Modifying Basel Ajax Product Search with functions.php

Greetings! I am about to go live with my company store and realized that when people search for “hat” they are getting product results that include any iteration of “hat” even if it’s in a word like “tHAT” or “wHAT” This is unacceptable. I’ve tried using other plugins, but they end up adding a search bar to the header and it throws the entire layout off balance.

SO, to fix this I added the following code to the child functions.php file. BUT, it’s not working! All I want to do is be able to search products using tags, categories, and titles while also excluding results from partial words. What am I mising? Can you please provide the code needed to make this happen using the child functions.php?

Your help is MUCH appreciated!!! THANKS IN ADVANCE!

/**
 * Custom Woocommerce search
 */
add_filter('the_posts', 'search_by_product_tag');

function search_by_product_tag($posts, $query = '') {
    if (is_search()) {
        $tags = explode(',', get_search_query());
    }
    if ($query != '') {
        $tags = explode(',', $query);
    }
    if (!$tags)
        return $posts;

    foreach($tags as $tag)
    {
        //Ignore already found posts from query..
        $ignoreIds = array(0);
        foreach($posts as $post)
        {
            $ignoreIds[] = $post->ID;
        }

        $matchedTags = get_post_by_tag(trim($tag), $ignoreIds);
        //var_dump($ignoreIds,$matchedTags);
        //die();
        if ($matchedTags)
        {
            foreach($matchedTags as $product_id)
            {
                $posts[] = get_post($product_id->post_id);
            }

        }
    }

    //var_dump($posts);
    return $posts;

}

function get_post_by_tag($tag, $ignoreIds) {
    //Check for
    global $wpdb, $wp_query;

    //$ordering_args = WC()->query->get_catalog_ordering_args( $orderby, $order );

    /**
     * Special code for removing duplicates if WPML plugin is installed
     * Its popular translation plugin that causes lots of product duplicate products that have different product ids
     * We need to check the wpml meta data of the product to work out the duplicates
     */

    $wmplEnabled = false;

    if(defined('WPML_TM_VERSION') && defined('WPML_ST_VERSION') && class_exists("woocommerce_wpml")){
        $wmplEnabled = true;
        //What language should we search for...
        $languageCode = ICL_LANGUAGE_CODE;
    }
    //  $wmplEnabled = false;
    $ignoreIdsForMySql = implode(",", $ignoreIds);
    //var_dump($ignoreIdsForMySql);
    $query = "
            select p.ID as post_id from $wpdb->terms t
            join $wpdb->term_taxonomy tt
            on t.term_id = tt.term_id
            join $wpdb->term_relationships tr
            on tt.term_taxonomy_id = tr.term_taxonomy_id
            join $wpdb->posts p
            on p.ID = tr.object_id
            join $wpdb->postmeta visibility
            on p.ID = visibility.post_id
            and visibility.meta_key = '_visibility'
            and visibility.meta_value <> 'hidden'
            ";

    //IF WPML Plugin is enabled join and get correct language product.
    if($wmplEnabled)
    {
        $query .=
            "join ".$wpdb->prefix."icl_translations trans on
         trans.element_id = p.ID
         and trans.element_type = 'post_product'
         and trans.language_code = '$languageCode'";
    }

    $query .= "
            WHERE
            tt.taxonomy = 'product_tag' and
            t.name LIKE '%$tag%'
            and p.post_status = 'publish'
            and p.post_type = 'product'
            and (p.post_parent = 0 or p.post_parent is null)
            and p.ID not in ($ignoreIdsForMySql)
            group by p.ID
             ;
";

    //Search for the sku of a variation and return the parent.
    $matchedProducts = $wpdb->get_results($query) ;

    //var_dump($matchedProducts);
    if(is_array($matchedProducts) && !empty($matchedProducts))
    {
        //var_dump($matchedProducts);
        $wp_query->found_posts += sizeof($matchedProducts);
        //var_dump($wp_query->found_posts, sizeof($matchedProducts));
        return $matchedProducts;

    }

    //return get_post($product_id);

    return null;
}