swp-pre-get-posts.php

<?php

add_action( 'pre_get_posts', function( $query ) {
	if ( ! defined( 'REST_REQUEST' ) || ! REST_REQUEST ) {
    return
  }
  
  if ( is_admin() || ! isset( $query->query['post_type'] ) || $query->query['post_type'] !== 'product' ) {
    return;
  }
  
  if ( isset( $_GET['search'] ) && ! empty( $_GET['search'] ) && class_exists( '\SWP_Query' ) ) {
    /** Let's build a SWP_Query and get some search results */
    $args = [
			's' => $_GET['search'],
      'fields' => 'ids',
      'posts_per_page' => $query->get( 'posts_per_page' ),
    ];

    if ( ! empty( $query->get( 'tax_query' ) ) ) {
      $args['tax_query'] = $query->get( 'tax_query' );
    }

    if ( ! empty( $query->get( 'meta_query' ) ) ) {
      $args['meta_query'] = $query->get( 'meta_query' );
    }

    /** Now we take our search results and punch them into the query */
    $swp = new \SWP_Query( $args );
    if ( ! empty( $swp->posts ) ) {
      $query->set( 'post__in', $swp->posts );
      // Tell the query it's not a search anymore or we get screwed up results
      $query->set( 's', '' );
    }
  }
  
}, 1, 1 );