diff --git a/payment/uc_payment/uc_payment.module b/payment/uc_payment/uc_payment.module
index 5750d18..969dfe7 100644
--- a/payment/uc_payment/uc_payment.module
+++ b/payment/uc_payment/uc_payment.module
@@ -150,7 +150,7 @@ function uc_payment_enter($order_id, $method, $amount, $uid = 0, $data = NULL, $
     'amount' => $amount,
     'currency' => $order->getCurrency(),
     'uid' => $uid,
-    'data' => $data,
+    'data' => is_array($data) ? $data : serialize($data),
     'comment' => $comment,
     'received' => $received,
   ]);
diff --git a/payment/uc_paypal/src/Form/WppSettingsForm.php b/payment/uc_paypal/src/Form/WppSettingsForm.php
deleted file mode 100644
index dd45aa1..0000000
--- a/payment/uc_paypal/src/Form/WppSettingsForm.php
+++ /dev/null
@@ -1,49 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\uc_2checkout\Form\WppSettingsForm.
- */
-
-namespace Drupal\uc_paypal\Form;
-
-use Drupal\Core\Form\FormBase;
-use Drupal\Core\Form\FormStateInterface;
-
-/**
- * Settings for Website Payments Pro on the credit card gateways form.
- *
- * This provides a subset of the Express Checkout settings.
- */
-class WppSettingsForm extends FormBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getFormId() {
-    return 'uc_paypal_wpp_settings_form';
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function buildForm(array $form, FormStateInterface $form_state) {
-    // This form is buildConfigurationForm() from PayPalPaymentMethodPluginBase
-
-    // @todo: figure out how to get that in here - doesn't matter right now
-    // because we don't have a payement gateway architecture yet so this
-    // WppSettingsForm may look entirely different.
-
-    //$form = uc_payment_method_paypal_ec('settings');
-
-    return $form;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function submitForm(array &$form, FormStateInterface $form_state) {
-    parent::submitForm($form, $form_state);
-  }
-
-}
diff --git a/payment/uc_paypal/src/Controller/WppController.php b/payment/uc_paypal/src/Plugin/Ubercart/PaymentMethod/PayPalWebsitePaymentsPro.php
similarity index 54%
rename from payment/uc_paypal/src/Controller/WppController.php
rename to payment/uc_paypal/src/Plugin/Ubercart/PaymentMethod/PayPalWebsitePaymentsPro.php
index a3e5d8f..297f978 100644
--- a/payment/uc_paypal/src/Controller/WppController.php
+++ b/payment/uc_paypal/src/Plugin/Ubercart/PaymentMethod/PayPalWebsitePaymentsPro.php
@@ -2,28 +2,111 @@
 
 /**
  * @file
- * Contains \Drupal\uc_paypal\Controller\WppController.
+ * Contains \Drupal\uc_paypal\Plugin\Ubercart\PaymentMethod\PayPalWebsitePaymentsPro.
  */
 
-namespace Drupal\uc_paypal\Controller;
+namespace Drupal\uc_paypal\Plugin\Ubercart\PaymentMethod;
 
 use Drupal\Component\Utility\SafeMarkup;
-use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Link;
 use Drupal\Core\Url;
+use Drupal\uc_credit\CreditCardPaymentMethodBase;
+use Drupal\uc_order\OrderInterface;
+use GuzzleHttp\Exception\TransferException;
 
 /**
- * Processes a credit card payment through Website Payments Pro.
+ * Defines the PayPal Website Payments Pro payment method.
+ *
+ * @UbercartPaymentMethod(
+ *   id = "paypal_wpp",
+ *   name = @Translation("PayPal Website Payments Pro"),
+ * )
  */
-class WppController extends ControllerBase {
+class PayPalWebsitePaymentsPro extends CreditCardPaymentMethodBase {
 
-  public function wppCharge($order_id, $amount, $data) {
-    $order = Order::load($order_id);
-    $paypal_config = $this->config('uc_paypal.settings');
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultConfiguration() {
+    return parent::defaultConfiguration() + [
+      'wps_email' => '',
+      'wpp_server' => 'https://api-3t.sandbox.paypal.com/nvp',
+      'api' => [
+        'api_username' => '',
+        'api_password' => '',
+        'api_signature' => '',
+      ],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $form = parent::buildConfigurationForm($form, $form_state);
+
+    $form['wps_email'] = array(
+      '#type' => 'email',
+      '#title' => $this->t('PayPal e-mail address'),
+      '#description' => $this->t('The e-mail address you use for the PayPal account you want to receive payments.'),
+      '#default_value' => $this->configuration['wps_email'],
+    );
+    $form['wpp_server'] = array(
+      '#type' => 'select',
+      '#title' => $this->t('API server'),
+      '#description' => $this->t('Sign up for and use a Sandbox account for testing.'),
+      '#options' => array(
+        'https://api-3t.sandbox.paypal.com/nvp' => $this->t('Sandbox'),
+        'https://api-3t.paypal.com/nvp' => $this->t('Live'),
+      ),
+      '#default_value' => $this->configuration['wpp_server'],
+    );
+    $form['api'] = array(
+      '#type' => 'details',
+      '#title' => $this->t('API credentials'),
+      '#description' => $this->t('@link for information on obtaining credentials.  You need to acquire an API Signature.  If you have already requested API credentials, you can review your settings under the API Access section of your PayPal profile.', ['@link' => Link::fromTextAndUrl($this->t('Click here'), Url::fromUri('https://developer.paypal.com/docs/classic/api/apiCredentials/'))->toString()]),
+      '#open' => TRUE,
+    );
+    $form['api']['api_username'] = array(
+      '#type' => 'textfield',
+      '#title' => $this->t('API username'),
+      '#default_value' => $this->configuration['api']['api_username'],
+    );
+    $form['api']['api_password'] = array(
+      '#type' => 'textfield',
+      '#title' => $this->t('API password'),
+      '#default_value' => $this->configuration['api']['api_password'],
+    );
+    $form['api']['api_signature'] = array(
+      '#type' => 'textfield',
+      '#title' => $this->t('Signature'),
+      '#default_value' => $this->configuration['api']['api_signature'],
+    );
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+    parent::submitConfigurationForm($form, $form_state);
+    $this->configuration['wps_email'] = trim($form_state->getValue('wps_email'));
+    $this->configuration['wpp_server'] = $form_state->getValue('wpp_server');
+    $this->configuration['api']['api_username'] = $form_state->getValue(['settings', 'api', 'api_username']);
+    $this->configuration['api']['api_password'] = $form_state->getValue(['settings', 'api', 'api_password']);
+    $this->configuration['api']['api_signature'] = $form_state->getValue(['settings', 'api', 'api_signature']);
+  }
 
-    if ($data['txn_type'] == UC_CREDIT_PRIOR_AUTH_CAPTURE) {
+  /**
+   * {@inheritdoc}
+   */
+  protected function chargeCard(OrderInterface $order, $amount, $txn_type, $reference = NULL) {
+    if ($txn_type == UC_CREDIT_PRIOR_AUTH_CAPTURE) {
       $nvp_request = array(
         'METHOD' => 'DoCapture',
-        'AUTHORIZATIONID' => $data['auth_id'],
+        'AUTHORIZATIONID' => $reference,
         'AMT' => uc_currency_format($amount, FALSE, FALSE, '.'),
         'CURRENCYCODE' => $order->getCurrency(),
         'COMPLETETYPE' => 'Complete',
@@ -68,51 +151,48 @@ class WppController extends ControllerBase {
       // PayPal doesn't accept IPv6 addresses.
       $ip_address = ltrim(\Drupal::request()->getClientIp(), '::ffff:');
 
+      $address = $order->getAddress('billing');
       $nvp_request = array(
         'METHOD' => 'DoDirectPayment',
-        'PAYMENTACTION' => $data['txn_type'] == UC_CREDIT_AUTH_ONLY ? 'Authorization' : 'Sale',
+        'PAYMENTACTION' => $txn_type == UC_CREDIT_AUTH_ONLY ? 'Authorization' : 'Sale',
         'IPADDRESS' => $ip_address,
         'AMT' => uc_currency_format($amount, FALSE, FALSE, '.'),
         'CREDITCARDTYPE' => $cc_type,
         'ACCT' =>  $order->payment_details['cc_number'],
         'EXPDATE' => $expdate,
         'CVV2' => $order->payment_details['cc_cvv'],
-        'FIRSTNAME' => substr($order->billing_first_name, 0, 25),
-        'LASTNAME' => substr($order->billing_last_name, 0, 25),
-        'STREET' => substr($order->billing_street1, 0, 100),
-        'STREET2' => substr($order->billing_street2, 0, 100),
-        'CITY' => substr($order->billing_city, 0, 40),
-        'STATE' => $order->billing_zone,
-        'ZIP' => $order->billing_postal_code,
-        'COUNTRYCODE' => $order->billing_country,
+        'FIRSTNAME' => substr($address->first_name, 0, 25),
+        'LASTNAME' => substr($address->last_name, 0, 25),
+        'STREET' => substr($address->street1, 0, 100),
+        'STREET2' => substr($address->street2, 0, 100),
+        'CITY' => substr($address->city, 0, 40),
+        'STATE' => $address->zone,
+        'ZIP' => $address->postal_code,
+        'COUNTRYCODE' => $address->country,
         'CURRENCYCODE' => $order->getCurrency(),
         'DESC' => $this->t('Order @order_id at @store', ['@order_id' => $order->id(), '@store' => uc_store_name()]),
-        'INVNUM' => $order_id . '-' . REQUEST_TIME,
+        'INVNUM' => $order->id() . '-' . REQUEST_TIME,
         'BUTTONSOURCE' => 'Ubercart_ShoppingCart_DP_US',
         'NOTIFYURL' => Url::fromRoute('uc_paypal.ipn', [], ['absolute' => TRUE])->toString(),
         'EMAIL' => substr($order->getEmail(), 0, 127),
-        'PHONENUM' => substr($order->billing_phone, 0, 20),
+        'PHONENUM' => substr($address->phone, 0, 20),
       );
 
-      if ($order->isShippable() && !empty($order->delivery_first_name)) {
-        $shipdata = array(
-          'SHIPTONAME' => substr($order->delivery_first_name . ' ' . $order->delivery_last_name, 0, 25),
-          'SHIPTOSTREET' => substr($order->delivery_street1, 0, 100),
-          'SHIPTOSTREET2' => substr($order->delivery_street2, 0, 100),
-          'SHIPTOCITY' => substr($order->delivery_city, 0, 40),
-          'SHIPTOSTATE' => $order->delivery_zone,
-          'SHIPTOZIP' => $order->delivery_postal_code,
-          'SHIPTOCOUNTRYCODE' => $order->delivery_country,
+      if ($order->isShippable()) {
+        $address = $order->getAddress('delivery');
+        $nvp_request += array(
+          'SHIPTONAME' => substr($address->first_name . ' ' . $address->last_name, 0, 25),
+          'SHIPTOSTREET' => substr($address->street1, 0, 100),
+          'SHIPTOSTREET2' => substr($address->street2, 0, 100),
+          'SHIPTOCITY' => substr($address->city, 0, 40),
+          'SHIPTOSTATE' => $address->zone,
+          'SHIPTOZIP' => $address->postal_code,
+          'SHIPTOCOUNTRYCODE' => $address->country,
         );
-        $nvp_request += $shipdata;
-      }
-
-      if ($paypal_config->get('uc_credit_cvv_enabled')) {
-        $nvp_request['CVV2'] = $order->payment_details['cc_cvv'];
       }
     }
 
-    $nvp_response = uc_paypal_api_request($nvp_request, $paypal_config->get('wpp_server'));
+    $nvp_response = $this->sendNvpRequest($nvp_request);
     $types = uc_credit_transaction_types();
 
     switch ($nvp_response['ACK']) {
@@ -120,34 +200,32 @@ class WppController extends ControllerBase {
         \Drupal::logger('uc_paypal')->warning('<b>@type succeeded with a warning.</b>@paypal_message',
           array(
             '@paypal_message' => $this->buildErrorMessages($nvp_response),
-            '@type' => $types[$data['txn_type']],
+            '@type' => $types[$txn_type],
             'link' => $order->toLink($this->t('view order'))->toString(),
           )
         );
-        // Fall through.
+      // Fall through.
       case 'Success':
-        $message = t('<b>@type</b><br /><b>Success: </b>@amount @currency', ['@type' => $types[$data['txn_type']], '@amount' => uc_currency_format($nvp_response['AMT'], FALSE), '@currency' => $nvp_response['CURRENCYCODE']]);
-        if ($data['txn_type'] != UC_CREDIT_PRIOR_AUTH_CAPTURE) {
+        $message = t('<b>@type</b><br /><b>Success: </b>@amount @currency', ['@type' => $types[$txn_type], '@amount' => uc_currency_format($nvp_response['AMT'], FALSE), '@currency' => $nvp_response['CURRENCYCODE']]);
+        if ($txn_type != UC_CREDIT_PRIOR_AUTH_CAPTURE) {
           $message .= '<br />' . t('<b>Address:</b> @avscode', ['@avscode' => $this->avscodeMessage($nvp_response['AVSCODE'])]);
-          if ($paypal_config->get('uc_credit_cvv_enabled')) {
-            $message .= '<br />' . t('<b>CVV2:</b> @cvvmatch', ['@cvvmatch' => $this->cvvmatchMessage($nvp_response['CVV2MATCH'])]);
-          }
+          $message .= '<br />' . t('<b>CVV2:</b> @cvvmatch', ['@cvvmatch' => $this->cvvmatchMessage($nvp_response['CVV2MATCH'])]);
         }
         $result = array(
           'success' => TRUE,
           'comment' => t('PayPal transaction ID: @transactionid', ['@transactionid' => $nvp_response['TRANSACTIONID']]),
           'message' => $message,
           'data' => SafeMarkup::checkPlain($nvp_response['TRANSACTIONID']),
-          'uid' => $this->currentUser()->id(),
+          'uid' => \Drupal::currentUser()->id(),
         );
 
         // If this was an authorization only transaction...
-        if ($data['txn_type'] == UC_CREDIT_AUTH_ONLY) {
+        if ($txn_type == UC_CREDIT_AUTH_ONLY) {
           // Log the authorization to the order.
-          uc_credit_log_authorization($order_id, $nvp_response['TRANSACTIONID'], $nvp_response['AMT']);
+          uc_credit_log_authorization($order->id(), $nvp_response['TRANSACTIONID'], $nvp_response['AMT']);
         }
-        elseif ($data['txn_type'] == UC_CREDIT_PRIOR_AUTH_CAPTURE) {
-          uc_credit_log_prior_auth_capture($order_id, $data['auth_id']);
+        elseif ($txn_type == UC_CREDIT_PRIOR_AUTH_CAPTURE) {
+          uc_credit_log_prior_auth_capture($order->id(), $reference);
         }
 
         // Log the IPN to the database.
@@ -167,11 +245,11 @@ class WppController extends ControllerBase {
       case 'FailureWithWarning':
         // Fall through.
       case 'Failure':
-        $message = t('<b>@type failed.</b>', ['@type' => $types[$data['txn_type']]]) . $this->buildErrorMessages($nvp_response);
+        $message = t('<b>@type failed.</b>', ['@type' => $types[$txn_type]]) . $this->buildErrorMessages($nvp_response);
         $result = array(
           'success' => FALSE,
           'message' => $message,
-          'uid' => $this->currentUser()->id(),
+          'uid' => \Drupal::currentUser()->id(),
         );
         break;
       default:
@@ -179,15 +257,15 @@ class WppController extends ControllerBase {
         $result = array(
           'success' => NULL,
           'message' => $message,
-          'uid' => $this->currentUser()->id(),
+          'uid' => \Drupal::currentUser()->id(),
         );
         break;
     }
 
-    uc_order_comment_save($order_id, $this->currentUser()->id(), $message, 'admin');
+    uc_order_comment_save($order->id(), \Drupal::currentUser()->id(), $message, 'admin');
 
     // Don't log this as a payment money wasn't actually captured.
-    if (in_array($data['txn_type'], array(UC_CREDIT_AUTH_ONLY))) {
+    if (in_array($txn_type, array(UC_CREDIT_AUTH_ONLY))) {
       $result['log_payment'] = FALSE;
     }
 
@@ -195,6 +273,30 @@ class WppController extends ControllerBase {
   }
 
   /**
+   * Sends a request to the PayPal NVP API.
+   */
+  public function sendNvpRequest($params) {
+    $host = $this->configuration['wpp_server'];
+    $params += [
+      'USER' => $this->configuration['api']['api_username'],
+      'PWD' => $this->configuration['api']['api_password'],
+      'SIGNATURE' => $this->configuration['api']['api_signature'],
+      'VERSION' => '3.0',
+    ];
+
+    try {
+      $response = \Drupal::httpClient()->request('POST', $host, [
+        'form_params' => $params,
+      ]);
+      parse_str($response->getBody(), $output);
+      return $output;
+    }
+    catch (TransferException $e) {
+      \Drupal::logger('uc_paypal')->error('NVP API request failed with HTTP error %error.', ['%error' => $e->getMessage()]);
+    }
+  }
+
+  /**
    * Builds error message(s) from PayPal failure responses.
    */
   protected function buildErrorMessages($nvp_response) {
diff --git a/payment/uc_paypal/uc_paypal.module b/payment/uc_paypal/uc_paypal.module
index 0c69c3f..0cdc433 100644
--- a/payment/uc_paypal/uc_paypal.module
+++ b/payment/uc_paypal/uc_paypal.module
@@ -10,7 +10,6 @@
  */
 
 use Drupal\Core\Routing\RouteMatchInterface;
-use Drupal\Core\Url;
 
 /**
  * Implements hook_help().
@@ -36,46 +35,3 @@ function uc_paypal_help($route_name, RouteMatchInterface $route_match) {
     }
   }
 }
-
-/**
- * Implements hook_uc_payment_gateway().
- */
-function uc_paypal_uc_payment_gateway() {
-  if (!\Drupal::moduleHandler()->moduleExists('uc_credit')) {
-    drupal_set_message(t('You must <a href=":modules">enable the Credit Card module</a> to use PayPal Website Payments Pro.', [':modules' => Url::fromRoute('system.modules_list', [], ['fragment' => 'edit-modules-ubercart-payment'])->toString()]), 'warning');
-    return;
-  }
-
-  $gateways['paypal_wpp'] = array(
-    'title' => t('PayPal Website Payments Pro'),
-    'description' => t('Process credit card payments using Website Payments Pro.'),
-    'settings' => 'uc_paypal_wpp_settings_form',
-    'credit' => 'uc_paypal_wpp_charge',
-    'credit_txn_types' => array(UC_CREDIT_AUTH_ONLY, UC_CREDIT_PRIOR_AUTH_CAPTURE, UC_CREDIT_AUTH_CAPTURE),
-  );
-
-  return $gateways;
-}
-
-  // Payment method titles ...
-  //
-  // $title1 = '<img src="https://www.paypal.com/en_US/i/logo/PayPal_mark_37x23.gif" alt="PayPal" class="uc-credit-cctype" />'
-  //       . ' ' . t('PayPal - pay without sharing your financial information.');
-  /*
-  $title2 = '<br /><span id="paypal-includes">' . t('Includes:');
-  $cc_types = array(
-    'visa' => t('Visa'),
-    'mastercard' => t('MasterCard'),
-    'discover' => t('Discover'),
-    'amex' => t('American Express'),
-    'echeck' => t('eCheck'),
-  );
-  foreach ($cc_types as $type => $label) {
-    $title2 .= ' ' . theme('image', array(
-      'uri' => drupal_get_path('module', 'uc_credit') . '/images/' . $type . '.gif',
-      'alt' => $label,
-      'attributes' => array('class' => array('uc-credit-cctype', 'uc-credit-cctype-' . $type)),
-    ));
-  }
-  $title2 .= ' <img src="https://www.paypal.com/en_US/i/logo/PayPal_mark_37x23.gif" alt="PayPal" class="uc-credit-cctype" /></span>';
-  */