增加onepagecheckout插件

app/code/Magento/Checkout/Controller/Cart/Add.php

@@ -137,13 +137,13 @@ class Add extends \Magento\Checkout\Controller\Cart implements HttpPostActionInt
             );
 
             if (!$this->_checkoutSession->getNoCartRedirect(true)) {
-                if ($this->shouldRedirectToCart()) {
-                    $message = __(
-                        'You added %1 to your shopping cart.',
-                        $product->getName()
-                    );
-                    $this->messageManager->addSuccessMessage($message);
-                }
+//                if ($this->shouldRedirectToCart()) {
+//                    $message = __(
+//                        'You added %1 to your shopping cart.',
+//                        $product->getName()
+//                    );
+//                    $this->messageManager->addSuccessMessage($message);
+//                }
                 if ($this->cart->getQuote()->getHasError()) {
                     $errors = $this->cart->getQuote()->getErrors();
                     foreach ($errors as $error) {

app/code/Magento/Checkout/i18n/en_US.csv

@@ -65,7 +65,7 @@ Message,Message
 "Print receipt","Print receipt"
 "Apply Discount Code","Apply Discount Code"
 "Enter discount code","Enter discount code"
-"Apply Discount","Apply Discount"
+"Apply Discount","Apply Code"
 "Cancel Coupon","Cancel Coupon"
 "Shopping Cart Items","Shopping Cart Items"
 Item,Item

app/code/Rokanthemes/OnePageCheckout/Api/Data/UpdateItemDetailsInterface.php

+<?php
+
+namespace Rokanthemes\OnePageCheckout\Api\Data;
+
+/**
+ * Interface UpdateItemDetailsInterface
+ * @api
+ */
+interface UpdateItemDetailsInterface
+{
+    /**
+     * Constants defined for keys of array, makes typos less likely
+     */
+    const PAYMENT_METHODS = 'payment_methods';
+
+    const TOTALS = 'totals';
+
+    const SHIPPING_METHODS = 'shipping_methods';
+
+    const MESSAGE = 'message';
+
+    const STATUS = 'status';
+
+    const HAS_ERROR = 'has_error';
+
+    const GIFT_WRAP_DISPLAY = 'gift_wrap_display';
+
+    const GIFT_WRAP_LABEL = 'gift_wrap_label';
+
+    /**
+     * @return \Magento\Quote\Api\Data\PaymentMethodInterface[]
+     */
+    public function getPaymentMethods();
+
+    /**
+     * @param \Magento\Quote\Api\Data\PaymentMethodInterface[] $paymentMethods
+     * @return $this
+     */
+    public function setPaymentMethods($paymentMethods);
+
+    /**
+     * @return \Magento\Quote\Api\Data\TotalsInterface
+     */
+    public function getTotals();
+
+    /**
+     * @param \Magento\Quote\Api\Data\TotalsInterface $totals
+     * @return $this
+     */
+    public function setTotals($totals);
+
+    /**
+     * @return \Magento\Quote\Api\Data\ShippingMethodInterface[]
+     */
+    public function getShippingMethods();
+
+    /**
+     * @param \Magento\Quote\Api\Data\ShippingMethodInterface[] $shippingMethods
+     * @return $this
+     */
+    public function setShippingMethods($shippingMethods);
+
+    /**
+     * @return string
+     */
+    public function getMessage();
+
+    /**
+     * @param string $message
+     * @return $this
+     */
+    public function setMessage($message);
+
+    /**
+     * @return bool
+     */
+    public function getStatus();
+
+    /**
+     * @param bool $status
+     * @return $this
+     */
+    public function setStatus($status);
+
+    /**
+     * @return bool
+     */
+    public function getHasError();
+
+    /**
+     * @param bool $error
+     * @return $this
+     */
+    public function setHasError($error);
+
+    /**
+     * @return bool
+     */
+}

app/code/Rokanthemes/OnePageCheckout/Api/GuestUpdateItemManagementInterface.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Api;
+
+/**
+ * Interface GuestUpdateItemManagementInterface
+ * @api
+ */
+interface GuestUpdateItemManagementInterface
+{
+    /**
+     * @param string $cartId
+     * @param \Magento\Quote\Api\Data\EstimateAddressInterface $address
+     * @param int $itemId
+     * @param float $qty
+     * @return \Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterface
+     */
+    public function update($cartId, \Magento\Quote\Api\Data\EstimateAddressInterface $address, $itemId, $qty);
+}

app/code/Rokanthemes/OnePageCheckout/Api/UpdateItemManagementInterface.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Api;
+
+/**
+ * Interface UpdateItemManagementInterface
+ * @api
+ */
+interface UpdateItemManagementInterface
+{
+    /**
+     * @param int $cartId
+     * @param \Magento\Quote\Api\Data\EstimateAddressInterface $address
+     * @param int $itemId
+     * @param float $qty
+     * @return \Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterface
+     * @throws \Magento\Framework\Exception\CouldNotSaveException
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
+     */
+    public function update($cartId, \Magento\Quote\Api\Data\EstimateAddressInterface $address, $itemId, $qty);
+}

app/code/Rokanthemes/OnePageCheckout/Block/Adminhtml/Field/AbstractField.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Block\Adminhtml\Field;
+
+use Magento\Backend\Block\Template;
+use Magento\Backend\Block\Widget\Context;
+use Magento\Customer\Model\Attribute;
+use Rokanthemes\OnePageCheckout\Helper\Address;
+
+/**
+ * Class AbstractField
+ * @package Rokanthemes\OnePageCheckout\Block\Adminhtml\Field
+ */
+abstract class AbstractField extends Template
+{
+    const BLOCK_ID = '';
+
+    /**
+     * @var string
+     */
+    protected $_template = 'Rokanthemes_OnePageCheckout::field/position.phtml';
+
+    /**
+     * @var Address
+     */
+    protected $helper;
+
+    /**
+     * @var Attribute[]
+     */
+    protected $sortedFields = [];
+
+    /**
+     * @var Attribute[]
+     */
+    protected $availableFields = [];
+
+    /**
+     * AbstractField constructor.
+     *
+     * @param Context $context
+     * @param Address $helper
+     * @param array $data
+     */
+    public function __construct(
+        Context $context,
+        Address $helper,
+        array $data = []
+    ) {
+        $this->helper = $helper;
+
+        parent::__construct($context, $data);
+    }
+
+    /**
+     * Retrieve the header text
+     *
+     * @return string
+     */
+    abstract public function getBlockTitle();
+
+    /**
+     * @return string
+     */
+    public function getBlockId()
+    {
+        return static::BLOCK_ID;
+    }
+
+    /**
+     * @return Attribute[]
+     */
+    public function getSortedFields()
+    {
+        return $this->sortedFields;
+    }
+
+    /**
+     * @return Attribute[]
+     */
+    public function getAvailableFields()
+    {
+        return $this->availableFields;
+    }
+
+    /**
+     * @return Address
+     */
+    public function getHelperData()
+    {
+        return $this->helper;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isVisible()
+    {
+        return true;
+    }
+
+    /**
+     * @return bool
+     */
+    public function hasFields()
+    {
+        return true;
+    }
+
+    /**
+     * @return string
+     */
+    public function getNoticeMessage()
+    {
+        return '';
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Block/Adminhtml/Field/Address.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Block\Adminhtml\Field;
+
+/**
+ * Class Address
+ * @package Rokanthemes\OnePageCheckout\Block\Adminhtml\Field
+ */
+class Address extends AbstractField
+{
+    const BLOCK_ID = 'admin-address-information';
+
+    /**
+     * @inheritdoc
+     */
+    protected function _construct()
+    {
+        parent::_construct();
+
+        /** Prepare collection */
+        list($this->sortedFields, $this->availableFields) = $this->helper->getSortedField(false);
+    }
+
+    /**
+     * @return string
+     */
+    public function getBlockTitle()
+    {
+        return (string) __('Address Information');
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Block/Adminhtml/Field/Tabs.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Block\Adminhtml\Field;
+
+use Magento\Backend\Block\Widget\Container;
+use Magento\Backend\Block\Widget\Context;
+
+class Tabs extends Container
+{
+    public function __construct(
+        Context $context,
+        array $data = []
+    ) {
+        parent::__construct($context, $data);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    protected function _construct()
+    {
+        parent::_construct();
+
+        $this->addButton('save', [
+            'label' => __('Save Position'),
+            'class' => 'save primary admin-save-position',
+        ]);
+    }
+
+    /**
+     * Retrieve the header text
+     *
+     * @return string
+     */
+    public function getHeaderText()
+    {
+        return (string) __('Manage Fields');
+    }
+
+    /**
+     * @return string
+     */
+    public function getAjaxUrl()
+    {
+        return $this->getUrl('*/*/save');
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Block/Config.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Block;
+
+
+class Config extends \Magento\Framework\View\Element\Template
+{
+   protected $helper;
+
+    /**
+     * Construct
+     *
+     * @param \Magento\Framework\View\Element\Template\Context $context
+     * @param \Magento\Customer\Model\Session $customerSession
+     * @param array $data
+     */
+    public function __construct(
+        \Magento\Framework\View\Element\Template\Context $context,
+        \Rokanthemes\OnePageCheckout\Helper\Data $helper,
+        array $data = []
+    ) {
+        parent::__construct($context, $data);
+        $this->helper = $helper;
+    }
+    public function getShortDescription()
+    {
+        return $this->helper->getGeneral('short_description');
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Controller/Account/Save.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Controller\Account;
+
+class Save extends \Magento\Framework\App\Action\Action
+{
+    /**
+     * @var \Magento\Checkout\Helper\Cart
+     */
+    protected $checkoutSession;
+
+    /**
+     * @var \Magento\Framework\Controller\Result\JsonFactory
+     */
+    protected $resultJsonFactory;
+
+    /**
+     * Save constructor.
+     * @param \Magento\Framework\App\Action\Context $context
+     * @param \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory
+     * @param \Magento\Checkout\Model\Session $checkoutSession
+     */
+    public function __construct(
+        \Magento\Framework\App\Action\Context $context,
+        \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory,
+        \Magento\Checkout\Model\Session $checkoutSession
+    ) {
+        parent::__construct($context);
+        $this->checkoutSession = $checkoutSession;
+        $this->resultJsonFactory = $resultJsonFactory;
+    }
+
+    /**
+     * @return \Magento\Framework\App\ResponseInterface|\Magento\Framework\Controller\Result\Json|\Magento\Framework\Controller\ResultInterface
+     */
+    public function execute()
+    {
+        $result = $this->resultJsonFactory->create();
+        try {
+            $params = $this->getRequest()->getParams();
+            if (isset($params['email'])
+                && isset($params['pass'])
+                && isset($params['confirmpass'])
+                && $params['pass'] == $params['confirmpass']
+            ) {
+                $this->checkoutSession->setNewAccountInformaton(
+                    ['email' => $params['email'], 'pass' => $params['pass']]
+                );
+            } else {
+                $this->checkoutSession->unsNewAccountInformaton();
+            }
+        } catch (\Exception $e) {
+            return $result->setData($e->getMessage());
+        }
+        return $result->setData('done');
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Controller/Adminhtml/Field/Manage.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Controller\Adminhtml\Field;
+
+use Magento\Backend\App\Action;
+use Magento\Backend\App\Action\Context;
+use Magento\Framework\View\Result\Page;
+use Magento\Framework\View\Result\PageFactory;
+
+/**
+ * Class Position
+ * @package Rokanthemes\OnePageCheckout\Controller\Adminhtml\Field
+ */
+class Manage extends Action
+{
+    /**
+     * @var PageFactory
+     */
+    protected $resultPageFactory;
+
+    /**
+     * @param Context $context
+     * @param PageFactory $resultPageFactory
+     */
+    public function __construct(
+        Context $context,
+        PageFactory $resultPageFactory
+    ) {
+        $this->resultPageFactory = $resultPageFactory;
+        parent::__construct($context);
+    }
+
+    /**
+     * @return Page
+     */
+    public function execute()
+    {
+        $resultPage = $this->resultPageFactory->create();
+        $resultPage->getConfig()->getTitle()->prepend(__('Manage Fields'));
+        $resultPage->addBreadcrumb(__('One Page Checkout'), __('One Page Checkout'));
+        $resultPage->addBreadcrumb(__('Manage Fields'), __('Manage Fields'));
+
+        return $resultPage;
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Controller/Adminhtml/Field/Save.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Controller\Adminhtml\Field;
+
+use Exception;
+use Magento\Backend\App\Action;
+use Magento\Backend\App\Action\Context;
+use Magento\Config\Model\ResourceModel\Config;
+use Magento\Framework\App\Config\ReinitableConfigInterface;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\App\ResponseInterface;
+use Magento\Framework\Controller\Result\Json;
+use Magento\Framework\Controller\Result\JsonFactory;
+use Magento\Framework\Controller\ResultInterface;
+use Rokanthemes\OnePageCheckout\Helper\Data as OpcHelper;
+
+/**
+ * Class Save
+ * @package Rokanthemes\OnePageCheckout\Controller\Adminhtml\Field
+ */
+class Save extends Action
+{
+    /**
+     * @var Config
+     */
+    private $resourceConfig;
+
+    /**
+     * @var ScopeConfigInterface
+     */
+    private $_appConfig;
+
+    /**
+     * @var JsonFactory
+     */
+    private $resultJsonFactory;
+
+    /**
+     * Save constructor.
+     *
+     * @param Context $context
+     * @param Config $resourceConfig
+     * @param ReinitableConfigInterface $config
+     * @param JsonFactory $resultJsonFactory
+     */
+    public function __construct(
+        Context $context,
+        Config $resourceConfig,
+        ReinitableConfigInterface $config,
+        JsonFactory $resultJsonFactory
+    ) {
+        $this->resourceConfig    = $resourceConfig;
+        $this->_appConfig        = $config;
+        $this->resultJsonFactory = $resultJsonFactory;
+
+        parent::__construct($context);
+    }
+
+    /**
+     * Save position to config
+     *
+     * @return ResponseInterface|Json|ResultInterface
+     */
+    public function execute()
+    {
+        /** @var Json $resultJson */
+        $resultJson = $this->resultJsonFactory->create();
+
+        $result = [
+            'message' => (string) __('Error during save field position.'),
+            'type'    => 'error',
+        ];
+
+        $fields   = $this->getRequest()->getParam('fields', false);
+        if ($fields) {
+            try {
+                $this->resourceConfig->saveConfig(
+                    OpcHelper::XML_PATH_SORTED_FIELD_POSITION,
+                    $fields,
+                    ScopeConfigInterface::SCOPE_TYPE_DEFAULT,
+                    0
+                );
+            } catch (Exception $e) {
+                $result['message'] = $e->getMessage();
+
+                return $resultJson->setData($result);
+            }
+
+            // re-init configuration
+            $this->_appConfig->reinit();
+
+            $result['message'] = (string) __('All fields have been saved.');
+            $result['type']    = 'success';
+        }
+
+        return $resultJson->setData($result);
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Controller/Index/Index.php

+<?php
+
+namespace Rokanthemes\OnePageCheckout\Controller\Index;
+
+use Magento\Customer\Api\AccountManagementInterface;
+use Magento\Customer\Api\CustomerRepositoryInterface;
+use Magento\Checkout\Controller\Onepage;
+use Magento\Framework\App\Action\Context;
+use Magento\Customer\Model\Session;
+use Magento\Framework\Registry;
+use Magento\Framework\Translate\InlineInterface;
+use Magento\Framework\Data\Form\FormKey\Validator;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\View\LayoutFactory;
+use Magento\Quote\Api\CartRepositoryInterface;
+use Magento\Framework\View\Result\PageFactory;
+use Magento\Framework\View\Result\LayoutFactory as ResultLayout;
+use Magento\Framework\Controller\Result\RawFactory;
+use Magento\Framework\Controller\Result\JsonFactory;
+use Magento\Checkout\Helper\Data;
+use Magento\Checkout\Model\Session as SessionModel;
+
+class Index extends Onepage
+{
+    /**
+     * Checkout helper
+     *
+     * @var Data
+     */
+    private $checkoutHelper;
+
+    /**
+     * Checkout session
+     *
+     * @var Session
+     */
+    private $checkoutSession;
+
+    /**
+     * One step checkout helper
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    /**
+     * Initialize dependencies.
+     *
+     * @param Context $context
+     * @param Session $customerSession
+     * @param CustomerRepositoryInterface $customerRepository
+     * @param AccountManagementInterface $accountManagement
+     * @param Registry $coreRegistry
+     * @param InlineInterface $translateInline
+     * @param Validator $formKeyValidator
+     * @param ScopeConfigInterface $scopeConfig
+     * @param LayoutFactory $layoutFactory
+     * @param CartRepositoryInterface $quoteRepository
+     * @param PageFactory $resultPageFactory
+     * @param ResultLayout $resultLayoutFactory
+     * @param RawFactory $resultRawFactory
+     * @param JsonFactory $resultJsonFactory
+     * @param Data $checkoutHelper
+     * @param SessionModel $checkoutSession
+     * @param Config $configHelper
+     * @SuppressWarnings(PHPMD.ExcessiveParameterList)
+     */
+    public function __construct(
+        Context $context,
+        Session $customerSession,
+        CustomerRepositoryInterface $customerRepository,
+        AccountManagementInterface $accountManagement,
+        Registry $coreRegistry,
+        InlineInterface $translateInline,
+        Validator $formKeyValidator,
+        ScopeConfigInterface $scopeConfig,
+        LayoutFactory $layoutFactory,
+        CartRepositoryInterface $quoteRepository,
+        PageFactory $resultPageFactory,
+        ResultLayout $resultLayoutFactory,
+        RawFactory $resultRawFactory,
+        JsonFactory $resultJsonFactory,
+        Data $checkoutHelper,
+        SessionModel $checkoutSession,
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+    ) {
+        $this->checkoutHelper = $checkoutHelper;
+        $this->checkoutSession = $checkoutSession;
+        $this->configHelper = $configHelper;
+        parent::__construct(
+            $context,
+            $customerSession,
+            $customerRepository,
+            $accountManagement,
+            $coreRegistry,
+            $translateInline,
+            $formKeyValidator,
+            $scopeConfig,
+            $layoutFactory,
+            $quoteRepository,
+            $resultPageFactory,
+            $resultLayoutFactory,
+            $resultRawFactory,
+            $resultJsonFactory
+        );
+    }
+
+    /**
+     * Checkout page
+     *
+     * @return \Magento\Framework\Controller\ResultInterface
+     */
+    public function execute()
+    {
+        if (!$this->configHelper->getModuleStatus()) {
+            return $this->resultRedirectFactory->create()->setPath('checkout');
+        }
+
+        if (!$this->checkoutHelper->canOnepageCheckout()) {
+            $this->messageManager->addErrorMessage(__('One-page checkout is turned off.'));
+            return $this->resultRedirectFactory->create()->setPath('checkout/cart');
+        }
+
+        $quote = $this->getOnepage()->getQuote();
+        if (!$quote->hasItems() || $quote->getHasError() || !$quote->validateMinimumAmount()) {
+            return $this->resultRedirectFactory->create()->setPath('checkout/cart');
+        }
+
+        if (!$this->_customerSession->isLoggedIn() && !$this->checkoutHelper->isAllowedGuestCheckout($quote)) {
+            $this->messageManager->addErrorMessage(__('Guest checkout is disabled.'));
+            return $this->resultRedirectFactory->create()->setPath('checkout/cart');
+        }
+
+        $currentUrl = $this->_url->getUrl('*/*/*', ['_secure' => true]);
+        $this->_customerSession->setBeforeAuthUrl($currentUrl);
+        $this->_customerSession->regenerateId();
+
+        $this->checkoutSession->setCartWasUpdated(false);
+        $this->getOnepage()->initCheckout();
+        $resultPage = $this->resultPageFactory->create();
+        $title = trim($this->configHelper->getGeneral('page_title'));
+        if (!$title || $title == '') {
+            $title = __('Express Checkout');
+        }
+        if($this->configHelper->isDisplayField('show_full_layout'))
+        {
+            $resultPage->getLayout()->getUpdate()->addHandle('onepagecheckout_index_index_full');
+        }
+        else{
+            $resultPage->getLayout()->getUpdate()->addHandle('onepagecheckout_index_index_default');
+        }
+
+        $resultPage->getConfig()->getTitle()->set($title);
+        return $resultPage;
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Controller/Router.php

+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Rokanthemes\OnePageCheckout\Controller;
+
+use Magento\Framework\App\Request\Http as HttpRequest;
+use Magento\Framework\App\Response\Http as HttpResponse;
+use Magento\UrlRewrite\Controller\Adminhtml\Url\Rewrite;
+use Magento\UrlRewrite\Model\UrlFinderInterface;
+use Magento\UrlRewrite\Service\V1\Data\UrlRewrite;
+use Magento\Framework\UrlInterface;
+use Magento\Framework\App\Action\Redirect;
+use Magento\Framework\App\ActionInterface;
+
+/**
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
+class Router implements \Magento\Framework\App\RouterInterface
+{
+    /**
+     * @var \Magento\Framework\App\ActionFactory
+     */
+    protected $actionFactory;
+    /**
+     * @var \Magento\Framework\App\Config\ScopeConfigInterface
+     */
+    protected $_helper;
+
+    /**
+     * Router constructor.
+     * @param \Magento\Framework\App\ActionFactory $actionFactory
+     * @param \Rokanthemes\OnePageCheckout\Helper\Data $helper
+     */
+    public function __construct(
+        \Magento\Framework\App\ActionFactory $actionFactory,
+        \Rokanthemes\OnePageCheckout\Helper\Data $helper
+    ) {
+        $this->_helper = $helper;
+        $this->actionFactory = $actionFactory;
+    }
+
+    /**
+     * Match corresponding URL Rewrite and modify request
+     *
+     * @param \Magento\Framework\App\RequestInterface|HttpRequest $request
+     * @return ActionInterface|null
+     */
+    public function match(\Magento\Framework\App\RequestInterface $request)
+    {
+        $identifier = trim($request->getPathInfo(), '/');
+        if(!$this->_helper->getModuleStatus() || $this->_helper->getConfigUrl() != $identifier)
+            return null;
+        $moduleFrontName = 'Rokanthemes_OnePageCheckout';
+        $actionPath = 'index';
+        $action = 'index';
+        $currentModuleName = 'Rokanthemes_OnePageCheckout';
+        $routeName = 'onepagecheckout';
+        $request->setModuleName($moduleFrontName);
+        $request->setControllerName($actionPath);
+        $request->setActionName($action);
+        $request->setControllerModule($currentModuleName);
+        $request->setRouteName($routeName);
+        return $this->actionFactory->create(\Magento\Framework\App\Action\Forward::class);
+    }    /**
+     * @param \Magento\Framework\App\RequestInterface|HttpRequest $request
+     * @param string  $url
+     * @param integer $code
+     * @return ActionInterface
+     */
+    protected function redirect($request, $url, $code)
+    {
+        $this->response->setRedirect($url, $code);
+        $request->setDispatched(true);
+        return $this->actionFactory->create(Redirect::class);
+    }
+
+}

app/code/Rokanthemes/OnePageCheckout/Helper/Address.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Helper;
+
+use Exception;
+use Magento\Config\Model\ResourceModel\Config;
+use Magento\Customer\Helper\Address as CustomerAddressHelper;
+use Magento\Customer\Model\Attribute;
+use Magento\Customer\Model\AttributeMetadataDataProvider;
+use Magento\Directory\Model\Region;
+use Magento\Framework\App\Config\ReinitableConfigInterface;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\App\Filesystem\DirectoryList;
+use Magento\Framework\App\Helper\Context;
+use Magento\Framework\Locale\Resolver;
+use Magento\Framework\ObjectManagerInterface;
+use Magento\Store\Model\StoreManagerInterface;
+
+/**
+ * Class Address
+ * @package Rokanthemes\OnePageCheckout\Helper
+ */
+class Address extends Data
+{
+    /**
+     * @var DirectoryList
+     */
+    protected $_directoryList;
+
+    /**
+     * @var Resolver
+     */
+    protected $_localeResolver;
+
+    /**
+     * @var Region
+     */
+    protected $_regionModel;
+
+    /**
+     * @var CustomerAddressHelper
+     */
+    protected $addressHelper;
+
+    protected $jsonHelper;
+
+    /**
+     * @var AttributeMetadataDataProvider
+     */
+    private $attributeMetadataDataProvider;
+
+    /**
+     * @var Config
+     */
+    private $resourceConfig;
+
+    /**
+     * @var ReinitableConfigInterface
+     */
+    private $appConfig;
+
+    /**
+     * Address constructor.
+     *
+     * @param Context $context
+     * @param ObjectManagerInterface $objectManager
+     * @param StoreManagerInterface $storeManager
+     * @param DirectoryList $directoryList
+     * @param Resolver $localeResolver
+     * @param Region $regionModel
+     * @param CustomerAddressHelper $addressHelper
+     * @param AttributeMetadataDataProvider $attributeMetadataDataProvider
+     * @param Config $resourceConfig
+     * @param ReinitableConfigInterface $appConfig
+     */
+    public function __construct(
+        Context $context,
+        ObjectManagerInterface $objectManager,
+        StoreManagerInterface $storeManager,
+        DirectoryList $directoryList,
+        Resolver $localeResolver,
+        Region $regionModel,
+        CustomerAddressHelper $addressHelper,
+        AttributeMetadataDataProvider $attributeMetadataDataProvider,
+        Config $resourceConfig,
+        \Magento\Framework\Json\Helper\Data $jsonHelper,
+        ReinitableConfigInterface $appConfig
+    ) {
+        $this->_directoryList                = $directoryList;
+        $this->_localeResolver               = $localeResolver;
+        $this->_regionModel                  = $regionModel;
+        $this->addressHelper                 = $addressHelper;
+        $this->attributeMetadataDataProvider = $attributeMetadataDataProvider;
+        $this->resourceConfig                = $resourceConfig;
+        $this->appConfig                     = $appConfig;
+        $this->jsonHelper                     = $jsonHelper;
+
+        parent::__construct($context, $objectManager, $storeManager);
+    }
+
+    /**
+     * Address Fields
+     *
+     * @return array
+     */
+    public function getAddressFields()
+    {
+        $fieldPosition = $this->getAddressFieldPosition();
+
+        $fields = array_keys($fieldPosition);
+        if (!in_array('country_id', $fields, true)) {
+            array_unshift($fields, 'country_id');
+        }
+
+        if (in_array('region_id', $fields, true)) {
+            $fields[] = 'region_id_input';
+        }
+
+        return $fields;
+    }
+
+    /**
+     * Get position to display on one step checkout
+     *
+     * @return array
+     */
+    public function getAddressFieldPosition()
+    {
+        $fieldPosition = [];
+        $sortedField   = $this->getSortedField();
+        foreach ($sortedField as $field) {
+            $fieldPosition[$field->getAttributeCode()] = [
+                'sortOrder' => $field->getSortOrder(),
+                'colspan'   => $field->getColspan(),
+                'required'  => $field->getIsRequiredMp(),
+                'isNewRow'  => $field->getIsNewRow(),
+            ];
+        }
+
+        return $fieldPosition;
+    }
+
+    /**
+     * Get attribute collection to show on process checkout
+     *
+     * @param bool|true $onlySorted
+     *
+     * @return array
+     */
+    public function getSortedField($onlySorted = true)
+    {
+        $availableFields = [];
+        $sortedFields    = [];
+        $sortOrder       = 1;
+
+        $collection = $this->attributeMetadataDataProvider->loadAttributesCollection(
+            'customer_address',
+            'customer_register_address'
+        );
+        /** @var Attribute $field */
+        foreach ($collection as $field) {
+            if ($this->isAddressAttributeVisible($field)) {
+                $availableFields[$field->getAttributeCode()] = $field;
+            }
+        }
+
+        $collection = $this->attributeMetadataDataProvider->loadAttributesCollection(
+            'customer',
+            'customer_account_create'
+        );
+        /** @var Attribute $field */
+        foreach ($collection as $field) {
+            if ($this->isCustomerAttributeVisible($field)) {
+                $availableFields[$field->getAttributeCode()] = $field;
+            }
+        }
+
+        $collection = $this->attributeMetadataDataProvider->loadAttributesCollection(
+            'customer_address',
+            'onestepcheckout_index_index'
+        );
+        /** @var Attribute $field */
+        foreach ($collection as $field) {
+            if ($field->getIsVisible()) {
+                $availableFields[$field->getAttributeCode()] = $field;
+            }
+        }
+
+        // apply Custom Field label config
+        for ($i = 1; $i <= 3; $i++) {
+            $key   = 'custom_field_' . $i;
+            $field = $availableFields[$key] ?? null;
+            if ($field) {
+                $field->setDefaultFrontendLabel($this->getCustomFieldLabel($i));
+            }
+        }
+
+        $colCount = 0;
+        foreach ($this->getFieldPosition() as $field) {
+            foreach ($availableFields as $code => $avField) {
+                if ($field['code'] === $code) {
+                    unset($availableFields[$code]);
+                    $avField
+                        ->setColspan($field['colspan'])
+                        ->setSortOrder($sortOrder++)
+                        ->setColStyle($this->getColStyle($field['colspan']))
+                        ->setIsNewRow($this->getIsNewRow($field['colspan'], $colCount));
+
+                    if (isset($field['required'])) {
+                        // cannot set IS_REQUIRED because attribute is not user defined
+                        $avField->setIsRequiredMp($field['required']);
+                    }
+
+                    $sortedFields[$code] = $avField;
+                    break;
+                }
+            }
+        }
+
+        return $onlySorted ? $sortedFields : [$sortedFields, $availableFields];
+    }
+
+    /**
+     * Check if address attribute can be visible on frontend
+     *
+     * @param Attribute $attribute
+     *
+     * @return bool|null|string
+     */
+    public function isAddressAttributeVisible($attribute)
+    {
+//        if ($this->isEnableCustomerAttributes() && $attribute->getIsUserDefined()) {
+//            return false; // Prevent duplicated customer attributes
+//        }
+
+        $code   = $attribute->getAttributeCode();
+        $result = $attribute->getIsVisible();
+        switch ($code) {
+            case 'vat_id':
+                $result = $this->addressHelper->isVatAttributeVisible();
+                break;
+            case 'region':
+                $result = false;
+                break;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Check if customer attribute can be visible on frontend
+     *
+     * @param Attribute $attribute
+     *
+     * @return bool|null|string
+     */
+    public function isCustomerAttributeVisible($attribute)
+    {
+        $code = $attribute->getAttributeCode();
+        if (in_array($code, ['gender', 'taxvat', 'dob'])) {
+            return $attribute->getIsVisible();
+        }
+
+        return $attribute->getIsUserDefined();
+    }
+
+    /**
+     * @return array
+     */
+    public function getFieldPosition()
+    {
+        $fields = $this->getConfigValue(self::XML_PATH_SORTED_FIELD_POSITION);
+        if(!$fields)
+        {
+            $fields = '[{"code":"firstname","colspan":12,"required":true},{"code":"lastname","colspan":12,"required":true},{"code":"street","colspan":12,"required":false},{"code":"city","colspan":12,"required":false},{"code":"postcode","colspan":12,"required":false},{"code":"country_id","colspan":12,"required":true},{"code":"region_id","colspan":12,"required":true},{"code":"company","colspan":12,"required":false},{"code":"telephone","colspan":12,"required":true}]';
+        }
+
+        return $this->jsonHelper->jsonDecode($fields);
+    }
+
+
+    /**
+     * @param int $colSpan
+     *
+     * @return string
+     */
+    public function getColStyle($colSpan)
+    {
+        switch ($colSpan) {
+            case 12:
+                return 'wide';
+            case 9:
+                return 'medium';
+            case 3:
+                return 'short';
+            default:
+                return '';
+        }
+    }
+
+    /**
+     * @param int $colSpan
+     * @param int $colCount
+     *
+     * @return bool
+     */
+    public function getIsNewRow($colSpan, &$colCount)
+    {
+        $result = $colCount === 0;
+
+        $colCount += $colSpan;
+
+        if ($colCount >= 12) {
+            $colCount = 0;
+        }
+
+        return $result;
+    }
+
+}

app/code/Rokanthemes/OnePageCheckout/Helper/Data.php

+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Rokanthemes\OnePageCheckout\Helper;
+
+use Magento\Framework\App\Helper\AbstractHelper;
+use Magento\Store\Model\ScopeInterface;
+use Magento\GiftMessage\Helper\Message;
+use Magento\Framework\ObjectManagerInterface;
+/**
+ * Catalog category helper
+ *
+ * @SuppressWarnings(PHPMD.LongVariable)
+ */
+class Data extends AbstractHelper
+{
+    const XML_PATH_STATUS_ONEPAGECHECKOUT = 'onepagecheckout/general/enabled';
+    const XML_PATH_URL_ONEPAGECHECKOUT = 'onepagecheckout/general/seourl';
+    const GENERAL_GROUP = 'onepagecheckout/general/';
+    const XML_PATH_SORTED_FIELD_POSITION = 'onepagecheckout/field/position';
+
+    /**
+     * Store manager
+     *
+     * @var \Magento\Store\Model\StoreManagerInterface
+     */
+    protected $_storeManager;
+    protected $objectManager;
+
+    public function __construct(
+        \Magento\Framework\App\Helper\Context $context,
+        ObjectManagerInterface $objectManager,
+        \Magento\Store\Model\StoreManagerInterface $storeManager
+    ) {
+        $this->_storeManager = $storeManager;
+        $this->objectManager = $objectManager;
+        parent::__construct($context);
+    }
+    public function getConfigUrl()
+    {
+        return $this->scopeConfig->getValue(self::XML_PATH_URL_ONEPAGECHECKOUT);
+    }
+    public function getModuleStatus()
+    {
+        return $this->scopeConfig->getValue(self::XML_PATH_STATUS_ONEPAGECHECKOUT);
+    }
+    public function getGeneral($field, $storeId = null)
+    {
+        if (!$this->getModuleStatus()) {
+            return false;
+        }
+        return $this->scopeConfig->getValue(
+            self::GENERAL_GROUP . $field,
+            ScopeInterface::SCOPE_STORE,
+            $storeId
+        );
+    }
+    /**
+     * @param string $field
+     * @param null|int $storeId
+     * @return mixed
+     */
+    public function isDisplayField($field, $storeId = null)
+    {
+        if (!$this->getModuleStatus()) {
+            return false;
+        }
+        return $this->scopeConfig->isSetFlag(
+            self::GENERAL_GROUP . $field,
+            ScopeInterface::SCOPE_STORE,
+            $storeId
+        );
+    }
+    public function getPaymentOnlineMethods()
+    {
+        $onlineMethodList = [
+            'payflowpro',
+            'payflow_link',
+            'payflow_advanced',
+            'braintree_paypal',
+            'paypal_express_bml',
+            'payflow_express_bml',
+            'payflow_express',
+            'paypal_express',
+            'authorizenet_directpost',
+            'realexpayments_hpp',
+            'braintree'
+        ];
+        return $onlineMethodList;
+    }
+    public function isMessagesAllowed($store = null)
+    {
+        if (!$this->getModuleStatus()) {
+            return false;
+        }
+        return $this->scopeConfig->isSetFlag(
+            Message::XPATH_CONFIG_GIFT_MESSAGE_ALLOW_ORDER,
+            ScopeInterface::SCOPE_STORE,
+            $store
+        );
+    }
+    public function getDefaultCustomerGroupId($storeId = null)
+    {
+        return $this->scopeConfig->getValue(
+            'customer/create_account/default_group',
+            ScopeInterface::SCOPE_STORE,
+            $storeId
+        );
+    }
+    public function getConfigValue($field, $scopeValue = null, $scopeType = ScopeInterface::SCOPE_STORE)
+    {
+        return $this->scopeConfig->getValue($field, $scopeType, $scopeValue);
+    }
+    /**
+     * @return bool
+     */
+    public function isEnableAmazonPay()
+    {
+        return $this->isModuleOutputEnabled('Amazon_Payment');
+    }/**
+ * @param $path
+ *
+ * @return mixed
+ */
+    public function getObject($path)
+    {
+        return $this->objectManager->get($path);
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Model/AdditionalData.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Model;
+
+use Magento\Sales\Model\Order\Status\HistoryFactory;
+use Magento\Newsletter\Model\Subscriber;
+use Psr\Log\LoggerInterface;
+use Magento\Sales\Api\OrderRepositoryInterface;
+
+/**
+ * Class AdditionalData
+ *
+ * @package Rokanthemes\OnePageCheckout\Model
+ */
+class AdditionalData
+{
+    /**
+     * Order history factory
+     *
+     * @var HistoryFactory $historyFactory
+     */
+    private $historyFactory;
+
+    /**
+     * @var \Magento\Sales\Api\OrderRepositoryInterface
+     */
+    private $orderRepository;
+
+    /**
+     * Subcriber
+     *
+     * @var \Magento\Newsletter\Model\Subscriber
+     */
+    private $subscriber;
+
+    /**
+     * Logger
+     *
+     * @var \Psr\Log\LoggerInterface
+     */
+    private $logger;
+
+    /**
+     * Initialize dependencies.
+     *
+     * @param HistoryFactory $historyFactory
+     * @param OrderRepositoryInterface $orderRepository
+     * @param Subscriber $subscriber
+     * @param LoggerInterface $logger
+     */
+    public function __construct(
+        HistoryFactory $historyFactory,
+        OrderRepositoryInterface $orderRepository,
+        Subscriber $subscriber,
+        LoggerInterface $logger
+    ) {
+        $this->historyFactory = $historyFactory;
+        $this->orderRepository = $orderRepository;
+        $this->subscriber = $subscriber;
+        $this->logger = $logger;
+    }
+
+    /**
+     * @param \Magento\Quote\Model\Quote $quote
+     * @param array $additionalData
+     * @return void
+     */
+    public function saveDelivery($quote, $additionalData)
+    {
+        if (isset($additionalData['customer_shipping_date'])) {
+            $quote->setCustomerShippingDate($additionalData['customer_shipping_date']);
+        }
+        if (isset($additionalData['customer_shipping_comments'])) {
+            $quote->setCustomerShippingComments($additionalData['customer_shipping_comments']);
+        }
+    }
+
+    /**
+     * @param int $orderId
+     * @param array $additionalData
+     * @return void
+     */
+    public function saveComment($orderId, $additionalData)
+    {
+        $order = $this->orderRepository->get($orderId);
+        try {
+            if (isset($additionalData['order_comment']) && $additionalData['order_comment']) {
+                $comment = $order->getCustomerName();
+                $comment .= ': ';
+                $comment .= $additionalData['order_comment'];
+                if ($order->getId()) {
+                    $status = $order->getStatus();
+                    $history = $this->historyFactory->create();
+                    $history->setComment($comment)
+                        ->setParentId($orderId)
+                        ->setIsVisibleOnFront(1)
+                        ->setIsCustomerNotified(0)
+                        ->setEntityName('order')
+                        ->setStatus($status)
+                        ->save();
+                }
+            }
+        } catch (\Exception $e) {
+            $this->logger->error($e->getMessage());
+        }
+    }
+
+    /**
+     * @param int $orderId
+     * @param array $additionalData
+     * @return void
+     */
+    public function subscriber($orderId, $additionalData)
+    {
+        $order = $this->orderRepository->get($orderId);
+        try {
+            if (isset($additionalData['subscribe']) && $additionalData['subscribe']) {
+                if ($order->getCustomerId()) {
+                    $subscriberModel = $this->subscriber->loadByCustomerId($order->getCustomerId());
+                    if (!$subscriberModel->isSubscribed()) {
+                        $this->subscriber->subscribeCustomerById($order->getCustomerId());
+                    }
+                } else {
+                    $subscriberModel = $this->subscriber->loadByEmail($order->getCustomerEmail());
+                    if (!$subscriberModel->isSubscribed()) {
+                        $this->subscriber->subscribe($order->getCustomerEmail());
+                    }
+                }
+            }
+        } catch (\Exception $e) {
+            $this->logger->error($e->getMessage());
+        }
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Model/CompositeConfigProvider.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Model;
+
+use Magento\Checkout\Model\ConfigProviderInterface;
+use Magento\GiftMessage\Model\CompositeConfigProvider as GiftMessageConfig;
+use Magento\Framework\Serialize\Serializer\Json;
+use Magento\Framework\View\LayoutInterface;
+use Rokanthemes\OnePageCheckout\Model\ResourceModel\CompositeConfig;
+use Magento\Framework\HTTP\PhpEnvironment\RemoteAddress;
+use Magento\Framework\HTTP\Client\Curl;
+use Psr\Log\LoggerInterface;
+
+class CompositeConfigProvider implements ConfigProviderInterface
+{
+    /**
+     * config helper.
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    /**
+     * @var GiftMessageConfig
+     */
+    private $configProvider;
+
+    /**
+     * @var Json
+     */
+    private $serializer;
+
+    /**
+     * @var LayoutInterface
+     */
+    private $layout;
+
+    /**
+     * @var CompositeConfig
+     */
+    private $compositeConfig;
+
+    /**
+     * @var RemoteAddress
+     */
+    private $remoteAddress;
+
+    /**
+     * @var LoggerInterface
+     */
+    private $logger;
+
+    /**
+     * @var Curl
+     */
+    private $curl;
+
+    /**
+     * CompositeConfigProvider constructor.
+     * @param \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+     * @param GiftMessageConfig $configProvider
+     * @param Json $serializer
+     * @param LayoutInterface $layout
+     * @param CompositeConfig $compositeConfig
+     * @param RemoteAddress $remoteAddress
+     * @param Curl $curl
+     * @param LoggerInterface $logger
+     */
+    public function __construct(
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper,
+        GiftMessageConfig $configProvider,
+        Json $serializer,
+        LayoutInterface $layout,
+        CompositeConfig $compositeConfig,
+        RemoteAddress $remoteAddress,
+        Curl $curl,
+        LoggerInterface $logger
+    ) {
+        $this->configHelper = $configHelper;
+        $this->configProvider = $configProvider;
+        $this->serializer = $serializer;
+        $this->layout = $layout;
+        $this->compositeConfig = $compositeConfig;
+        $this->remoteAddress = $remoteAddress;
+        $this->curl = $curl;
+        $this->logger = $logger;
+    }
+
+    /**
+     * Get Config
+     *
+     * @return array
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
+     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
+     * @SuppressWarnings(PHPMD.NPathComplexity)
+     */
+    public function getConfig()
+    {
+        $output = [];
+        $helper = $this->configHelper;
+        if ($helper->getModuleStatus()) {
+            $config['googleApiAutoComplete'] = false;
+            $config['googleApiListCountries'] = $this->compositeConfig->getCountryHasRegion();
+            $config['autoCreateNewAccount']['enable'] = true;
+            $config['autoCreateNewAccount']['minLength'] = 8;
+            $config['autoCreateNewAccount']['minCharacterSets'] = 3;
+            $config['titlePlaceOrder'] = $this->configHelper->getGeneral('title_place_order');
+            if ($helper->isDisplayField('show_gift_message') && $helper->isMessagesAllowed()) {
+                $config['giftOptionsConfig'] = $this->getGiftOptionsConfigJson();
+            }
+            $output['OnePageCheckout'] = $config;
+            $output['paypal_in_context'] = false;
+            $output['rewrite_email_element'] = true;
+            $output['opcWidget'] = $this->getOpcWidget();
+        }
+        return $output;
+    }
+
+    /**
+     * Get Widget
+     *
+     * @return array
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
+     */
+    private function getOpcWidget()
+    {
+        $result = [];
+        if($this->configHelper->isDisplayField('show_widget_box') && $this->configHelper->getGeneral('widget_after_placeorder'))
+        {
+            $result['widget_after_placeorder'][] =
+                $this->layout->createBlock(\Magento\Cms\Block\Block::class)
+                    ->setBlockId($this->configHelper->getGeneral('widget_after_placeorder'))->toHtml();
+        }
+        return $result;
+    }
+    /**
+     * Retrieve gift message configuration
+     *
+     * @return string
+     */
+    private function getGiftOptionsConfigJson()
+    {
+        return $this->configProvider->getConfig();
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Model/GuestUpdateItemManagement.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Model;
+
+use Rokanthemes\OnePageCheckout\Api\GuestUpdateItemManagementInterface;
+use Magento\Quote\Model\QuoteIdMaskFactory;
+use Rokanthemes\OnePageCheckout\Api\UpdateItemManagementInterface;
+
+/**
+ * Class GuestUpdateItemManagement
+ *
+ * @package Rokanthemes\OnePageCheckout\Model
+ */
+class GuestUpdateItemManagement implements GuestUpdateItemManagementInterface
+{
+    /**
+     * @var \Magento\Quote\Model\QuoteIdMaskFactory
+     */
+    private $quoteIdMaskFactory;
+
+    /**
+     * @var \Rokanthemes\OnePageCheckout\Api\UpdateItemManagementInterface
+     */
+    private $updateItemManagement;
+
+    /**
+     * @param QuoteIdMaskFactory $quoteIdMaskFactory
+     * @param UpdateItemManagementInterface $updateItemManagement
+     */
+    public function __construct(
+        QuoteIdMaskFactory $quoteIdMaskFactory,
+        UpdateItemManagementInterface $updateItemManagement
+    ) {
+        $this->quoteIdMaskFactory = $quoteIdMaskFactory;
+        $this->updateItemManagement = $updateItemManagement;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function update($cartId, \Magento\Quote\Api\Data\EstimateAddressInterface $address, $itemId, $qty)
+    {
+        $quoteIdMask = $this->quoteIdMaskFactory->create()->load($cartId, 'masked_id');
+        $quoteId = (int) $quoteIdMask->getQuoteId();
+        return $this->updateItemManagement->update($quoteId, $address, $itemId, $qty);
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Model/ResourceModel/CompositeConfig.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Model\ResourceModel;
+
+class CompositeConfig
+{
+    /**
+     * @var array
+     */
+    protected $tableNames = [];
+
+    /**
+     * @var ResourceConnection
+     */
+    protected $resourceConnection;
+
+    /**
+     * @var \Magento\Framework\DB\Adapter\AdapterInterface
+     */
+    protected $readAdapter;
+
+    /**
+     * @var \Magento\Store\Model\StoreManagerInterface
+     */
+    protected $storeManager;
+
+    /**
+     * compositeConfig constructor.
+     * @param \Magento\Framework\App\ResourceConnection $resourceConnection
+     * @param \Magento\Store\Model\StoreManagerInterface $storeManager
+     */
+    public function __construct(
+        \Magento\Framework\App\ResourceConnection $resourceConnection,
+        \Magento\Store\Model\StoreManagerInterface $storeManager
+    ) {
+        $this->resourceConnection = $resourceConnection;
+        $this->storeManager = $storeManager;
+        $this->readAdapter = $this->resourceConnection->getConnection('core_read');
+    }
+
+    /**
+     * Get Widget
+     *
+     * @return array
+     * @throws \Magento\Framework\Exception\NoSuchEntityException
+     */
+    public function getOpcWidget()
+    {
+        $storeId = $this->storeManager->getStore()->getId();
+        $select = $this->readAdapter->select()
+            ->from(
+                ['t1' => $this->getTableName('widget_instance_page')],
+                ['t1.block_reference']
+            )->joinLeft(
+                ['t2' => $this->getTableName('widget_instance')],
+                't1.instance_id = t2.instance_id',
+                ['t2.widget_parameters']
+            )->where("t1.layout_handle = 'rokanthemes_opc'")
+            ->where("FIND_IN_SET(0, store_ids) OR FIND_IN_SET(" . $storeId . ", store_ids)")
+            ->order('t2.sort_order ASC')
+            ->order('t2.instance_id ASC');
+        // @codingStandardsIgnoreStart
+        return $this->readAdapter->fetchAll($select);
+        // @codingStandardsIgnoreEnd
+    }
+
+    /**
+     * Get Country
+     *
+     * @return array
+     */
+    public function getCountryHasRegion()
+    {
+        // @codingStandardsIgnoreStart
+        $select = $this->readAdapter->select()
+            ->from(
+                [$this->getTableName('directory_country_region')],
+                'country_id'
+            )->group('country_id');
+        // @codingStandardsIgnoreEnd
+        $result = $this->readAdapter->fetchCol($select);
+        return $result;
+    }
+
+    /**
+     * Get Table Name
+     *
+     * @param String $entity
+     * @return bool|mixed
+     */
+    public function getTableName($entity)
+    {
+        if (!isset($this->tableNames[$entity])) {
+            try {
+                $this->tableNames[$entity] = $this->resourceConnection->getTableName($entity);
+            } catch (\Exception $e) {
+                return false;
+            }
+        }
+        return $this->tableNames[$entity];
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Model/UpdateItemDetails.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Model;
+
+use Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterface;
+use Magento\Framework\Model\AbstractExtensibleModel;
+
+/**
+ * Class GuestUpdateItemManagement
+ *
+ * @package Rokanthemes\OnePageCheckout\Model
+ */
+class UpdateItemDetails extends AbstractExtensibleModel implements UpdateItemDetailsInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function getPaymentMethods()
+    {
+        return $this->getData(self::PAYMENT_METHODS);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setPaymentMethods($paymentMethods)
+    {
+        return $this->setData(self::PAYMENT_METHODS, $paymentMethods);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getTotals()
+    {
+        return $this->getData(self::TOTALS);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setTotals($totals)
+    {
+        return $this->setData(self::TOTALS, $totals);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getShippingMethods()
+    {
+        return $this->getData(self::SHIPPING_METHODS);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setShippingMethods($shippingMethods)
+    {
+        return $this->setData(self::SHIPPING_METHODS, $shippingMethods);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getMessage()
+    {
+        return $this->getData(self::MESSAGE);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setMessage($message)
+    {
+        return $this->setData(self::MESSAGE, $message);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getStatus()
+    {
+        return $this->getData(self::STATUS);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setStatus($status)
+    {
+        return $this->setData(self::STATUS, $status);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getHasError()
+    {
+        return $this->getData(self::HAS_ERROR);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setHasError($error)
+    {
+        return $this->setData(self::HAS_ERROR, $error);
+    }
+
+}

app/code/Rokanthemes/OnePageCheckout/Model/UpdateItemManagement.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Model;
+
+use Rokanthemes\OnePageCheckout\Api\UpdateItemManagementInterface;
+use Magento\Framework\Exception\CouldNotSaveException;
+use Magento\Framework\Exception\NoSuchEntityException;
+use Magento\Quote\Api\CartRepositoryInterface;
+use Magento\Framework\Exception\LocalizedException;
+use Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterfaceFactory;
+use Magento\Quote\Api\ShippingMethodManagementInterface;
+use Magento\Quote\Api\PaymentMethodManagementInterface;
+use Magento\Quote\Api\CartTotalRepositoryInterface;
+use Magento\Framework\Escaper;
+
+/**
+ * Class UpdateItemManagement
+ *
+ * @package Rokanthemes\OnePageCheckout\Model
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
+class UpdateItemManagement implements UpdateItemManagementInterface
+{
+    /**
+     * @var CartRepositoryInterface
+     */
+    private $cartRepository;
+
+    /**
+     * @var UpdateItemDetailsInterfaceFactory
+     */
+    private $updateItemDetails;
+
+    /**
+     * @var ShippingMethodManagementInterface
+     */
+    private $shippingMethodManagement;
+
+    /**
+     * @var PaymentMethodManagementInterface
+     */
+    private $paymentMethodManagement;
+
+    /**
+     * @var CartTotalRepositoryInterface
+     */
+    private $cartTotalRepository;
+
+    /**
+     * @var Escaper
+     */
+    private $escaper;
+
+    /**
+     * UpdateItemManagement constructor.
+     * @param CartRepositoryInterface $cartRepository
+     * @param UpdateItemDetailsInterfaceFactory $updateItemDetails
+     * @param ShippingMethodManagementInterface $shippingMethodManagement
+     * @param PaymentMethodManagementInterface $paymentMethodManagement
+     * @param CartTotalRepositoryInterface $cartTotalRepository
+     * @param Escaper $escaper
+     */
+    public function __construct(
+        CartRepositoryInterface $cartRepository,
+        UpdateItemDetailsInterfaceFactory $updateItemDetails,
+        ShippingMethodManagementInterface $shippingMethodManagement,
+        PaymentMethodManagementInterface $paymentMethodManagement,
+        CartTotalRepositoryInterface $cartTotalRepository,
+        Escaper $escaper
+    ) {
+        $this->cartRepository = $cartRepository;
+        $this->updateItemDetails = $updateItemDetails;
+        $this->shippingMethodManagement = $shippingMethodManagement;
+        $this->paymentMethodManagement = $paymentMethodManagement;
+        $this->cartTotalRepository = $cartTotalRepository;
+        $this->escaper = $escaper;
+    }
+
+    /**
+     * @param int $cartId
+     * @param \Magento\Quote\Api\Data\EstimateAddressInterface $address
+     * @param int $itemId
+     * @param float $qty
+     * @return \Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterface
+     * @throws CouldNotSaveException
+     * @throws NoSuchEntityException
+     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
+     */
+    public function update(
+        $cartId,
+        \Magento\Quote\Api\Data\EstimateAddressInterface $address,
+        $itemId,
+        $qty
+    ) {
+        $status = false;
+        /** @var \Magento\Quote\Model\Quote $quote */
+        $quote = $this->cartRepository->getActive($cartId);
+        if (!$quote) {
+            throw new NoSuchEntityException(__('This quote does not exist.'));
+        }
+        $quoteItem = $quote->getItemById($itemId);
+        if (!$quoteItem) {
+            throw new NoSuchEntityException(__('We can\'t find the quote item.'));
+        }
+        try {
+            if (!$qty || $qty <= 0) {
+                $quote->removeItem($itemId);
+                $this->cartRepository->save($quote);
+                $status = true;
+                $message = __(
+                    '%1 was removed in your shopping cart.',
+                    $this->escaper->escapeHtml($quoteItem->getProduct()->getName())
+                );
+            } else {
+                $quoteItem->setQty($qty);
+                if ($quoteItem->getHasError()) {
+                    throw new CouldNotSaveException(__($quoteItem->getMessage()));
+                } else {
+                    $quoteItem->save();
+                    $status = true;
+                    $message = __(
+                        '%1 was updated in your shopping cart.',
+                        $this->escaper->escapeHtml($quoteItem->getProduct()->getName())
+                    );
+                }
+            }
+            $this->cartRepository->save($quote);
+        } catch (LocalizedException $e) {
+            $message = $e->getMessage();
+        } catch (\Exception $e) {
+            $message = $e->getMessage();
+        }
+        return $this->getUpdateCartDetails($quote, $address, $cartId, $message, $status);
+    }
+
+    /**
+     * @param \Magento\Quote\Model\Quote $quote
+     * @param \Magento\Quote\Api\Data\EstimateAddressInterface $address
+     * @param int $quoteId
+     * @param string $message
+     * @param boolean $status
+     * @return \Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterface
+     * @throws NoSuchEntityException
+     */
+    private function getUpdateCartDetails($quote, $address, $quoteId, $message, $status)
+    {
+        $cartDetails = $this->updateItemDetails->create();
+        $paymentMethods = $this->paymentMethodManagement->getList($quoteId);
+        $totals = $this->cartTotalRepository->get($quoteId);
+        $shippingAddress = $quote->getShippingAddress();
+        if ($shippingAddress && $shippingAddress->getCustomerAddressId()) {
+            $shippingMethods = $this->shippingMethodManagement->estimateByAddressId(
+                $quoteId,
+                $shippingAddress->getCustomerAddressId()
+            );
+        } else {
+            $shippingMethods = $this->shippingMethodManagement->estimateByAddress($quoteId, $address);
+        }
+        $cartDetails->setShippingMethods($shippingMethods);
+        $cartDetails->setPaymentMethods($paymentMethods);
+        $cartDetails->setTotals($totals);
+        $cartDetails->setMessage($message);
+        $cartDetails->setStatus($status);
+        if (!$quote->hasItems() || $quote->getHasError() || !$quote->validateMinimumAmount()) {
+            $cartDetails->setHasError(true);
+        }
+
+        return $cartDetails;
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Observer/Admin/CoreLayoutRenderElementObserver.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Observer\Admin;
+
+use Magento\Framework\Event\Observer as EventObserver;
+use Magento\Framework\Event\ObserverInterface;
+use Magento\Framework\View\LayoutInterface;
+
+class CoreLayoutRenderElementObserver implements ObserverInterface
+{
+    /**
+     * @var LayoutInterface
+     */
+    private $layout;
+    /**
+     * One step checkout config helper
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    public function __construct(
+        LayoutInterface $layout,
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+    ) {
+        $this->layout = $layout;
+        $this->configHelper = $configHelper;
+    }
+
+    /**
+     * Execute observer
+     *
+     * @param EventObserver $observer
+     * @return void
+     */
+    public function execute(EventObserver $observer)
+    {
+        if ($observer->getElementName() == 'order_shipping_view' &&
+            $this->configHelper->getModuleStatus() ) {
+            $orderShippingViewBlock = $observer->getLayout()->getBlock($observer->getElementName());
+            $order = $orderShippingViewBlock->getOrder();
+            $deliveryBlock = $this->layout->createBlock(\Magento\Framework\View\Element\Template::class);
+            $date = $order->getCustomerShippingDate();
+            $deliveryBlock->setCustomerShippingDate($date)
+                ->setCustomerShippingComments($order->getCustomerShippingComments())
+                ->setActiveJs(true)
+                ->setTemplate('Rokanthemes_OnePageCheckout::delivery.phtml');
+            $html = $observer->getTransport()->getOutput() . $deliveryBlock->toHtml();
+            $observer->getTransport()->setOutput($html);
+        }
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Observer/SalesModelServiceQuoteSubmitBeforeObserver.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Observer;
+
+use Magento\Framework\Event\ObserverInterface;
+use Magento\Framework\Event\Observer;
+
+class SalesModelServiceQuoteSubmitBeforeObserver implements ObserverInterface
+{
+    /**
+     * @var \Rokanthemes\OnePageCheckout\Helper\Data|Config
+     */
+    private $configHelper;
+
+    public function __construct(
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+    ) {
+        $this->configHelper = $configHelper;
+    }
+
+    /**
+     * @param Observer $observer
+     * @return $this|void
+     */
+    public function execute(Observer $observer)
+    {
+        $quote = $observer->getEvent()->getQuote();
+        $order = $observer->getEvent()->getOrder();
+        if ($this->configHelper->getModuleStatus()) {
+            $order->setCustomerShippingDate($quote->getCustomerShippingDate());
+            $order->setCustomerShippingComments($quote->getCustomerShippingComments());
+        }
+        return $this;
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Plugin/Checkout/Controller/Index/Index.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Plugin\Checkout\Controller\Index;
+
+use Magento\Framework\Controller\Result\RedirectFactory;
+use Magento\Checkout\Controller\Index\Index as CheckoutIndex;
+use Magento\Framework\UrlInterface;
+class Index
+{
+    /**
+     * @var RedirectFactory
+     */
+    private $resultRedirectFactory;
+
+    /**
+     * One step checkout helper
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    /**
+     * @var UrlInterface
+     */
+    private $urlBuilder;
+
+    /**
+     * @param RedirectFactory $resultRedirectFactory
+     * @param Config $configHelper
+     * @param UrlInterface $urlBuilder
+     */
+    public function __construct(
+        RedirectFactory $resultRedirectFactory,
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper,
+        UrlInterface $urlBuilder
+    ) {
+        $this->resultRedirectFactory = $resultRedirectFactory;
+        $this->configHelper = $configHelper;
+        $this->urlBuilder = $urlBuilder;
+    }
+
+    /**
+     * @param CheckoutIndex $subject
+     * @param callable $proceed
+     * @return mixed
+     * @SuppressWarnings(PHPMD.UnusedLocalVariable)
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function aroundExecute(
+        CheckoutIndex $subject,
+        $proceed
+    ) {
+        if ($this->configHelper->getModuleStatus()) {
+            $path = 'onepagecheckout';
+            $router = $this->configHelper->getConfigUrl();
+            if ($router) {
+                $router = preg_replace('/\s+/', '', $router);
+                $router = preg_replace('/\/+/', '', $router);
+                $path = trim($router, '/');
+            }
+            $url = trim($this->urlBuilder->getUrl($path), '/');
+            return $this->resultRedirectFactory->create()->setUrl($url);
+        } else {
+            return $proceed();
+        }
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Plugin/Checkout/Helper/Data.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Plugin\Checkout\Helper;
+class Data
+{
+    /**
+     * config helper.
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    /**
+     * @param Config $configHelper
+     */
+    public function __construct(
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+    ) {
+        $this->configHelper = $configHelper;
+    }
+
+    /**
+     * @param \Magento\Checkout\Helper\Data $subject
+     * @param callable $proceed
+     * @return bool
+     * @SuppressWarnings(PHPMD.UnusedLocalVariable)
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function afterIsDisplayBillingOnPaymentMethodAvailable(
+        \Magento\Checkout\Helper\Data $subject,
+        $result
+    ) {
+        if ($this->configHelper->getModuleStatus()) {
+            $result = false;
+        }
+        return $result;
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Plugin/Checkout/Model/CustomerAdditionalData.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Plugin\Checkout\Model;
+
+use Rokanthemes\OnePageCheckout\Model\AdditionalData;
+use Magento\Quote\Api\CartRepositoryInterface;
+
+class CustomerAdditionalData
+{
+    /**
+     * @var AdditionalData
+     */
+    private $additionalDataModel;
+
+    /**
+     * @var CartRepositoryInterface
+     */
+    private $cartRepository;
+
+    /**
+     * @var Magento\Checkout\Model\SessionFactory
+     */
+    private $checkoutSession;
+
+    /**
+     * One step checkout helper
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    /**
+     * CustomerAdditionalData constructor.
+     * @param AdditionalData $additionalDataModel
+     * @param CartRepositoryInterface $cartRepository
+     * @param \Magento\Checkout\Model\SessionFactory $checkoutSession
+     * @param Config $configHelper
+     */
+    public function __construct(
+        AdditionalData $additionalDataModel,
+        CartRepositoryInterface $cartRepository,
+        \Magento\Checkout\Model\SessionFactory $checkoutSession,
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+    ) {
+        $this->additionalDataModel = $additionalDataModel;
+        $this->cartRepository = $cartRepository;
+        $this->checkoutSession = $checkoutSession;
+        $this->configHelper = $configHelper;
+    }
+    public function aroundSavePaymentInformationAndPlaceOrder(
+        \Magento\Checkout\Api\PaymentInformationManagementInterface $subject,
+        \Closure $proceed,
+        $cartId,
+        \Magento\Quote\Api\Data\PaymentInterface $paymentMethod,
+        \Magento\Quote\Api\Data\AddressInterface $billingAddress = null
+    ) {
+        if ($paymentMethod->getExtensionAttributes() !== null
+            && $this->configHelper->getModuleStatus()
+            && $paymentMethod->getExtensionAttributes()->getRokanthemesOpc() !== null
+        ) {
+            $additionalData = $paymentMethod->getExtensionAttributes()->getRokanthemesOpc();
+            $orderId = $proceed($cartId, $paymentMethod, $billingAddress);
+            if (!empty($additionalData) && isset($additionalData['order_comment'])) {
+                $this->additionalDataModel->saveComment($orderId, $additionalData);
+            }
+            if (!empty($additionalData)
+                && $this->configHelper->isDisplayField('show_subscribe_newsletter')
+            ) {
+                $this->additionalDataModel->subscriber($orderId, $additionalData);
+            }
+        } else {
+            return $proceed($cartId, $paymentMethod, $billingAddress);
+        }
+    }
+    public function beforeSavePaymentInformation(
+        \Magento\Checkout\Api\PaymentInformationManagementInterface $subject,
+        $cartId,
+        \Magento\Quote\Api\Data\PaymentInterface $paymentMethod,
+        \Magento\Quote\Api\Data\AddressInterface $billingAddress = null
+    ) {
+        if ($paymentMethod->getExtensionAttributes() !== null
+            && $this->configHelper->getModuleStatus()
+            && $paymentMethod->getExtensionAttributes()->getRokanthemesOpc() !== null
+        ) {
+            $additionalData = $paymentMethod->getExtensionAttributes()->getRokanthemesOpc();
+            $quote = $this->cartRepository->getActive($cartId);
+            if (!empty($additionalData)) {
+                $this->additionalDataModel->saveDelivery($quote, $additionalData);
+                if (in_array($paymentMethod->getMethod(), $this->configHelper->getPaymentOnlineMethods())) {
+                    $this->checkoutSession->create()->setRokanthemesOpcAdditionalData($additionalData);
+                }
+            }
+        }
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Plugin/Checkout/Model/GuestAdditionalData.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Plugin\Checkout\Model;
+
+use Rokanthemes\OnePageCheckout\Model\AdditionalData;
+use Magento\Quote\Api\CartRepositoryInterface;
+use Magento\Quote\Model\QuoteIdMaskFactory;
+
+class GuestAdditionalData
+{
+    /**
+     * @var AdditionalData
+     */
+    private $additionalDataModel;
+
+    /**
+     * @var CartRepositoryInterface
+     */
+    private $cartRepository;
+
+    /**
+     * @var QuoteIdMaskFactory
+     */
+    private $quoteIdMaskFactory;
+
+    /**
+     * @var Magento\Checkout\Model\SessionFactory
+     */
+    private $checkoutSession;
+
+    /**
+     * One step checkout helper
+     *
+     * @var Config
+     */
+    private $configHelper;
+
+    /**
+     * GuestAdditionalData constructor.
+     * @param AdditionalData $additionalDataModel
+     * @param CartRepositoryInterface $cartRepository
+     * @param QuoteIdMaskFactory $quoteIdMaskFactory
+     * @param \Magento\Checkout\Model\SessionFactory $checkoutSession
+     * @param \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+     */
+    public function __construct(
+        AdditionalData $additionalDataModel,
+        CartRepositoryInterface $cartRepository,
+        QuoteIdMaskFactory $quoteIdMaskFactory,
+        \Magento\Checkout\Model\SessionFactory $checkoutSession,
+        \Rokanthemes\OnePageCheckout\Helper\Data $configHelper
+    ) {
+        $this->additionalDataModel = $additionalDataModel;
+        $this->cartRepository = $cartRepository;
+        $this->quoteIdMaskFactory = $quoteIdMaskFactory;
+        $this->checkoutSession = $checkoutSession;
+        $this->configHelper = $configHelper;
+    }
+
+    public function aroundSavePaymentInformationAndPlaceOrder(
+        \Magento\Checkout\Api\GuestPaymentInformationManagementInterface $subject,
+        \Closure $proceed,
+        $cartId,
+        $email,
+        \Magento\Quote\Api\Data\PaymentInterface $paymentMethod,
+        \Magento\Quote\Api\Data\AddressInterface $billingAddress = null
+    ) {
+        if ($paymentMethod->getExtensionAttributes() !== null
+            && $this->configHelper->getModuleStatus()
+            && $paymentMethod->getExtensionAttributes()->getRokanthemesOpc() !== null
+        ) {
+            $additionalData = $paymentMethod->getExtensionAttributes()->getRokanthemesOpc();
+            $orderId = $proceed($cartId, $email, $paymentMethod, $billingAddress);
+            if (!empty($additionalData) && isset($additionalData['order_comment'])) {
+                $this->additionalDataModel->saveComment($orderId, $additionalData);
+            }
+            if (!empty($additionalData)
+                && $this->configHelper->isDisplayField('show_subscribe_newsletter')
+            ) {
+                $this->additionalDataModel->subscriber($orderId, $additionalData);
+            }
+        } else {
+            return $proceed($cartId, $email, $paymentMethod, $billingAddress);
+        }
+    }
+    public function beforeSavePaymentInformation(
+        \Magento\Checkout\Api\GuestPaymentInformationManagementInterface $subject,
+        $cartId,
+        $email,
+        \Magento\Quote\Api\Data\PaymentInterface $paymentMethod,
+        \Magento\Quote\Api\Data\AddressInterface $billingAddress = null
+    ) {
+        if ($paymentMethod->getExtensionAttributes() !== null
+            && $this->configHelper->getModuleStatus()
+            && $paymentMethod->getExtensionAttributes()->getRokanthemesOpc() !== null
+        ) {
+            $additionalData = $paymentMethod->getExtensionAttributes()->getRokanthemesOpc();
+            $quoteIdMask = $this->quoteIdMaskFactory->create()->load($cartId, 'masked_id');
+            $quote = $this->cartRepository->getActive($quoteIdMask->getQuoteId());
+            if (!empty($additionalData)) {
+                $this->additionalDataModel->saveDelivery($quote, $additionalData);
+                if (in_array($paymentMethod->getMethod(), $this->configHelper->getPaymentOnlineMethods())) {
+                    $this->checkoutSession->create()->setRokanthemesOpcAdditionalData($additionalData);
+                }
+            }
+        }
+    }
+}

app/code/Rokanthemes/OnePageCheckout/Setup/InstallData.php

+<?php
+namespace Rokanthemes\OnePageCheckout\Setup;
+
+use Magento\Framework\DB\Ddl\Table;
+use Magento\Framework\Setup\InstallDataInterface;
+use Magento\Framework\Setup\ModuleContextInterface;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Quote\Setup\QuoteSetupFactory;
+use Magento\Sales\Setup\SalesSetupFactory;
+
+
+class InstallData implements InstallDataInterface
+{
+    /**
+     * @var Magento\Sales\Setup\SalesSetupFactory
+     */
+    protected $_salesSetupFactory;
+
+    /**
+     * @var Magento\Quote\Setup\QuoteSetupFactory
+     */
+    protected $_quoteSetupFactory;
+
+    /**
+     * @param SalesSetupFactory $salesSetupFactory
+     * @param QuoteSetupFactory $quoteSetupFactory
+     */
+    public function __construct(
+        SalesSetupFactory $salesSetupFactory,
+        QuoteSetupFactory $quoteSetupFactory
+    ) {
+        $this->_salesSetupFactory = $salesSetupFactory;
+        $this->_quoteSetupFactory = $quoteSetupFactory;
+    }
+
+    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
+    {
+        $installer = $setup;
+        $installer->startSetup();
+        // @var \Magento\Sales\Setup\SalesSetup $salesInstaller
+        $columnExist = $installer->getConnection()->tableColumnExists(
+            $installer->getTable('sales_order'),
+            'customer_shipping_date'
+        );
+        if (!$columnExist) {
+            $installer->getConnection()->addColumn(
+                $installer->getTable('quote'),
+                'customer_shipping_date',
+                [
+                    'type' => Table::TYPE_DATETIME,
+                    'nullable' => true,
+                    'comment' => 'Customer Shipping Delivery Date'
+                ]
+            );
+
+            $installer->getConnection()->addColumn(
+                $installer->getTable('quote'),
+                'customer_shipping_comments',
+                [
+                    'type' => Table::TYPE_TEXT,
+                    'nullable' => true,
+                    'comment' => 'Customer Shipping Delivery Comment'
+                ]
+            );
+
+            $installer->getConnection()->addColumn(
+                $installer->getTable('sales_order'),
+                'customer_shipping_date',
+                [
+                    'type' => Table::TYPE_DATETIME,
+                    'nullable' => true,
+                    'comment' => 'Customer Shipping Delivery Date'
+                ]
+            );
+
+            $installer->getConnection()->addColumn(
+                $installer->getTable('sales_order'),
+                'customer_shipping_comments',
+                [
+                    'type' => Table::TYPE_TEXT,
+                    'nullable' => true,
+                    'comment' => 'Customer Shipping Delivery Comment'
+                ]
+            );
+
+            $installer->getConnection()->addColumn(
+                $installer->getTable('sales_order_grid'),
+                'customer_shipping_date',
+                [
+                    'type' => Table::TYPE_DATETIME,
+                    'nullable' => true,
+                    'comment' => 'Customer Shipping Delivery Date'
+                ]
+            );
+        }
+
+        $setup->endSetup();
+    }
+}

app/code/Rokanthemes/OnePageCheckout/composer.json

+{
+    "name": "rokanthemes/module-onepagecheckout",
+    "description": "",
+    "type": "magento2-module",
+    "license": "OSL-3.0",
+    "authors": [
+    ],
+    "minimum-stability": "dev",
+    "require": {},
+    "autoload": {
+        "files": [
+            "registration.php"
+        ],
+        "psr-4": {
+            "Rokanthemes\\OnePageCheckout\\": ""
+        }
+    }
+}

app/code/Rokanthemes/OnePageCheckout/etc/acl.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
+    <acl>
+        <resources>
+            <resource id="Magento_Backend::admin">
+                <resource id="Magento_Backend::stores">
+                    <resource id="Magento_Backend::stores_settings">
+                        <resource id="Magento_Config::config">
+                            <resource id="Rokanthemes_OnePageCheckout::onepagecheckout_config" title="One Page Checkout" />
+                        </resource>
+                    </resource>
+                </resource>
+                <resource id="Rokanthemes_RokanBase::rokanbase">
+                    <resource id="Rokanthemes_OnePageCheckout::onepagecheckout" title="One Page Checkout" translate="title" sortOrder="20">
+                        <resource id="Rokanthemes_OnePageCheckout::onepagecheckout_menu_config" title="Configuration" translate="title" sortOrder="10" />
+                        <resource id="Rokanthemes_OnePageCheckout::onepagecheckout_sorting_fields" title="Sorting Fields" translate="title" sortOrder="20" />
+                    </resource>
+                </resource>
+            </resource>
+        </resources>
+    </acl>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/adminhtml/events.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
+    <event name="core_layout_render_element">
+        <observer name="rokanthemes_onepagecheckout_core_layout_render_element" instance="Rokanthemes\OnePageCheckout\Observer\Admin\CoreLayoutRenderElementObserver" />
+    </event>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/adminhtml/menu.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
+    <menu>
+        <add id="Rokanthemes_OnePageCheckout::onepagecheckout" title="One Page Checkout" module="Rokanthemes_OnePageCheckout" sortOrder="20" parent="Rokanthemes_RokanBase::rokanbase" resource="Rokanthemes_OnePageCheckout::onepagecheckout" />
+        <add id="Rokanthemes_OnePageCheckout::onepagecheckout_menu_config" title="Configuration" module="Rokanthemes_OnePageCheckout" sortOrder="10" parent="Rokanthemes_OnePageCheckout::onepagecheckout" resource="Rokanthemes_OnePageCheckout::onepagecheckout_menu_config" action="adminhtml/system_config/edit/section/onepagecheckout" />
+        <add id="Rokanthemes_OnePageCheckout::onepagecheckout_sorting_fields" title="Sort Address Fields" module="Rokanthemes_OnePageCheckout" sortOrder="10" parent="Rokanthemes_OnePageCheckout::onepagecheckout" resource="Rokanthemes_OnePageCheckout::onepagecheckout_sorting_fields" action="onepagecheckout/field/manage" />
+    </menu>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/adminhtml/routes.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
+    <router id="admin">
+        <route id="onepagecheckout" frontName="onepagecheckout">
+            <module name="Rokanthemes_OnePageCheckout" before="Magento_Backend"/>
+        </route>
+    </router>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/adminhtml/system.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <section id="onepagecheckout" translate="label" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1">
+            <class>separator-top</class>
+            <label>One Page Checkout</label>
+            <tab>sales</tab>
+            <resource>Rokanthemes_OnePageCheckout::onepagecheckout_config</resource>
+            <group id="general" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="1"
+                   showInStore="1">
+                <label>General Options</label>
+                <field id="enabled" translate="label" type="select" sortOrder="20" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Enable Express Checkout</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                </field>
+                <field id="seourl" translate="label" type="text" sortOrder="30" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Seo Url</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="page_title" translate="label" type="text" sortOrder="40" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Page Title</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="short_description" translate="label" type="textarea" sortOrder="45" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Short Description</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="show_order_comment" translate="label" type="select" sortOrder="50" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Order Comment on Checkout</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <!--field id="title_box_order_comment" translate="label" type="text" sortOrder="55" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Title Box Order Comment</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                        <field id="show_order_comment">1</field>
+                    </depends>
+                </field-->
+                <field id="show_subscribe_newsletter" translate="label" type="select" sortOrder="60" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Checkbox Subscribe on Checkout</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="title_box_subscribe" translate="label" type="text" sortOrder="65" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Title Box Subscribe Newletter</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                        <field id="show_subscribe_newsletter">1</field>
+                    </depends>
+                </field>
+                <field id="default_newletter_checkbox" translate="label" type="select" sortOrder="70" showInDefault="1" showInWebsite="1"
+                               showInStore="1">
+                    <label>Default checkbox Subscribe on Checkout</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                        <field id="show_subscribe_newsletter">1</field>
+                    </depends>
+                </field>
+                <field id="show_discount_box" translate="label" type="select" sortOrder="80" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Discount Box on Checkout</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="show_gift_message" translate="label" type="select" sortOrder="80" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Gift Message on Checkout</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="show_widget_box" translate="label" type="select" sortOrder="90" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Widget After Place Order</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="widget_after_placeorder" translate="label" type="select" sortOrder="100" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Cms Show after Place Order</label>
+                    <source_model>Magento\Cms\Model\Config\Source\Block</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                        <field id="show_widget_box">1</field>
+                    </depends>
+                </field>
+                <field id="show_shipping_delivery_date" translate="label" type="select" sortOrder="100" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Shipping Delivery Date</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="title_box_shipping_delivery_date" translate="label" type="text" sortOrder="110" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Title Box Shipping Delivery Date</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                        <field id="show_shipping_delivery_date">1</field>
+                    </depends>
+                </field>
+                <field id="show_shipping_delivery_comment" translate="label" type="select" sortOrder="120" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show Shipping Delivery Comment</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="title_box_shipping_delivery_comment" translate="label" type="text" sortOrder="130" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Title Box Shipping Delivery Comment</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                        <field id="show_shipping_delivery_comment">1</field>
+                    </depends>
+                </field>
+                <field id="show_full_layout" translate="label" type="select" sortOrder="140" showInDefault="1" showInWebsite="1"
+                       showInStore="1">
+                    <label>Show full Header and Footer</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+                <field id="title_place_order" translate="label" type="text" sortOrder="150" showInDefault="1" showInWebsite="1"
+                       showInStore="1" >
+                    <label>Title Button Place Order</label>
+                    <depends>
+                        <field id="enabled">1</field>
+                    </depends>
+                </field>
+            </group>
+        </section>
+    </system>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/config.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
+    <default>
+        <onepagecheckout>
+            <general>
+                <enabled>1</enabled>
+                <seourl>expresscheckout.html</seourl>
+                <page_title>Express Checkout</page_title>
+                <show_shipping_delivery_date>1</show_shipping_delivery_date>
+                <show_shipping_delivery_comment>1</show_shipping_delivery_comment>
+                <show_order_comment>1</show_order_comment>
+                <show_subscribe_newsletter>1</show_subscribe_newsletter>
+                <show_gift_message>1</show_gift_message>
+                <default_newletter_checkbox>0</default_newletter_checkbox>
+                <show_discount_box>1</show_discount_box>
+                <title_box_shipping_delivery_date>Shipping Delivery Date</title_box_shipping_delivery_date>
+                <title_box_shipping_delivery_comment>Shipping Delivery Comment</title_box_shipping_delivery_comment>
+                <title_box_order_comment>Order Comment</title_box_order_comment>
+                <title_box_subscribe>Check To Subscribe Order Newsletter</title_box_subscribe>
+                <title_place_order>Place Order</title_place_order>
+            </general>
+        </onepagecheckout>
+    </default>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/di.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
+    <preference for="Rokanthemes\OnePageCheckout\Api\UpdateItemManagementInterface"
+                type="Rokanthemes\OnePageCheckout\Model\UpdateItemManagement"/>
+    <preference for="Rokanthemes\OnePageCheckout\Api\GuestUpdateItemManagementInterface"
+                type="Rokanthemes\OnePageCheckout\Model\GuestUpdateItemManagement"/>
+    <preference for="Rokanthemes\OnePageCheckout\Api\Data\UpdateItemDetailsInterface"
+                type="Rokanthemes\OnePageCheckout\Model\UpdateItemDetails"/>
+    <type name="Magento\Checkout\Api\PaymentInformationManagementInterface">
+        <plugin name="rokanthemes_opc_additional_data" type="Rokanthemes\OnePageCheckout\Plugin\Checkout\Model\CustomerAdditionalData"/>
+    </type>
+    <type name="Magento\Checkout\Api\GuestPaymentInformationManagementInterface">
+        <plugin name="rokanthemes_opc_guest_additional_data"
+                type="Rokanthemes\OnePageCheckout\Plugin\Checkout\Model\GuestAdditionalData"/>
+    </type>
+    <virtualType name="Magento\Sales\Model\ResourceModel\Order\Grid" type="Magento\Sales\Model\ResourceModel\Grid">
+        <arguments>
+            <argument name="columns" xsi:type="array">
+                <item name="customer_shipping_date" xsi:type="string">sales_order.customer_shipping_date</item>
+            </argument>
+        </arguments>
+    </virtualType>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/events.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
+    <event name="sales_model_service_quote_submit_before">
+        <observer name="rokanthemes_onepagecheckout_sales_model_service_quote_submit_before" instance="Rokanthemes\OnePageCheckout\Observer\SalesModelServiceQuoteSubmitBeforeObserver" shared="false" />
+    </event>
+    <event name="sales_order_place_after">
+        <observer name="rokanthemes_onepagecheckout_sales_order_place_after" instance="Rokanthemes\OnePageCheckout\Observer\SalesOrderPlaceAfterObserver" />
+    </event>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/extension_attributes.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
+    <extension_attributes for="Magento\Quote\Api\Data\PaymentInterface">
+        <attribute code="rokanthemes_opc" type="string[]" />
+    </extension_attributes>
+    <extension_attributes for="Magento\Sales\Api\Data\OrderInterface">
+        <attribute code="customer_shipping_date" type="string" />
+        <attribute code="customer_shipping_comments" type="string" />
+    </extension_attributes>
+    <extension_attributes for="Magento\Sales\Api\Data\InvoiceInterface">
+        <attribute code="customer_shipping_date" type="string" />
+        <attribute code="customer_shipping_comments" type="string" />
+    </extension_attributes>
+    <extension_attributes for="Magento\Sales\Api\Data\ShipmentInterface">
+        <attribute code="customer_shipping_date" type="string" />
+        <attribute code="customer_shipping_comments" type="string" />
+    </extension_attributes>
+    <extension_attributes for="Magento\Sales\Api\Data\CreditmemoInterface">
+        <attribute code="customer_shipping_date" type="string" />
+        <attribute code="customer_shipping_comments" type="string" />
+    </extension_attributes>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/frontend/di.xml

+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
+    <type name="\Magento\Checkout\Block\Checkout\LayoutProcessor">
+        <plugin name="onepagecheckout_checkout_layout_processor" type="Rokanthemes\OnePageCheckout\Plugin\Checkout\Block\Checkout\LayoutProcessor" />
+    </type>
+    <type name="\Magento\Checkout\Helper\Data">
+        <plugin name="onepagecheckout_checkout_helper_data" type="Rokanthemes\OnePageCheckout\Plugin\Checkout\Helper\Data" />
+    </type>
+    <type name="Magento\Checkout\Model\CompositeConfigProvider">
+        <arguments>
+            <argument name="configProviders" xsi:type="array">
+                <item name="onepagecheckout_checkout_composite_config" xsi:type="object">Rokanthemes\OnePageCheckout\Model\CompositeConfigProvider</item>
+            </argument>
+        </arguments>
+    </type>
+    <type name="Magento\Framework\App\RouterList">
+        <arguments>
+            <argument name="routerList" xsi:type="array">
+                <item name="onepagecheckout" xsi:type="array">
+                    <item name="class" xsi:type="string">Rokanthemes\OnePageCheckout\Controller\Router</item>
+                    <item name="disable" xsi:type="boolean">false</item>
+                    <item name="sortOrder" xsi:type="string">90</item>
+                </item>
+            </argument>
+        </arguments>
+    </type>
+    <type name="Magento\Checkout\Controller\Index\Index">
+        <plugin name="onepagecheckout_checkout_redirect_link"
+                type="Rokanthemes\OnePageCheckout\Plugin\Checkout\Controller\Index\Index" />
+    </type>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/frontend/routes.xml

+<?xml version="1.0" ?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
+	<router id="standard">
+		<route frontName="onepagecheckout" id="onepagecheckout">
+			<module name="Rokanthemes_OnePageCheckout"/>
+		</route>
+	</router>
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/module.xml

+<?xml version="1.0" ?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
+	<module name="Rokanthemes_OnePageCheckout" setup_version="1.0.0" />
+</config>

app/code/Rokanthemes/OnePageCheckout/etc/webapi.xml

+<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Webapi:etc/webapi.xsd">
+    <route url="/V1/rokanthemes-opc/carts/mine/update-item-qty" method="POST">
+        <service class="Rokanthemes\OnePageCheckout\Api\UpdateItemManagementInterface" method="update"/>
+        <resources>
+            <resource ref="self"/>
+        </resources>
+        <data>
+            <parameter name="cartId" force="true">%cart_id%</parameter>
+        </data>
+    </route>
+    <route url="/V1/rokanthemes-opc/guest-carts/:cartId/update-item-qty" method="POST">
+        <service class="Rokanthemes\OnePageCheckout\Api\GuestUpdateItemManagementInterface" method="update"/>
+        <resources>
+            <resource ref="anonymous"/>
+        </resources>
+    </route>
+</routes>

app/code/Rokanthemes/OnePageCheckout/registration.php

+<?php
+use Magento\Framework\Component\ComponentRegistrar;
+
+ComponentRegistrar::register(ComponentRegistrar::MODULE, 'Rokanthemes_OnePageCheckout', __DIR__);
+

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/layout/onepagecheckout_field_manage.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="admin-1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <head>
+        <css src="Rokanthemes_OnePageCheckout::css/style.css"/>
+        <css src="Rokanthemes_OnePageCheckout::css/jquery-ui.min.css"/>
+    </head>
+    <body>
+        <referenceContainer name="content">
+            <block class="Rokanthemes\OnePageCheckout\Block\Adminhtml\Field\Tabs" name="admin.field.tabs" template="Rokanthemes_OnePageCheckout::field/tabs.phtml">
+                <block class="Rokanthemes\OnePageCheckout\Block\Adminhtml\Field\Address" name="admin.field.address"/>
+            </block>
+        </referenceContainer>
+    </body>
+</page>

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/templates/delivery.phtml

+<div class="customer_shipping_delivery" style="display:none;">
+    <?php
+    $date = $block->getCustomerShippingDate();
+    if ($date && $date != '0000-00-00 00:00:00') :
+        ?>
+        <div id="shipping-delivery-date">
+            <br />
+            <strong><?= $block->escapeHtml(__('Customer Delivery Date:')) ?></strong>
+            <span><?= $block->formatDate($date, \IntlDateFormatter::MEDIUM); ?></span>
+        </div>
+    <?php endif; ?>
+    <?php if ($comment = $block->getCustomerShippingComments()) : ?>
+        <div id="shipping-delivery-comment">
+            <br />
+            <strong><?= $block->escapeHtml(__('Customer Delivery Comment:')) ?></strong>
+            <span><?php echo $comment; ?></span>
+        </div>
+    <?php endif; ?>
+</div>
+<?php if ($block->getActiveJs()) : ?>
+    <script type="text/x-magento-init">
+        {
+            "body": {
+                "Rokanthemes_OnePageCheckout/js/shippingdelivery": {}
+            }
+        }
+    </script>
+<?php endif; ?>

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/templates/field/position.phtml

+<?php
+/** @var \Rokanthemes\OnePageCheckout\Block\Adminhtml\Field\AbstractField $block */
+?>
+
+<div id="<?= $block->escapeQuote($block->getBlockId()) ?>" class="admin-field-container">
+    <?php if ($block->isVisible() && $block->hasFields()) : ?>
+        <div class="containment row">
+            <div class="field-wrapper available-wrapper col-m-4">
+                <div><?= __('Area Removed'); ?></div>
+                <ul class="sortable-list ui-sortable">
+                    <?php foreach ($block->getAvailableFields() as $field) : ?>
+                        <li class="sortable-item" id="<?= $block->escapeQuote($field->getId()) ?>"
+                            data-code="<?= $block->escapeQuote($field->getAttributeCode()) ?>">
+                            <div class="attribute-label">
+                                <span><?= $block->escapeHtml($field->getFrontendLabel()) ?></span>
+                                <div class="attribute-required">
+                                    <input type="checkbox" title="<?= $block->escapeQuote(__('Is Required?')) ?>"
+                                        <?php if ($field->getIsRequired()) {
+                                            echo ' checked';
+                                        } ?>>
+                                </div>
+                            </div>
+                        </li>
+                    <?php endforeach; ?>
+                </ul>
+
+            </div>
+            <div class="field-wrapper sorted-wrapper col-m-8">
+                <div><?= __('Area Sorting'); ?></div>
+                <ul class="sortable-list ui-sortable">
+                    <?php foreach ($block->getSortedFields() as $field) : ?>
+                        <li class="sortable-item <?= $block->escapeQuote($field->getColStyle()) ?>"
+                            id="<?= $block->escapeQuote($field->getId()) ?>"
+                            data-code="<?= $block->escapeQuote($field->getAttributeCode()) ?>">
+                            <div class="attribute-label">
+                                <span><?= $block->escapeHtml($field->getFrontendLabel()) ?></span>
+                                <?php if ($field->getId()) : ?>
+                                    <div class="attribute-required">
+                                        <input type="checkbox" title="<?= $block->escapeQuote(__('Is Required?')) ?>"
+                                            <?php if ($field->getIsRequiredMp()) {
+                                                echo ' checked';
+                                            } ?>>
+                                    </div>
+                                <?php endif; ?>
+                            </div>
+                        </li>
+                    <?php endforeach; ?>
+                </ul>
+            </div>
+        </div>
+
+        <script type="text/x-magento-init">
+        {
+            "*": {
+                "Rokanthemes_OnePageCheckout/js/field-position": {
+                    "blockId": "<?= /** @noEscape */ $block->getBlockId() ?>"
+                }
+            }
+        }
+        </script>
+    <?php else : ?>
+        <div class="messages">
+            <div class="message message-info info">
+                <span><?= /** @noEscape */ $block->getNoticeMessage() ?></span>
+            </div>
+        </div>
+    <?php endif; ?>
+</div>

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/templates/field/tabs.phtml

+<div id="position-save-messages" class="messages"></div>
+
+<div id="admin-field-tabs" class="row">
+    <a class="button action-default col-m-12" href="#address-information">
+        <i class="fa fa-home"></i>
+        <span><?= $block->escapeHtml(__('Address Information')) ?></span>
+    </a>
+</div>
+
+<div id="field-position-sortable">
+    <?= $block->getChildHtml() ?>
+</div>
+
+<script type="text/x-magento-init">
+{
+    "*": {
+        "Rokanthemes_OnePageCheckout/js/field-tabs": {
+            "url": "<?= $block->escapeUrl($block->getAjaxUrl()) ?>"
+        }
+    }
+}
+</script>

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/web/css/style.css

+#field-position-sortable .suggest-position {
+    background: #cccccc;
+    height: 4rem;
+    float: left;
+}
+
+/* ------------------------------------------------------------------- */
+
+/* General */
+
+.field-wrapper.sorted-wrapper {
+    background-color: #fafafa;
+    border-left: none;
+}
+
+.field-wrapper.available-wrapper {
+    background-color: #e3e3e3;
+    border-right: none;
+}
+
+.field-wrapper {
+    display: table-cell;
+    vertical-align: top;
+    float: unset;
+    border: 1px solid #adadad;
+    border-top: none;
+}
+
+.field-wrapper ul {
+    width: 100%;
+    min-height: 450px;
+    padding-top: 5px;
+    list-style-type: none;
+}
+
+.field-wrapper ul li {
+    width: 48%;
+    margin: 1%;
+}
+
+.field-wrapper ul li.wide {
+    width: 98%;
+}
+
+.field-wrapper ul li.medium {
+    width: 72%;
+}
+
+.field-wrapper ul li.short {
+    width: 23%;
+}
+
+.field-wrapper.available-wrapper ul li {
+    width: 96%;
+    margin: 2%;
+}
+
+.field-wrapper ul li .attribute-label {
+    border: 1px solid #cccccc;
+    text-align: center;
+    padding: 10px 10px;
+    cursor: move;
+    background: #ffffff;
+    height: 20px !important;
+    box-sizing: content-box;
+}
+
+.field-wrapper ul li.ui-state-disabled {
+    opacity: 1;
+}
+
+.field-wrapper ul li.ui-state-disabled .attribute-label {
+    background-color: #514943;
+    border-color: #514943;
+    color: #ffffff;
+}
+
+.available-wrapper .ui-resizable-handle {
+    display: none !important;
+}
+
+#field-position-sortable .ui-resizable-s {
+    display: none !important;
+}
+
+/* Containment area */
+
+.ui-resizable-border {
+    border: 1px dotted #cccccc;
+}
+
+#admin-field-tabs a {
+    padding: 5px;
+    font-size: 2rem;
+    line-height: 1.5;
+    white-space: nowrap;
+    text-overflow: ellipsis;
+    overflow: hidden;
+}
+
+#admin-field-tabs a._active {
+    background-color: #1979c3;
+    border-color: #1979c3;
+    color: #ffffff;
+}
+
+#field-position-sortable .attribute-required {
+    position: absolute;
+    top: 3px;
+    right: 3px;
+}
+
+.available-wrapper .attribute-required, .admin-field-container {
+    display: none;
+}
+
+.admin-field-container .containment.row {
+    display: flex;
+}
+
+.f-left {
+    float: left;
+}
+
+#field-position-sortable > .admin-field-container > .messages {
+    margin-top: 3rem;
+}
+
+#field-position-sortable > .admin-field-container > .messages > .message:last-child {
+    margin: 0;
+}

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/web/js/field-position.js

+define(['jquery', 'jquery/ui'], function ($) {
+    'use strict';
+
+    $.widget('admin.field_position', {
+        _create: function () {
+            this.initGrid();
+        },
+
+        initGrid: function () {
+            var selector = '#' + this.options.blockId + ' ',
+                list     = $(selector + '.sortable-list'),
+                field, elemWidth;
+
+            var options = {
+                tolerance: 'pointer',
+                connectWith: '.sortable-list',
+                dropOnEmpty: true,
+                containment: 'body',
+                cancel: '.ui-state-disabled',
+                placeholder: 'suggest-position',
+                zIndex: 10,
+                scroll: false,
+                start: function (e, hash) {
+                    if (hash.item.hasClass('wide')) {
+                        hash.placeholder.addClass('wide');
+                    }
+
+                    if (hash.item.hasClass('medium')) {
+                        hash.placeholder.addClass('medium');
+                    }
+
+                    if (hash.item.hasClass('short')) {
+                        hash.placeholder.addClass('short');
+                    }
+                }
+            };
+
+            if (this.options.blockId === 'admin-order-summary') {
+                options.items = 'li:not(.ui-state-disabled)';
+            }
+
+            list.sortable(options);
+
+            $(selector + '.sortable-list li').disableSelection();
+            $(selector + '.sortable-list li').addClass('f-left');
+
+            $(selector + '.containment ul li .attribute-label').resizable({
+                maxHeight: 40,
+                minHeight: 40,
+                zIndex: 10,
+                cancel: '.ui-state-disabled',
+                helper: 'ui-resizable-border',
+                stop: function (e, ui) {
+                    field     = ui.element.parent();
+                    elemWidth = ui.element.width() / 2;
+
+                    field.removeClass('wide');
+                    field.removeClass('medium');
+                    field.removeClass('short');
+
+                    if (elemWidth < field.width() * 0.3) {
+                        field.addClass('short');
+                    } else if (elemWidth > field.width() * 0.6 && elemWidth < field.width() * 0.8) {
+                        field.addClass('medium');
+                    } else if (elemWidth > field.width() * 0.8) {
+                        field.addClass('wide');
+                    }
+
+                    ui.element.css({width: ''});
+                }
+            });
+        }
+    });
+
+    return $.admin.field_position;
+});

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/web/js/field-tabs.js

+define(['jquery'], function ($) {
+    'use strict';
+
+    $.widget('admin.field_tabs', {
+        _create: function () {
+            this.initTabEvent();
+            this.initSaveEvent();
+        },
+
+        initTabEvent: function () {
+            var elem = $('#admin-field-tabs .action-default');
+            $('.admin-field-container').show();
+            elem.on('click', function () {
+                elem.removeClass('_active');
+                $(this).addClass('_active');
+                return false;
+            });
+        },
+
+        initSaveEvent: function () {
+            var self = this;
+
+            $('.admin-save-position').on('click', function () {
+                self.savePosition(self.options.url);
+            });
+        },
+
+        savePosition: function (url) {
+            var self     = this,
+                fields   = [],
+                oaFields = [],
+                field    = {},
+                parent   = null;
+
+            $('#position-save-messages').html('');
+
+            $('.sorted-wrapper .sortable-item').each(function (index, el) {
+                parent = $(el).parents('.admin-field-container');
+
+                field = {
+                    code: $(el).attr('data-code'),
+                    colspan: self.getColspan($(el)),
+                    required: !!$(el).find('.attribute-required input').is(':checked')
+                };
+
+                if ($(el).parents('#admin-address-information').length) {
+                    fields.push(field);
+                }
+            });
+
+            $.ajax({
+                method: 'post',
+                showLoader: true,
+                url: url,
+                data: {
+                    fields: JSON.stringify(fields)
+                },
+                success: function (response) {
+                    $('#position-save-messages').html(
+                        '<div class="message message-' + response.type + ' ' + response.type + ' ">' +
+                        '<span>' + response.message + '</span>' +
+                        '</div>'
+                    );
+                }
+            });
+        },
+
+        getColspan: function (elem) {
+            if (elem.hasClass('wide')) {
+                return 12;
+            } else if (elem.hasClass('medium')) {
+                return 9;
+            } else if (elem.hasClass('short')) {
+                return 3;
+            }
+
+            return 6;
+        }
+    });
+
+    return $.admin.field_tabs;
+});

app/code/Rokanthemes/OnePageCheckout/view/adminhtml/web/js/shippingdelivery.js

+define([
+    'jquery'
+], function ($) {
+    'use strict';
+
+    if ($('#shipping-delivery-date').length) {
+        var date = $('#shipping-delivery-date').detach();
+        $('.order-shipping-method').append(date);
+    }
+    if ($('#shipping-delivery-comment').length) {
+        var comment = $('#shipping-delivery-comment').detach();
+        $('.order-shipping-method').append(comment);
+    }
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/layout/onepagecheckout_index_index_default.xml

+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceContainer name="sidebar.additional" remove="true"/>
+        <referenceBlock name="top.search" remove="true"/>
+        <!-- <referenceBlock name="minicart" remove="true"/> -->
+        <!--<referenceContainer name="footer-container" remove="true"/>-->
+        <referenceBlock name="header.panel.wrapper" remove="true"/>
+    </body>
+</page>

app/code/Rokanthemes/OnePageCheckout/view/frontend/layout/onepagecheckout_index_index_full.xml

+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <attribute name="class" value="rokanthemes-onepagecheckout-full"/>
+        <attribute name="class" value="checkout-index-index"/>
+    </body>
+</page>

app/code/Rokanthemes/OnePageCheckout/view/frontend/requirejs-config.js

+var config = {
+    map: {
+        '*': {
+            'Magento_Checkout/template/billing-address/form.html':
+                'Rokanthemes_OnePageCheckout/template/billing-address/form.html',
+            'Magento_Checkout/js/model/shipping-rate-service':
+                'Rokanthemes_OnePageCheckout/js/model/shipping-rate-service',
+            'Magento_Checkout/js/action/get-payment-information':
+                'Rokanthemes_OnePageCheckout/js/action/get-payment-information'
+        }
+    },
+    config: {
+        mixins: {
+            'Magento_Checkout/js/action/place-order': {
+                'Rokanthemes_OnePageCheckout/js/model/place-order-mixin': true,
+                'Magento_CheckoutAgreements/js/model/place-order-mixin': false
+            },
+            'Magento_Checkout/js/model/step-navigator': {
+                'Rokanthemes_OnePageCheckout/js/model/step-navigator-mixin': true
+            },
+            'Magento_Checkout/js/action/set-payment-information': {
+                'Magento_CheckoutAgreements/js/model/set-payment-information-mixin': false,
+                'Rokanthemes_OnePageCheckout/js/model/set-payment-information-mixin': true
+            },
+            'Magento_Checkout/js/model/shipping-rates-validation-rules': {
+                'Rokanthemes_OnePageCheckout/js/model/shipping-rates-validation-rules-mixin': true
+            },
+            'Magento_Paypal/js/in-context/express-checkout-wrapper': {
+                'Rokanthemes_OnePageCheckout/js/paypal/in-context/express-checkout-wrapper-mixin': true
+            },
+               'Magento_Paypal/js/view/payment/method-renderer/in-context/checkout-express': {
+                'Rokanthemes_OnePageCheckout/js/paypal/view/payment/method-renderer/in-context/checkout-express-mixin': true
+            },
+            'Amazon_Payment/js/view/payment/list': {
+                'Rokanthemes_OnePageCheckout/js/amazon-pay/view/payment-list': true
+            },
+            'Amazon_Payment/js/view/checkout-revert': {
+                'Rokanthemes_OnePageCheckout/js/amazon-pay/view/checkout-revert-rewrite': true
+            }
+        }
+    }
+};

app/code/Rokanthemes/OnePageCheckout/view/frontend/requirejs-config.js-o

+var config = {
+    map: {
+        '*': {
+            'Magento_Checkout/template/billing-address/form.html':
+                'Rokanthemes_OnePageCheckout/template/billing-address/form.html',
+            'Magento_Checkout/js/model/shipping-rate-service':
+                'Rokanthemes_OnePageCheckout/js/model/shipping-rate-service',
+            'Magento_Checkout/js/action/get-payment-information':
+                'Rokanthemes_OnePageCheckout/js/action/get-payment-information'
+        }
+    },
+    config: {
+        mixins: {
+            'Magento_Checkout/js/action/place-order': {
+                'Rokanthemes_OnePageCheckout/js/model/place-order-mixin': true,
+                'Magento_CheckoutAgreements/js/model/place-order-mixin': false
+            },
+            'Magento_Checkout/js/model/step-navigator': {
+                'Rokanthemes_OnePageCheckout/js/model/step-navigator-mixin': true
+            },
+            'Magento_Checkout/js/action/set-payment-information': {
+                'Magento_CheckoutAgreements/js/model/set-payment-information-mixin': false,
+                'Rokanthemes_OnePageCheckout/js/model/set-payment-information-mixin': true
+            },
+            'Magento_Checkout/js/model/shipping-rates-validation-rules': {
+                'Rokanthemes_OnePageCheckout/js/model/shipping-rates-validation-rules-mixin': true
+            },
+            'Magento_Paypal/js/in-context/express-checkout-wrapper': {
+                'Rokanthemes_OnePageCheckout/js/paypal/in-context/express-checkout-wrapper-mixin': true
+            },
+        //    'Magento_Paypal/js/view/payment/method-renderer/in-context/checkout-express': {
+          //      'Rokanthemes_OnePageCheckout/js/paypal/view/payment/method-renderer/in-context/checkout-express': true
+        //    },
+            'Amazon_Payment/js/view/payment/list': {
+                'Rokanthemes_OnePageCheckout/js/amazon-pay/view/payment-list': true
+            },
+            'Amazon_Payment/js/view/checkout-revert': {
+                'Rokanthemes_OnePageCheckout/js/amazon-pay/view/checkout-revert-rewrite': true
+            }
+        }
+    }
+};

app/code/Rokanthemes/OnePageCheckout/view/frontend/templates/short_description.phtml

+<?php
+/**
+ * @var $block \Rokanthemes\OnePageCheckout\Block\Config
+ */
+?>
+<div class="short-description">
+    <?= $block->getShortDescription() ?>
+</div>

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/action/get-payment-information.js

+define([
+    'jquery',
+    'Magento_Checkout/js/model/quote',
+    'Magento_Checkout/js/model/url-builder',
+    'mage/storage',
+    'Magento_Checkout/js/model/error-processor',
+    'Magento_Customer/js/model/customer',
+    'Magento_Checkout/js/model/payment/method-converter',
+    'Magento_Checkout/js/model/payment-service'
+], function ($, quote, urlBuilder, storage, errorProcessor, customer, methodConverter, paymentService) {
+    'use strict';
+
+    return function (deferred, messageContainer) {
+        var serviceUrl;
+
+        deferred = deferred || $.Deferred();
+
+        /**
+         * Checkout for guest and registered customer.
+         */
+        if (!customer.isLoggedIn()) {
+            serviceUrl = urlBuilder.createUrl('/guest-carts/:cartId/payment-information', {
+                cartId: quote.getQuoteId()
+            });
+        } else {
+            serviceUrl = urlBuilder.createUrl('/carts/mine/payment-information', {});
+        }
+
+        if (!window.isPlaceOrderDispatched) {
+            window.isPlaceOrderDispatched = false;
+            return storage.get(
+                serviceUrl, false
+            ).done(function (response) {
+                quote.setTotals(response.totals);
+                paymentService.setPaymentMethods(methodConverter(response['payment_methods']));
+                deferred.resolve();
+            }).fail(function (response) {
+                errorProcessor.process(response, messageContainer);
+                deferred.reject();
+            });
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/action/gift-options.js

+define([
+    'Rokanthemes_OnePageCheckout/js/model/url-builder',
+    'mage/storage',
+    'Magento_Ui/js/model/messageList',
+    'Magento_Checkout/js/model/error-processor',
+    'mage/url',
+    'Magento_Checkout/js/model/quote',
+    'underscore'
+], function (urlBuilder, storage, messageList, errorProcessor, url, quote, _) {
+    'use strict';
+
+    return function (giftMessage, remove) {
+        var serviceUrl;
+
+        url.setBaseUrl(giftMessage.getConfigValue('baseUrl'));
+
+        if (giftMessage.getConfigValue('isCustomerLoggedIn')) {
+            serviceUrl = urlBuilder.createUrl('/carts/mine/gift-message', {});
+
+            if (giftMessage.itemId != 'orderLevel') { //eslint-disable-line eqeqeq
+                serviceUrl = urlBuilder.createUrl('/carts/mine/gift-message/:itemId', {
+                    itemId: giftMessage.itemId
+                });
+            }
+        } else {
+            serviceUrl = urlBuilder.createUrl('/guest-carts/:cartId/gift-message', {
+                cartId: quote.getQuoteId()
+            });
+
+            if (giftMessage.itemId != 'orderLevel') { //eslint-disable-line eqeqeq
+                serviceUrl = urlBuilder.createUrl(
+                    '/guest-carts/:cartId/gift-message/:itemId',
+                    {
+                        cartId: quote.getQuoteId(), itemId: giftMessage.itemId
+                    }
+                );
+            }
+        }
+        messageList.clear();
+
+        storage.post(
+            serviceUrl,
+            JSON.stringify({
+                'gift_message': giftMessage.getSubmitParams(remove)
+            })
+        ).done(function () {
+            giftMessage.reset();
+            _.each(giftMessage.getAfterSubmitCallbacks(), function (callback) {
+                if (_.isFunction(callback)) {
+                    callback();
+                }
+            });
+        }).fail(function (response) {
+            errorProcessor.process(response);
+        });
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/action/payment-total-information.js

+define(
+    [
+        'jquery',
+        'Magento_Checkout/js/model/quote',
+        'Rokanthemes_OnePageCheckout/js/model/resource-url-manager',
+        'mage/storage',
+        'Magento_Checkout/js/model/error-processor',
+        'Magento_Customer/js/model/customer',
+        'Magento_Checkout/js/model/payment/method-converter',
+        'Magento_Checkout/js/model/payment-service',
+        'Magento_Checkout/js/model/shipping-service',
+        'Magento_Checkout/js/model/full-screen-loader',
+        'uiRegistry'
+    ],
+    function ($,
+              quote,
+              resourceUrlManager,
+              storage,
+              errorProcessor,
+              customer,
+              methodConverter,
+              paymentService,
+              shippingService,
+              opcLoader,
+              registry) {
+        'use strict';
+
+        return function () {
+            opcLoader.startLoader();
+
+            return storage.post(
+                resourceUrlManager.getUrlForUpdatePaymentTotalInformation(quote)
+            ).done(
+                function (response) {
+                    var options, paths;
+
+                    if (response.redirect_url) {
+                        window.location.href = response.redirect_url;
+                        return;
+                    }
+
+                    // remove downloadable options on cart item reload
+                    $('#downloadable-links-list').remove();
+                    $('#links-advice-container').remove();
+
+                    if (response.image_data) {
+                        registry.get('checkout.sidebar.summary.cart_items.details.thumbnail').imageData
+                            = JSON.parse(response.image_data);
+                    }
+
+                    if (response.options) {
+                        options = JSON.parse(response.options);
+
+                        response.totals.items.forEach(function (item) {
+                            item.rkopc = options[item.item_id];
+                        });
+                    }
+
+                    if (response.request_path) {
+                        paths = JSON.parse(response.request_path);
+
+                        response.totals.items.forEach(function (item) {
+                            item.request_path = paths[item.item_id];
+                        });
+                    }
+
+                    quote.setTotals(response.totals);
+                    paymentService.setPaymentMethods(methodConverter(response.payment_methods));
+                }
+            ).fail(
+                function (response) {
+                    errorProcessor.process(response);
+                }
+            ).always(
+                function () {
+                    opcLoader.stopLoader();
+                }
+            );
+        };
+    }
+);

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/action/set-shipping-information.js

+define([
+    'Magento_Checkout/js/model/quote',
+    'Rokanthemes_OnePageCheckout/js/model/shipping-save-processor'
+], function (quote, shippingSaveProcessor) {
+    'use strict';
+
+    return function () {
+        return shippingSaveProcessor.saveShippingInformation(quote.shippingAddress().getType());
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/action/update-item.js

+define([
+    'jquery',
+    'underscore',
+    'Rokanthemes_OnePageCheckout/js/model/url-builder',
+    'mage/storage',
+    'Magento_Checkout/js/model/error-processor',
+    'Magento_Checkout/js/model/shipping-service',
+    'Magento_Checkout/js/model/totals',
+    'Rokanthemes_OnePageCheckout/js/model/payment-service',
+    'mage/url',
+    'Magento_Checkout/js/model/quote',
+    'Magento_Checkout/js/model/payment/method-converter',
+    'Magento_Checkout/js/model/payment-service',
+    'Rokanthemes_OnePageCheckout/js/model/update-item-service',
+    'Magento_Ui/js/model/messageList',
+    'Magento_Checkout/js/action/get-totals'
+], function (
+    $,
+    _,
+    urlBuilder,
+    storage,
+    errorProcessor,
+    shippingService,
+    totals,
+    paymentService,
+    url,
+    quote,
+    methodConverter,
+    paymentServiceDefault,
+    updateItemService,
+    globalMessageList,
+    getTotalsAction
+) {
+    'use strict';
+
+    return function (item) {
+        var serviceUrl = urlBuilder.getUpdateQtyUrl(),
+            address = quote.shippingAddress();
+
+        shippingService.isLoading(true);
+        totals.isLoading(true);
+        paymentService.isLoading(true);
+
+        return storage.post(
+            serviceUrl,
+            JSON.stringify({
+                address: {
+                    'region_id': address.regionId,
+                    'region': address.region,
+                    'country_id': address.countryId,
+                    'postcode': address.postcode
+                },
+                itemId: parseInt(item.item_id),
+                qty: parseFloat(item.qty)
+            })
+        ).done(function (response) {
+            if (response.has_error && response.status) {
+                globalMessageList.addSuccessMessage(response);
+                window.location.replace(url.build('checkout/cart/'));
+            } else {
+                if (response.status) {
+                    globalMessageList.addSuccessMessage(response);
+                    updateItemService.hasUpdateResult(true);
+                    shippingService.setShippingRates(response.shipping_methods);
+                    paymentServiceDefault.setPaymentMethods(methodConverter(response.payment_methods));
+                    updateItemService.hasUpdateResult(false);
+                    response.totals.coupon_code ? paymentService.isAppliedCoupon(true) : paymentService.isAppliedCoupon(false);
+                    var deferred = $.Deferred();
+                    getTotalsAction([], deferred);
+
+                    $('.items-in-cart').find('[data-bind="text: getCartSummaryItemsCount()"]')
+                        .text(response['totals']['items_qty']);
+
+                } else {
+                    globalMessageList.addErrorMessage(response);
+                }
+            }
+        }).fail(function (response) {
+            errorProcessor.process(response);
+        }).always(function () {
+            shippingService.isLoading(false);
+            totals.isLoading(false);
+            paymentService.isLoading(false);
+        });
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/action/validate-shipping-information.js

+define([
+    'Rokanthemes_OnePageCheckout/js/model/shipping-save-processor/validate'
+], function (validateProcessor) {
+    'use strict';
+
+    return function () {
+        return validateProcessor.saveShippingInformation();
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/amazon-pay/view/checkout-revert-rewrite.js

+define([
+    'jquery',
+    'underscore',
+    'ko',
+    'uiComponent',
+    'Amazon_Payment/js/model/storage',
+    'mage/storage',
+    'Magento_Checkout/js/model/error-processor',
+    'Magento_Checkout/js/model/url-builder',
+    'Magento_Checkout/js/model/full-screen-loader',
+], function (
+    $,
+    _,
+    ko,
+    Component,
+    amazonStorage,
+    storage,
+    errorProcessor,
+    urlBuilder,
+    fullScreenLoader,
+) {
+    'use strict';
+
+    var mixin = {
+        /**
+         * Revert checkout
+         */
+        revertCheckout: function () {
+            var serviceUrl = urlBuilder.createUrl('/amazon/order-ref', {});
+
+            fullScreenLoader.startLoader();
+            storage.delete(
+                serviceUrl
+            ).done(
+                function () {
+                    amazonStorage.amazonlogOut();
+                    fullScreenLoader.stopLoader();
+
+                    // Amazon pay hot-fix: reload page after Customer click "Return to standard checkout"
+                    // to reload other payment method
+                    location.reload();
+                }
+            ).fail(
+                function (response) {
+                    fullScreenLoader.stopLoader();
+                    errorProcessor.process(response);
+                }
+            );
+        }
+    };
+
+    return function (target) {
+        return target.extend(mixin);
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/amazon-pay/view/payment-list.js

+define([
+    'jquery',
+    'underscore'
+], function (
+    $,
+    _
+) {
+    'use strict';
+
+    var mixin = {
+        /**
+         * @param {Object} group
+         * @returns {Boolean}
+         */
+        showFormShared: function (group) {
+            var isShow = false,
+                self = this;
+            if (self.paymentGroupsList().length) {
+                if (_.first(self.paymentGroupsList()).alias == group().alias) {
+                    isShow = true;
+                }
+            }
+            return isShow;
+        },
+    };
+
+    return function (target) {
+        return target.extend(mixin);
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/lib/jquery/jquery-ui-addon-slider-access.js

+(function ($) {
+
+    $.fn.extend({
+        sliderAccess: function (options) {
+            options = options || {};
+            options.touchonly = options.touchonly !== undefined ? options.touchonly : true;
+
+            if (options.touchonly === true && !("ontouchend" in document))
+                return $(this);
+
+            return $(this).each(function (i, obj) {
+                var $t = $(this),
+                    o = $.extend({}, {
+                        where: 'after',
+                        step: $t.slider('option', 'step'),
+                        upIcon: 'ui-icon-plus',
+                        downIcon: 'ui-icon-minus',
+                        text: false,
+                        upText: '+',
+                        downText: '-',
+                        buttonset: true,
+                        buttonsetTag: 'span',
+                        speed: 150
+                    }, options),
+                    $buttons = $('<' + o.buttonsetTag + ' class="ui-slider-access">' +
+                        '<button data-icon="' + o.downIcon + '" data-step="-' + o.step + '">' + o.downText + '</button>' +
+                        '<button data-icon="' + o.upIcon + '" data-step="' + o.step + '">' + o.upText + '</button>' +
+                        '</' + o.buttonsetTag + '>');
+
+                $buttons.children('button').each(function (j, jobj) {
+                    var $jt = $(this),
+                        timeout = null,
+                        increment = function ($jt, $t, e) {
+                            var step = $jt.data('step'),
+                                curr = $t.slider('value'),
+                                newval = curr += step * 1,
+                                minval = $t.slider('option', 'min'),
+                                maxval = $t.slider('option', 'max');
+                            e.preventDefault();
+                            if (newval < minval || newval > maxval)
+                                return;
+                            $t.slider('value', newval);
+                            $t.slider("option", "slide").call($t, null, {value: newval});
+                        };
+
+                    $jt.button({
+                        text: o.text,
+                        icons: {primary: $jt.data('icon')}
+                    })
+                        .bind('touchstart mousedown', function (e) {
+                            increment($jt, $t, e);
+                            timeout = setInterval(function () {
+                                increment($jt, $t, e);
+                            }, o.speed);
+                        });
+
+                    $(document).bind('touchend mouseup', function (e) {
+                        clearInterval(timeout);
+                        return e.type == 'touchend';
+                    });
+
+                });
+
+                // before or after
+                $t[o.where]($buttons);
+
+                if (o.buttonset) {
+                    $buttons.removeClass('ui-corner-right').removeClass('ui-corner-left').buttonset();
+                    $buttons.eq(0).addClass('ui-corner-left');
+                    $buttons.eq(1).addClass('ui-corner-right');
+                }
+
+                // adjust the width so we don't break the original layout
+                var bOuterWidth = $buttons.css({
+                    marginLeft: (o.where == 'after' ? 10 : 0),
+                    marginRight: (o.where == 'before' ? 10 : 0)
+                }).outerWidth(true) + 5;
+                var tOuterWidth = $t.outerWidth(true);
+
+                // support "always" hide the slider
+                if (o.hideSlider == 'always' || (o.hideSlider == 'touch' && ("ontouchend" in document))) {
+                    $t.css('display', 'none');
+                } else {
+                    $t.css('display', 'inline-block').width(tOuterWidth - bOuterWidth);
+                }
+            });
+        }
+    });
+
+})(jQuery);

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/additional-data.js

+define([
+    'jquery',
+    'uiRegistry',
+    'underscore'
+], function ($, registry, _) {
+    'use strict';
+
+    return function (paymentData) {
+        var additionalData = {};
+        var shippingAddressComponent = registry.get('checkout.steps.shipping-step.shippingAddress');
+        if (!_.isEmpty(shippingAddressComponent)) {
+            var deliveryDate = shippingAddressComponent.getChild('before-shipping-method-form').getChild('rokanthemes_opc_shipping_delivery_date');
+            var deliveryComment = shippingAddressComponent.getChild('before-shipping-method-form').getChild('rokanthemes_opc_shipping_delivery_comment');
+        }
+        var orderComment = registry.get('checkout.sidebar.rokanthemes_opc_order_comment');
+        var subscribe = registry.get('checkout.sidebar.subscribe');
+
+        if (!_.isUndefined(deliveryDate)) {
+            additionalData['customer_shipping_date'] = deliveryDate.value();
+        }
+        if (!_.isUndefined(deliveryComment)) {
+            additionalData['customer_shipping_comments'] = deliveryComment.value();
+        }
+        if (!_.isUndefined(orderComment)) {
+            additionalData['order_comment'] = orderComment.value();
+        }
+        if (!_.isUndefined(subscribe)) {
+            additionalData['subscribe'] = subscribe.value();
+        }
+        if (!additionalData) {
+            return;
+        }
+        if (paymentData['extension_attributes'] === undefined) {
+            paymentData['extension_attributes'] = {};
+        }
+        console.log(additionalData);
+        paymentData['extension_attributes']['rokanthemes_opc'] = additionalData;
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/agreement-validator.js

+define([
+    'jquery',
+    'mage/validation'
+], function ($) {
+    'use strict';
+
+    var checkoutConfig = window.checkoutConfig,
+        agreementsConfig = checkoutConfig ? checkoutConfig.checkoutAgreements : {},
+        agreementsInputPath = '.rokanthemes-onepagecheckout #opc-sidebar div.checkout-agreements input';
+
+    return {
+        /**
+         * Validate checkout agreements
+         *
+         * @returns {Boolean}
+         */
+        validate: function () {
+            var isValid = true;
+
+            if (!agreementsConfig.isEnabled || $(agreementsInputPath).length === 0) {
+                return true;
+            }
+
+            $(agreementsInputPath).each(function (index, agreementsInput) {
+                if (!$('#onepagecheckout-form-checkout-agreements').validate({
+                    errorClass: 'mage-error',
+                    errorElement: 'div',
+                    meta: 'validate',
+                    errorPlacement: function (error, element) {
+                        var errorPlacement = element;
+                        if (element.is(':checkbox') || element.is(':radio')) {
+                            errorPlacement = element.siblings('label').last();
+                        }
+                        errorPlacement.after(error);
+                    }
+                }).element(agreementsInput)) {
+                    isValid = false;
+                }
+            });
+
+            return isValid;
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/agreements-assigner.js

+define([
+    'jquery'
+], function ($) {
+    'use strict';
+
+    var agreementsConfig = window.checkoutConfig.checkoutAgreements;
+
+    /** Override default place order action and add agreement_ids to request */
+    return function (paymentData) {
+        var agreementForm,
+            agreementData,
+            agreementIds;
+
+        if (!agreementsConfig.isEnabled) {
+            return;
+        }
+
+        agreementForm = $('.payment-method._active div[data-role=checkout-agreements] input');
+        if (!_.isUndefined(window.checkoutConfig.OnePageCheckout) && $('.rokanthemes-onepagecheckout').length) {
+            agreementForm = $('.rokanthemes-onepagecheckout #opc-sidebar div[data-role=checkout-agreements] input');
+        }
+        agreementData = agreementForm.serializeArray();
+        agreementIds = [];
+
+        agreementData.forEach(function (item) {
+            agreementIds.push(item.value);
+        });
+
+        if (paymentData['extension_attributes'] === undefined) {
+            paymentData['extension_attributes'] = {};
+        }
+
+        paymentData['extension_attributes']['agreement_ids'] = agreementIds;
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/compatible/amazon-pay.js

+define(['ko'], function (ko) {
+    'use strict';
+    var hasLogin = window.checkoutConfig.OnePageCheckout.isAmazonAccountLoggedIn;
+    return {
+        isAmazonAccountLoggedIn: ko.observable(hasLogin),
+        setLogin: function (value) {
+            return this.isAmazonAccountLoggedIn(value);
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/create-new-account-validator.js

+define([
+    'jquery',
+    'Magento_Customer/js/model/customer',
+    'Rokanthemes_OnePageCheckout/js/model/save-new-account-information',
+    'mage/validation'
+], function ($, customer, saveNewAccountInformation) {
+    'use strict';
+
+    return {
+        /**
+         * Validate checkout agreements
+         *
+         * @returns {Boolean}
+         */
+        validate: function () {
+            var validationResult = true,
+                createNewAccountCheckBoxId = 'create-new-customer',
+                loginFormSelector = 'form[data-role=email-with-possible-login]';
+
+            if (!customer.isLoggedIn() && $(loginFormSelector + ' #'+createNewAccountCheckBoxId).is(":checked")) {
+                $(loginFormSelector).validation();
+                validationResult = Boolean($(loginFormSelector + ' input[name=newcustomerpassword]').valid());
+                if (validationResult == true) {
+                    validationResult = Boolean($(loginFormSelector + ' input[name=newcustomerpassword_confirmation]').valid());
+                }
+            }
+            saveNewAccountInformation.ajaxSave();
+            return validationResult;
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/default-validation-rules.js

+define([], function () {
+    'use strict';
+
+    return {
+        /**
+         * @return {Object}
+         */
+        getRules: function () {
+            return {
+                'country_id': {
+                    'required': true
+                }
+            };
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/default-validator.js

+define([
+    'jquery',
+    'mageUtils',
+    './default-validation-rules',
+    'mage/translate'
+], function ($, utils, validationRules, $t) {
+    'use strict';
+
+    return {
+        validationErrors: [],
+
+        /**
+         * @param {Object} address
+         * @return {Boolean}
+         */
+        validate: function (address) {
+            var self = this;
+
+            this.validationErrors = [];
+            $.each(validationRules.getRules(), function (field, rule) {
+                var message;
+
+                if (rule.required && utils.isEmpty(address[field])) {
+                    message = $t('Field ') + field + $t(' is required.');
+
+                    self.validationErrors.push(message);
+                }
+            });
+
+            return !this.validationErrors.length;
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/gift-message.js

+/**
+ * @api
+ */
+define([
+    'Magento_GiftMessage/js/model/gift-message'
+], function (GiftMessage) {
+    'use strict';
+
+    window.giftOptionsConfig = window.checkoutConfig.OnePageCheckout.giftOptionsConfig;
+
+    return function (itemId) {
+        return new GiftMessage(itemId);
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/payment-service-default.js

+define([
+    'underscore',
+    'Magento_Checkout/js/model/quote',
+    'Magento_Checkout/js/model/payment/method-list',
+    'Magento_Checkout/js/action/select-payment-method',
+    'Magento_Checkout/js/model/payment-service'
+], function (_, quote, methodList, selectPaymentMethod, paymentService) {
+    'use strict';
+
+    /**
+    * Free method filter
+    * @param {Object} paymentMethod
+    * @return {Boolean}
+    */
+    var isFreePaymentMethod = function (paymentMethod) {
+            return paymentMethod.method === 'free';
+        },
+
+        /**
+         * Grabs the grand total from quote
+         * @return {Number}
+         */
+        getGrandTotal = function () {
+            return quote.totals()['grand_total'];
+        };
+
+    return {
+
+        /**
+         * Populate the list of payment methods
+         * @param {Array} methods
+         */
+        setPaymentMethods: function (methods) {
+            var freeMethod,
+                filteredMethods,
+                methodIsAvailable,
+                methodNames;
+
+            freeMethod = _.find(methods, isFreePaymentMethod);
+            paymentService.isFreeAvailable = !!freeMethod;
+
+            if (freeMethod && getGrandTotal() <= 0) {
+                methods.splice(0, methods.length, freeMethod);
+                selectPaymentMethod(freeMethod);
+            }
+
+            filteredMethods = _.without(methods, freeMethod);
+
+            if (filteredMethods.length === 1) {
+                selectPaymentMethod(filteredMethods[0]);
+            } else if (quote.paymentMethod()) {
+                methodIsAvailable = methods.some(function (item) {
+                    return item.method === quote.paymentMethod().method;
+                });
+                //Unset selected payment method if not available
+                if (!methodIsAvailable) {
+                    selectPaymentMethod(null);
+                }
+            }
+
+            /**
+             * Overwrite methods with existing methods to preserve ko array references.
+             * This prevent ko from re-rendering those methods.
+             */
+            methodNames = _.pluck(methods, 'method');
+            _.map(methodList(), function (existingMethod) {
+                var existingMethodIndex = methodNames.indexOf(existingMethod.method);
+
+                if (existingMethodIndex !== -1) {
+                    methods[existingMethodIndex] = existingMethod;
+                }
+            });
+
+            methodList(methods);
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/payment-service.js

+define([
+    'ko',
+    'Magento_Checkout/js/model/quote'
+], function (ko, quote) {
+    'use strict';
+
+    var totals = quote.getTotals(),
+        couponCode = ko.observable(null);
+
+    if (totals()) {
+        couponCode(totals()['coupon_code']);
+    }
+
+    return {
+        isLoading: ko.observable(false),
+        isAppliedCoupon: ko.observable(couponCode() != null)
+    }
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/place-order-mixin.js

+define([
+    'jquery',
+    'underscore',
+    'mage/utils/wrapper',
+    'Rokanthemes_OnePageCheckout/js/model/additional-data',
+    'Rokanthemes_OnePageCheckout/js/model/agreements-assigner'
+], function ($, _, wrapper, additionalData, agreementsAssigner) {
+    'use strict';
+
+    return function (placeOrderAction) {
+
+        return wrapper.wrap(placeOrderAction, function (originalAction, paymentData, messageContainer) {
+            if (!_.isUndefined(window.checkoutConfig.OnePageCheckout)) {
+                additionalData(paymentData);
+            }
+            agreementsAssigner(paymentData);
+            return originalAction(paymentData, messageContainer);
+        });
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/resource-url-manager.js

+define(
+    [
+        'jquery',
+        'Magento_Checkout/js/model/resource-url-manager'
+    ],
+    function ($, resourceUrlManager) {
+        "use strict";
+
+        return $.extend({
+            /** Get url for update item qty and remove item */
+            getUrlForUpdatePaymentTotalInformation: function (quote) {
+                var params = this.getCheckoutMethod() === 'guest' ? {cartId: quote.getQuoteId()} : {};
+                var urls   = {
+                    'guest': '/guest-carts/:cartId/payment-total-information',
+                    'customer': '/carts/mine/payment-total-information'
+                };
+
+                return this.getUrl(urls, params);
+            }
+        }, resourceUrlManager);
+    }
+);

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/save-new-account-information.js

+define([
+    'jquery',
+    'ko',
+    'uiComponent',
+    'Magento_Checkout/js/model/full-screen-loader',
+    'mage/url'
+], function (
+    $,
+    ko,
+    Component,
+    fullScreenLoader,
+    urlBuilder
+) {
+    return {
+        ajaxSave: function () {
+            var createNewAccountCheckBoxId = 'create-new-customer',
+                loginFormSelector = 'form[data-role=email-with-possible-login]';
+            var data = {};
+            if ($(loginFormSelector + ' #' + createNewAccountCheckBoxId).is(":checked")) {
+                data['email'] = $(loginFormSelector + ' input[name=username]').val();
+                data['pass'] = $(loginFormSelector + ' input[name=newcustomerpassword]').val();
+                data['confirmpass'] = $(loginFormSelector + ' input[name=newcustomerpassword_confirmation]').val();
+            }
+            var saveUrl = 'onepagecheckout/account/save';
+            fullScreenLoader.startLoader();
+            $.ajax({
+                url: urlBuilder.build(saveUrl),
+                data: data,
+                type: 'post',
+                dataType: 'json',
+
+                /** @inheritdoc */
+                success: function (response) {
+                    fullScreenLoader.stopLoader();
+                },
+
+                /** @inheritdoc */
+                error: function () {
+                    alert({
+                        content: $.mage.__('Sorry, something went wrong. Please try again later.')
+                    });
+                }
+            });
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/set-payment-information-mixin.js

+define([
+    'jquery',
+    'mage/utils/wrapper',
+    'Rokanthemes_OnePageCheckout/js/model/additional-data',
+    'Rokanthemes_OnePageCheckout/js/model/agreements-assigner',
+    'underscore',
+    'Magento_Checkout/js/checkout-data',
+], function ($, wrapper, additionalData, agreementsAssigner, _, checkoutData) {
+    'use strict';
+
+    return function (placeOrderAction) {
+
+        /** Override place-order-mixin for set-payment-information action as they differs only by method signature */
+        return wrapper.wrap(placeOrderAction, function (originalAction, messageContainer, paymentData) {
+            if (!_.isUndefined(window.checkoutConfig.OnePageCheckout)) {
+                additionalData(paymentData);
+            }
+            agreementsAssigner(paymentData);
+
+            // only send request when email is filled
+            if (window.checkoutConfig.isCustomerLoggedIn &&
+			!_.isEmpty(checkoutData.getSelectedShippingAddress())) {
+                return originalAction(messageContainer, paymentData);
+            }
+            if (!_.isEmpty(checkoutData.getValidatedEmailValue())) {
+                return originalAction(messageContainer, paymentData);
+            }
+            return originalAction(messageContainer, paymentData);
+        });
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-rate-processor/customer-address.js

+define([
+    'Magento_Checkout/js/model/resource-url-manager',
+    'Magento_Checkout/js/model/quote',
+    'mage/storage',
+    'Magento_Checkout/js/model/shipping-service',
+    'Magento_Checkout/js/model/shipping-rate-registry',
+    'Magento_Checkout/js/model/error-processor'
+], function (resourceUrlManager, quote, storage, shippingService, rateRegistry, errorProcessor) {
+    'use strict';
+
+    return function (address) {
+        shippingService.isLoading(true);
+        return storage.post(
+            resourceUrlManager.getUrlForEstimationShippingMethodsByAddressId(),
+            JSON.stringify({
+                addressId: address.customerAddressId
+            }),
+            false
+        ).done(function (result) {
+            console.log('register');
+            rateRegistry.set(address.getKey(), result);
+            shippingService.setShippingRates(result);
+        }).fail(function (response) {
+
+            console.log('cccc');
+            shippingService.setShippingRates([]);
+            errorProcessor.process(response);
+        }).always(function () {
+
+            console.log('ddd');
+                shippingService.isLoading(false);
+            }
+        );
+    }
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-rate-processor/new-address.js

+define([
+    'Magento_Checkout/js/model/resource-url-manager',
+    'Magento_Checkout/js/model/quote',
+    'mage/storage',
+    'Magento_Checkout/js/model/shipping-service',
+    'Magento_Checkout/js/model/shipping-rate-registry',
+    'Magento_Checkout/js/model/error-processor'
+], function (resourceUrlManager, quote, storage, shippingService, rateRegistry, errorProcessor) {
+    'use strict';
+
+    return function (address) {
+        var serviceUrl, payload;
+        shippingService.isLoading(true);
+        serviceUrl = resourceUrlManager.getUrlForEstimationShippingMethodsForNewAddress(quote);
+        payload = JSON.stringify({
+                address: {
+                    'street': address.street,
+                    'city': address.city,
+                    'region_id': address.regionId,
+                    'region': address.region,
+                    'country_id': address.countryId,
+                    'postcode': address.postcode,
+                    'email': address.email,
+                    'customer_id': address.customerId,
+                    'firstname': address.firstname,
+                    'lastname': address.lastname,
+                    'middlename': address.middlename,
+                    'prefix': address.prefix,
+                    'suffix': address.suffix,
+                    'vat_id': address.vatId,
+                    'company': address.company,
+                    'telephone': address.telephone,
+                    'fax': address.fax,
+                    'custom_attributes': address.customAttributes,
+                    'save_in_address_book': address.saveInAddressBook
+                }
+            }
+        );
+        return storage.post(
+            serviceUrl, payload, false
+        ).done(function (result) {
+            rateRegistry.set(address.getCacheKey(), result);
+            shippingService.setShippingRates(result);
+        }).fail(function (response) {
+            shippingService.setShippingRates([]);
+            errorProcessor.process(response);
+        }).always(function () {
+            shippingService.isLoading(false);
+        });
+    }
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-rate-service.js

+define([
+    'jquery',
+    'Magento_Checkout/js/model/quote',
+    'Magento_Checkout/js/model/shipping-rate-processor/new-address',
+    'Magento_Checkout/js/model/shipping-rate-processor/customer-address'
+], function ($, quote, defaultProcessor, customerAddressProcessor) {
+    'use strict';
+
+    var processors = [];
+
+    processors.default =  defaultProcessor;
+    processors['customer-address'] = customerAddressProcessor;
+
+    quote.shippingAddress.subscribe(function () {
+        if (typeof window.shippingAddress === "undefined" || $.isEmptyObject(window.shippingAddress)) {
+            var type = quote.shippingAddress().getType();
+
+            if (processors[type]) {
+                processors[type].getRates(quote.shippingAddress());
+            } else {
+                processors.default.getRates(quote.shippingAddress());
+            }
+        }
+    });
+
+    return {
+        /**
+         * @param {String} type
+         * @param {*} processor
+         */
+        registerProcessor: function (type, processor) {
+            processors[type] = processor;
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-rates-validation-rules-mixin.js

+
+define(['jquery'], function ($) {
+    'use strict';
+    return function (target) {
+        target.getObservableFields = function () {
+            var self = this,
+                observableFields = [];
+
+            $.each(self.getRules(), function (carrier, fields) {
+                $.each(fields, function (field) {
+                    if (observableFields.indexOf(field) === -1) {
+                        observableFields.push(field);
+                    }
+                });
+            });
+            observableFields.push('telephone'); // Load shipping method on Phone Number change
+            return observableFields;
+        };
+        return target;
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-rates-validator.js

+define([
+    'jquery',
+    'ko',
+    'underscore',
+    'Magento_Checkout/js/model/shipping-rates-validation-rules',
+    'Magento_Checkout/js/model/address-converter',
+    'Magento_Checkout/js/action/select-shipping-address',
+    'Magento_Checkout/js/model/postcode-validator',
+    'Rokanthemes_OnePageCheckout/js/model/default-validator',
+    'mage/translate',
+    'uiRegistry',
+    'Magento_Checkout/js/model/shipping-address/form-popup-state',
+    'Magento_Checkout/js/model/quote',
+    'Magento_Checkout/js/model/shipping-rates-validator'
+], function (
+    $,
+    ko,
+    _,
+    shippingRatesValidationRules,
+    addressConverter,
+    selectShippingAddress,
+    postcodeValidator,
+    defaultValidator,
+    $t,
+    uiRegistry,
+    formPopUpState,
+    quote,
+    shippingRatesValidator
+) {
+    'use strict';
+
+    var validators = [],
+        postcodeElement = null,
+        postcodeElementName = 'postcode';
+
+    validators.push(defaultValidator);
+
+    shippingRatesValidator.doElementBinding = function (element, force, delay) {
+        var observableFields = shippingRatesValidationRules.getObservableFields();
+        if (_.isUndefined(delay)) {
+            if (element.index === 'country_id' || element.index === 'region_id') {
+                delay = 0;
+            } else {
+                delay = 700;
+            }
+        }
+        if (element && (observableFields.indexOf(element.index) !== -1 || force)) {
+            if (element.index !== postcodeElementName) {
+                this.bindHandler(element, delay);
+            }
+        }
+
+        if (element.index === postcodeElementName) {
+            this.bindHandler(element, delay);
+            postcodeElement = element;
+        }
+    };
+
+    return shippingRatesValidator;
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-save-processor.js

+define([
+    'Rokanthemes_OnePageCheckout/js/model/shipping-save-processor/default'
+], function (defaultProcessor) {
+    'use strict';
+
+    var processors = [];
+
+    processors['default'] =  defaultProcessor;
+
+    return {
+        /**
+         * @param {String} type
+         * @param {*} processor
+         */
+        registerProcessor: function (type, processor) {
+            processors[type] = processor;
+        },
+
+        /**
+         * @param {String} type
+         * @return {Array}
+         */
+        saveShippingInformation: function (type) {
+            var rates = [];
+
+            if (processors[type]) {
+                rates = processors[type].saveShippingInformation();
+            } else {
+                rates = processors['default'].saveShippingInformation();
+            }
+
+            return rates;
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-save-processor/default.js

+define([
+    'ko',
+    'underscore',
+    'Magento_Checkout/js/model/quote',
+    'Magento_Checkout/js/model/resource-url-manager',
+    'mage/storage',
+    'Rokanthemes_OnePageCheckout/js/model/payment-service-default',
+    'Magento_Checkout/js/model/payment/method-converter',
+    'Magento_Checkout/js/model/error-processor',
+    'Magento_Checkout/js/action/select-billing-address',
+    'Rokanthemes_OnePageCheckout/js/model/shipping-save-processor/payload-extender',
+    'Magento_Customer/js/model/customer'
+], function (
+    ko,
+    _,
+    quote,
+    resourceUrlManager,
+    storage,
+    paymentService,
+    methodConverter,
+    errorProcessor,
+    selectBillingAddressAction,
+    payloadExtender,
+    customer
+) {
+    'use strict';
+
+    return {
+        /**
+         * @return {jQuery.Deferred}
+         */
+        saveShippingInformation: function () {
+            var payload;
+
+            if (!quote.billingAddress()) {
+                selectBillingAddressAction(quote.shippingAddress());
+            }
+
+            var billingAddress = quote.billingAddress();
+
+            if (!customer.isLoggedIn()) {
+                if (billingAddress) {
+                    if (!_.isUndefined(billingAddress.street)) {
+                        if (billingAddress.street.length == 0) {
+                            delete billingAddress.street;
+                        }
+                    } else {
+                        delete billingAddress.street;
+                    }
+                }
+            }
+
+            payload = {
+                addressInformation: {
+                    'shipping_address': quote.shippingAddress(),
+                    'billing_address': quote.billingAddress(),
+                    'shipping_method_code': quote.shippingMethod()['method_code'],
+                    'shipping_carrier_code': quote.shippingMethod()['carrier_code']
+                }
+            };
+
+            payloadExtender(payload);
+
+            return storage.post(
+                resourceUrlManager.getUrlForSetShippingInformation(quote),
+                JSON.stringify(payload)
+            ).done(
+                function (response) {
+                    quote.setTotals(response.totals);
+                    paymentService.setPaymentMethods(methodConverter(response['payment_methods']));
+                }
+            ).fail(
+                function (response) {
+                    errorProcessor.process(response);
+                }
+            );
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-save-processor/payload-extender.js

+define([
+    'jquery'
+], function ($) {
+    'use strict';
+
+    return function (payload) {
+        payload.addressInformation['extension_attributes'] = {};
+        if ($('#shipping #customer_shipping_date').length || $('#opc-shipping_method #customer_shipping_date').length) {
+            payload.addressInformation['extension_attributes']['customer_shipping_date'] = $('#customer_shipping_date').val();
+        }
+        if ($('#shipping #customer_shipping_comments').length || $('#opc-shipping_method #customer_shipping_comments').length) {
+            payload.addressInformation['extension_attributes']['customer_shipping_comments'] = $('#customer_shipping_comments').val();
+        }
+        if ($('#shipping #delivery_time_slot').length || $('#opc-shipping_method #delivery_time_slot').length) {
+            payload.addressInformation['extension_attributes']['delivery_time_slot'] = $('#delivery_time_slot').val();
+        }
+        return payload;
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/shipping-save-processor/validate.js

+define([
+    'ko',
+    'underscore',
+    'Magento_Checkout/js/model/quote',
+    'mage/storage',
+    'Magento_Checkout/js/model/error-processor',
+    'Magento_Checkout/js/action/select-billing-address',
+    'Magento_Checkout/js/model/resource-url-manager',
+    'Rokanthemes_OnePageCheckout/js/model/shipping-save-processor/payload-extender',
+    'Magento_Customer/js/model/customer'
+], function (
+    ko,
+    _,
+    quote,
+    storage,
+    errorProcessor,
+    selectBillingAddressAction,
+    resourceUrlManager,
+    payloadExtender,
+    customer
+) {
+    'use strict';
+
+    return {
+        /**
+         * @return {jQuery.Deferred}
+         */
+        saveShippingInformation: function () {
+            var payload;
+
+            if (!quote.billingAddress()) {
+                selectBillingAddressAction(quote.shippingAddress());
+            }
+
+            var billingAddress = quote.billingAddress();
+
+            if (!customer.isLoggedIn()) {
+                if (billingAddress) {
+                    if (!_.isUndefined(billingAddress.street)) {
+                        if (billingAddress.street.length == 0) {
+                            delete billingAddress.street;
+                        }
+                    } else {
+                        delete billingAddress.street;
+                    }
+                }
+            }
+
+            payload = {
+                addressInformation: {
+                    'shipping_address': quote.shippingAddress(),
+                    'billing_address': quote.billingAddress(),
+                    'shipping_method_code': quote.shippingMethod()['method_code'],
+                    'shipping_carrier_code': quote.shippingMethod()['carrier_code']
+                }
+            };
+
+            payloadExtender(payload);
+
+            return storage.post(
+                resourceUrlManager.getUrlForSetShippingInformation(quote),
+                JSON.stringify(payload)
+            ).fail(
+                function (response) {
+                    errorProcessor.process(response);
+                }
+            );
+        }
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/step-navigator-mixin.js

+define([
+    'underscore'
+], function (_) {
+    'use strict';
+
+    return function (stepNavigator) {
+        if (!_.isUndefined(window.checkoutConfig.OnePageCheckout)) {
+            stepNavigator.isProcessed = function () {
+                return true;
+            };
+        }
+        return stepNavigator;
+    };
+});

app/code/Rokanthemes/OnePageCheckout/view/frontend/web/js/model/step-navigator.js

+define([
+    'jquery',
+    'ko',
+    'Magento_Checkout/js/model/step-navigator'
+], function ($, ko, stepNavigator) {
+    'use strict';
+
+    var steps = ko.observableArray();
+
+    return {
+
+        /**
+         * @param {String} code
+         * @param {*} alias
+         * @param {*} title
+         * @param {Function} isVisible
+         * @param {*} navigate
+         * @param {*} sortOrder
+         */
+        registerStep: function (code, alias, title, isVisible, navigate, sortOrder) {
+            var hash, active;
+
+            if ($.inArray(code, stepNavigator.validCodes) !== -1) {
+                throw new DOMException('Step code [' + code + '] already registered in step navigator');
+            }
+
+            if (alias != null) {
+                if ($.inArray(alias, stepNavigator.validCodes) !== -1) {
+                    throw new DOMException('Step code [' + alias + '] already registered in step navigator');
+                }
+                stepNavigator.validCodes.push(alias);
+            }
+            stepNavigator.validCodes.push(code);
+            steps.push({
+                code: code,
+                alias: alias != null ? alias : code,
+                title: title,
+                isVisible: isVisible,
+                navigate: navigate,
+                sortOrder: sortOrder
+            });
+            active = stepNavigator.getActiveItemIndex();
+            steps.each(function (elem, index) {
+                if (active !== index && elem.code !== 'payment') {
+                    elem.isVisible(false);
+                }
+            });
+            stepNavigator.stepCodes.push(code);
+            hash = window.location.hash.replace('#', '');
+
+            if (hash != '' && hash != code) {
+                isVisible(false);
+            }
+        }
+    };
+});