eventespresso / event-espresso-core

modules/single_page_checkout/EED_Single_Page_Checkout.module.php

Indentation +1792 added lines, -1792 removed lines

@@ -15,1796 +15,1796 @@
 class EED_Single_Page_Checkout extends EED_Module
 {
 
-    /**
-     * $_initialized - has the SPCO controller already been initialized ?
-     *
-     * @access private
-     * @var bool $_initialized
-     */
-    private static $_initialized = false;
-
-
-    /**
-     * $_checkout_verified - is the EE_Checkout verified as correct for this request ?
-     *
-     * @access private
-     * @var bool $_valid_checkout
-     */
-    private static $_checkout_verified = true;
-
-    /**
-     *    $_reg_steps_array - holds initial array of reg steps
-     *
-     * @access private
-     * @var array $_reg_steps_array
-     */
-    private static $_reg_steps_array = array();
-
-    /**
-     *    $checkout - EE_Checkout object for handling the properties of the current checkout process
-     *
-     * @access public
-     * @var EE_Checkout $checkout
-     */
-    public $checkout;
-
-
-    /**
-     * @return EED_Module|EED_Single_Page_Checkout
-     */
-    public static function instance()
-    {
-        add_filter('EED_Single_Page_Checkout__SPCO_active', '__return_true');
-        return parent::get_instance(__CLASS__);
-    }
-
-
-    /**
-     * @return EE_CART
-     */
-    public function cart()
-    {
-        return $this->checkout->cart;
-    }
-
-
-    /**
-     * @return EE_Transaction
-     */
-    public function transaction()
-    {
-        return $this->checkout->transaction;
-    }
-
-
-    /**
-     *    set_hooks - for hooking into EE Core, other modules, etc
-     *
-     * @access    public
-     * @return    void
-     * @throws EE_Error
-     */
-    public static function set_hooks()
-    {
-        EED_Single_Page_Checkout::set_definitions();
-    }
-
-
-    /**
-     *    set_hooks_admin - for hooking into EE Admin Core, other modules, etc
-     *
-     * @access    public
-     * @return    void
-     * @throws EE_Error
-     */
-    public static function set_hooks_admin()
-    {
-        EED_Single_Page_Checkout::set_definitions();
-        if (! (defined('DOING_AJAX') && DOING_AJAX)) {
-            return;
-        }
-        // going to start an output buffer in case anything gets accidentally output
-        // that might disrupt our JSON response
-        ob_start();
-        EED_Single_Page_Checkout::load_request_handler();
-        EED_Single_Page_Checkout::load_reg_steps();
-        // set ajax hooks
-        add_action('wp_ajax_process_reg_step', array('EED_Single_Page_Checkout', 'process_reg_step'));
-        add_action('wp_ajax_nopriv_process_reg_step', array('EED_Single_Page_Checkout', 'process_reg_step'));
-        add_action('wp_ajax_display_spco_reg_step', array('EED_Single_Page_Checkout', 'display_reg_step'));
-        add_action('wp_ajax_nopriv_display_spco_reg_step', array('EED_Single_Page_Checkout', 'display_reg_step'));
-        add_action('wp_ajax_update_reg_step', array('EED_Single_Page_Checkout', 'update_reg_step'));
-        add_action('wp_ajax_nopriv_update_reg_step', array('EED_Single_Page_Checkout', 'update_reg_step'));
-    }
-
-
-    /**
-     *    process ajax request
-     *
-     * @param string $ajax_action
-     * @throws EE_Error
-     */
-    public static function process_ajax_request($ajax_action)
-    {
-        EE_Registry::instance()->REQ->set('action', $ajax_action);
-        EED_Single_Page_Checkout::instance()->_initialize();
-    }
-
-
-    /**
-     *    ajax display registration step
-     *
-     * @throws EE_Error
-     */
-    public static function display_reg_step()
-    {
-        EED_Single_Page_Checkout::process_ajax_request('display_spco_reg_step');
-    }
-
-
-    /**
-     *    ajax process registration step
-     *
-     * @throws EE_Error
-     */
-    public static function process_reg_step()
-    {
-        EED_Single_Page_Checkout::process_ajax_request('process_reg_step');
-    }
-
-
-    /**
-     *    ajax process registration step
-     *
-     * @throws EE_Error
-     */
-    public static function update_reg_step()
-    {
-        EED_Single_Page_Checkout::process_ajax_request('update_reg_step');
-    }
-
-
-    /**
-     *   update_checkout
-     *
-     * @access public
-     * @return void
-     * @throws EE_Error
-     */
-    public static function update_checkout()
-    {
-        EED_Single_Page_Checkout::process_ajax_request('update_checkout');
-    }
-
-
-    /**
-     *    load_request_handler
-     *
-     * @access    public
-     * @return    void
-     */
-    public static function load_request_handler()
-    {
-        // load core Request_Handler class
-        if (EE_Registry::instance()->REQ !== null) {
-            EE_Registry::instance()->load_core('Request_Handler');
-        }
-    }
-
-
-    /**
-     *    set_definitions
-     *
-     * @access    public
-     * @return    void
-     * @throws EE_Error
-     */
-    public static function set_definitions()
-    {
-        if (defined('SPCO_BASE_PATH')) {
-            return;
-        }
-        define(
-            'SPCO_BASE_PATH',
-            rtrim(str_replace(array('\\', '/'), '/', plugin_dir_path(__FILE__)), '/') . '/'
-        );
-        define('SPCO_CSS_URL', plugin_dir_url(__FILE__) . 'css/');
-        define('SPCO_IMG_URL', plugin_dir_url(__FILE__) . 'img/');
-        define('SPCO_JS_URL', plugin_dir_url(__FILE__) . 'js/');
-        define('SPCO_INC_PATH', SPCO_BASE_PATH . 'inc/');
-        define('SPCO_REG_STEPS_PATH', SPCO_BASE_PATH . 'reg_steps/');
-        define('SPCO_TEMPLATES_PATH', SPCO_BASE_PATH . 'templates/');
-        EEH_Autoloader::register_autoloaders_for_each_file_in_folder(SPCO_BASE_PATH, true);
-        EE_Registry::$i18n_js_strings['registration_expiration_notice'] = EED_Single_Page_Checkout::getRegistrationExpirationNotice(
-        );
-    }
-
-
-    /**
-     * load_reg_steps
-     * loads and instantiates each reg step based on the EE_Registry::instance()->CFG->registration->reg_steps array
-     *
-     * @access    private
-     * @throws EE_Error
-     */
-    public static function load_reg_steps()
-    {
-        static $reg_steps_loaded = false;
-        if ($reg_steps_loaded) {
-            return;
-        }
-        // filter list of reg_steps
-        $reg_steps_to_load = (array) apply_filters(
-            'AHEE__SPCO__load_reg_steps__reg_steps_to_load',
-            EED_Single_Page_Checkout::get_reg_steps()
-        );
-        // sort by key (order)
-        ksort($reg_steps_to_load);
-        // loop through folders
-        foreach ($reg_steps_to_load as $order => $reg_step) {
-            // we need a
-            if (isset($reg_step['file_path'], $reg_step['class_name'], $reg_step['slug'])) {
-                // copy over to the reg_steps_array
-                EED_Single_Page_Checkout::$_reg_steps_array[ $order ] = $reg_step;
-                // register custom key route for each reg step
-                // ie: step=>"slug" - this is the entire reason we load the reg steps array now
-                EE_Config::register_route(
-                    $reg_step['slug'],
-                    'EED_Single_Page_Checkout',
-                    'run',
-                    'step'
-                );
-                // add AJAX or other hooks
-                if (isset($reg_step['has_hooks']) && $reg_step['has_hooks']) {
-                    // setup autoloaders if necessary
-                    if (! class_exists($reg_step['class_name'])) {
-                        EEH_Autoloader::register_autoloaders_for_each_file_in_folder(
-                            $reg_step['file_path'],
-                            true
-                        );
-                    }
-                    if (is_callable($reg_step['class_name'], 'set_hooks')) {
-                        call_user_func(array($reg_step['class_name'], 'set_hooks'));
-                    }
-                }
-            }
-        }
-        $reg_steps_loaded = true;
-    }
-
-
-    /**
-     *    get_reg_steps
-     *
-     * @access    public
-     * @return    array
-     */
-    public static function get_reg_steps()
-    {
-        $reg_steps = EE_Registry::instance()->CFG->registration->reg_steps;
-        if (empty($reg_steps)) {
-            $reg_steps = array(
-                10  => array(
-                    'file_path'  => SPCO_REG_STEPS_PATH . 'attendee_information',
-                    'class_name' => 'EE_SPCO_Reg_Step_Attendee_Information',
-                    'slug'       => 'attendee_information',
-                    'has_hooks'  => false,
-                ),
-                30  => array(
-                    'file_path'  => SPCO_REG_STEPS_PATH . 'payment_options',
-                    'class_name' => 'EE_SPCO_Reg_Step_Payment_Options',
-                    'slug'       => 'payment_options',
-                    'has_hooks'  => true,
-                ),
-                999 => array(
-                    'file_path'  => SPCO_REG_STEPS_PATH . 'finalize_registration',
-                    'class_name' => 'EE_SPCO_Reg_Step_Finalize_Registration',
-                    'slug'       => 'finalize_registration',
-                    'has_hooks'  => false,
-                ),
-            );
-        }
-        return $reg_steps;
-    }
-
-
-    /**
-     *    registration_checkout_for_admin
-     *
-     * @access    public
-     * @return    string
-     * @throws EE_Error
-     */
-    public static function registration_checkout_for_admin()
-    {
-        EED_Single_Page_Checkout::load_request_handler();
-        EE_Registry::instance()->REQ->set('step', 'attendee_information');
-        EE_Registry::instance()->REQ->set('action', 'display_spco_reg_step');
-        EE_Registry::instance()->REQ->set('process_form_submission', false);
-        EED_Single_Page_Checkout::instance()->_initialize();
-        EED_Single_Page_Checkout::instance()->_display_spco_reg_form();
-        return EE_Registry::instance()->REQ->get_output();
-    }
-
-
-    /**
-     * process_registration_from_admin
-     *
-     * @access public
-     * @return \EE_Transaction
-     * @throws EE_Error
-     */
-    public static function process_registration_from_admin()
-    {
-        EED_Single_Page_Checkout::load_request_handler();
-        EE_Registry::instance()->REQ->set('step', 'attendee_information');
-        EE_Registry::instance()->REQ->set('action', 'process_reg_step');
-        EE_Registry::instance()->REQ->set('process_form_submission', true);
-        EED_Single_Page_Checkout::instance()->_initialize();
-        if (EED_Single_Page_Checkout::instance()->checkout->current_step->completed()) {
-            $final_reg_step = end(EED_Single_Page_Checkout::instance()->checkout->reg_steps);
-            if ($final_reg_step instanceof EE_SPCO_Reg_Step_Finalize_Registration) {
-                EED_Single_Page_Checkout::instance()->checkout->set_reg_step_initiated($final_reg_step);
-                if ($final_reg_step->process_reg_step()) {
-                    $final_reg_step->set_completed();
-                    EED_Single_Page_Checkout::instance()->checkout->update_txn_reg_steps_array();
-                    return EED_Single_Page_Checkout::instance()->checkout->transaction;
-                }
-            }
-        }
-        return null;
-    }
-
-
-    /**
-     *    run
-     *
-     * @access    public
-     * @param WP_Query $WP_Query
-     * @return    void
-     * @throws EE_Error
-     */
-    public function run($WP_Query)
-    {
-        if ($WP_Query instanceof WP_Query
-            && $WP_Query->is_main_query()
-            && apply_filters('FHEE__EED_Single_Page_Checkout__run', true)
-            && $this->_is_reg_checkout()
-        ) {
-            $this->_initialize();
-        }
-    }
-
-
-    /**
-     * determines whether current url matches reg page url
-     *
-     * @return bool
-     */
-    protected function _is_reg_checkout()
-    {
-        // get current permalink for reg page without any extra query args
-        $reg_page_url = \get_permalink(EE_Config::instance()->core->reg_page_id);
-        // get request URI for current request, but without the scheme or host
-        $current_request_uri = \EEH_URL::filter_input_server_url('REQUEST_URI');
-        $current_request_uri = html_entity_decode($current_request_uri);
-        // get array of query args from the current request URI
-        $query_args = \EEH_URL::get_query_string($current_request_uri);
-        // grab page id if it is set
-        $page_id = isset($query_args['page_id']) ? absint($query_args['page_id']) : 0;
-        // and remove the page id from the query args (we will re-add it later)
-        unset($query_args['page_id']);
-        // now strip all query args from current request URI
-        $current_request_uri = remove_query_arg(array_keys($query_args), $current_request_uri);
-        // and re-add the page id if it was set
-        if ($page_id) {
-            $current_request_uri = add_query_arg('page_id', $page_id, $current_request_uri);
-        }
-        // remove slashes and ?
-        $current_request_uri = trim($current_request_uri, '?/');
-        // is current request URI part of the known full reg page URL ?
-        return ! empty($current_request_uri) && strpos($reg_page_url, $current_request_uri) !== false;
-    }
-
-
-    /**
-     * @param WP_Query $wp_query
-     * @return    void
-     * @throws EE_Error
-     */
-    public static function init($wp_query)
-    {
-        EED_Single_Page_Checkout::instance()->run($wp_query);
-    }
-
-
-    /**
-     *    _initialize - initial module setup
-     *
-     * @access    private
-     * @throws EE_Error
-     * @return    void
-     */
-    private function _initialize()
-    {
-        // ensure SPCO doesn't run twice
-        if (EED_Single_Page_Checkout::$_initialized) {
-            return;
-        }
-        try {
-            EED_Single_Page_Checkout::load_reg_steps();
-            $this->_verify_session();
-            // setup the EE_Checkout object
-            $this->checkout = $this->_initialize_checkout();
-            // filter checkout
-            $this->checkout = apply_filters('FHEE__EED_Single_Page_Checkout___initialize__checkout', $this->checkout);
-            // get the $_GET
-            $this->_get_request_vars();
-            if ($this->_block_bots()) {
-                return;
-            }
-            // filter continue_reg
-            $this->checkout->continue_reg = apply_filters(
-                'FHEE__EED_Single_Page_Checkout__init___continue_reg',
-                true,
-                $this->checkout
-            );
-            // load the reg steps array
-            if (! $this->_load_and_instantiate_reg_steps()) {
-                EED_Single_Page_Checkout::$_initialized = true;
-                return;
-            }
-            // set the current step
-            $this->checkout->set_current_step($this->checkout->step);
-            // and the next step
-            $this->checkout->set_next_step();
-            // verify that everything has been setup correctly
-            if (! ($this->_verify_transaction_and_get_registrations() && $this->_final_verifications())) {
-                EED_Single_Page_Checkout::$_initialized = true;
-                return;
-            }
-            // lock the transaction
-            $this->checkout->transaction->lock();
-            // make sure all of our cached objects are added to their respective model entity mappers
-            $this->checkout->refresh_all_entities();
-            // set amount owing
-            $this->checkout->amount_owing = $this->checkout->transaction->remaining();
-            // initialize each reg step, which gives them the chance to potentially alter the process
-            $this->_initialize_reg_steps();
-            // DEBUG LOG
-            // $this->checkout->log( __CLASS__, __FUNCTION__, __LINE__ );
-            // get reg form
-            if (! $this->_check_form_submission()) {
-                EED_Single_Page_Checkout::$_initialized = true;
-                return;
-            }
-            // checkout the action!!!
-            $this->_process_form_action();
-            // add some style and make it dance
-            $this->add_styles_and_scripts($this);
-            // kk... SPCO has successfully run
-            EED_Single_Page_Checkout::$_initialized = true;
-            // set no cache headers and constants
-            EE_System::do_not_cache();
-            // add anchor
-            add_action('loop_start', array($this, 'set_checkout_anchor'), 1);
-            // remove transaction lock
-            add_action('shutdown', array($this, 'unlock_transaction'), 1);
-        } catch (Exception $e) {
-            EE_Error::add_error($e->getMessage(), __FILE__, __FUNCTION__, __LINE__);
-        }
-    }
-
-
-    /**
-     *    _verify_session
-     * checks that the session is valid and not expired
-     *
-     * @access    private
-     * @throws EE_Error
-     */
-    private function _verify_session()
-    {
-        if (! EE_Registry::instance()->SSN instanceof EE_Session) {
-            throw new EE_Error(esc_html__('The EE_Session class could not be loaded.', 'event_espresso'));
-        }
-        $clear_session_requested = filter_var(
-            EE_Registry::instance()->REQ->get('clear_session', false),
-            FILTER_VALIDATE_BOOLEAN
-        );
-        // is session still valid ?
-        if ($clear_session_requested
-            || (EE_Registry::instance()->SSN->expired()
-                && EE_Registry::instance()->REQ->get('e_reg_url_link', '') === ''
-            )
-        ) {
-            $this->checkout = new EE_Checkout();
-            EE_Registry::instance()->SSN->clear_session(__CLASS__, __FUNCTION__);
-            // EE_Registry::instance()->SSN->reset_cart();
-            // EE_Registry::instance()->SSN->reset_checkout();
-            // EE_Registry::instance()->SSN->reset_transaction();
-            if (! $clear_session_requested) {
-                EE_Error::add_attention(
-                    EE_Registry::$i18n_js_strings['registration_expiration_notice'],
-                    __FILE__,
-                    __FUNCTION__,
-                    __LINE__
-                );
-            }
-            // EE_Registry::instance()->SSN->reset_expired();
-        }
-    }
-
-
-    /**
-     *    _initialize_checkout
-     * loads and instantiates EE_Checkout
-     *
-     * @access    private
-     * @throws EE_Error
-     * @return EE_Checkout
-     */
-    private function _initialize_checkout()
-    {
-        // look in session for existing checkout
-        /** @type EE_Checkout $checkout */
-        $checkout = EE_Registry::instance()->SSN->checkout();
-        // verify
-        if (! $checkout instanceof EE_Checkout) {
-            // instantiate EE_Checkout object for handling the properties of the current checkout process
-            $checkout = EE_Registry::instance()->load_file(
-                SPCO_INC_PATH,
-                'EE_Checkout',
-                'class',
-                array(),
-                false
-            );
-        } else {
-            if ($checkout->current_step->is_final_step() && $checkout->exit_spco() === true) {
-                $this->unlock_transaction();
-                wp_safe_redirect($checkout->redirect_url);
-                exit();
-            }
-        }
-        $checkout = apply_filters('FHEE__EED_Single_Page_Checkout___initialize_checkout__checkout', $checkout);
-        // verify again
-        if (! $checkout instanceof EE_Checkout) {
-            throw new EE_Error(esc_html__('The EE_Checkout class could not be loaded.', 'event_espresso'));
-        }
-        // reset anything that needs a clean slate for each request
-        $checkout->reset_for_current_request();
-        return $checkout;
-    }
-
-
-    /**
-     *    _get_request_vars
-     *
-     * @access    private
-     * @return    void
-     * @throws EE_Error
-     */
-    private function _get_request_vars()
-    {
-        // load classes
-        EED_Single_Page_Checkout::load_request_handler();
-        // make sure this request is marked as belonging to EE
-        EE_Registry::instance()->REQ->set_espresso_page(true);
-        // which step is being requested ?
-        $this->checkout->step = EE_Registry::instance()->REQ->get('step', $this->_get_first_step());
-        // which step is being edited ?
-        $this->checkout->edit_step = EE_Registry::instance()->REQ->get('edit_step', '');
-        // and what we're doing on the current step
-        $this->checkout->action = EE_Registry::instance()->REQ->get('action', 'display_spco_reg_step');
-        // timestamp
-        $this->checkout->uts = EE_Registry::instance()->REQ->get('uts', 0);
-        // returning to edit ?
-        $this->checkout->reg_url_link = EE_Registry::instance()->REQ->get('e_reg_url_link', '');
-        // add reg url link to registration query params
-        if ($this->checkout->reg_url_link && strpos($this->checkout->reg_url_link, '1-') !== 0) {
-            $this->checkout->reg_cache_where_params[0]['REG_url_link'] = $this->checkout->reg_url_link;
-        }
-        // or some other kind of revisit ?
-        $this->checkout->revisit = filter_var(
-            EE_Registry::instance()->REQ->get('revisit', false),
-            FILTER_VALIDATE_BOOLEAN
-        );
-        // and whether or not to generate a reg form for this request
-        $this->checkout->generate_reg_form = filter_var(
-            EE_Registry::instance()->REQ->get('generate_reg_form', true),
-            FILTER_VALIDATE_BOOLEAN
-        );
-        // and whether or not to process a reg form submission for this request
-        $this->checkout->process_form_submission = filter_var(
-            EE_Registry::instance()->REQ->get(
-                'process_form_submission',
-                $this->checkout->action === 'process_reg_step'
-            ),
-            FILTER_VALIDATE_BOOLEAN
-        );
-        $this->checkout->process_form_submission = filter_var(
-            $this->checkout->action !== 'display_spco_reg_step'
-                ? $this->checkout->process_form_submission
-                : false,
-            FILTER_VALIDATE_BOOLEAN
-        );
-        // $this->_display_request_vars();
-    }
-
-
-    /**
-     *  _display_request_vars
-     *
-     * @access    protected
-     * @return    void
-     */
-    protected function _display_request_vars()
-    {
-        if (! WP_DEBUG) {
-            return;
-        }
-        EEH_Debug_Tools::printr($_REQUEST, '$_REQUEST', __FILE__, __LINE__);
-        EEH_Debug_Tools::printr($this->checkout->step, '$this->checkout->step', __FILE__, __LINE__);
-        EEH_Debug_Tools::printr($this->checkout->edit_step, '$this->checkout->edit_step', __FILE__, __LINE__);
-        EEH_Debug_Tools::printr($this->checkout->action, '$this->checkout->action', __FILE__, __LINE__);
-        EEH_Debug_Tools::printr($this->checkout->reg_url_link, '$this->checkout->reg_url_link', __FILE__, __LINE__);
-        EEH_Debug_Tools::printr($this->checkout->revisit, '$this->checkout->revisit', __FILE__, __LINE__);
-        EEH_Debug_Tools::printr(
-            $this->checkout->generate_reg_form,
-            '$this->checkout->generate_reg_form',
-            __FILE__,
-            __LINE__
-        );
-        EEH_Debug_Tools::printr(
-            $this->checkout->process_form_submission,
-            '$this->checkout->process_form_submission',
-            __FILE__,
-            __LINE__
-        );
-    }
-
-
-    /**
-     * _block_bots
-     * checks that the incoming request has either of the following set:
-     *  a uts (unix timestamp) which indicates that the request was redirected from the Ticket Selector
-     *  a REG URL Link, which indicates that the request is a return visit to SPCO for a valid TXN
-     * so if you're not coming from the Ticket Selector nor returning for a valid IP...
-     * then where you coming from man?
-     *
-     * @return boolean
-     */
-    private function _block_bots()
-    {
-        $invalid_checkout_access = EED_Invalid_Checkout_Access::getInvalidCheckoutAccess();
-        if ($invalid_checkout_access->checkoutAccessIsInvalid($this->checkout)) {
-            return true;
-        }
-        return false;
-    }
-
-
-    /**
-     *    _get_first_step
-     *  gets slug for first step in $_reg_steps_array
-     *
-     * @access    private
-     * @throws EE_Error
-     * @return    string
-     */
-    private function _get_first_step()
-    {
-        $first_step = reset(EED_Single_Page_Checkout::$_reg_steps_array);
-        return isset($first_step['slug']) ? $first_step['slug'] : 'attendee_information';
-    }
-
-
-    /**
-     * instantiates each reg step based on the loaded reg_steps array
-     *
-     * @return    bool
-     * @throws EE_Error
-     * @throws InvalidArgumentException
-     * @throws InvalidDataTypeException
-     * @throws InvalidInterfaceException
-     */
-    private function _load_and_instantiate_reg_steps()
-    {
-        do_action('AHEE__Single_Page_Checkout___load_and_instantiate_reg_steps__start', $this->checkout);
-        // have reg_steps already been instantiated ?
-        if (empty($this->checkout->reg_steps)
-            || apply_filters('FHEE__Single_Page_Checkout__load_reg_steps__reload_reg_steps', false, $this->checkout)
-        ) {
-            // if not, then loop through raw reg steps array
-            foreach (EED_Single_Page_Checkout::$_reg_steps_array as $order => $reg_step) {
-                if (! $this->_load_and_instantiate_reg_step($reg_step, $order)) {
-                    return false;
-                }
-            }
-            if (isset($this->checkout->reg_steps['registration_confirmation'])) {
-                // skip the registration_confirmation page ?
-                if (EE_Registry::instance()->CFG->registration->skip_reg_confirmation) {
-                    // just remove it from the reg steps array
-                    $this->checkout->remove_reg_step('registration_confirmation', false);
-                } elseif (EE_Registry::instance()->CFG->registration->reg_confirmation_last
-                ) {
-                    // set the order to something big like 100
-                    $this->checkout->set_reg_step_order('registration_confirmation', 100);
-                }
-            }
-            // filter the array for good luck
-            $this->checkout->reg_steps = apply_filters(
-                'FHEE__Single_Page_Checkout__load_reg_steps__reg_steps',
-                $this->checkout->reg_steps
-            );
-            // finally re-sort based on the reg step class order properties
-            $this->checkout->sort_reg_steps();
-        } else {
-            foreach ($this->checkout->reg_steps as $reg_step) {
-                // set all current step stati to FALSE
-                $reg_step->set_is_current_step(false);
-            }
-        }
-        if (empty($this->checkout->reg_steps)) {
-            EE_Error::add_error(
-                esc_html__('No Reg Steps were loaded..', 'event_espresso'),
-                __FILE__,
-                __FUNCTION__,
-                __LINE__
-            );
-            return false;
-        }
-        // make reg step details available to JS
-        $this->checkout->set_reg_step_JSON_info();
-        return true;
-    }
-
-
-    /**
-     *     _load_and_instantiate_reg_step
-     *
-     * @access    private
-     * @param array $reg_step
-     * @param int   $order
-     * @return bool
-     */
-    private function _load_and_instantiate_reg_step($reg_step = array(), $order = 0)
-    {
-        // we need a file_path, class_name, and slug to add a reg step
-        if (isset($reg_step['file_path'], $reg_step['class_name'], $reg_step['slug'])) {
-            // if editing a specific step, but this is NOT that step... (and it's not the 'finalize_registration' step)
-            if ($this->checkout->reg_url_link
-                && $this->checkout->step !== $reg_step['slug']
-                && $reg_step['slug'] !== 'finalize_registration'
-                // normally at this point we would NOT load the reg step, but this filter can change that
-                && apply_filters(
-                    'FHEE__Single_Page_Checkout___load_and_instantiate_reg_step__bypass_reg_step',
-                    true,
-                    $reg_step,
-                    $this->checkout
-                )
-            ) {
-                return true;
-            }
-            // instantiate step class using file path and class name
-            $reg_step_obj = EE_Registry::instance()->load_file(
-                $reg_step['file_path'],
-                $reg_step['class_name'],
-                'class',
-                $this->checkout,
-                false
-            );
-            // did we gets the goods ?
-            if ($reg_step_obj instanceof EE_SPCO_Reg_Step) {
-                // set reg step order based on config
-                $reg_step_obj->set_order($order);
-                // add instantiated reg step object to the master reg steps array
-                $this->checkout->add_reg_step($reg_step_obj);
-            } else {
-                EE_Error::add_error(
-                    esc_html__('The current step could not be set.', 'event_espresso'),
-                    __FILE__,
-                    __FUNCTION__,
-                    __LINE__
-                );
-                return false;
-            }
-        } else {
-            if (WP_DEBUG) {
-                EE_Error::add_error(
-                    sprintf(
-                        esc_html__(
-                            'A registration step could not be loaded. One or more of the following data points is invalid:%4$s%5$sFile Path: %1$s%6$s%5$sClass Name: %2$s%6$s%5$sSlug: %3$s%6$s%7$s',
-                            'event_espresso'
-                        ),
-                        isset($reg_step['file_path']) ? $reg_step['file_path'] : '',
-                        isset($reg_step['class_name']) ? $reg_step['class_name'] : '',
-                        isset($reg_step['slug']) ? $reg_step['slug'] : '',
-                        '<ul>',
-                        '<li>',
-                        '</li>',
-                        '</ul>'
-                    ),
-                    __FILE__,
-                    __FUNCTION__,
-                    __LINE__
-                );
-            }
-            return false;
-        }
-        return true;
-    }
-
-
-    /**
-     * _verify_transaction_and_get_registrations
-     *
-     * @access private
-     * @return bool
-     * @throws InvalidDataTypeException
-     * @throws InvalidEntityException
-     * @throws EE_Error
-     */
-    private function _verify_transaction_and_get_registrations()
-    {
-        // was there already a valid transaction in the checkout from the session ?
-        if (! $this->checkout->transaction instanceof EE_Transaction) {
-            // get transaction from db or session
-            $this->checkout->transaction = $this->checkout->reg_url_link && ! is_admin()
-                ? $this->_get_transaction_and_cart_for_previous_visit()
-                : $this->_get_cart_for_current_session_and_setup_new_transaction();
-            if (! $this->checkout->transaction instanceof EE_Transaction) {
-                EE_Error::add_error(
-                    esc_html__(
-                        'Your Registration and Transaction information could not be retrieved from the db.',
-                        'event_espresso'
-                    ),
-                    __FILE__,
-                    __FUNCTION__,
-                    __LINE__
-                );
-                $this->checkout->transaction = EE_Transaction::new_instance();
-                // add some style and make it dance
-                $this->add_styles_and_scripts($this);
-                EED_Single_Page_Checkout::$_initialized = true;
-                return false;
-            }
-            // and the registrations for the transaction
-            $this->_get_registrations($this->checkout->transaction);
-        }
-        return true;
-    }
-
-
-    /**
-     * _get_transaction_and_cart_for_previous_visit
-     *
-     * @access private
-     * @return mixed EE_Transaction|NULL
-     */
-    private function _get_transaction_and_cart_for_previous_visit()
-    {
-        /** @var $TXN_model EEM_Transaction */
-        $TXN_model = EE_Registry::instance()->load_model('Transaction');
-        // because the reg_url_link is present in the request,
-        // this is a return visit to SPCO, so we'll get the transaction data from the db
-        $transaction = $TXN_model->get_transaction_from_reg_url_link($this->checkout->reg_url_link);
-        // verify transaction
-        if ($transaction instanceof EE_Transaction) {
-            // and get the cart that was used for that transaction
-            $this->checkout->cart = $this->_get_cart_for_transaction($transaction);
-            return $transaction;
-        }
-        EE_Error::add_error(
-            esc_html__('Your Registration and Transaction information could not be retrieved from the db.', 'event_espresso'),
-            __FILE__,
-            __FUNCTION__,
-            __LINE__
-        );
-        return null;
-    }
-
-
-    /**
-     * _get_cart_for_transaction
-     *
-     * @access private
-     * @param EE_Transaction $transaction
-     * @return EE_Cart
-     */
-    private function _get_cart_for_transaction($transaction)
-    {
-        return $this->checkout->get_cart_for_transaction($transaction);
-    }
-
-
-    /**
-     * get_cart_for_transaction
-     *
-     * @access public
-     * @param EE_Transaction $transaction
-     * @return EE_Cart
-     */
-    public function get_cart_for_transaction(EE_Transaction $transaction)
-    {
-        return $this->checkout->get_cart_for_transaction($transaction);
-    }
-
-
-    /**
-     * _get_transaction_and_cart_for_current_session
-     *    generates a new EE_Transaction object and adds it to the $_transaction property.
-     *
-     * @access private
-     * @return EE_Transaction
-     * @throws EE_Error
-     */
-    private function _get_cart_for_current_session_and_setup_new_transaction()
-    {
-        //  if there's no transaction, then this is the FIRST visit to SPCO
-        // so load up the cart ( passing nothing for the TXN because it doesn't exist yet )
-        $this->checkout->cart = $this->_get_cart_for_transaction(null);
-        // and then create a new transaction
-        $transaction = $this->_initialize_transaction();
-        // verify transaction
-        if ($transaction instanceof EE_Transaction) {
-            // save it so that we have an ID for other objects to use
-            $transaction->save();
-            // and save TXN data to the cart
-            $this->checkout->cart->get_grand_total()->save_this_and_descendants_to_txn($transaction->ID());
-        } else {
-            EE_Error::add_error(
-                esc_html__('A Valid Transaction could not be initialized.', 'event_espresso'),
-                __FILE__,
-                __FUNCTION__,
-                __LINE__
-            );
-        }
-        return $transaction;
-    }
-
-
-    /**
-     *    generates a new EE_Transaction object and adds it to the $_transaction property.
-     *
-     * @access private
-     * @return mixed EE_Transaction|NULL
-     */
-    private function _initialize_transaction()
-    {
-        try {
-            // ensure cart totals have been calculated
-            $this->checkout->cart->get_grand_total()->recalculate_total_including_taxes();
-            // grab the cart grand total
-            $cart_total = $this->checkout->cart->get_cart_grand_total();
-            // create new TXN
-            $transaction = EE_Transaction::new_instance(
-                array(
-                    'TXN_reg_steps' => $this->checkout->initialize_txn_reg_steps_array(),
-                    'TXN_total'     => $cart_total > 0 ? $cart_total : 0,
-                    'TXN_paid'      => 0,
-                    'STS_ID'        => EEM_Transaction::failed_status_code,
-                )
-            );
-            // save it so that we have an ID for other objects to use
-            $transaction->save();
-            // set cron job for following up on TXNs after their session has expired
-            EE_Cron_Tasks::schedule_expired_transaction_check(
-                EE_Registry::instance()->SSN->expiration() + 1,
-                $transaction->ID()
-            );
-            return $transaction;
-        } catch (Exception $e) {
-            EE_Error::add_error($e->getMessage(), __FILE__, __FUNCTION__, __LINE__);
-        }
-        return null;
-    }
-
-
-    /**
-     * _get_registrations
-     *
-     * @access private
-     * @param EE_Transaction $transaction
-     * @return void
-     * @throws InvalidDataTypeException
-     * @throws InvalidEntityException
-     * @throws EE_Error
-     */
-    private function _get_registrations(EE_Transaction $transaction)
-    {
-        // first step: grab the registrants  { : o
-        $registrations = $transaction->registrations($this->checkout->reg_cache_where_params, false);
-        $this->checkout->total_ticket_count = count($registrations);
-        // verify registrations have been set
-        if (empty($registrations)) {
-            // if no cached registrations, then check the db
-            $registrations = $transaction->registrations($this->checkout->reg_cache_where_params, false);
-            // still nothing ? well as long as this isn't a revisit
-            if (empty($registrations) && ! $this->checkout->revisit) {
-                // generate new registrations from scratch
-                $registrations = $this->_initialize_registrations($transaction);
-            }
-        }
-        // sort by their original registration order
-        usort($registrations, array('EED_Single_Page_Checkout', 'sort_registrations_by_REG_count'));
-        // then loop thru the array
-        foreach ($registrations as $registration) {
-            // verify each registration
-            if ($registration instanceof EE_Registration) {
-                // we display all attendee info for the primary registrant
-                if ($this->checkout->reg_url_link === $registration->reg_url_link()
-                    && $registration->is_primary_registrant()
-                ) {
-                    $this->checkout->primary_revisit = true;
-                    break;
-                }
-                if ($this->checkout->revisit && $this->checkout->reg_url_link !== $registration->reg_url_link()) {
-                    // but hide info if it doesn't belong to you
-                    $transaction->clear_cache('Registration', $registration->ID());
-                    $this->checkout->total_ticket_count--;
-                }
-                $this->checkout->set_reg_status_updated($registration->ID(), false);
-            }
-        }
-    }
-
-
-    /**
-     *    adds related EE_Registration objects for each ticket in the cart to the current EE_Transaction object
-     *
-     * @access private
-     * @param EE_Transaction $transaction
-     * @return    array
-     * @throws InvalidDataTypeException
-     * @throws InvalidEntityException
-     * @throws EE_Error
-     */
-    private function _initialize_registrations(EE_Transaction $transaction)
-    {
-        $att_nmbr = 0;
-        $registrations = array();
-        if ($transaction instanceof EE_Transaction) {
-            /** @type EE_Registration_Processor $registration_processor */
-            $registration_processor = EE_Registry::instance()->load_class('Registration_Processor');
-            $this->checkout->total_ticket_count = $this->checkout->cart->all_ticket_quantity_count();
-            // now let's add the cart items to the $transaction
-            foreach ($this->checkout->cart->get_tickets() as $line_item) {
-                // do the following for each ticket of this type they selected
-                for ($x = 1; $x <= $line_item->quantity(); $x++) {
-                    $att_nmbr++;
-                    /** @var EventEspresso\core\services\commands\registration\CreateRegistrationCommand $CreateRegistrationCommand */
-                    $CreateRegistrationCommand = EE_Registry::instance()->create(
-                        'EventEspresso\core\services\commands\registration\CreateRegistrationCommand',
-                        array(
-                            $transaction,
-                            $line_item,
-                            $att_nmbr,
-                            $this->checkout->total_ticket_count,
-                        )
-                    );
-                    // override capabilities for frontend registrations
-                    if (! is_admin()) {
-                        $CreateRegistrationCommand->setCapCheck(
-                            new PublicCapabilities('', 'create_new_registration')
-                        );
-                    }
-                    $registration = EE_Registry::instance()->BUS->execute($CreateRegistrationCommand);
-                    if (! $registration instanceof EE_Registration) {
-                        throw new InvalidEntityException($registration, 'EE_Registration');
-                    }
-                    $registrations[ $registration->ID() ] = $registration;
-                }
-            }
-            $registration_processor->fix_reg_final_price_rounding_issue($transaction);
-        }
-        return $registrations;
-    }
-
-
-    /**
-     * sorts registrations by REG_count
-     *
-     * @access public
-     * @param EE_Registration $reg_A
-     * @param EE_Registration $reg_B
-     * @return int
-     */
-    public static function sort_registrations_by_REG_count(EE_Registration $reg_A, EE_Registration $reg_B)
-    {
-        // this shouldn't ever happen within the same TXN, but oh well
-        if ($reg_A->count() === $reg_B->count()) {
-            return 0;
-        }
-        return ($reg_A->count() > $reg_B->count()) ? 1 : -1;
-    }
-
-
-    /**
-     *    _final_verifications
-     * just makes sure that everything is set up correctly before proceeding
-     *
-     * @access    private
-     * @return    bool
-     * @throws EE_Error
-     */
-    private function _final_verifications()
-    {
-        // filter checkout
-        $this->checkout = apply_filters(
-            'FHEE__EED_Single_Page_Checkout___final_verifications__checkout',
-            $this->checkout
-        );
-        // verify that current step is still set correctly
-        if (! $this->checkout->current_step instanceof EE_SPCO_Reg_Step) {
-            EE_Error::add_error(
-                esc_html__(
-                    'We\'re sorry but the registration process can not proceed because one or more registration steps were not setup correctly. Please refresh the page and try again or contact support.',
-                    'event_espresso'
-                ),
-                __FILE__,
-                __FUNCTION__,
-                __LINE__
-            );
-            return false;
-        }
-        // if returning to SPCO, then verify that primary registrant is set
-        if (! empty($this->checkout->reg_url_link)) {
-            $valid_registrant = $this->checkout->transaction->primary_registration();
-            if (! $valid_registrant instanceof EE_Registration) {
-                EE_Error::add_error(
-                    esc_html__(
-                        'We\'re sorry but there appears to be an error with the "reg_url_link" or the primary registrant for this transaction. Please refresh the page and try again or contact support.',
-                        'event_espresso'
-                    ),
-                    __FILE__,
-                    __FUNCTION__,
-                    __LINE__
-                );
-                return false;
-            }
-            $valid_registrant = null;
-            foreach ($this->checkout->transaction->registrations($this->checkout->reg_cache_where_params) as $registration) {
-                if ($registration instanceof EE_Registration
-                    && $registration->reg_url_link() === $this->checkout->reg_url_link
-                ) {
-                    $valid_registrant = $registration;
-                }
-            }
-            if (! $valid_registrant instanceof EE_Registration) {
-                // hmmm... maybe we have the wrong session because the user is opening multiple tabs ?
-                if (EED_Single_Page_Checkout::$_checkout_verified) {
-                    // clear the session, mark the checkout as unverified, and try again
-                    EE_Registry::instance()->SSN->clear_session(__CLASS__, __FUNCTION__);
-                    EED_Single_Page_Checkout::$_initialized = false;
-                    EED_Single_Page_Checkout::$_checkout_verified = false;
-                    $this->_initialize();
-                    EE_Error::reset_notices();
-                    return false;
-                }
-                EE_Error::add_error(
-                    esc_html__(
-                        'We\'re sorry but there appears to be an error with the "reg_url_link" or the transaction itself. Please refresh the page and try again or contact support.',
-                        'event_espresso'
-                    ),
-                    __FILE__,
-                    __FUNCTION__,
-                    __LINE__
-                );
-                return false;
-            }
-        }
-        // now that things have been kinda sufficiently verified,
-        // let's add the checkout to the session so that it's available to other systems
-        EE_Registry::instance()->SSN->set_checkout($this->checkout);
-        return true;
-    }
-
-
-    /**
-     *    _initialize_reg_steps
-     * first makes sure that EE_Transaction_Processor::set_reg_step_initiated() is called as required
-     * then loops thru all of the active reg steps and calls the initialize_reg_step() method
-     *
-     * @access    private
-     * @param bool $reinitializing
-     * @throws EE_Error
-     */
-    private function _initialize_reg_steps($reinitializing = false)
-    {
-        $this->checkout->set_reg_step_initiated($this->checkout->current_step);
-        // loop thru all steps to call their individual "initialize" methods and set i18n strings for JS
-        foreach ($this->checkout->reg_steps as $reg_step) {
-            if (! $reg_step->initialize_reg_step()) {
-                // if not initialized then maybe this step is being removed...
-                if (! $reinitializing && $reg_step->is_current_step()) {
-                    // if it was the current step, then we need to start over here
-                    $this->_initialize_reg_steps(true);
-                    return;
-                }
-                continue;
-            }
-            // add css and JS for current step
-            $this->add_styles_and_scripts($reg_step);
-            if ($reg_step->is_current_step()) {
-                // the text that appears on the reg step form submit button
-                $reg_step->set_submit_button_text();
-            }
-        }
-        // dynamically creates hook point like: AHEE__Single_Page_Checkout___initialize_reg_step__attendee_information
-        do_action(
-            "AHEE__Single_Page_Checkout___initialize_reg_step__{$this->checkout->current_step->slug()}",
-            $this->checkout->current_step
-        );
-    }
-
-
-    /**
-     * _check_form_submission
-     *
-     * @access private
-     * @return boolean
-     */
-    private function _check_form_submission()
-    {
-        // does this request require the reg form to be generated ?
-        if ($this->checkout->generate_reg_form) {
-            // ever heard that song by Blue Rodeo ?
-            try {
-                $this->checkout->current_step->reg_form = $this->checkout->current_step->generate_reg_form();
-                // if not displaying a form, then check for form submission
-                if ($this->checkout->process_form_submission
-                    && $this->checkout->current_step->reg_form->was_submitted()
-                ) {
-                    // clear out any old data in case this step is being run again
-                    $this->checkout->current_step->set_valid_data(array());
-                    // capture submitted form data
-                    $this->checkout->current_step->reg_form->receive_form_submission(
-                        apply_filters(
-                            'FHEE__Single_Page_Checkout___check_form_submission__request_params',
-                            EE_Registry::instance()->REQ->params(),
-                            $this->checkout
-                        )
-                    );
-                    // validate submitted form data
-                    if (! $this->checkout->continue_reg || ! $this->checkout->current_step->reg_form->is_valid()) {
-                        // thou shall not pass !!!
-                        $this->checkout->continue_reg = false;
-                        // any form validation errors?
-                        if ($this->checkout->current_step->reg_form->submission_error_message() !== '') {
-                            EE_Error::add_error(
-                                $this->checkout->current_step->reg_form->submission_error_message(),
-                                __FILE__,
-                                __FUNCTION__,
-                                __LINE__
-                            );
-                        }
-                        // well not really... what will happen is
-                        // we'll just get redirected back to redo the current step
-                        $this->go_to_next_step();
-                        return false;
-                    }
-                }
-            } catch (EE_Error $e) {
-                $e->get_error();
-            }
-        }
-        return true;
-    }
-
-
-    /**
-     * _process_action
-     *
-     * @access private
-     * @return void
-     * @throws EE_Error
-     */
-    private function _process_form_action()
-    {
-        // what cha wanna do?
-        switch ($this->checkout->action) {
-            // AJAX next step reg form
-            case 'display_spco_reg_step':
-                $this->checkout->redirect = false;
-                if (EE_Registry::instance()->REQ->ajax) {
-                    $this->checkout->json_response->set_reg_step_html(
-                        $this->checkout->current_step->display_reg_form()
-                    );
-                }
-                break;
-            default:
-                // meh... do one of those other steps first
-                if (! empty($this->checkout->action)
-                    && is_callable(array($this->checkout->current_step, $this->checkout->action))
-                ) {
-                    // dynamically creates hook point like:
-                    //   AHEE__Single_Page_Checkout__before_attendee_information__process_reg_step
-                    do_action(
-                        "AHEE__Single_Page_Checkout__before_{$this->checkout->current_step->slug()}__{$this->checkout->action}",
-                        $this->checkout->current_step
-                    );
-                    // call action on current step
-                    if (call_user_func(array($this->checkout->current_step, $this->checkout->action))) {
-                        // good registrant, you get to proceed
-                        if ($this->checkout->current_step->success_message() !== ''
-                            && apply_filters(
-                                'FHEE__Single_Page_Checkout___process_form_action__display_success',
-                                false
-                            )
-                        ) {
-                            EE_Error::add_success(
-                                $this->checkout->current_step->success_message()
-                                . '<br />' . $this->checkout->next_step->_instructions()
-                            );
-                        }
-                        // pack it up, pack it in...
-                        $this->_setup_redirect();
-                    }
-                    // dynamically creates hook point like:
-                    //  AHEE__Single_Page_Checkout__after_payment_options__process_reg_step
-                    do_action(
-                        "AHEE__Single_Page_Checkout__after_{$this->checkout->current_step->slug()}__{$this->checkout->action}",
-                        $this->checkout->current_step
-                    );
-                } else {
-                    EE_Error::add_error(
-                        sprintf(
-                            esc_html__(
-                                'The requested form action "%s" does not exist for the current "%s" registration step.',
-                                'event_espresso'
-                            ),
-                            $this->checkout->action,
-                            $this->checkout->current_step->name()
-                        ),
-                        __FILE__,
-                        __FUNCTION__,
-                        __LINE__
-                    );
-                }
-            // end default
-        }
-        // store our progress so far
-        $this->checkout->stash_transaction_and_checkout();
-        // advance to the next step! If you pass GO, collect $200
-        $this->go_to_next_step();
-    }
-
-
-    /**
-     * @param EED_Single_Page_Checkout|EE_SPCO_Reg_Step $target
-     * @param object $target an object with the method `translate_js_strings` and `enqueue_styles_and_scripts`.
-     * @return        void
-     */
-    public function add_styles_and_scripts($target)
-    {
-        // i18n
-        $target->translate_js_strings();
-        if ($this->checkout->admin_request) {
-            add_action('admin_enqueue_scripts', array($target, 'enqueue_styles_and_scripts'), 10);
-        } else {
-            add_action('wp_enqueue_scripts', array($target, 'enqueue_styles_and_scripts'), 10);
-        }
-    }
-
-    /**
-     *        translate_js_strings
-     *
-     * @access        public
-     * @return        void
-     */
-    public function translate_js_strings()
-    {
-        EE_Registry::$i18n_js_strings['revisit'] = $this->checkout->revisit;
-        EE_Registry::$i18n_js_strings['e_reg_url_link'] = $this->checkout->reg_url_link;
-        EE_Registry::$i18n_js_strings['server_error'] = esc_html__(
-            'An unknown error occurred on the server while attempting to process your request. Please refresh the page and try again or contact support.',
-            'event_espresso'
-        );
-        EE_Registry::$i18n_js_strings['invalid_json_response'] = esc_html__(
-            'An invalid response was returned from the server while attempting to process your request. Please refresh the page and try again or contact support.',
-            'event_espresso'
-        );
-        EE_Registry::$i18n_js_strings['validation_error'] = esc_html__(
-            'There appears to be a problem with the form validation configuration! Please check the admin settings or contact support.',
-            'event_espresso'
-        );
-        EE_Registry::$i18n_js_strings['invalid_payment_method'] = esc_html__(
-            'There appears to be a problem with the payment method configuration! Please refresh the page and try again or contact support.',
-            'event_espresso'
-        );
-        EE_Registry::$i18n_js_strings['reg_step_error'] = esc_html__(
-            'This registration step could not be completed. Please refresh the page and try again.',
-            'event_espresso'
-        );
-        EE_Registry::$i18n_js_strings['invalid_coupon'] = esc_html__(
-            'We\'re sorry but that coupon code does not appear to be valid. If this is incorrect, please contact the site administrator.',
-            'event_espresso'
-        );
-        EE_Registry::$i18n_js_strings['process_registration'] = sprintf(
-            esc_html__(
-                'Please wait while we process your registration.%sDo not refresh the page or navigate away while this is happening.%sThank you for your patience.',
-                'event_espresso'
-            ),
-            '<br/>',
-            '<br/>'
-        );
-        EE_Registry::$i18n_js_strings['language'] = get_bloginfo('language');
-        EE_Registry::$i18n_js_strings['EESID'] = EE_Registry::instance()->SSN->id();
-        EE_Registry::$i18n_js_strings['currency'] = EE_Registry::instance()->CFG->currency;
-        EE_Registry::$i18n_js_strings['datepicker_yearRange'] = '-150:+20';
-        EE_Registry::$i18n_js_strings['timer_years'] = esc_html__('years', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_months'] = esc_html__('months', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_weeks'] = esc_html__('weeks', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_days'] = esc_html__('days', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_hours'] = esc_html__('hours', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_minutes'] = esc_html__('minutes', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_seconds'] = esc_html__('seconds', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_year'] = esc_html__('year', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_month'] = esc_html__('month', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_week'] = esc_html__('week', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_day'] = esc_html__('day', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_hour'] = esc_html__('hour', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_minute'] = esc_html__('minute', 'event_espresso');
-        EE_Registry::$i18n_js_strings['timer_second'] = esc_html__('second', 'event_espresso');
-        EE_Registry::$i18n_js_strings['registration_expiration_notice'] = EED_Single_Page_Checkout::getRegistrationExpirationNotice(
-        );
-        EE_Registry::$i18n_js_strings['ajax_submit'] = apply_filters(
-            'FHEE__Single_Page_Checkout__translate_js_strings__ajax_submit',
-            true
-        );
-        EE_Registry::$i18n_js_strings['session_extension'] = absint(
-            apply_filters('FHEE__EE_Session__extend_expiration__seconds_added', 10 * MINUTE_IN_SECONDS)
-        );
-        EE_Registry::$i18n_js_strings['session_expiration'] = gmdate(
-            'M d, Y H:i:s',
-            EE_Registry::instance()->SSN->expiration() + (get_option('gmt_offset') * HOUR_IN_SECONDS)
-        );
-    }
-
-
-    /**
-     *    enqueue_styles_and_scripts
-     *
-     * @access        public
-     * @return        void
-     * @throws EE_Error
-     */
-    public function enqueue_styles_and_scripts()
-    {
-        // load css
-        wp_register_style(
-            'single_page_checkout',
-            SPCO_CSS_URL . 'single_page_checkout.css',
-            array('espresso_default'),
-            EVENT_ESPRESSO_VERSION
-        );
-        wp_enqueue_style('single_page_checkout');
-        // load JS
-        wp_register_script(
-            'jquery_plugin',
-            EE_THIRD_PARTY_URL . 'jquery	.plugin.min.js',
-            array('jquery'),
-            '1.0.1',
-            true
-        );
-        wp_register_script(
-            'jquery_countdown',
-            EE_THIRD_PARTY_URL . 'jquery	.countdown.min.js',
-            array('jquery_plugin'),
-            '2.1.0',
-            true
-        );
-        wp_register_script(
-            'single_page_checkout',
-            SPCO_JS_URL . 'single_page_checkout.js',
-            array('espresso_core', 'underscore', 'ee_form_section_validation'),
-            EVENT_ESPRESSO_VERSION,
-            true
-        );
-        if ($this->checkout->registration_form instanceof EE_Form_Section_Proper) {
-            $this->checkout->registration_form->enqueue_js();
-        }
-        if ($this->checkout->current_step->reg_form instanceof EE_Form_Section_Proper) {
-            $this->checkout->current_step->reg_form->enqueue_js();
-        }
-        wp_enqueue_script('single_page_checkout');
-        if (apply_filters('FHEE__registration_page_wrapper_template__display_time_limit', false)) {
-            wp_enqueue_script('jquery_countdown');
-        }
-        /**
-         * global action hook for enqueueing styles and scripts with
-         * spco calls.
-         */
-        do_action('AHEE__EED_Single_Page_Checkout__enqueue_styles_and_scripts', $this);
-        /**
-         * dynamic action hook for enqueueing styles and scripts with spco calls.
-         * The hook will end up being something like:
-         *      AHEE__EED_Single_Page_Checkout__enqueue_styles_and_scripts__attendee_information
-         */
-        do_action(
-            'AHEE__EED_Single_Page_Checkout__enqueue_styles_and_scripts__' . $this->checkout->current_step->slug(),
-            $this
-        );
-    }
-
-
-    /**
-     *    display the Registration Single Page Checkout Form
-     *
-     * @access    private
-     * @return    void
-     * @throws EE_Error
-     */
-    private function _display_spco_reg_form()
-    {
-        // if registering via the admin, just display the reg form for the current step
-        if ($this->checkout->admin_request) {
-            EE_Registry::instance()->REQ->add_output($this->checkout->current_step->display_reg_form());
-        } else {
-            // add powered by EE msg
-            add_action('AHEE__SPCO__reg_form_footer', array('EED_Single_Page_Checkout', 'display_registration_footer'));
-            $empty_cart = count($this->checkout->transaction
-                                    ->registrations($this->checkout->reg_cache_where_params)) < 1;
-            EE_Registry::$i18n_js_strings['empty_cart'] = $empty_cart;
-            $cookies_not_set_msg = '';
-            if ($empty_cart) {
-                $cookies_not_set_msg = apply_filters(
-                    'FHEE__Single_Page_Checkout__display_spco_reg_form__cookies_not_set_msg',
-                    sprintf(
-                        esc_html__(
-                            '%1$s%3$sIt appears your browser is not currently set to accept Cookies%4$s%5$sIn order to register for events, you need to enable cookies.%7$sIf you require assistance, then click the following link to learn how to %8$senable cookies%9$s%6$s%2$s',
-                            'event_espresso'
-                        ),
-                        '<div class="ee-attention hidden" id="ee-cookies-not-set-msg">',
-                        '</div>',
-                        '<h6 class="important-notice">',
-                        '</h6>',
-                        '<p>',
-                        '</p>',
-                        '<br />',
-                        '<a href="http://www.whatarecookies.com/enable.asp" target="_blank" rel="noopener noreferrer">',
-                        '</a>'
-                    )
-                );
-            }
-            $this->checkout->registration_form = new EE_Form_Section_Proper(
-                array(
-                    'name'            => 'single-page-checkout',
-                    'html_id'         => 'ee-single-page-checkout-dv',
-                    'layout_strategy' =>
-                        new EE_Template_Layout(
-                            array(
-                                'layout_template_file' => SPCO_TEMPLATES_PATH . 'registration_page_wrapper.template.php',
-                                'template_args'        => array(
-                                    'empty_cart'              => $empty_cart,
-                                    'revisit'                 => $this->checkout->revisit,
-                                    'reg_steps'               => $this->checkout->reg_steps,
-                                    'next_step'               => $this->checkout->next_step instanceof EE_SPCO_Reg_Step
-                                        ? $this->checkout->next_step->slug()
-                                        : '',
-                                    'empty_msg'               => apply_filters(
-                                        'FHEE__Single_Page_Checkout__display_spco_reg_form__empty_msg',
-                                        sprintf(
-                                            esc_html__(
-                                                'You need to %1$sReturn to Events list%2$sselect at least one event%3$s before you can proceed with the registration process.',
-                                                'event_espresso'
-                                            ),
-                                            '<a href="'
-                                            . get_post_type_archive_link('espresso_events')
-                                            . '" title="',
-                                            '">',
-                                            '</a>'
-                                        )
-                                    ),
-                                    'cookies_not_set_msg'     => $cookies_not_set_msg,
-                                    'registration_time_limit' => $this->checkout->get_registration_time_limit(),
-                                    'session_expiration'      => gmdate(
-                                        'M d, Y H:i:s',
-                                        EE_Registry::instance()->SSN->expiration()
-                                        + (get_option('gmt_offset') * HOUR_IN_SECONDS)
-                                    ),
-                                ),
-                            )
-                        ),
-                )
-            );
-            // load template and add to output sent that gets filtered into the_content()
-            EE_Registry::instance()->REQ->add_output($this->checkout->registration_form->get_html());
-        }
-    }
-
-
-    /**
-     *    add_extra_finalize_registration_inputs
-     *
-     * @access    public
-     * @param $next_step
-     * @internal  param string $label
-     * @return void
-     */
-    public function add_extra_finalize_registration_inputs($next_step)
-    {
-        if ($next_step === 'finalize_registration') {
-            echo '<div id="spco-extra-finalize_registration-inputs-dv"></div>';
-        }
-    }
-
-
-    /**
-     *    display_registration_footer
-     *
-     * @access    public
-     * @return    string
-     */
-    public static function display_registration_footer()
-    {
-        if (apply_filters(
-            'FHEE__EE_Front__Controller__show_reg_footer',
-            EE_Registry::instance()->CFG->admin->show_reg_footer
-        )) {
-            add_filter(
-                'FHEE__EEH_Template__powered_by_event_espresso__url',
-                function ($url) {
-                    return apply_filters('FHEE__EE_Front_Controller__registration_footer__url', $url);
-                }
-            );
-            echo apply_filters(
-                'FHEE__EE_Front_Controller__display_registration_footer',
-                \EEH_Template::powered_by_event_espresso(
-                    '',
-                    'espresso-registration-footer-dv',
-                    array('utm_content' => 'registration_checkout')
-                )
-            );
-        }
-        return '';
-    }
-
-
-    /**
-     *    unlock_transaction
-     *
-     * @access    public
-     * @return    void
-     * @throws EE_Error
-     */
-    public function unlock_transaction()
-    {
-        if ($this->checkout->transaction instanceof EE_Transaction) {
-            $this->checkout->transaction->unlock();
-        }
-    }
-
-
-    /**
-     *        _setup_redirect
-     *
-     * @access    private
-     * @return void
-     */
-    private function _setup_redirect()
-    {
-        if ($this->checkout->continue_reg && $this->checkout->next_step instanceof EE_SPCO_Reg_Step) {
-            $this->checkout->redirect = true;
-            if (empty($this->checkout->redirect_url)) {
-                $this->checkout->redirect_url = $this->checkout->next_step->reg_step_url();
-            }
-            $this->checkout->redirect_url = apply_filters(
-                'FHEE__EED_Single_Page_Checkout___setup_redirect__checkout_redirect_url',
-                $this->checkout->redirect_url,
-                $this->checkout
-            );
-        }
-    }
-
-
-    /**
-     *   handle ajax message responses and redirects
-     *
-     * @access public
-     * @return void
-     * @throws EE_Error
-     */
-    public function go_to_next_step()
-    {
-        if (EE_Registry::instance()->REQ->ajax) {
-            // capture contents of output buffer we started earlier in the request, and insert into JSON response
-            $this->checkout->json_response->set_unexpected_errors(ob_get_clean());
-        }
-        $this->unlock_transaction();
-        // just return for these conditions
-        if ($this->checkout->admin_request
-            || $this->checkout->action === 'redirect_form'
-            || $this->checkout->action === 'update_checkout'
-        ) {
-            return;
-        }
-        // AJAX response
-        $this->_handle_json_response();
-        // redirect to next step or the Thank You page
-        $this->_handle_html_redirects();
-        // hmmm... must be something wrong, so let's just display the form again !
-        $this->_display_spco_reg_form();
-    }
-
-
-    /**
-     *   _handle_json_response
-     *
-     * @access protected
-     * @return void
-     */
-    protected function _handle_json_response()
-    {
-        // if this is an ajax request
-        if (EE_Registry::instance()->REQ->ajax) {
-            $this->checkout->json_response->set_registration_time_limit(
-                $this->checkout->get_registration_time_limit()
-            );
-            $this->checkout->json_response->set_payment_amount($this->checkout->amount_owing);
-            // just send the ajax (
-            $json_response = apply_filters(
-                'FHEE__EE_Single_Page_Checkout__JSON_response',
-                $this->checkout->json_response
-            );
-            echo $json_response;
-            exit();
-        }
-    }
-
-
-    /**
-     *   _handle_redirects
-     *
-     * @access protected
-     * @return void
-     */
-    protected function _handle_html_redirects()
-    {
-        // going somewhere ?
-        if ($this->checkout->redirect && ! empty($this->checkout->redirect_url)) {
-            // store notices in a transient
-            EE_Error::get_notices(false, true, true);
-            wp_safe_redirect($this->checkout->redirect_url);
-            exit();
-        }
-    }
-
-
-    /**
-     *   set_checkout_anchor
-     *
-     * @access public
-     * @return void
-     */
-    public function set_checkout_anchor()
-    {
-        echo '<a id="checkout" style="float: left; margin-left: -999em;"></a>';
-    }
-
-    /**
-     *    getRegistrationExpirationNotice
-     *
-     * @since     4.9.59.p
-     * @access    public
-     * @return    string
-     */
-    public static function getRegistrationExpirationNotice()
-    {
-        return sprintf(
-            esc_html__(
-                '%1$sWe\'re sorry, but your registration time has expired.%2$s%3$s%4$sIf you still wish to complete your registration, please return to the %5$sEvent List%6$sEvent List%7$s and reselect your tickets if available. Please accept our apologies for any inconvenience this may have caused.%8$s',
-                'event_espresso'
-            ),
-            '<h4 class="important-notice">',
-            '</h4>',
-            '<br />',
-            '<p>',
-            '<a href="' . get_post_type_archive_link('espresso_events') . '" title="',
-            '">',
-            '</a>',
-            '</p>'
-        );
-    }
+	/**
+	 * $_initialized - has the SPCO controller already been initialized ?
+	 *
+	 * @access private
+	 * @var bool $_initialized
+	 */
+	private static $_initialized = false;
+
+
+	/**
+	 * $_checkout_verified - is the EE_Checkout verified as correct for this request ?
+	 *
+	 * @access private
+	 * @var bool $_valid_checkout
+	 */
+	private static $_checkout_verified = true;
+
+	/**
+	 *    $_reg_steps_array - holds initial array of reg steps
+	 *
+	 * @access private
+	 * @var array $_reg_steps_array
+	 */
+	private static $_reg_steps_array = array();
+
+	/**
+	 *    $checkout - EE_Checkout object for handling the properties of the current checkout process
+	 *
+	 * @access public
+	 * @var EE_Checkout $checkout
+	 */
+	public $checkout;
+
+
+	/**
+	 * @return EED_Module|EED_Single_Page_Checkout
+	 */
+	public static function instance()
+	{
+		add_filter('EED_Single_Page_Checkout__SPCO_active', '__return_true');
+		return parent::get_instance(__CLASS__);
+	}
+
+
+	/**
+	 * @return EE_CART
+	 */
+	public function cart()
+	{
+		return $this->checkout->cart;
+	}
+
+
+	/**
+	 * @return EE_Transaction
+	 */
+	public function transaction()
+	{
+		return $this->checkout->transaction;
+	}
+
+
+	/**
+	 *    set_hooks - for hooking into EE Core, other modules, etc
+	 *
+	 * @access    public
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	public static function set_hooks()
+	{
+		EED_Single_Page_Checkout::set_definitions();
+	}
+
+
+	/**
+	 *    set_hooks_admin - for hooking into EE Admin Core, other modules, etc
+	 *
+	 * @access    public
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	public static function set_hooks_admin()
+	{
+		EED_Single_Page_Checkout::set_definitions();
+		if (! (defined('DOING_AJAX') && DOING_AJAX)) {
+			return;
+		}
+		// going to start an output buffer in case anything gets accidentally output
+		// that might disrupt our JSON response
+		ob_start();
+		EED_Single_Page_Checkout::load_request_handler();
+		EED_Single_Page_Checkout::load_reg_steps();
+		// set ajax hooks
+		add_action('wp_ajax_process_reg_step', array('EED_Single_Page_Checkout', 'process_reg_step'));
+		add_action('wp_ajax_nopriv_process_reg_step', array('EED_Single_Page_Checkout', 'process_reg_step'));
+		add_action('wp_ajax_display_spco_reg_step', array('EED_Single_Page_Checkout', 'display_reg_step'));
+		add_action('wp_ajax_nopriv_display_spco_reg_step', array('EED_Single_Page_Checkout', 'display_reg_step'));
+		add_action('wp_ajax_update_reg_step', array('EED_Single_Page_Checkout', 'update_reg_step'));
+		add_action('wp_ajax_nopriv_update_reg_step', array('EED_Single_Page_Checkout', 'update_reg_step'));
+	}
+
+
+	/**
+	 *    process ajax request
+	 *
+	 * @param string $ajax_action
+	 * @throws EE_Error
+	 */
+	public static function process_ajax_request($ajax_action)
+	{
+		EE_Registry::instance()->REQ->set('action', $ajax_action);
+		EED_Single_Page_Checkout::instance()->_initialize();
+	}
+
+
+	/**
+	 *    ajax display registration step
+	 *
+	 * @throws EE_Error
+	 */
+	public static function display_reg_step()
+	{
+		EED_Single_Page_Checkout::process_ajax_request('display_spco_reg_step');
+	}
+
+
+	/**
+	 *    ajax process registration step
+	 *
+	 * @throws EE_Error
+	 */
+	public static function process_reg_step()
+	{
+		EED_Single_Page_Checkout::process_ajax_request('process_reg_step');
+	}
+
+
+	/**
+	 *    ajax process registration step
+	 *
+	 * @throws EE_Error
+	 */
+	public static function update_reg_step()
+	{
+		EED_Single_Page_Checkout::process_ajax_request('update_reg_step');
+	}
+
+
+	/**
+	 *   update_checkout
+	 *
+	 * @access public
+	 * @return void
+	 * @throws EE_Error
+	 */
+	public static function update_checkout()
+	{
+		EED_Single_Page_Checkout::process_ajax_request('update_checkout');
+	}
+
+
+	/**
+	 *    load_request_handler
+	 *
+	 * @access    public
+	 * @return    void
+	 */
+	public static function load_request_handler()
+	{
+		// load core Request_Handler class
+		if (EE_Registry::instance()->REQ !== null) {
+			EE_Registry::instance()->load_core('Request_Handler');
+		}
+	}
+
+
+	/**
+	 *    set_definitions
+	 *
+	 * @access    public
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	public static function set_definitions()
+	{
+		if (defined('SPCO_BASE_PATH')) {
+			return;
+		}
+		define(
+			'SPCO_BASE_PATH',
+			rtrim(str_replace(array('\\', '/'), '/', plugin_dir_path(__FILE__)), '/') . '/'
+		);
+		define('SPCO_CSS_URL', plugin_dir_url(__FILE__) . 'css/');
+		define('SPCO_IMG_URL', plugin_dir_url(__FILE__) . 'img/');
+		define('SPCO_JS_URL', plugin_dir_url(__FILE__) . 'js/');
+		define('SPCO_INC_PATH', SPCO_BASE_PATH . 'inc/');
+		define('SPCO_REG_STEPS_PATH', SPCO_BASE_PATH . 'reg_steps/');
+		define('SPCO_TEMPLATES_PATH', SPCO_BASE_PATH . 'templates/');
+		EEH_Autoloader::register_autoloaders_for_each_file_in_folder(SPCO_BASE_PATH, true);
+		EE_Registry::$i18n_js_strings['registration_expiration_notice'] = EED_Single_Page_Checkout::getRegistrationExpirationNotice(
+		);
+	}
+
+
+	/**
+	 * load_reg_steps
+	 * loads and instantiates each reg step based on the EE_Registry::instance()->CFG->registration->reg_steps array
+	 *
+	 * @access    private
+	 * @throws EE_Error
+	 */
+	public static function load_reg_steps()
+	{
+		static $reg_steps_loaded = false;
+		if ($reg_steps_loaded) {
+			return;
+		}
+		// filter list of reg_steps
+		$reg_steps_to_load = (array) apply_filters(
+			'AHEE__SPCO__load_reg_steps__reg_steps_to_load',
+			EED_Single_Page_Checkout::get_reg_steps()
+		);
+		// sort by key (order)
+		ksort($reg_steps_to_load);
+		// loop through folders
+		foreach ($reg_steps_to_load as $order => $reg_step) {
+			// we need a
+			if (isset($reg_step['file_path'], $reg_step['class_name'], $reg_step['slug'])) {
+				// copy over to the reg_steps_array
+				EED_Single_Page_Checkout::$_reg_steps_array[ $order ] = $reg_step;
+				// register custom key route for each reg step
+				// ie: step=>"slug" - this is the entire reason we load the reg steps array now
+				EE_Config::register_route(
+					$reg_step['slug'],
+					'EED_Single_Page_Checkout',
+					'run',
+					'step'
+				);
+				// add AJAX or other hooks
+				if (isset($reg_step['has_hooks']) && $reg_step['has_hooks']) {
+					// setup autoloaders if necessary
+					if (! class_exists($reg_step['class_name'])) {
+						EEH_Autoloader::register_autoloaders_for_each_file_in_folder(
+							$reg_step['file_path'],
+							true
+						);
+					}
+					if (is_callable($reg_step['class_name'], 'set_hooks')) {
+						call_user_func(array($reg_step['class_name'], 'set_hooks'));
+					}
+				}
+			}
+		}
+		$reg_steps_loaded = true;
+	}
+
+
+	/**
+	 *    get_reg_steps
+	 *
+	 * @access    public
+	 * @return    array
+	 */
+	public static function get_reg_steps()
+	{
+		$reg_steps = EE_Registry::instance()->CFG->registration->reg_steps;
+		if (empty($reg_steps)) {
+			$reg_steps = array(
+				10  => array(
+					'file_path'  => SPCO_REG_STEPS_PATH . 'attendee_information',
+					'class_name' => 'EE_SPCO_Reg_Step_Attendee_Information',
+					'slug'       => 'attendee_information',
+					'has_hooks'  => false,
+				),
+				30  => array(
+					'file_path'  => SPCO_REG_STEPS_PATH . 'payment_options',
+					'class_name' => 'EE_SPCO_Reg_Step_Payment_Options',
+					'slug'       => 'payment_options',
+					'has_hooks'  => true,
+				),
+				999 => array(
+					'file_path'  => SPCO_REG_STEPS_PATH . 'finalize_registration',
+					'class_name' => 'EE_SPCO_Reg_Step_Finalize_Registration',
+					'slug'       => 'finalize_registration',
+					'has_hooks'  => false,
+				),
+			);
+		}
+		return $reg_steps;
+	}
+
+
+	/**
+	 *    registration_checkout_for_admin
+	 *
+	 * @access    public
+	 * @return    string
+	 * @throws EE_Error
+	 */
+	public static function registration_checkout_for_admin()
+	{
+		EED_Single_Page_Checkout::load_request_handler();
+		EE_Registry::instance()->REQ->set('step', 'attendee_information');
+		EE_Registry::instance()->REQ->set('action', 'display_spco_reg_step');
+		EE_Registry::instance()->REQ->set('process_form_submission', false);
+		EED_Single_Page_Checkout::instance()->_initialize();
+		EED_Single_Page_Checkout::instance()->_display_spco_reg_form();
+		return EE_Registry::instance()->REQ->get_output();
+	}
+
+
+	/**
+	 * process_registration_from_admin
+	 *
+	 * @access public
+	 * @return \EE_Transaction
+	 * @throws EE_Error
+	 */
+	public static function process_registration_from_admin()
+	{
+		EED_Single_Page_Checkout::load_request_handler();
+		EE_Registry::instance()->REQ->set('step', 'attendee_information');
+		EE_Registry::instance()->REQ->set('action', 'process_reg_step');
+		EE_Registry::instance()->REQ->set('process_form_submission', true);
+		EED_Single_Page_Checkout::instance()->_initialize();
+		if (EED_Single_Page_Checkout::instance()->checkout->current_step->completed()) {
+			$final_reg_step = end(EED_Single_Page_Checkout::instance()->checkout->reg_steps);
+			if ($final_reg_step instanceof EE_SPCO_Reg_Step_Finalize_Registration) {
+				EED_Single_Page_Checkout::instance()->checkout->set_reg_step_initiated($final_reg_step);
+				if ($final_reg_step->process_reg_step()) {
+					$final_reg_step->set_completed();
+					EED_Single_Page_Checkout::instance()->checkout->update_txn_reg_steps_array();
+					return EED_Single_Page_Checkout::instance()->checkout->transaction;
+				}
+			}
+		}
+		return null;
+	}
+
+
+	/**
+	 *    run
+	 *
+	 * @access    public
+	 * @param WP_Query $WP_Query
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	public function run($WP_Query)
+	{
+		if ($WP_Query instanceof WP_Query
+			&& $WP_Query->is_main_query()
+			&& apply_filters('FHEE__EED_Single_Page_Checkout__run', true)
+			&& $this->_is_reg_checkout()
+		) {
+			$this->_initialize();
+		}
+	}
+
+
+	/**
+	 * determines whether current url matches reg page url
+	 *
+	 * @return bool
+	 */
+	protected function _is_reg_checkout()
+	{
+		// get current permalink for reg page without any extra query args
+		$reg_page_url = \get_permalink(EE_Config::instance()->core->reg_page_id);
+		// get request URI for current request, but without the scheme or host
+		$current_request_uri = \EEH_URL::filter_input_server_url('REQUEST_URI');
+		$current_request_uri = html_entity_decode($current_request_uri);
+		// get array of query args from the current request URI
+		$query_args = \EEH_URL::get_query_string($current_request_uri);
+		// grab page id if it is set
+		$page_id = isset($query_args['page_id']) ? absint($query_args['page_id']) : 0;
+		// and remove the page id from the query args (we will re-add it later)
+		unset($query_args['page_id']);
+		// now strip all query args from current request URI
+		$current_request_uri = remove_query_arg(array_keys($query_args), $current_request_uri);
+		// and re-add the page id if it was set
+		if ($page_id) {
+			$current_request_uri = add_query_arg('page_id', $page_id, $current_request_uri);
+		}
+		// remove slashes and ?
+		$current_request_uri = trim($current_request_uri, '?/');
+		// is current request URI part of the known full reg page URL ?
+		return ! empty($current_request_uri) && strpos($reg_page_url, $current_request_uri) !== false;
+	}
+
+
+	/**
+	 * @param WP_Query $wp_query
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	public static function init($wp_query)
+	{
+		EED_Single_Page_Checkout::instance()->run($wp_query);
+	}
+
+
+	/**
+	 *    _initialize - initial module setup
+	 *
+	 * @access    private
+	 * @throws EE_Error
+	 * @return    void
+	 */
+	private function _initialize()
+	{
+		// ensure SPCO doesn't run twice
+		if (EED_Single_Page_Checkout::$_initialized) {
+			return;
+		}
+		try {
+			EED_Single_Page_Checkout::load_reg_steps();
+			$this->_verify_session();
+			// setup the EE_Checkout object
+			$this->checkout = $this->_initialize_checkout();
+			// filter checkout
+			$this->checkout = apply_filters('FHEE__EED_Single_Page_Checkout___initialize__checkout', $this->checkout);
+			// get the $_GET
+			$this->_get_request_vars();
+			if ($this->_block_bots()) {
+				return;
+			}
+			// filter continue_reg
+			$this->checkout->continue_reg = apply_filters(
+				'FHEE__EED_Single_Page_Checkout__init___continue_reg',
+				true,
+				$this->checkout
+			);
+			// load the reg steps array
+			if (! $this->_load_and_instantiate_reg_steps()) {
+				EED_Single_Page_Checkout::$_initialized = true;
+				return;
+			}
+			// set the current step
+			$this->checkout->set_current_step($this->checkout->step);
+			// and the next step
+			$this->checkout->set_next_step();
+			// verify that everything has been setup correctly
+			if (! ($this->_verify_transaction_and_get_registrations() && $this->_final_verifications())) {
+				EED_Single_Page_Checkout::$_initialized = true;
+				return;
+			}
+			// lock the transaction
+			$this->checkout->transaction->lock();
+			// make sure all of our cached objects are added to their respective model entity mappers
+			$this->checkout->refresh_all_entities();
+			// set amount owing
+			$this->checkout->amount_owing = $this->checkout->transaction->remaining();
+			// initialize each reg step, which gives them the chance to potentially alter the process
+			$this->_initialize_reg_steps();
+			// DEBUG LOG
+			// $this->checkout->log( __CLASS__, __FUNCTION__, __LINE__ );
+			// get reg form
+			if (! $this->_check_form_submission()) {
+				EED_Single_Page_Checkout::$_initialized = true;
+				return;
+			}
+			// checkout the action!!!
+			$this->_process_form_action();
+			// add some style and make it dance
+			$this->add_styles_and_scripts($this);
+			// kk... SPCO has successfully run
+			EED_Single_Page_Checkout::$_initialized = true;
+			// set no cache headers and constants
+			EE_System::do_not_cache();
+			// add anchor
+			add_action('loop_start', array($this, 'set_checkout_anchor'), 1);
+			// remove transaction lock
+			add_action('shutdown', array($this, 'unlock_transaction'), 1);
+		} catch (Exception $e) {
+			EE_Error::add_error($e->getMessage(), __FILE__, __FUNCTION__, __LINE__);
+		}
+	}
+
+
+	/**
+	 *    _verify_session
+	 * checks that the session is valid and not expired
+	 *
+	 * @access    private
+	 * @throws EE_Error
+	 */
+	private function _verify_session()
+	{
+		if (! EE_Registry::instance()->SSN instanceof EE_Session) {
+			throw new EE_Error(esc_html__('The EE_Session class could not be loaded.', 'event_espresso'));
+		}
+		$clear_session_requested = filter_var(
+			EE_Registry::instance()->REQ->get('clear_session', false),
+			FILTER_VALIDATE_BOOLEAN
+		);
+		// is session still valid ?
+		if ($clear_session_requested
+			|| (EE_Registry::instance()->SSN->expired()
+				&& EE_Registry::instance()->REQ->get('e_reg_url_link', '') === ''
+			)
+		) {
+			$this->checkout = new EE_Checkout();
+			EE_Registry::instance()->SSN->clear_session(__CLASS__, __FUNCTION__);
+			// EE_Registry::instance()->SSN->reset_cart();
+			// EE_Registry::instance()->SSN->reset_checkout();
+			// EE_Registry::instance()->SSN->reset_transaction();
+			if (! $clear_session_requested) {
+				EE_Error::add_attention(
+					EE_Registry::$i18n_js_strings['registration_expiration_notice'],
+					__FILE__,
+					__FUNCTION__,
+					__LINE__
+				);
+			}
+			// EE_Registry::instance()->SSN->reset_expired();
+		}
+	}
+
+
+	/**
+	 *    _initialize_checkout
+	 * loads and instantiates EE_Checkout
+	 *
+	 * @access    private
+	 * @throws EE_Error
+	 * @return EE_Checkout
+	 */
+	private function _initialize_checkout()
+	{
+		// look in session for existing checkout
+		/** @type EE_Checkout $checkout */
+		$checkout = EE_Registry::instance()->SSN->checkout();
+		// verify
+		if (! $checkout instanceof EE_Checkout) {
+			// instantiate EE_Checkout object for handling the properties of the current checkout process
+			$checkout = EE_Registry::instance()->load_file(
+				SPCO_INC_PATH,
+				'EE_Checkout',
+				'class',
+				array(),
+				false
+			);
+		} else {
+			if ($checkout->current_step->is_final_step() && $checkout->exit_spco() === true) {
+				$this->unlock_transaction();
+				wp_safe_redirect($checkout->redirect_url);
+				exit();
+			}
+		}
+		$checkout = apply_filters('FHEE__EED_Single_Page_Checkout___initialize_checkout__checkout', $checkout);
+		// verify again
+		if (! $checkout instanceof EE_Checkout) {
+			throw new EE_Error(esc_html__('The EE_Checkout class could not be loaded.', 'event_espresso'));
+		}
+		// reset anything that needs a clean slate for each request
+		$checkout->reset_for_current_request();
+		return $checkout;
+	}
+
+
+	/**
+	 *    _get_request_vars
+	 *
+	 * @access    private
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	private function _get_request_vars()
+	{
+		// load classes
+		EED_Single_Page_Checkout::load_request_handler();
+		// make sure this request is marked as belonging to EE
+		EE_Registry::instance()->REQ->set_espresso_page(true);
+		// which step is being requested ?
+		$this->checkout->step = EE_Registry::instance()->REQ->get('step', $this->_get_first_step());
+		// which step is being edited ?
+		$this->checkout->edit_step = EE_Registry::instance()->REQ->get('edit_step', '');
+		// and what we're doing on the current step
+		$this->checkout->action = EE_Registry::instance()->REQ->get('action', 'display_spco_reg_step');
+		// timestamp
+		$this->checkout->uts = EE_Registry::instance()->REQ->get('uts', 0);
+		// returning to edit ?
+		$this->checkout->reg_url_link = EE_Registry::instance()->REQ->get('e_reg_url_link', '');
+		// add reg url link to registration query params
+		if ($this->checkout->reg_url_link && strpos($this->checkout->reg_url_link, '1-') !== 0) {
+			$this->checkout->reg_cache_where_params[0]['REG_url_link'] = $this->checkout->reg_url_link;
+		}
+		// or some other kind of revisit ?
+		$this->checkout->revisit = filter_var(
+			EE_Registry::instance()->REQ->get('revisit', false),
+			FILTER_VALIDATE_BOOLEAN
+		);
+		// and whether or not to generate a reg form for this request
+		$this->checkout->generate_reg_form = filter_var(
+			EE_Registry::instance()->REQ->get('generate_reg_form', true),
+			FILTER_VALIDATE_BOOLEAN
+		);
+		// and whether or not to process a reg form submission for this request
+		$this->checkout->process_form_submission = filter_var(
+			EE_Registry::instance()->REQ->get(
+				'process_form_submission',
+				$this->checkout->action === 'process_reg_step'
+			),
+			FILTER_VALIDATE_BOOLEAN
+		);
+		$this->checkout->process_form_submission = filter_var(
+			$this->checkout->action !== 'display_spco_reg_step'
+				? $this->checkout->process_form_submission
+				: false,
+			FILTER_VALIDATE_BOOLEAN
+		);
+		// $this->_display_request_vars();
+	}
+
+
+	/**
+	 *  _display_request_vars
+	 *
+	 * @access    protected
+	 * @return    void
+	 */
+	protected function _display_request_vars()
+	{
+		if (! WP_DEBUG) {
+			return;
+		}
+		EEH_Debug_Tools::printr($_REQUEST, '$_REQUEST', __FILE__, __LINE__);
+		EEH_Debug_Tools::printr($this->checkout->step, '$this->checkout->step', __FILE__, __LINE__);
+		EEH_Debug_Tools::printr($this->checkout->edit_step, '$this->checkout->edit_step', __FILE__, __LINE__);
+		EEH_Debug_Tools::printr($this->checkout->action, '$this->checkout->action', __FILE__, __LINE__);
+		EEH_Debug_Tools::printr($this->checkout->reg_url_link, '$this->checkout->reg_url_link', __FILE__, __LINE__);
+		EEH_Debug_Tools::printr($this->checkout->revisit, '$this->checkout->revisit', __FILE__, __LINE__);
+		EEH_Debug_Tools::printr(
+			$this->checkout->generate_reg_form,
+			'$this->checkout->generate_reg_form',
+			__FILE__,
+			__LINE__
+		);
+		EEH_Debug_Tools::printr(
+			$this->checkout->process_form_submission,
+			'$this->checkout->process_form_submission',
+			__FILE__,
+			__LINE__
+		);
+	}
+
+
+	/**
+	 * _block_bots
+	 * checks that the incoming request has either of the following set:
+	 *  a uts (unix timestamp) which indicates that the request was redirected from the Ticket Selector
+	 *  a REG URL Link, which indicates that the request is a return visit to SPCO for a valid TXN
+	 * so if you're not coming from the Ticket Selector nor returning for a valid IP...
+	 * then where you coming from man?
+	 *
+	 * @return boolean
+	 */
+	private function _block_bots()
+	{
+		$invalid_checkout_access = EED_Invalid_Checkout_Access::getInvalidCheckoutAccess();
+		if ($invalid_checkout_access->checkoutAccessIsInvalid($this->checkout)) {
+			return true;
+		}
+		return false;
+	}
+
+
+	/**
+	 *    _get_first_step
+	 *  gets slug for first step in $_reg_steps_array
+	 *
+	 * @access    private
+	 * @throws EE_Error
+	 * @return    string
+	 */
+	private function _get_first_step()
+	{
+		$first_step = reset(EED_Single_Page_Checkout::$_reg_steps_array);
+		return isset($first_step['slug']) ? $first_step['slug'] : 'attendee_information';
+	}
+
+
+	/**
+	 * instantiates each reg step based on the loaded reg_steps array
+	 *
+	 * @return    bool
+	 * @throws EE_Error
+	 * @throws InvalidArgumentException
+	 * @throws InvalidDataTypeException
+	 * @throws InvalidInterfaceException
+	 */
+	private function _load_and_instantiate_reg_steps()
+	{
+		do_action('AHEE__Single_Page_Checkout___load_and_instantiate_reg_steps__start', $this->checkout);
+		// have reg_steps already been instantiated ?
+		if (empty($this->checkout->reg_steps)
+			|| apply_filters('FHEE__Single_Page_Checkout__load_reg_steps__reload_reg_steps', false, $this->checkout)
+		) {
+			// if not, then loop through raw reg steps array
+			foreach (EED_Single_Page_Checkout::$_reg_steps_array as $order => $reg_step) {
+				if (! $this->_load_and_instantiate_reg_step($reg_step, $order)) {
+					return false;
+				}
+			}
+			if (isset($this->checkout->reg_steps['registration_confirmation'])) {
+				// skip the registration_confirmation page ?
+				if (EE_Registry::instance()->CFG->registration->skip_reg_confirmation) {
+					// just remove it from the reg steps array
+					$this->checkout->remove_reg_step('registration_confirmation', false);
+				} elseif (EE_Registry::instance()->CFG->registration->reg_confirmation_last
+				) {
+					// set the order to something big like 100
+					$this->checkout->set_reg_step_order('registration_confirmation', 100);
+				}
+			}
+			// filter the array for good luck
+			$this->checkout->reg_steps = apply_filters(
+				'FHEE__Single_Page_Checkout__load_reg_steps__reg_steps',
+				$this->checkout->reg_steps
+			);
+			// finally re-sort based on the reg step class order properties
+			$this->checkout->sort_reg_steps();
+		} else {
+			foreach ($this->checkout->reg_steps as $reg_step) {
+				// set all current step stati to FALSE
+				$reg_step->set_is_current_step(false);
+			}
+		}
+		if (empty($this->checkout->reg_steps)) {
+			EE_Error::add_error(
+				esc_html__('No Reg Steps were loaded..', 'event_espresso'),
+				__FILE__,
+				__FUNCTION__,
+				__LINE__
+			);
+			return false;
+		}
+		// make reg step details available to JS
+		$this->checkout->set_reg_step_JSON_info();
+		return true;
+	}
+
+
+	/**
+	 *     _load_and_instantiate_reg_step
+	 *
+	 * @access    private
+	 * @param array $reg_step
+	 * @param int   $order
+	 * @return bool
+	 */
+	private function _load_and_instantiate_reg_step($reg_step = array(), $order = 0)
+	{
+		// we need a file_path, class_name, and slug to add a reg step
+		if (isset($reg_step['file_path'], $reg_step['class_name'], $reg_step['slug'])) {
+			// if editing a specific step, but this is NOT that step... (and it's not the 'finalize_registration' step)
+			if ($this->checkout->reg_url_link
+				&& $this->checkout->step !== $reg_step['slug']
+				&& $reg_step['slug'] !== 'finalize_registration'
+				// normally at this point we would NOT load the reg step, but this filter can change that
+				&& apply_filters(
+					'FHEE__Single_Page_Checkout___load_and_instantiate_reg_step__bypass_reg_step',
+					true,
+					$reg_step,
+					$this->checkout
+				)
+			) {
+				return true;
+			}
+			// instantiate step class using file path and class name
+			$reg_step_obj = EE_Registry::instance()->load_file(
+				$reg_step['file_path'],
+				$reg_step['class_name'],
+				'class',
+				$this->checkout,
+				false
+			);
+			// did we gets the goods ?
+			if ($reg_step_obj instanceof EE_SPCO_Reg_Step) {
+				// set reg step order based on config
+				$reg_step_obj->set_order($order);
+				// add instantiated reg step object to the master reg steps array
+				$this->checkout->add_reg_step($reg_step_obj);
+			} else {
+				EE_Error::add_error(
+					esc_html__('The current step could not be set.', 'event_espresso'),
+					__FILE__,
+					__FUNCTION__,
+					__LINE__
+				);
+				return false;
+			}
+		} else {
+			if (WP_DEBUG) {
+				EE_Error::add_error(
+					sprintf(
+						esc_html__(
+							'A registration step could not be loaded. One or more of the following data points is invalid:%4$s%5$sFile Path: %1$s%6$s%5$sClass Name: %2$s%6$s%5$sSlug: %3$s%6$s%7$s',
+							'event_espresso'
+						),
+						isset($reg_step['file_path']) ? $reg_step['file_path'] : '',
+						isset($reg_step['class_name']) ? $reg_step['class_name'] : '',
+						isset($reg_step['slug']) ? $reg_step['slug'] : '',
+						'<ul>',
+						'<li>',
+						'</li>',
+						'</ul>'
+					),
+					__FILE__,
+					__FUNCTION__,
+					__LINE__
+				);
+			}
+			return false;
+		}
+		return true;
+	}
+
+
+	/**
+	 * _verify_transaction_and_get_registrations
+	 *
+	 * @access private
+	 * @return bool
+	 * @throws InvalidDataTypeException
+	 * @throws InvalidEntityException
+	 * @throws EE_Error
+	 */
+	private function _verify_transaction_and_get_registrations()
+	{
+		// was there already a valid transaction in the checkout from the session ?
+		if (! $this->checkout->transaction instanceof EE_Transaction) {
+			// get transaction from db or session
+			$this->checkout->transaction = $this->checkout->reg_url_link && ! is_admin()
+				? $this->_get_transaction_and_cart_for_previous_visit()
+				: $this->_get_cart_for_current_session_and_setup_new_transaction();
+			if (! $this->checkout->transaction instanceof EE_Transaction) {
+				EE_Error::add_error(
+					esc_html__(
+						'Your Registration and Transaction information could not be retrieved from the db.',
+						'event_espresso'
+					),
+					__FILE__,
+					__FUNCTION__,
+					__LINE__
+				);
+				$this->checkout->transaction = EE_Transaction::new_instance();
+				// add some style and make it dance
+				$this->add_styles_and_scripts($this);
+				EED_Single_Page_Checkout::$_initialized = true;
+				return false;
+			}
+			// and the registrations for the transaction
+			$this->_get_registrations($this->checkout->transaction);
+		}
+		return true;
+	}
+
+
+	/**
+	 * _get_transaction_and_cart_for_previous_visit
+	 *
+	 * @access private
+	 * @return mixed EE_Transaction|NULL
+	 */
+	private function _get_transaction_and_cart_for_previous_visit()
+	{
+		/** @var $TXN_model EEM_Transaction */
+		$TXN_model = EE_Registry::instance()->load_model('Transaction');
+		// because the reg_url_link is present in the request,
+		// this is a return visit to SPCO, so we'll get the transaction data from the db
+		$transaction = $TXN_model->get_transaction_from_reg_url_link($this->checkout->reg_url_link);
+		// verify transaction
+		if ($transaction instanceof EE_Transaction) {
+			// and get the cart that was used for that transaction
+			$this->checkout->cart = $this->_get_cart_for_transaction($transaction);
+			return $transaction;
+		}
+		EE_Error::add_error(
+			esc_html__('Your Registration and Transaction information could not be retrieved from the db.', 'event_espresso'),
+			__FILE__,
+			__FUNCTION__,
+			__LINE__
+		);
+		return null;
+	}
+
+
+	/**
+	 * _get_cart_for_transaction
+	 *
+	 * @access private
+	 * @param EE_Transaction $transaction
+	 * @return EE_Cart
+	 */
+	private function _get_cart_for_transaction($transaction)
+	{
+		return $this->checkout->get_cart_for_transaction($transaction);
+	}
+
+
+	/**
+	 * get_cart_for_transaction
+	 *
+	 * @access public
+	 * @param EE_Transaction $transaction
+	 * @return EE_Cart
+	 */
+	public function get_cart_for_transaction(EE_Transaction $transaction)
+	{
+		return $this->checkout->get_cart_for_transaction($transaction);
+	}
+
+
+	/**
+	 * _get_transaction_and_cart_for_current_session
+	 *    generates a new EE_Transaction object and adds it to the $_transaction property.
+	 *
+	 * @access private
+	 * @return EE_Transaction
+	 * @throws EE_Error
+	 */
+	private function _get_cart_for_current_session_and_setup_new_transaction()
+	{
+		//  if there's no transaction, then this is the FIRST visit to SPCO
+		// so load up the cart ( passing nothing for the TXN because it doesn't exist yet )
+		$this->checkout->cart = $this->_get_cart_for_transaction(null);
+		// and then create a new transaction
+		$transaction = $this->_initialize_transaction();
+		// verify transaction
+		if ($transaction instanceof EE_Transaction) {
+			// save it so that we have an ID for other objects to use
+			$transaction->save();
+			// and save TXN data to the cart
+			$this->checkout->cart->get_grand_total()->save_this_and_descendants_to_txn($transaction->ID());
+		} else {
+			EE_Error::add_error(
+				esc_html__('A Valid Transaction could not be initialized.', 'event_espresso'),
+				__FILE__,
+				__FUNCTION__,
+				__LINE__
+			);
+		}
+		return $transaction;
+	}
+
+
+	/**
+	 *    generates a new EE_Transaction object and adds it to the $_transaction property.
+	 *
+	 * @access private
+	 * @return mixed EE_Transaction|NULL
+	 */
+	private function _initialize_transaction()
+	{
+		try {
+			// ensure cart totals have been calculated
+			$this->checkout->cart->get_grand_total()->recalculate_total_including_taxes();
+			// grab the cart grand total
+			$cart_total = $this->checkout->cart->get_cart_grand_total();
+			// create new TXN
+			$transaction = EE_Transaction::new_instance(
+				array(
+					'TXN_reg_steps' => $this->checkout->initialize_txn_reg_steps_array(),
+					'TXN_total'     => $cart_total > 0 ? $cart_total : 0,
+					'TXN_paid'      => 0,
+					'STS_ID'        => EEM_Transaction::failed_status_code,
+				)
+			);
+			// save it so that we have an ID for other objects to use
+			$transaction->save();
+			// set cron job for following up on TXNs after their session has expired
+			EE_Cron_Tasks::schedule_expired_transaction_check(
+				EE_Registry::instance()->SSN->expiration() + 1,
+				$transaction->ID()
+			);
+			return $transaction;
+		} catch (Exception $e) {
+			EE_Error::add_error($e->getMessage(), __FILE__, __FUNCTION__, __LINE__);
+		}
+		return null;
+	}
+
+
+	/**
+	 * _get_registrations
+	 *
+	 * @access private
+	 * @param EE_Transaction $transaction
+	 * @return void
+	 * @throws InvalidDataTypeException
+	 * @throws InvalidEntityException
+	 * @throws EE_Error
+	 */
+	private function _get_registrations(EE_Transaction $transaction)
+	{
+		// first step: grab the registrants  { : o
+		$registrations = $transaction->registrations($this->checkout->reg_cache_where_params, false);
+		$this->checkout->total_ticket_count = count($registrations);
+		// verify registrations have been set
+		if (empty($registrations)) {
+			// if no cached registrations, then check the db
+			$registrations = $transaction->registrations($this->checkout->reg_cache_where_params, false);
+			// still nothing ? well as long as this isn't a revisit
+			if (empty($registrations) && ! $this->checkout->revisit) {
+				// generate new registrations from scratch
+				$registrations = $this->_initialize_registrations($transaction);
+			}
+		}
+		// sort by their original registration order
+		usort($registrations, array('EED_Single_Page_Checkout', 'sort_registrations_by_REG_count'));
+		// then loop thru the array
+		foreach ($registrations as $registration) {
+			// verify each registration
+			if ($registration instanceof EE_Registration) {
+				// we display all attendee info for the primary registrant
+				if ($this->checkout->reg_url_link === $registration->reg_url_link()
+					&& $registration->is_primary_registrant()
+				) {
+					$this->checkout->primary_revisit = true;
+					break;
+				}
+				if ($this->checkout->revisit && $this->checkout->reg_url_link !== $registration->reg_url_link()) {
+					// but hide info if it doesn't belong to you
+					$transaction->clear_cache('Registration', $registration->ID());
+					$this->checkout->total_ticket_count--;
+				}
+				$this->checkout->set_reg_status_updated($registration->ID(), false);
+			}
+		}
+	}
+
+
+	/**
+	 *    adds related EE_Registration objects for each ticket in the cart to the current EE_Transaction object
+	 *
+	 * @access private
+	 * @param EE_Transaction $transaction
+	 * @return    array
+	 * @throws InvalidDataTypeException
+	 * @throws InvalidEntityException
+	 * @throws EE_Error
+	 */
+	private function _initialize_registrations(EE_Transaction $transaction)
+	{
+		$att_nmbr = 0;
+		$registrations = array();
+		if ($transaction instanceof EE_Transaction) {
+			/** @type EE_Registration_Processor $registration_processor */
+			$registration_processor = EE_Registry::instance()->load_class('Registration_Processor');
+			$this->checkout->total_ticket_count = $this->checkout->cart->all_ticket_quantity_count();
+			// now let's add the cart items to the $transaction
+			foreach ($this->checkout->cart->get_tickets() as $line_item) {
+				// do the following for each ticket of this type they selected
+				for ($x = 1; $x <= $line_item->quantity(); $x++) {
+					$att_nmbr++;
+					/** @var EventEspresso\core\services\commands\registration\CreateRegistrationCommand $CreateRegistrationCommand */
+					$CreateRegistrationCommand = EE_Registry::instance()->create(
+						'EventEspresso\core\services\commands\registration\CreateRegistrationCommand',
+						array(
+							$transaction,
+							$line_item,
+							$att_nmbr,
+							$this->checkout->total_ticket_count,
+						)
+					);
+					// override capabilities for frontend registrations
+					if (! is_admin()) {
+						$CreateRegistrationCommand->setCapCheck(
+							new PublicCapabilities('', 'create_new_registration')
+						);
+					}
+					$registration = EE_Registry::instance()->BUS->execute($CreateRegistrationCommand);
+					if (! $registration instanceof EE_Registration) {
+						throw new InvalidEntityException($registration, 'EE_Registration');
+					}
+					$registrations[ $registration->ID() ] = $registration;
+				}
+			}
+			$registration_processor->fix_reg_final_price_rounding_issue($transaction);
+		}
+		return $registrations;
+	}
+
+
+	/**
+	 * sorts registrations by REG_count
+	 *
+	 * @access public
+	 * @param EE_Registration $reg_A
+	 * @param EE_Registration $reg_B
+	 * @return int
+	 */
+	public static function sort_registrations_by_REG_count(EE_Registration $reg_A, EE_Registration $reg_B)
+	{
+		// this shouldn't ever happen within the same TXN, but oh well
+		if ($reg_A->count() === $reg_B->count()) {
+			return 0;
+		}
+		return ($reg_A->count() > $reg_B->count()) ? 1 : -1;
+	}
+
+
+	/**
+	 *    _final_verifications
+	 * just makes sure that everything is set up correctly before proceeding
+	 *
+	 * @access    private
+	 * @return    bool
+	 * @throws EE_Error
+	 */
+	private function _final_verifications()
+	{
+		// filter checkout
+		$this->checkout = apply_filters(
+			'FHEE__EED_Single_Page_Checkout___final_verifications__checkout',
+			$this->checkout
+		);
+		// verify that current step is still set correctly
+		if (! $this->checkout->current_step instanceof EE_SPCO_Reg_Step) {
+			EE_Error::add_error(
+				esc_html__(
+					'We\'re sorry but the registration process can not proceed because one or more registration steps were not setup correctly. Please refresh the page and try again or contact support.',
+					'event_espresso'
+				),
+				__FILE__,
+				__FUNCTION__,
+				__LINE__
+			);
+			return false;
+		}
+		// if returning to SPCO, then verify that primary registrant is set
+		if (! empty($this->checkout->reg_url_link)) {
+			$valid_registrant = $this->checkout->transaction->primary_registration();
+			if (! $valid_registrant instanceof EE_Registration) {
+				EE_Error::add_error(
+					esc_html__(
+						'We\'re sorry but there appears to be an error with the "reg_url_link" or the primary registrant for this transaction. Please refresh the page and try again or contact support.',
+						'event_espresso'
+					),
+					__FILE__,
+					__FUNCTION__,
+					__LINE__
+				);
+				return false;
+			}
+			$valid_registrant = null;
+			foreach ($this->checkout->transaction->registrations($this->checkout->reg_cache_where_params) as $registration) {
+				if ($registration instanceof EE_Registration
+					&& $registration->reg_url_link() === $this->checkout->reg_url_link
+				) {
+					$valid_registrant = $registration;
+				}
+			}
+			if (! $valid_registrant instanceof EE_Registration) {
+				// hmmm... maybe we have the wrong session because the user is opening multiple tabs ?
+				if (EED_Single_Page_Checkout::$_checkout_verified) {
+					// clear the session, mark the checkout as unverified, and try again
+					EE_Registry::instance()->SSN->clear_session(__CLASS__, __FUNCTION__);
+					EED_Single_Page_Checkout::$_initialized = false;
+					EED_Single_Page_Checkout::$_checkout_verified = false;
+					$this->_initialize();
+					EE_Error::reset_notices();
+					return false;
+				}
+				EE_Error::add_error(
+					esc_html__(
+						'We\'re sorry but there appears to be an error with the "reg_url_link" or the transaction itself. Please refresh the page and try again or contact support.',
+						'event_espresso'
+					),
+					__FILE__,
+					__FUNCTION__,
+					__LINE__
+				);
+				return false;
+			}
+		}
+		// now that things have been kinda sufficiently verified,
+		// let's add the checkout to the session so that it's available to other systems
+		EE_Registry::instance()->SSN->set_checkout($this->checkout);
+		return true;
+	}
+
+
+	/**
+	 *    _initialize_reg_steps
+	 * first makes sure that EE_Transaction_Processor::set_reg_step_initiated() is called as required
+	 * then loops thru all of the active reg steps and calls the initialize_reg_step() method
+	 *
+	 * @access    private
+	 * @param bool $reinitializing
+	 * @throws EE_Error
+	 */
+	private function _initialize_reg_steps($reinitializing = false)
+	{
+		$this->checkout->set_reg_step_initiated($this->checkout->current_step);
+		// loop thru all steps to call their individual "initialize" methods and set i18n strings for JS
+		foreach ($this->checkout->reg_steps as $reg_step) {
+			if (! $reg_step->initialize_reg_step()) {
+				// if not initialized then maybe this step is being removed...
+				if (! $reinitializing && $reg_step->is_current_step()) {
+					// if it was the current step, then we need to start over here
+					$this->_initialize_reg_steps(true);
+					return;
+				}
+				continue;
+			}
+			// add css and JS for current step
+			$this->add_styles_and_scripts($reg_step);
+			if ($reg_step->is_current_step()) {
+				// the text that appears on the reg step form submit button
+				$reg_step->set_submit_button_text();
+			}
+		}
+		// dynamically creates hook point like: AHEE__Single_Page_Checkout___initialize_reg_step__attendee_information
+		do_action(
+			"AHEE__Single_Page_Checkout___initialize_reg_step__{$this->checkout->current_step->slug()}",
+			$this->checkout->current_step
+		);
+	}
+
+
+	/**
+	 * _check_form_submission
+	 *
+	 * @access private
+	 * @return boolean
+	 */
+	private function _check_form_submission()
+	{
+		// does this request require the reg form to be generated ?
+		if ($this->checkout->generate_reg_form) {
+			// ever heard that song by Blue Rodeo ?
+			try {
+				$this->checkout->current_step->reg_form = $this->checkout->current_step->generate_reg_form();
+				// if not displaying a form, then check for form submission
+				if ($this->checkout->process_form_submission
+					&& $this->checkout->current_step->reg_form->was_submitted()
+				) {
+					// clear out any old data in case this step is being run again
+					$this->checkout->current_step->set_valid_data(array());
+					// capture submitted form data
+					$this->checkout->current_step->reg_form->receive_form_submission(
+						apply_filters(
+							'FHEE__Single_Page_Checkout___check_form_submission__request_params',
+							EE_Registry::instance()->REQ->params(),
+							$this->checkout
+						)
+					);
+					// validate submitted form data
+					if (! $this->checkout->continue_reg || ! $this->checkout->current_step->reg_form->is_valid()) {
+						// thou shall not pass !!!
+						$this->checkout->continue_reg = false;
+						// any form validation errors?
+						if ($this->checkout->current_step->reg_form->submission_error_message() !== '') {
+							EE_Error::add_error(
+								$this->checkout->current_step->reg_form->submission_error_message(),
+								__FILE__,
+								__FUNCTION__,
+								__LINE__
+							);
+						}
+						// well not really... what will happen is
+						// we'll just get redirected back to redo the current step
+						$this->go_to_next_step();
+						return false;
+					}
+				}
+			} catch (EE_Error $e) {
+				$e->get_error();
+			}
+		}
+		return true;
+	}
+
+
+	/**
+	 * _process_action
+	 *
+	 * @access private
+	 * @return void
+	 * @throws EE_Error
+	 */
+	private function _process_form_action()
+	{
+		// what cha wanna do?
+		switch ($this->checkout->action) {
+			// AJAX next step reg form
+			case 'display_spco_reg_step':
+				$this->checkout->redirect = false;
+				if (EE_Registry::instance()->REQ->ajax) {
+					$this->checkout->json_response->set_reg_step_html(
+						$this->checkout->current_step->display_reg_form()
+					);
+				}
+				break;
+			default:
+				// meh... do one of those other steps first
+				if (! empty($this->checkout->action)
+					&& is_callable(array($this->checkout->current_step, $this->checkout->action))
+				) {
+					// dynamically creates hook point like:
+					//   AHEE__Single_Page_Checkout__before_attendee_information__process_reg_step
+					do_action(
+						"AHEE__Single_Page_Checkout__before_{$this->checkout->current_step->slug()}__{$this->checkout->action}",
+						$this->checkout->current_step
+					);
+					// call action on current step
+					if (call_user_func(array($this->checkout->current_step, $this->checkout->action))) {
+						// good registrant, you get to proceed
+						if ($this->checkout->current_step->success_message() !== ''
+							&& apply_filters(
+								'FHEE__Single_Page_Checkout___process_form_action__display_success',
+								false
+							)
+						) {
+							EE_Error::add_success(
+								$this->checkout->current_step->success_message()
+								. '<br />' . $this->checkout->next_step->_instructions()
+							);
+						}
+						// pack it up, pack it in...
+						$this->_setup_redirect();
+					}
+					// dynamically creates hook point like:
+					//  AHEE__Single_Page_Checkout__after_payment_options__process_reg_step
+					do_action(
+						"AHEE__Single_Page_Checkout__after_{$this->checkout->current_step->slug()}__{$this->checkout->action}",
+						$this->checkout->current_step
+					);
+				} else {
+					EE_Error::add_error(
+						sprintf(
+							esc_html__(
+								'The requested form action "%s" does not exist for the current "%s" registration step.',
+								'event_espresso'
+							),
+							$this->checkout->action,
+							$this->checkout->current_step->name()
+						),
+						__FILE__,
+						__FUNCTION__,
+						__LINE__
+					);
+				}
+			// end default
+		}
+		// store our progress so far
+		$this->checkout->stash_transaction_and_checkout();
+		// advance to the next step! If you pass GO, collect $200
+		$this->go_to_next_step();
+	}
+
+
+	/**
+	 * @param EED_Single_Page_Checkout|EE_SPCO_Reg_Step $target
+	 * @param object $target an object with the method `translate_js_strings` and `enqueue_styles_and_scripts`.
+	 * @return        void
+	 */
+	public function add_styles_and_scripts($target)
+	{
+		// i18n
+		$target->translate_js_strings();
+		if ($this->checkout->admin_request) {
+			add_action('admin_enqueue_scripts', array($target, 'enqueue_styles_and_scripts'), 10);
+		} else {
+			add_action('wp_enqueue_scripts', array($target, 'enqueue_styles_and_scripts'), 10);
+		}
+	}
+
+	/**
+	 *        translate_js_strings
+	 *
+	 * @access        public
+	 * @return        void
+	 */
+	public function translate_js_strings()
+	{
+		EE_Registry::$i18n_js_strings['revisit'] = $this->checkout->revisit;
+		EE_Registry::$i18n_js_strings['e_reg_url_link'] = $this->checkout->reg_url_link;
+		EE_Registry::$i18n_js_strings['server_error'] = esc_html__(
+			'An unknown error occurred on the server while attempting to process your request. Please refresh the page and try again or contact support.',
+			'event_espresso'
+		);
+		EE_Registry::$i18n_js_strings['invalid_json_response'] = esc_html__(
+			'An invalid response was returned from the server while attempting to process your request. Please refresh the page and try again or contact support.',
+			'event_espresso'
+		);
+		EE_Registry::$i18n_js_strings['validation_error'] = esc_html__(
+			'There appears to be a problem with the form validation configuration! Please check the admin settings or contact support.',
+			'event_espresso'
+		);
+		EE_Registry::$i18n_js_strings['invalid_payment_method'] = esc_html__(
+			'There appears to be a problem with the payment method configuration! Please refresh the page and try again or contact support.',
+			'event_espresso'
+		);
+		EE_Registry::$i18n_js_strings['reg_step_error'] = esc_html__(
+			'This registration step could not be completed. Please refresh the page and try again.',
+			'event_espresso'
+		);
+		EE_Registry::$i18n_js_strings['invalid_coupon'] = esc_html__(
+			'We\'re sorry but that coupon code does not appear to be valid. If this is incorrect, please contact the site administrator.',
+			'event_espresso'
+		);
+		EE_Registry::$i18n_js_strings['process_registration'] = sprintf(
+			esc_html__(
+				'Please wait while we process your registration.%sDo not refresh the page or navigate away while this is happening.%sThank you for your patience.',
+				'event_espresso'
+			),
+			'<br/>',
+			'<br/>'
+		);
+		EE_Registry::$i18n_js_strings['language'] = get_bloginfo('language');
+		EE_Registry::$i18n_js_strings['EESID'] = EE_Registry::instance()->SSN->id();
+		EE_Registry::$i18n_js_strings['currency'] = EE_Registry::instance()->CFG->currency;
+		EE_Registry::$i18n_js_strings['datepicker_yearRange'] = '-150:+20';
+		EE_Registry::$i18n_js_strings['timer_years'] = esc_html__('years', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_months'] = esc_html__('months', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_weeks'] = esc_html__('weeks', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_days'] = esc_html__('days', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_hours'] = esc_html__('hours', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_minutes'] = esc_html__('minutes', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_seconds'] = esc_html__('seconds', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_year'] = esc_html__('year', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_month'] = esc_html__('month', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_week'] = esc_html__('week', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_day'] = esc_html__('day', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_hour'] = esc_html__('hour', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_minute'] = esc_html__('minute', 'event_espresso');
+		EE_Registry::$i18n_js_strings['timer_second'] = esc_html__('second', 'event_espresso');
+		EE_Registry::$i18n_js_strings['registration_expiration_notice'] = EED_Single_Page_Checkout::getRegistrationExpirationNotice(
+		);
+		EE_Registry::$i18n_js_strings['ajax_submit'] = apply_filters(
+			'FHEE__Single_Page_Checkout__translate_js_strings__ajax_submit',
+			true
+		);
+		EE_Registry::$i18n_js_strings['session_extension'] = absint(
+			apply_filters('FHEE__EE_Session__extend_expiration__seconds_added', 10 * MINUTE_IN_SECONDS)
+		);
+		EE_Registry::$i18n_js_strings['session_expiration'] = gmdate(
+			'M d, Y H:i:s',
+			EE_Registry::instance()->SSN->expiration() + (get_option('gmt_offset') * HOUR_IN_SECONDS)
+		);
+	}
+
+
+	/**
+	 *    enqueue_styles_and_scripts
+	 *
+	 * @access        public
+	 * @return        void
+	 * @throws EE_Error
+	 */
+	public function enqueue_styles_and_scripts()
+	{
+		// load css
+		wp_register_style(
+			'single_page_checkout',
+			SPCO_CSS_URL . 'single_page_checkout.css',
+			array('espresso_default'),
+			EVENT_ESPRESSO_VERSION
+		);
+		wp_enqueue_style('single_page_checkout');
+		// load JS
+		wp_register_script(
+			'jquery_plugin',
+			EE_THIRD_PARTY_URL . 'jquery	.plugin.min.js',
+			array('jquery'),
+			'1.0.1',
+			true
+		);
+		wp_register_script(
+			'jquery_countdown',
+			EE_THIRD_PARTY_URL . 'jquery	.countdown.min.js',
+			array('jquery_plugin'),
+			'2.1.0',
+			true
+		);
+		wp_register_script(
+			'single_page_checkout',
+			SPCO_JS_URL . 'single_page_checkout.js',
+			array('espresso_core', 'underscore', 'ee_form_section_validation'),
+			EVENT_ESPRESSO_VERSION,
+			true
+		);
+		if ($this->checkout->registration_form instanceof EE_Form_Section_Proper) {
+			$this->checkout->registration_form->enqueue_js();
+		}
+		if ($this->checkout->current_step->reg_form instanceof EE_Form_Section_Proper) {
+			$this->checkout->current_step->reg_form->enqueue_js();
+		}
+		wp_enqueue_script('single_page_checkout');
+		if (apply_filters('FHEE__registration_page_wrapper_template__display_time_limit', false)) {
+			wp_enqueue_script('jquery_countdown');
+		}
+		/**
+		 * global action hook for enqueueing styles and scripts with
+		 * spco calls.
+		 */
+		do_action('AHEE__EED_Single_Page_Checkout__enqueue_styles_and_scripts', $this);
+		/**
+		 * dynamic action hook for enqueueing styles and scripts with spco calls.
+		 * The hook will end up being something like:
+		 *      AHEE__EED_Single_Page_Checkout__enqueue_styles_and_scripts__attendee_information
+		 */
+		do_action(
+			'AHEE__EED_Single_Page_Checkout__enqueue_styles_and_scripts__' . $this->checkout->current_step->slug(),
+			$this
+		);
+	}
+
+
+	/**
+	 *    display the Registration Single Page Checkout Form
+	 *
+	 * @access    private
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	private function _display_spco_reg_form()
+	{
+		// if registering via the admin, just display the reg form for the current step
+		if ($this->checkout->admin_request) {
+			EE_Registry::instance()->REQ->add_output($this->checkout->current_step->display_reg_form());
+		} else {
+			// add powered by EE msg
+			add_action('AHEE__SPCO__reg_form_footer', array('EED_Single_Page_Checkout', 'display_registration_footer'));
+			$empty_cart = count($this->checkout->transaction
+									->registrations($this->checkout->reg_cache_where_params)) < 1;
+			EE_Registry::$i18n_js_strings['empty_cart'] = $empty_cart;
+			$cookies_not_set_msg = '';
+			if ($empty_cart) {
+				$cookies_not_set_msg = apply_filters(
+					'FHEE__Single_Page_Checkout__display_spco_reg_form__cookies_not_set_msg',
+					sprintf(
+						esc_html__(
+							'%1$s%3$sIt appears your browser is not currently set to accept Cookies%4$s%5$sIn order to register for events, you need to enable cookies.%7$sIf you require assistance, then click the following link to learn how to %8$senable cookies%9$s%6$s%2$s',
+							'event_espresso'
+						),
+						'<div class="ee-attention hidden" id="ee-cookies-not-set-msg">',
+						'</div>',
+						'<h6 class="important-notice">',
+						'</h6>',
+						'<p>',
+						'</p>',
+						'<br />',
+						'<a href="http://www.whatarecookies.com/enable.asp" target="_blank" rel="noopener noreferrer">',
+						'</a>'
+					)
+				);
+			}
+			$this->checkout->registration_form = new EE_Form_Section_Proper(
+				array(
+					'name'            => 'single-page-checkout',
+					'html_id'         => 'ee-single-page-checkout-dv',
+					'layout_strategy' =>
+						new EE_Template_Layout(
+							array(
+								'layout_template_file' => SPCO_TEMPLATES_PATH . 'registration_page_wrapper.template.php',
+								'template_args'        => array(
+									'empty_cart'              => $empty_cart,
+									'revisit'                 => $this->checkout->revisit,
+									'reg_steps'               => $this->checkout->reg_steps,
+									'next_step'               => $this->checkout->next_step instanceof EE_SPCO_Reg_Step
+										? $this->checkout->next_step->slug()
+										: '',
+									'empty_msg'               => apply_filters(
+										'FHEE__Single_Page_Checkout__display_spco_reg_form__empty_msg',
+										sprintf(
+											esc_html__(
+												'You need to %1$sReturn to Events list%2$sselect at least one event%3$s before you can proceed with the registration process.',
+												'event_espresso'
+											),
+											'<a href="'
+											. get_post_type_archive_link('espresso_events')
+											. '" title="',
+											'">',
+											'</a>'
+										)
+									),
+									'cookies_not_set_msg'     => $cookies_not_set_msg,
+									'registration_time_limit' => $this->checkout->get_registration_time_limit(),
+									'session_expiration'      => gmdate(
+										'M d, Y H:i:s',
+										EE_Registry::instance()->SSN->expiration()
+										+ (get_option('gmt_offset') * HOUR_IN_SECONDS)
+									),
+								),
+							)
+						),
+				)
+			);
+			// load template and add to output sent that gets filtered into the_content()
+			EE_Registry::instance()->REQ->add_output($this->checkout->registration_form->get_html());
+		}
+	}
+
+
+	/**
+	 *    add_extra_finalize_registration_inputs
+	 *
+	 * @access    public
+	 * @param $next_step
+	 * @internal  param string $label
+	 * @return void
+	 */
+	public function add_extra_finalize_registration_inputs($next_step)
+	{
+		if ($next_step === 'finalize_registration') {
+			echo '<div id="spco-extra-finalize_registration-inputs-dv"></div>';
+		}
+	}
+
+
+	/**
+	 *    display_registration_footer
+	 *
+	 * @access    public
+	 * @return    string
+	 */
+	public static function display_registration_footer()
+	{
+		if (apply_filters(
+			'FHEE__EE_Front__Controller__show_reg_footer',
+			EE_Registry::instance()->CFG->admin->show_reg_footer
+		)) {
+			add_filter(
+				'FHEE__EEH_Template__powered_by_event_espresso__url',
+				function ($url) {
+					return apply_filters('FHEE__EE_Front_Controller__registration_footer__url', $url);
+				}
+			);
+			echo apply_filters(
+				'FHEE__EE_Front_Controller__display_registration_footer',
+				\EEH_Template::powered_by_event_espresso(
+					'',
+					'espresso-registration-footer-dv',
+					array('utm_content' => 'registration_checkout')
+				)
+			);
+		}
+		return '';
+	}
+
+
+	/**
+	 *    unlock_transaction
+	 *
+	 * @access    public
+	 * @return    void
+	 * @throws EE_Error
+	 */
+	public function unlock_transaction()
+	{
+		if ($this->checkout->transaction instanceof EE_Transaction) {
+			$this->checkout->transaction->unlock();
+		}
+	}
+
+
+	/**
+	 *        _setup_redirect
+	 *
+	 * @access    private
+	 * @return void
+	 */
+	private function _setup_redirect()
+	{
+		if ($this->checkout->continue_reg && $this->checkout->next_step instanceof EE_SPCO_Reg_Step) {
+			$this->checkout->redirect = true;
+			if (empty($this->checkout->redirect_url)) {
+				$this->checkout->redirect_url = $this->checkout->next_step->reg_step_url();
+			}
+			$this->checkout->redirect_url = apply_filters(
+				'FHEE__EED_Single_Page_Checkout___setup_redirect__checkout_redirect_url',
+				$this->checkout->redirect_url,
+				$this->checkout
+			);
+		}
+	}
+
+
+	/**
+	 *   handle ajax message responses and redirects
+	 *
+	 * @access public
+	 * @return void
+	 * @throws EE_Error
+	 */
+	public function go_to_next_step()
+	{
+		if (EE_Registry::instance()->REQ->ajax) {
+			// capture contents of output buffer we started earlier in the request, and insert into JSON response
+			$this->checkout->json_response->set_unexpected_errors(ob_get_clean());
+		}
+		$this->unlock_transaction();
+		// just return for these conditions
+		if ($this->checkout->admin_request
+			|| $this->checkout->action === 'redirect_form'
+			|| $this->checkout->action === 'update_checkout'
+		) {
+			return;
+		}
+		// AJAX response
+		$this->_handle_json_response();
+		// redirect to next step or the Thank You page
+		$this->_handle_html_redirects();
+		// hmmm... must be something wrong, so let's just display the form again !
+		$this->_display_spco_reg_form();
+	}
+
+
+	/**
+	 *   _handle_json_response
+	 *
+	 * @access protected
+	 * @return void
+	 */
+	protected function _handle_json_response()
+	{
+		// if this is an ajax request
+		if (EE_Registry::instance()->REQ->ajax) {
+			$this->checkout->json_response->set_registration_time_limit(
+				$this->checkout->get_registration_time_limit()
+			);
+			$this->checkout->json_response->set_payment_amount($this->checkout->amount_owing);
+			// just send the ajax (
+			$json_response = apply_filters(
+				'FHEE__EE_Single_Page_Checkout__JSON_response',
+				$this->checkout->json_response
+			);
+			echo $json_response;
+			exit();
+		}
+	}
+
+
+	/**
+	 *   _handle_redirects
+	 *
+	 * @access protected
+	 * @return void
+	 */
+	protected function _handle_html_redirects()
+	{
+		// going somewhere ?
+		if ($this->checkout->redirect && ! empty($this->checkout->redirect_url)) {
+			// store notices in a transient
+			EE_Error::get_notices(false, true, true);
+			wp_safe_redirect($this->checkout->redirect_url);
+			exit();
+		}
+	}
+
+
+	/**
+	 *   set_checkout_anchor
+	 *
+	 * @access public
+	 * @return void
+	 */
+	public function set_checkout_anchor()
+	{
+		echo '<a id="checkout" style="float: left; margin-left: -999em;"></a>';
+	}
+
+	/**
+	 *    getRegistrationExpirationNotice
+	 *
+	 * @since     4.9.59.p
+	 * @access    public
+	 * @return    string
+	 */
+	public static function getRegistrationExpirationNotice()
+	{
+		return sprintf(
+			esc_html__(
+				'%1$sWe\'re sorry, but your registration time has expired.%2$s%3$s%4$sIf you still wish to complete your registration, please return to the %5$sEvent List%6$sEvent List%7$s and reselect your tickets if available. Please accept our apologies for any inconvenience this may have caused.%8$s',
+				'event_espresso'
+			),
+			'<h4 class="important-notice">',
+			'</h4>',
+			'<br />',
+			'<p>',
+			'<a href="' . get_post_type_archive_link('espresso_events') . '" title="',
+			'">',
+			'</a>',
+			'</p>'
+		);
+	}
 }