Use Groundhogg contact fields inside WPForms as smart tags

plugin.php

<?php
/**
 * Plugin Name: WPForms GH Contact Smart Tag
 * Plugin URI:
 * Description: Use Groundhogg contact fields inside WPForms with Smart Tags. Se here for more informations about WPFOrms Smart Tags: https://wpforms.com/docs/how-to-use-smart-tags-in-wpforms/
 * Version: 1.0
 * Author: Marco Michely
 * Author URI: https://www.michely-web-engineering.de
 */
defined( 'ABSPATH' ) or die( 'No script kiddies please!' );

/**
 * Register the Smart Tag so it will be available to select in the form builder.
 *
 * @link   https://wpforms.com/developers/how-to-create-a-custom-smart-tag/
 *
 * @param  array $tags
 * @return array
 */
function mwewpfghst_register_smarttag( $tags ) {

  if(is_plugin_active( 'groundhogg/groundhogg.php' )) {

    // Key is the tag, item is the tag name.
    $tags['ghcontact_first'] = "GH Contact First Name";
    $tags['ghcontact_last'] = "GH Contact Last Name";
    $tags['ghcontact_full_name'] = "GH Contact Full Name";
    $tags['ghcontact_job_title'] = "GH Contact Job Title";
    $tags['ghcontact_email'] = "GH Contact EMail";
    $tags['ghcontact_phone'] = "GH Contact Phone";
    $tags['ghcontact_phone_ext'] = "GH Contact Phone number extension";
    $tags['ghcontact_address'] = "GH Contact Address";
    $tags['ghcontact_company_name'] = "GH Contact Company Name";
    $tags['ghcontact_company_address'] = "GH Contact Company Address";
    $tags['ghcontact_username'] = "GH Contact User Name";
    // $tags['ghcontact_'] = "GH Contact ";
  }
  return $tags;
}
add_filter( 'wpforms_smart_tags', 'mwewpfghst_register_smarttag' );

/**
 * Process the Smart Tag.
 *
 * @link   https://wpforms.com/developers/how-to-create-a-custom-smart-tag/
 *
 * @param  string $content
 * @param  string $tag
 * @return string
 */
function mwewpfghst_process_smarttag( $content, $tag ) {

  // Only run if it is our desired tag.
  if ( strpos($tag, "ghcontact_") === 0 ) {

    $gh_field = str_replace("ghcontact_", "", $tag);

    // Replace the tag with Groundhogg contact information.
    $sc_processed = do_shortcode('[gh_is_contact][gh_replacements]{'.$gh_field.'}[/gh_replacements][/gh_is_contact]');
    /* $sc_processed = do_shortcode("[gh_is_contact][gh_contact
    field='".$gh_field."'][/gh_is_contact]"); */

    $replacement = ($sc_processed !== $gh_field) ? $sc_processed : NULL;

    $content = str_replace( '{ghcontact_' . $gh_field . '}', $replacement, $content );

  }
	return $content;
}
add_filter( 'wpforms_smart_tag_process', 'mwewpfghst_process_smarttag', 10, 2 );