Overview of how to log webform

webform_logging.php

<?php

// Inside civihr_employee_portal.module..

// this will enable logging before data is saved
function civihr_employee_portal_webform_submission_presave($node, &$submission) {
  // todo restrict to certain nodes
  $logger = Civi::container()->get(ApiChangelogWrapper::class);
  $logger->setIsActive(TRUE);
}

// this will just set up the wrapper
function civihr_employee_portal_civicrm_apiWrappers(&$wrappers, $apiRequest) {
  // This is a temp solution, will change to container hook
  if (!Civi::container()->has(ApiChangelogWrapper::class)) {
    Civi::container()->set(ApiChangelogWrapper::class, new ApiChangelogWrapper());
  }
  // We could also separate the wrapper from the logger (i.e. the wrapper would just call the logger service)
  $wrapper = Civi::container()->get(ApiChangelogWrapper::class);
  $wrappers[] = $wrapper;
}

// disable logging after inserting data, we have access to all requests here
function civihr_employee_portal_webform_submission_insert($node, $submission) {
  $logger = Civi::container()->get(ApiChangelogWrapper::class);
  $logger->setIsActive(FALSE);
}

// Inside the wrapper (abbreviated)
class ApiChangelogWrapper implements \API_Wrapper {

  /**
   * Logs the API request if logging is enabled
   *
   * @inheritdoc
   */
  public function fromApiInput($apiRequest) {
    if ($this->isActive) {
      // Just a sample filter, these should be configurable class properties
      $filter = function ($apiRequest) {
        return $apiRequest['action'] === 'create';
      };

      if ($filter($apiRequest)) {
        $this->changes[] = $apiRequest;
      }
      // this is just a sample where we store the request, we could 
      // fetch the existing value here and store the changelog
    }

    return $apiRequest;
  }
}