mod();
    $mod->set_local_table( $wpdb->posts );
    $mod->on( 'ID', [ 'column' => 'id' ] );
    
    $mod->relevance( function( $runtime ) use ( $wpdb, $min_total_sales, $bonus_weight, $sales_multiplier ) {
        $alias = $runtime->get_local_table_alias();
        
        return "
            CASE
                WHEN {$alias}.post_type = 'product'
                AND (
                    SELECT CAST(pm.meta_value AS UNSIGNED)
                    FROM {$wpdb->postmeta} pm
                    WHERE pm.post_id = {$alias}.ID
                    AND pm.meta_key = '_total_sales'
                    LIMIT 1
                ) >= {$min_total_sales}
                THEN
                    {$bonus_weight} +
                    (
                        SELECT CAST(pm.meta_value AS UNSIGNED)
                        FROM {$wpdb->postmeta} pm
                        WHERE pm.post_id = {$alias}.ID
                        AND pm.meta_key = '_total_sales'
                        LIMIT 1
                    ) * {$sales_multiplier}
                ELSE 0
            END
        ";
    });
    
    $mods[] = $mod;
    
    return $mods;
}, 20, 2 );