MODX Manager Redirect

managerRedirect.plugin.php

<?php
// Add a system setting per user or group for 'manager_start_page'. 
// The redirect contains action variable already, so you just need everything after '?a='
// Set the plugin to run OnManagerLogin
$managerurl = ((!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') || $_SERVER['SERVER_PORT'] == 443) ? 'https://' : 'http://';
$managerurl .= $_SERVER['HTTP_HOST'];
$managerurl .= $modx->getOption('manager_url');
//$modx->log(1,$managerurl. ' '.$_SERVER['HTTP_REFERER']);
if ($modx->event->name == 'OnManagerLogin' && $_SERVER['HTTP_REFERER'] == $managerurl){
    $managerRedirect = $modx->getOption('manager_start_page');
    if(!empty($user)){
      $settings = $user->getSettings();
      if(!empty($settings['manager_start_page'])){
          $managerRedirect = $settings['manager_start_page'];
      }
    }
    if(!empty($managerRedirect)) 
      $modx->sendRedirect($managerurl.'?a='.$managerRedirect);
}