ElasticPress query using prefix match

ep-prefix-search.php

<?php

/**
 * Wrapper for WP_Query that performs a prefix search.
 *
 * @param string $url The URL string to search for.
 * @param array $args Args to pass to WP_Query
 * @return WP_Query
 */
function ep_url_prefix_search( string $url, array $args = [] ) : WP_Query {
  $args['ep_integrate'] = true;
  $args['url_prefix_search'] = true;
  $args['s'] = $url;
  return new WP_Query( $args );
}

/**
 * Filter EP search query to do a prefix search on the permalink.
 *
 * @param array $query The current ElasticSearch query.
 * @param array $args The WP_Query args.
 * @return array
 */
function ep_url_prefix_search_query_args( array $query, array $args ) : array {
  if ( ! isset( $args['url_prefix_search'] ) ) {
    return $query;
  }
  // Return a simple prefix query.
  return [
    'prefix' => [
      // URL decode and trim wildcard chars, prefix query doesn't require them.
      'permalink' => urldecode( trim( $args['s'], '*' ) ),
    ],
  ];
}

add_filter( 'ep_formatted_args_query', 'ep_url_prefix_search_query_args', 11, 2 );