function ktc_sync_ldap_display_name($user_id, $username, $password) {
    $ldap_server = "ldap://your.ad.server"; // Or IP
    $ldap_dn = "CN=ServiceAccount,OU=Users,DC=krista,DC=local";
    $ldap_pass = "YourPassword";
    $base_dn = "OU=Users,DC=krista,DC=local";

    $ds = ldap_connect($ldap_server);
    ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION, 3);
    ldap_set_option($ds, LDAP_OPT_REFERRALS, 0);

    if (ldap_bind($ds, $ldap_dn, $ldap_pass)) {
        // Search by email (which is the WP username)
        $filter = "(mail=$username)";
        $sr = ldap_search($ds, $base_dn, $filter, array("displayname", "mail"));
        $info = ldap_get_entries($ds, $sr);

        if ($info["count"] > 0) {
            $friendly_name = $info[0]["displayname"][0];
            
            // Update WordPress User
            wp_update_user(array(
                'ID' => $user_id,
                'display_name' => $friendly_name,
                'nickname'     => $friendly_name
            ));
            
            // Force WP to use Display Name publicly
            update_user_meta($user_id, 'display_name', $friendly_name);
        }
    }
    ldap_unbind($ds);
}