<?php
	//include pmprogateway
	require_once(dirname(__FILE__) . "/class.pmprogateway.php");

	//load classes init method
	add_action('init', array('PMProGateway_paypalexpress', 'init'));

	class PMProGateway_paypalexpress extends PMProGateway
	{
		/** @var int Maximum number of request retries */
		protected static $maxNetworkRetries = 5;

		/** @var float Maximum delay between retries, in seconds */
		protected static $maxNetworkRetryDelay = 2.0;

		/** @var float Initial delay between retries, in seconds */
		protected static $initialNetworkRetryDelay = 0.5;


		function __construct($gateway = NULL)
		{
			$this->gateway = $gateway;
			return $this->gateway;
		}

		/**
		 * Run on WP init
		 *
		 * @since 1.8
		 */
		static function init()
		{
			//make sure PayPal Express is a gateway option
			add_filter('pmpro_gateways', array('PMProGateway_paypalexpress', 'pmpro_gateways'));

			//add fields to payment settings
			add_filter('pmpro_payment_options', array('PMProGateway_paypalexpress', 'pmpro_payment_options'));

			/*
				Filter pmpro_next_payment to get actual value
				via the PayPal API. This is disabled by default
				for performance reasons, but you can enable it
				by copying this line into a custom plugin or
				your active theme's functions.php and uncommenting
				it there.
			*/
			//add_filter('pmpro_next_payment', array('PMProGateway_paypalexpress', 'pmpro_next_payment'), 10, 3);

			/*
				This code is the same for PayPal Website Payments Pro, PayPal Express, and PayPal Standard
				So we only load it if we haven't already.
			*/
			global $pmpro_payment_option_fields_for_paypal;
			if(empty($pmpro_payment_option_fields_for_paypal))
			{
				add_filter('pmpro_payment_option_fields', array('PMProGateway_paypalexpress', 'pmpro_payment_option_fields'), 10, 2);
				$pmpro_payment_option_fields_for_paypal = true;
			}

			//code to add at checkout
			$gateway = pmpro_getGateway();
			if($gateway == "paypalexpress")
			{
				add_action('pmpro_checkout_preheader', array('PMProGateway_paypalexpress', 'pmpro_checkout_preheader'));
				add_filter('pmpro_include_billing_address_fields', '__return_false');
				add_filter('pmpro_include_payment_information_fields', '__return_false');
				add_filter('pmpro_required_billing_fields', array('PMProGateway_paypalexpress', 'pmpro_required_billing_fields'));
				add_filter('pmpro_checkout_new_user_array', array('PMProGateway_paypalexpress', 'pmpro_checkout_new_user_array'));
				add_filter('pmpro_checkout_confirmed', array('PMProGateway_paypalexpress', 'pmpro_checkout_confirmed'));
				add_action('pmpro_checkout_before_processing', array('PMProGateway_paypalexpress', 'pmpro_checkout_before_processing'));
				add_filter('pmpro_checkout_default_submit_button', array('PMProGateway_paypalexpress', 'pmpro_checkout_default_submit_button'));
				add_action('http_api_curl', array('PMProGateway_paypalexpress', 'http_api_curl'), 10, 3);
			}
			add_filter( 'pmpro_process_refund_paypalexpress', array('PMProGateway_paypalexpress', 'process_refund' ), 10, 2 );
		}

		/**
		 * Update the SSLVERSION for CURL to support PayPal Express moving to TLS 1.2
		 *
		 * @since 1.8.9.1
		 */
		static function http_api_curl($handle, $r, $url) {
			if(strpos($url, 'paypal.com') !== false)
				curl_setopt( $handle, CURLOPT_SSLVERSION, 6 );
		}

		/**
		 * Make sure this gateway is in the gateways list
		 *
		 * @since 1.8
		 */
		static function pmpro_gateways($gateways)
		{
			if(empty($gateways['paypalexpress']))
				$gateways['paypalexpress'] = __('PayPal Express', 'paid-memberships-pro' );

			return $gateways;
		}

		/**
		 * Get a list of payment options that the this gateway needs/supports.
		 *
		 * @since 1.8
		 */
		static function getGatewayOptions()
		{
			$options = array(
				'sslseal',
				'nuclear_HTTPS',
				'gateway_environment',
				'gateway_email',
				'apiusername',
				'apipassword',
				'apisignature',
				'currency',
				'use_ssl',
				'tax_state',
				'tax_rate',
				'paypalexpress_skip_confirmation',
			);

			return $options;
		}

		/**
		 * Set payment options for payment settings page.
		 *
		 * @since 1.8
		 */
		static function pmpro_payment_options($options)
		{
			//get options
			$paypal_options = PMProGateway_paypalexpress::getGatewayOptions();

			//merge with others.
			$options = array_merge($paypal_options, $options);

			return $options;
		}

		/**
		 * Display fields for this gateway's options.
		 *
		 * @since 1.8
		 */
		static function pmpro_payment_option_fields($values, $gateway)
		{
		?>
		<tr class="pmpro_settings_divider gateway gateway_paypal gateway_paypalexpress gateway_paypalstandard" <?php if($gateway != "paypal" && $gateway != "paypalexpress" && $gateway != "paypalstandard") { ?>style="display: none;"<?php } ?>>
			<td colspan="2">
				<hr />
				<h2 class="title"><?php esc_html_e( 'PayPal Settings', 'paid-memberships-pro' ); ?></h2>
			</td>
		</tr>
		<tr class="gateway gateway_paypalstandard" <?php if($gateway != "paypalstandard") { ?>style="display: none;"<?php } ?>>
			<td colspan="2" style="padding: 0px;">
				<p class="pmpro_message">
				<?php
					$allowed_message_html = array (
						'a' => array (
							'href' => array(),
							'target' => array(),
							'title' => array(),
						),
					);
					echo sprintf( wp_kses( __( 'Note: We do not recommend using PayPal Standard. We suggest using PayPal Express, Website Payments Pro (Legacy), or PayPal Pro (Payflow Pro). <a target="_blank" href="%s" title="More information on why can be found here">More information on why can be found here</a>.', 'paid-memberships-pro' ), $allowed_message_html ), 'https://www.paidmembershipspro.com/read-using-paypal-standard-paid-memberships-pro/?utm_source=plugin&utm_medium=pmpro-paymentsettings&utm_campaign=blog&utm_content=read-using-paypal-standard-paid-memberships-pro' );
				?>
				</p>
			</td>
		</tr>
		<tr class="gateway gateway_paypal gateway_paypalexpress gateway_paypalstandard" <?php if($gateway != "paypal" && $gateway != "paypalexpress" && $gateway != "paypalstandard") { ?>style="display: none;"<?php } ?>>
			<th scope="row" valign="top">
				<label for="gateway_email"><?php esc_html_e('Gateway Account Email', 'paid-memberships-pro' );?>:</label>
			</th>
			<td>
				<input type="text" id="gateway_email" name="gateway_email" value="<?php echo esc_attr($values['gateway_email'])?>" class="regular-text code" />
			</td>
		</tr>
		<tr class="gateway gateway_paypal gateway_paypalexpress" <?php if($gateway != "paypal" && $gateway != "paypalexpress") { ?>style="display: none;"<?php } ?>>
			<th scope="row" valign="top">
				<label for="apiusername"><?php esc_html_e('API Username', 'paid-memberships-pro' );?>:</label>
			</th>
			<td>
				<input type="text" id="apiusername" name="apiusername" value="<?php echo esc_attr($values['apiusername'])?>" class="regular-text code" />
			</td>
		</tr>
		<tr class="gateway gateway_paypal gateway_paypalexpress" <?php if($gateway != "paypal" && $gateway != "paypalexpress") { ?>style="display: none;"<?php } ?>>
			<th scope="row" valign="top">
				<label for="apipassword"><?php esc_html_e('API Password', 'paid-memberships-pro' );?>:</label>
			</th>
			<td>
				<input type="text" id="apipassword" name="apipassword" value="<?php echo esc_attr($values['apipassword'])?>" autocomplete="off" class="regular-text code pmpro-admin-secure-key" />
			</td>
		</tr>
		<tr class="gateway gateway_paypal gateway_paypalexpress" <?php if($gateway != "paypal" && $gateway != "paypalexpress") { ?>style="display: none;"<?php } ?>>
			<th scope="row" valign="top">
				<label for="apisignature"><?php esc_html_e('API Signature', 'paid-memberships-pro' );?>:</label>
			</th>
			<td>
				<input type="text" id="apisignature" name="apisignature" value="<?php echo esc_attr($values['apisignature'])?>" class="regular-text code" />
			</td>
		</tr>
		<tr class="gateway gateway_paypal gateway_paypalexpress" <?php if($gateway != "paypal" && $gateway != "paypalexpress") { ?>style="display: none;"<?php } ?>>
			<th scope="row" valign="top">
				<label for="paypalexpress_skip_confirmation"><?php esc_html_e('Confirmation Step', 'paid-memberships-pro' );?>:</label>
			</th>
			<td>
				<select id="paypalexpress_skip_confirmation" name="paypalexpress_skip_confirmation">
					<option value="0" <?php selected(pmpro_getOption('paypalexpress_skip_confirmation'), 0);?>><?php esc_html_e( 'Require an extra confirmation after users return from PayPal.', 'paid-memberships-pro' ) ?></option>
					<option value="1" <?php selected(pmpro_getOption('paypalexpress_skip_confirmation'), 1);?>><?php esc_html_e( 'Skip the extra confirmation after users return from PayPal.', 'paid-memberships-pro' ) ?></option>
				</select>
			</td>
		</tr>
		<tr class="gateway gateway_paypal gateway_paypalexpress gateway_paypalstandard" <?php if($gateway != "paypal" && $gateway != "paypalexpress" && $gateway != "paypalstandard") { ?>style="display: none;"<?php } ?>>
			<th scope="row" valign="top">
				<label><?php esc_html_e('IPN Handler URL', 'paid-memberships-pro' );?>:</label>
			</th>
			<td>
				<p class="description"><?php esc_html_e('To fully integrate with PayPal, be sure to set your IPN Handler URL to ', 'paid-memberships-pro' );?></p>
				<p><code><?php echo esc_html( add_query_arg( 'action', 'ipnhandler', admin_url('admin-ajax.php') ) );?></code></p>
			</td>
		</tr>
		<?php
		}

		/**
		 * Remove required billing fields
		 *
		 * @since 1.8
		 */
		static function pmpro_required_billing_fields($fields)
		{
			unset($fields['bfirstname']);
			unset($fields['blastname']);
			unset($fields['baddress1']);
			unset($fields['bcity']);
			unset($fields['bstate']);
			unset($fields['bzipcode']);
			unset($fields['bphone']);
			unset($fields['bemail']);
			unset($fields['bcountry']);
			unset($fields['CardType']);
			unset($fields['AccountNumber']);
			unset($fields['ExpirationMonth']);
			unset($fields['ExpirationYear']);
			unset($fields['CVV']);

			return $fields;
		}

		/**
		 * Code added to checkout preheader.
		 *
		 * @since 2.1
		 */
		static function pmpro_checkout_preheader() {
			global $gateway, $pmpro_level;

			$default_gateway = pmpro_getOption("gateway");

			if(($gateway == "paypal" || $default_gateway == "paypal") && !pmpro_isLevelFree($pmpro_level)) {
				wp_register_script( 'pmpro_paypal',
                            plugins_url( 'js/pmpro-paypal.js', PMPRO_BASE_FILE ),
                            array( 'jquery' ),
                            PMPRO_VERSION );
				//wp_localize_script( 'pmpro_paypal', 'pmpro_paypal', array());
				wp_enqueue_script( 'pmpro_paypal' );
			}
		}

		/**
		 * Save session vars before processing
		 *
		 * @since 1.8
		 */
		static function pmpro_checkout_before_processing() {
			global $current_user, $gateway;

			//save user fields for PayPal Express
			if(!$current_user->ID) {
				//get values from post
				if(isset($_REQUEST['username']))
					$username = trim(sanitize_text_field($_REQUEST['username']));
				else
					$username = "";
				if(isset($_REQUEST['password']))
					$password = $_REQUEST['password'];
				else
					$password = "";
				if(isset($_REQUEST['bemail']))
					$bemail = sanitize_email($_REQUEST['bemail']);
				else
					$bemail = "";

				//save to session
				$_SESSION['pmpro_signup_username'] = $username;
				$_SESSION['pmpro_signup_password'] = $password;
				$_SESSION['pmpro_signup_email'] = $bemail;
			}

			if( !empty( $_REQUEST['tos'] ) ) {
				$tospost = get_post( pmpro_getOption( 'tospage' ) );
				$_SESSION['tos'] = array(
					'post_id' => $tospost->ID,
					'post_modified' => $tospost->post_modified,
				);
			}

			//can use this hook to save some other variables to the session
			do_action("pmpro_paypalexpress_session_vars");
		}

		/**
		 * Review and Confirmation code.
		 *
		 * @since 1.8
		 */
		static function pmpro_checkout_confirmed($pmpro_confirmed)
		{
			global $pmpro_msg, $pmpro_msgt, $pmpro_level, $current_user, $pmpro_review, $pmpro_paypal_token, $discount_code, $bemail;

			//PayPal Express Call Backs
			if(!empty($_REQUEST['review']))
			{
				if(!empty($_REQUEST['PayerID']))
					$_SESSION['payer_id'] = sanitize_text_field($_REQUEST['PayerID']);
				if(!empty($_REQUEST['paymentAmount']))
					$_SESSION['paymentAmount'] = sanitize_text_field($_REQUEST['paymentAmount']);
				if(!empty($_REQUEST['currencyCodeType']))
					$_SESSION['currCodeType'] = sanitize_text_field($_REQUEST['currencyCodeType']);
				if(!empty($_REQUEST['paymentType']))
					$_SESSION['paymentType'] = sanitize_text_field($_REQUEST['paymentType']);

				$morder = new MemberOrder();
				$morder->getMemberOrderByPayPalToken(sanitize_text_field($_REQUEST['token']));

				if( $morder->status === 'token' ){
					$morder->Token = $morder->paypal_token; $pmpro_paypal_token = $morder->paypal_token;
					if($morder->Token)
					{
						if($morder->Gateway->getExpressCheckoutDetails($morder))
						{
							$pmpro_review = true;
						}
						else
						{
							$pmpro_msg = $morder->error;
							$pmpro_msgt = "pmpro_error";
						}
					}
					else
					{
						$pmpro_msg = __("The PayPal Token was lost.", 'paid-memberships-pro' );
						$pmpro_msgt = "pmpro_error";
					}
				}else{
					$pmpro_msg = __("Checkout was already processed.", 'paid-memberships-pro' );
					$pmpro_msgt = "pmpro_error";
				}
			}

			if(empty($pmpro_msg) &&
				(!empty($_REQUEST['confirm']) ||
				(pmpro_getOption('paypalexpress_skip_confirmation') && $pmpro_review))
			)
			{
				$morder = new MemberOrder();
				$morder->getMemberOrderByPayPalToken(sanitize_text_field($_REQUEST['token']));
				$morder->Token = $morder->paypal_token; $pmpro_paypal_token = $morder->paypal_token;
				if($morder->Token)
				{
					//set up values
					$morder->membership_id = $pmpro_level->id;
					$morder->membership_name = $pmpro_level->name;
					$morder->discount_code = $discount_code;
					$morder->InitialPayment = pmpro_round_price( $pmpro_level->initial_payment );
					$morder->PaymentAmount = pmpro_round_price( $pmpro_level->billing_amount );
					$morder->ProfileStartDate = date_i18n("Y-m-d\TH:i:s");
					$morder->BillingPeriod = $pmpro_level->cycle_period;
					$morder->BillingFrequency = $pmpro_level->cycle_number;
					$morder->Email = $bemail;

					//setup level var
					$morder->getMembershipLevelAtCheckout();

					//tax
					$morder->subtotal = $morder->InitialPayment;
					$morder->getTax();
					if($pmpro_level->billing_limit)
						$morder->TotalBillingCycles = $pmpro_level->billing_limit;

					if(pmpro_isLevelTrial($pmpro_level))
					{
						$morder->TrialBillingPeriod = $pmpro_level->cycle_period;
						$morder->TrialBillingFrequency = $pmpro_level->cycle_number;
						$morder->TrialBillingCycles = $pmpro_level->trial_limit;
						$morder->TrialAmount = pmpro_round_price( $pmpro_level->trial_amount );
					}

					if($morder->confirm())
					{
						$pmpro_confirmed = true;
					}
					else
					{
						$pmpro_msg = $morder->error;
						$pmpro_msgt = "pmpro_error";
					}
				}
				else
				{
					$pmpro_msg = __("The PayPal Token was lost.", 'paid-memberships-pro' );
					$pmpro_msgt = "pmpro_error";
				}
			}

			if(!empty($morder))
				return array("pmpro_confirmed"=>$pmpro_confirmed, "morder"=>$morder);
			else
				return $pmpro_confirmed;
		}

		/**
		 * Swap in user/pass/etc from session
		 *
		 * @since 1.8
		 */
		static function pmpro_checkout_new_user_array($new_user_array)
		{
			global $current_user;

			if(!$current_user->ID)
			{
				//reload the user fields
				if( ! empty( $_SESSION['pmpro_signup_username'] ) ){
					$new_user_array['user_login'] = $_SESSION['pmpro_signup_username'];
				}
				if( ! empty( $_SESSION['pmpro_signup_password'] ) ){
					$new_user_array['user_pass'] = $_SESSION['pmpro_signup_password'];
				}
				if( ! empty( $_SESSION['pmpro_signup_email'] ) ){
					$new_user_array['user_email'] = $_SESSION['pmpro_signup_email'];
				}

				//unset the user fields in session
				unset($_SESSION['pmpro_signup_username']);
				unset($_SESSION['pmpro_signup_password']);
				unset($_SESSION['pmpro_signup_email']);
			}

			return $new_user_array;
		}

		/**
		 * Process at checkout
		 *
		 * Repurposed in v2.0. The old process() method is now confirm().
		 */
		function process(&$order)
		{
			$order->payment_type = "PayPal Express";
			$order->cardtype = "";
			$order->ProfileStartDate = date_i18n("Y-m-d\TH:i:s", strtotime("+ " . $order->BillingFrequency . " " . $order->BillingPeriod));
			$order->ProfileStartDate = apply_filters("pmpro_profile_start_date", $order->ProfileStartDate, $order);
			// Convert to UTC for PayPal...
			$order->ProfileStartDate = get_gmt_from_date( $order->ProfileStartDate, 'Y-m-d\TH:i:s\Z' );

			return $this->setExpressCheckout($order);
		}

		/**
		 * Process charge or subscription after confirmation.
		 *
		 * @since 1.8
		 */
		function confirm(&$order)
		{
			if(pmpro_isLevelRecurring($order->membership_level))
			{
				$order->ProfileStartDate = date_i18n("Y-m-d\TH:i:s", strtotime("+ " . $order->BillingFrequency . " " . $order->BillingPeriod, current_time("timestamp")));
				$order->ProfileStartDate = apply_filters("pmpro_profile_start_date", $order->ProfileStartDate, $order);
				// Convert to UTC for PayPal...
				$order->ProfileStartDate = get_gmt_from_date( $order->ProfileStartDate, 'Y-m-d\TH:i:s\Z' );
				return $this->subscribe($order);
			}
			else
				return $this->charge($order);
		}

		/**
		 * Swap in our submit buttons.
		 *
		 * @since 1.8
		 */
		static function pmpro_checkout_default_submit_button($show)
		{
			global $gateway, $pmpro_requirebilling;

			//show our submit buttons
			?>
			<span id="pmpro_paypalexpress_checkout" <?php if(($gateway != "paypalexpress" && $gateway != "paypalstandard") || !$pmpro_requirebilling) { ?>style="display: none;"<?php } ?>>
				<input type="hidden" name="submit-checkout" value="1" />
				<input type="image" id="pmpro_btn-submit-paypalexpress" class="<?php echo pmpro_get_element_class( 'pmpro_btn-submit-checkout' ); ?>" value="<?php esc_attr_e('Check Out with PayPal', 'paid-memberships-pro' );?> &raquo;" src="<?php echo apply_filters("pmpro_paypal_button_image", "https://www.paypalobjects.com/webstatic/en_US/i/buttons/checkout-logo-medium.png");?>" />
			</span>

			<span id="pmpro_submit_span" <?php if(($gateway == "paypalexpress" || $gateway == "paypalstandard") && $pmpro_requirebilling) { ?>style="display: none;"<?php } ?>>
				<input type="hidden" name="submit-checkout" value="1" />
				<input type="submit" id="pmpro_btn-submit" class="<?php echo pmpro_get_element_class( 'pmpro_btn pmpro_btn-submit-checkout', 'pmpro_btn-submit-checkout' ); ?>" value="<?php if($pmpro_requirebilling) { _e('Submit and Check Out', 'paid-memberships-pro' ); } else { _e('Submit and Confirm', 'paid-memberships-pro' );}?> &raquo;" />
			</span>
			<?php

			//don't show the default
			return false;
		}

		//PayPal Express, this is run first to authorize from PayPal
		function setExpressCheckout(&$order)
		{
			global $pmpro_currency;

			if(empty($order->code))
				$order->code = $order->getRandomCode();

			//clean up a couple values
			$order->payment_type = "PayPal Express";
			$order->CardType = "";
			$order->cardtype = "";

			//taxes on initial amount
			$initial_payment = $order->InitialPayment;
			$initial_payment_tax = $order->getTaxForPrice($initial_payment);

			// Note: SetExpressCheckout expects this amount to be the total including tax.
			$initial_payment = pmpro_round_price_as_string( (float) $initial_payment + (float) $initial_payment_tax );

			//paypal profile stuff
			$nvpStr = "";
			$nvpStr .="&AMT=" . $initial_payment . "&CURRENCYCODE=" . $pmpro_currency;
			if(!empty($order->ProfileStartDate) && strtotime($order->ProfileStartDate, current_time("timestamp")) > 0)
				$nvpStr .= "&PROFILESTARTDATE=" . $order->ProfileStartDate;
			if(!empty($order->BillingFrequency))
				$nvpStr .= "&BILLINGPERIOD=" . $order->BillingPeriod . "&BILLINGFREQUENCY=" . $order->BillingFrequency . "&AUTOBILLOUTAMT=AddToNextBilling&L_BILLINGTYPE0=RecurringPayments";
			$nvpStr .= "&DESC=" . urlencode( apply_filters( 'pmpro_paypal_level_description', substr($order->membership_level->name . " at " . get_bloginfo("name"), 0, 127), $order->membership_level->name, $order, get_bloginfo("name")) );
			$nvpStr .= "&NOTIFYURL=" . urlencode( add_query_arg( 'action', 'ipnhandler', admin_url('admin-ajax.php') ) );
			$nvpStr .= "&NOSHIPPING=1&L_BILLINGAGREEMENTDESCRIPTION0=" . urlencode( apply_filters( 'pmpro_paypal_level_description', substr($order->membership_level->name . " at " . get_bloginfo("name"), 0, 127), $order->membership_level->name, $order, get_bloginfo("name") ) ) . "&L_PAYMENTTYPE0=Any";

			//if billing cycles are defined
			if(!empty($order->TotalBillingCycles))
				$nvpStr .= "&TOTALBILLINGCYCLES=" . $order->TotalBillingCycles;

			//if a trial period is defined
			if(!empty($order->TrialBillingPeriod))
			{
				$trial_amount = $order->TrialAmount;
				$trial_tax = $order->getTaxForPrice($trial_amount);

				// Note: SetExpressCheckout expects this amount to be the total including tax.
				$trial_amount = pmpro_round_price_as_string( (float) $trial_amount + (float) $trial_tax );

				$nvpStr .= "&TRIALBILLINGPERIOD=" . $order->TrialBillingPeriod . "&TRIALBILLINGFREQUENCY=" . $order->TrialBillingFrequency . "&TRIALAMT=" . $trial_amount;
			}
			if(!empty($order->TrialBillingCycles))
				$nvpStr .= "&TRIALTOTALBILLINGCYCLES=" . $order->TrialBillingCycles;

			if(!empty($order->discount_code))
			{
				$nvpStr .= "&ReturnUrl=" . urlencode(pmpro_url("checkout", "?level=" . $order->membership_level->id . "&discount_code=" . $order->discount_code . "&review=" . $order->code));
			}
			else
			{
				$nvpStr .= "&ReturnUrl=" . urlencode(pmpro_url("checkout", "?level=" . $order->membership_level->id . "&review=" . $order->code));
			}

			$additional_parameters = apply_filters("pmpro_paypal_express_return_url_parameters", array());
			if(!empty($additional_parameters))
			{
				foreach($additional_parameters as $key => $value)
					$nvpStr .= urlencode("&" . $key . "=" . $value);
			}

			$nvpStr .= "&CANCELURL=" . urlencode(pmpro_url("levels"));

			$account_optional = apply_filters('pmpro_paypal_account_optional', true);
    		if ($account_optional)
        		$nvpStr .= '&SOLUTIONTYPE=Sole&LANDINGPAGE=Billing';

			$nvpStr = apply_filters("pmpro_set_express_checkout_nvpstr", $nvpStr, $order);

			///echo str_replace("&", "&<br />", $nvpStr);
			///exit;

			$this->httpParsedResponseAr = $this->PPHttpPost('SetExpressCheckout', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"])) {
				$order->status = "token";
				$order->paypal_token = urldecode($this->httpParsedResponseAr['TOKEN']);

				//update order
				$order->saveOrder();

				/**
				 * Allow performing actions just before sending the user to the gateway to complete the payment.
				 *
				 * @since 2.6.5
				 *
				 * @param MemberOrder $order The new order with status = token.
				 */
				do_action( 'pmpro_before_commit_express_checkout', $order );

				//redirect to paypal
				$paypal_url = "https://www.paypal.com/webscr?cmd=_express-checkout&useraction=commit&token=" . $this->httpParsedResponseAr['TOKEN'];
				$environment = pmpro_getOption("gateway_environment");
				if("sandbox" === $environment || "beta-sandbox" === $environment)
				{
					$paypal_url = "https://www.sandbox.paypal.com/webscr?cmd=_express-checkout&useraction=commit&token="  . $this->httpParsedResponseAr['TOKEN'];
				}

				wp_redirect($paypal_url);
				exit;

				//exit('SetExpressCheckout Completed Successfully: '.print_r($this->httpParsedResponseAr, true));
			} else  {
				$order->errorcode = $this->httpParsedResponseAr['L_ERRORCODE0'];
				$order->error = urldecode($this->httpParsedResponseAr['L_LONGMESSAGE0']);
				$order->shorterror = urldecode($this->httpParsedResponseAr['L_SHORTMESSAGE0']);
				return false;
				//exit('SetExpressCheckout failed: ' . print_r($httpParsedResponseAr, true));
			}

			//write session?

			//redirect to PayPal
		}

		function getExpressCheckoutDetails(&$order)
		{
			$nvpStr="&TOKEN=".$order->Token;

			$nvpStr = apply_filters("pmpro_get_express_checkout_details_nvpstr", $nvpStr, $order);

			/* Make the API call and store the results in an array.  If the
			call was a success, show the authorization details, and provide
			an action to complete the payment.  If failed, show the error
			*/
			$this->httpParsedResponseAr = $this->PPHttpPost('GetExpressCheckoutDetails', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"])) {
				$order->status = "review";

				//update order

				$order->saveOrder();

				return true;
			} else  {
				$order->errorcode = $this->httpParsedResponseAr['L_ERRORCODE0'];
				$order->error = urldecode($this->httpParsedResponseAr['L_LONGMESSAGE0']);
				$order->shorterror = urldecode($this->httpParsedResponseAr['L_SHORTMESSAGE0']);
				return false;
				//exit('SetExpressCheckout failed: ' . print_r($httpParsedResponseAr, true));
			}
		}

		function charge(&$order)
		{
			global $pmpro_currency;

			if(empty($order->code))
				$order->code = $order->getRandomCode();

			//taxes on the amount
			$amount = $order->InitialPayment;
			$amount_tax = $order->getTaxForPrice($amount);
			$order->subtotal = $amount;

			// Note: DoExpressCheckoutPayment expects this amount to be the total including tax.
			$amount = pmpro_round_price_as_string( (float) $amount + (float) $amount_tax );

			//paypal profile stuff
			$nvpStr = "";
			if(!empty($order->Token))
				$nvpStr .= "&TOKEN=" . $order->Token;
			$nvpStr .="&AMT=" . $amount . "&CURRENCYCODE=" . $pmpro_currency;
			/*
			if(!empty($amount_tax))
				$nvpStr .= "&TAXAMT=" . $amount_tax;
			*/
			if(!empty($order->BillingFrequency))
				$nvpStr .= "&BILLINGPERIOD=" . $order->BillingPeriod . "&BILLINGFREQUENCY=" . $order->BillingFrequency . "&AUTOBILLOUTAMT=AddToNextBilling";
			$nvpStr .= "&DESC=" . urlencode( apply_filters( 'pmpro_paypal_level_description', substr($order->membership_level->name . " at " . get_bloginfo("name"), 0, 127), $order->membership_level->name, $order, get_bloginfo("name")) );
			$nvpStr .= "&NOTIFYURL=" . urlencode( add_query_arg( 'action', 'ipnhandler', admin_url('admin-ajax.php') ) );
			$nvpStr .= "&NOSHIPPING=1";

			$nvpStr .= "&PAYERID=" . $_SESSION['payer_id'] . "&PAYMENTACTION=sale";

			$nvpStr = apply_filters("pmpro_do_express_checkout_payment_nvpstr", $nvpStr, $order);

			$order->nvpStr = $nvpStr;

			$this->httpParsedResponseAr = $this->PPHttpPost('DoExpressCheckoutPayment', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"])) {
				$order->payment_transaction_id = urldecode($this->httpParsedResponseAr['TRANSACTIONID']);
				$order->status = "success";

				//update order
				$order->saveOrder();

				return true;
			} else  {
				$order->errorcode = $this->httpParsedResponseAr['L_ERRORCODE0'];
				$order->error = urldecode($this->httpParsedResponseAr['L_LONGMESSAGE0']);
				$order->shorterror = urldecode($this->httpParsedResponseAr['L_SHORTMESSAGE0']);
				return false;
				//exit('SetExpressCheckout failed: ' . print_r($httpParsedResponseAr, true));
			}
		}

		function subscribe(&$order)
		{
			global $pmpro_currency, $pmpro_review;

			if(empty($order->code))
				$order->code = $order->getRandomCode();

			//filter order before subscription. use with care.
			$order = apply_filters("pmpro_subscribe_order", $order, $this);

			//taxes on initial amount
			$initial_payment = $order->InitialPayment;
			$initial_payment_tax = $order->getTaxForPrice($initial_payment);

			// Note: CreateRecurringPaymentsProfile expects this amount to be the total including tax.
			$initial_payment = pmpro_round_price_as_string( (float) $initial_payment + (float) $initial_payment_tax );

			//taxes on the amount
			$amount = $order->PaymentAmount;
			$amount_tax = $order->getTaxForPrice( $amount );

			// Note: CreateRecurringPaymentsProfile expects this amount to be the total excluding tax.
			$amount = pmpro_round_price_as_string( $amount );

			//paypal profile stuff
			$nvpStr = "";
			if(!empty($order->Token))
				$nvpStr .= "&TOKEN=" . $order->Token;
			$nvpStr .="&INITAMT=" . $initial_payment . "&AMT=" . $amount . "&CURRENCYCODE=" . $pmpro_currency . "&PROFILESTARTDATE=" . $order->ProfileStartDate;
			if(!empty($amount_tax))
				$nvpStr .= "&TAXAMT=" . pmpro_round_price_as_string( $amount_tax );
			$nvpStr .= "&BILLINGPERIOD=" . $order->BillingPeriod . "&BILLINGFREQUENCY=" . $order->BillingFrequency . "&AUTOBILLOUTAMT=AddToNextBilling";
			$nvpStr .= "&NOTIFYURL=" . urlencode( add_query_arg( 'action', 'ipnhandler', admin_url('admin-ajax.php') ) );
			$nvpStr .= "&DESC=" . urlencode( apply_filters( 'pmpro_paypal_level_description', substr($order->membership_level->name . " at " . get_bloginfo("name"), 0, 127), $order->membership_level->name, $order, get_bloginfo("name")) );

			//if billing cycles are defined
			if(!empty($order->TotalBillingCycles))
				$nvpStr .= "&TOTALBILLINGCYCLES=" . $order->TotalBillingCycles;

			//if a trial period is defined
			if(!empty($order->TrialBillingPeriod))
			{
				$trial_amount = $order->TrialAmount;
				$trial_tax = $order->getTaxForPrice($trial_amount);

				/*
				 * Note: For the CreateRecurringPaymentsProfile API call, it expects the TRIALAMT to be the total excluding taxes.
				 *
				 * However, there is no TRIALTAXAMT for trial periods so this is a workaround.
				 */
				$trial_amount = pmpro_round_price_as_string( (float) $trial_amount + (float) $trial_tax );

				$nvpStr .= "&TRIALBILLINGPERIOD=" . $order->TrialBillingPeriod . "&TRIALBILLINGFREQUENCY=" . $order->TrialBillingFrequency . "&TRIALAMT=" . $trial_amount;
			}
			if(!empty($order->TrialBillingCycles))
				$nvpStr .= "&TRIALTOTALBILLINGCYCLES=" . $order->TrialBillingCycles;

			// Set MAXFAILEDPAYMENTS so subscriptions are cancelled after 1 failed payment.
			$nvpStr .= "&MAXFAILEDPAYMENTS=1";

			$nvpStr = apply_filters("pmpro_create_recurring_payments_profile_nvpstr", $nvpStr, $order);

			//for debugging let's add this to the class object
			$this->nvpStr = $nvpStr;

			///echo str_replace("&", "&<br />", $nvpStr);
			///exit;

			$this->httpParsedResponseAr = $this->PPHttpPost('CreateRecurringPaymentsProfile', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"])) {
				// PayPal docs says that PROFILESTATUS can be:
				// 1. ActiveProfile — The recurring payment profile has been successfully created and activated for scheduled payments according the billing instructions from the recurring payments profile.
				// 2. PendingProfile — The system is in the process of creating the recurring payment profile. Please check your IPN messages for an update.
				// Also, we have seen that PROFILESTATUS can be missing. That case would be an error.
				if(isset($this->httpParsedResponseAr["PROFILESTATUS"]) && in_array($this->httpParsedResponseAr["PROFILESTATUS"], array("ActiveProfile", "PendingProfile"))) {
					$order->status = "success";

					// this is wrong, but we don't know the real transaction id at this point
					$order->payment_transaction_id = urldecode($this->httpParsedResponseAr['PROFILEID']);
					$order->subscription_transaction_id = urldecode($this->httpParsedResponseAr['PROFILEID']);

					//update order
					$order->saveOrder();

					return true;
				} else {
					// stop processing the review request on checkout page
					$pmpro_review = false;

					$order->status = "error";

					// this is wrong, but we don't know the real transaction id at this point
					$order->payment_transaction_id = urldecode($this->httpParsedResponseAr['PROFILEID']);
					$order->subscription_transaction_id = urldecode($this->httpParsedResponseAr['PROFILEID']);

					$order->errorcode = '';
					$order->error = __( 'Something went wrong creating plan with PayPal; missing PROFILESTATUS.', 'paid-memberships-pro' );
					$order->shorterror = __( 'Error creating plan with PayPal.', 'paid-memberships-pro' );

					//update order
					$order->saveOrder();

					return false;
				}
			} else  {
				// stop processing the review request on checkout page
				$pmpro_review = false;

				$order->errorcode = $this->httpParsedResponseAr['L_ERRORCODE0'];
				$order->error = urldecode($this->httpParsedResponseAr['L_LONGMESSAGE0']);
				$order->shorterror = urldecode($this->httpParsedResponseAr['L_SHORTMESSAGE0']);

				return false;
			}
		}

		function cancel(&$order) {
			// Always cancel the order locally even if PayPal might fail
			$order->updateStatus("cancelled");

			// If we're processing an IPN request for this subscription, it's already cancelled at PayPal.
			if ( ( ! empty( $_POST['subscr_id'] ) && $_POST['subscr_id'] == $order->subscription_transaction_id ) ||
				 ( ! empty( $_POST['recurring_payment_id'] ) && $_POST['recurring_payment_id'] == $order->subscription_transaction_id ) ) {
				// recurring_payment_failed transaction still need to be cancelled
				if ( $_POST['txn_type'] !== 'recurring_payment_failed' ) {
					return true;
				}
			}

			// Cancel at gateway
			return $this->cancelSubscriptionAtGateway($order);
		}

		function cancelSubscriptionAtGateway(&$order) {
			// Build the nvp string for PayPal API
			$nvpStr = "";
			$nvpStr .= "&PROFILEID=" . urlencode($order->subscription_transaction_id) . "&ACTION=Cancel&NOTE=" . urlencode("User requested cancel.");

			$nvpStr = apply_filters("pmpro_manage_recurring_payments_profile_status_nvpstr", $nvpStr, $order);

			$this->httpParsedResponseAr = $this->PPHttpPost('ManageRecurringPaymentsProfileStatus', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"])) {
				return true;
			} else {
				$order->errorcode = $this->httpParsedResponseAr['L_ERRORCODE0'];
				$order->error = urldecode($this->httpParsedResponseAr['L_LONGMESSAGE0']) . ". " . __("Please contact the site owner or cancel your subscription from within PayPal to make sure you are not charged going forward.", 'paid-memberships-pro' );
				$order->shorterror = urldecode($this->httpParsedResponseAr['L_SHORTMESSAGE0']);

				return false;
			}
		}

		function getSubscriptionStatus(&$order)
		{
			if(empty($order->subscription_transaction_id))
				return false;

			//paypal profile stuff
			$nvpStr = "";
			$nvpStr .= "&PROFILEID=" . urlencode($order->subscription_transaction_id);

			$nvpStr = apply_filters("pmpro_get_recurring_payments_profile_details_nvpstr", $nvpStr, $order);

			$this->httpParsedResponseAr = $this->PPHttpPost('GetRecurringPaymentsProfileDetails', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"]))
			{
				return $this->httpParsedResponseAr;
			}
			else
			{
				$order->errorcode = $this->httpParsedResponseAr['L_ERRORCODE0'];
				$order->error = urldecode($this->httpParsedResponseAr['L_LONGMESSAGE0']);
				$order->shorterror = urldecode($this->httpParsedResponseAr['L_SHORTMESSAGE0']);

				return false;
			}
		}

		function getTransactionStatus(&$order) {
			$transaction_details = $order->Gateway->getTransactionDetailsByOrder( $order );
			if( false === $transaction_details ){
				return false;
			}

			if( ! isset( $transaction_details['PAYMENTSTATUS'] ) ){
				return false;
			}

			return $transaction_details['PAYMENTSTATUS'];
		}

		function getTransactionDetailsByOrder(&$order)
		{
			if(empty($order->payment_transaction_id))
				return false;

			if( $order->payment_transaction_id == $order->subscription_transaction_id ){
				$payment_transaction_id = $this->getRealPaymentTransactionId( $order );
				if( ! $payment_transaction_id ){
					return false;
				}

				return $this->getTransactionDetails( $payment_transaction_id );
			}else{
				/** Recurring payment **/
				return $this->getTransactionDetails( $order->payment_transaction_id );
			}
		}

		/**
		 * Try to recover the real payment_transaction_id when payment_transaction_id === subscription_transaction_id === I-xxxxxxxx.
		 *
		 * @since 1.8.5
		*/
		function getRealPaymentTransactionId(&$order)
		{
			/** Initial payment **/
			$nvpStr = "";
			// STARTDATE is Required, even if useless here. Start from 24h before the order timestamp, to avoid timezone related issues.
			$nvpStr .= "&STARTDATE=" . urlencode( gmdate( DATE_W3C, $order->getTimestamp() - DAY_IN_SECONDS ) . 'Z' );
			// filter results by a specific transaction id.
			$nvpStr .= "&TRANSACTIONID=" . urlencode($order->subscription_transaction_id);

			$this->httpParsedResponseAr = $this->PPHttpPost('TransactionSearch', $nvpStr);

			if( ! in_array( strtoupper( $this->httpParsedResponseAr["ACK"] ), [ 'SUCCESS', 'SUCCESSWITHWARNING' ] ) ){
				// since we are using TRANSACTIONID=I-... which is NOT a transaction id,
				// paypal is returning an error. but the results are actually filtered by that transaction id, usually.

				// let's double check it.
				if( ! isset( $this->httpParsedResponseAr['L_TRANSACTIONID0'] ) ){
					// really no results? it's a real error.
					return false;
				}
			}

			$transaction_ids = [];
			for( $i = 0; $i < PHP_INT_MAX; $i++ ){
				// loop until we have results
				if( ! isset( $this->httpParsedResponseAr["L_TRANSACTIONID$i"] ) ){
					break;
				}

				// ignore I-... results
				if( "I-" === substr( $this->httpParsedResponseAr["L_TRANSACTIONID$i"], 0 ,2 ) ){
					if( $order->subscription_transaction_id != $this->httpParsedResponseAr["L_TRANSACTIONID$i"] ){
						// if we got a result from another I- subscription transaction id,
						// then something changed into paypal responses.
						// var_dump( $this->httpParsedResponseAr, $this->httpParsedResponseAr["L_TRANSACTIONID$i"] );
						throw new Exception();
					}

					continue;
				}

				$transaction_ids[] = $this->httpParsedResponseAr["L_TRANSACTIONID$i"];
			}

			// no payment_transaction_ids in results
			if( empty( $transaction_ids ) ){
				return false;
			}

			// found the payment transaction id, it's the last one (the oldest)
			$payment_transaction_id = end( $transaction_ids );

			return $payment_transaction_id;
		}

		function getTransactionDetails($payment_transaction_id)
        	{
			$nvpStr = "";
			$nvpStr .= "&TRANSACTIONID=" . urlencode($payment_transaction_id);

			$this->httpParsedResponseAr = $this->PPHttpPost('GetTransactionDetails', $nvpStr);

			if("SUCCESS" == strtoupper($this->httpParsedResponseAr["ACK"]) || "SUCCESSWITHWARNING" == strtoupper($this->httpParsedResponseAr["ACK"]))
			{
				return $this->httpParsedResponseAr;
			}
			else
			{
				// var_dump( $this->httpParsedResponseAr, $this->httpParsedResponseAr["L_TRANSACTIONID$i"] );
				return false;
			}
		}

		/**
		 * Filter pmpro_next_payment to get date via API if possible
		 *
		 * @since 1.8.5
		*/
		static function pmpro_next_payment($timestamp, $user_id, $order_status)
		{
			//find the last order for this user
			if(!empty($user_id))
			{
				//get last order
				$order = new MemberOrder();
				$order->getLastMemberOrder($user_id, $order_status);

				//check if this is a paypal express order with a subscription transaction id
				if(!empty($order->id) && !empty($order->subscription_transaction_id) && $order->gateway == "paypalexpress")
				{
					//get the subscription status
					$status = $order->getGatewaySubscriptionStatus();

					if(!empty($status) && !empty($status['NEXTBILLINGDATE']))
					{
						//found the next billing date at PayPal, going to use that
						$timestamp = strtotime(urldecode($status['NEXTBILLINGDATE']), current_time('timestamp'));
					}
					elseif(!empty($status) && !empty($status['PROFILESTARTDATE']) && $order_status == "cancelled")
					{
						//startdate is in the future and we cancelled so going to use that as the next payment date
						$startdate_timestamp = strtotime(urldecode($status['PROFILESTARTDATE']), current_time('timestamp'));
						if($startdate_timestamp > current_time('timestamp'))
							$timestamp = $startdate_timestamp;
					}
				}
			}

			return $timestamp;
		}

		/**
		 * PAYPAL Function
		 * Send HTTP POST Request with retries
		 *
		 * @param string    The API method name
		 * @param string    The POST Message fields in &name=value pair format
		 *
		 * @return array    Parsed HTTP Response body
		 */
		function PPHttpPost( $methodName_, $nvpStr_ ) {
			// Create a UUID for this request, to enable idempotency which is supported
			// by PayPal Express even if it's legacy (thus it's not reported in the docs)
			// https://developer.paypal.com/docs/business/develop/idempotency/
			$uuid = self::RandomGenerator_uuid();

			$numRetries = 0;
			do {
				$httpParsedResponseAr = $this->PPHttpPost_DontDieOnError( $methodName_, $nvpStr_, $uuid );
				if ( is_wp_error( $httpParsedResponseAr ) ) {
					$numRetries++;
					sleep( self::sleepTime( $numRetries ) );
				} else {
					break;
				}
			} while ( $numRetries <= self::$maxNetworkRetries );

			// If we still have an error even with the retries, there's not much we can do.
			if ( is_wp_error( $httpParsedResponseAr ) ) {
				// exiting is never a good user experience and it's hard to debug, but we can
				// at least leave a trace in error log to make it easier to see this happening
				error_log( "Unable to complete $methodName_ request with $nvpStr_: " . $httpParsedResponseAr->get_error_message() );
				die( "Unable to complete $methodName_ request with $nvpStr_: " . $httpParsedResponseAr->get_error_message() );
			}

			/**
			 * Allow performing actions using the http post request's response.
			 *
			 * @since 2.8
			 *
			 * @param array $httpParsedResponseAr The parsed response.
			 * @param string $methodName_ The NVP API name.
			 */
			do_action( 'pmpro_paypal_handle_http_post_response', $httpParsedResponseAr, $methodName_ );
			
			return $httpParsedResponseAr;
		}

		/**
		 * Refunds an order (only supports full amounts)
		 *
		 * @param bool    $succes Status of the refund (default: false)
		 * @param object  $morder The Member Order Object
		 * @since 2.8
		 * 
		 * @return bool   Status of the processed refund
		 */
		public static function process_refund( $success, $morder ){

			//need a transaction id
			if ( empty( $morder->payment_transaction_id ) ) {
				return false;
			}

			$transaction_id = $morder->payment_transaction_id;

			//Get the real transaction ID
			if ( $transaction_id === $morder->subscription_transaction_id ) {
				$transaction_id = $morder->Gateway->getRealPaymentTransactionId( $morder );
			}

			$httpParsedResponseAr = $morder->Gateway->PPHttpPost( 'RefundTransaction', '&TRANSACTIONID='.$transaction_id );		

			if ( 'success' === strtolower( $httpParsedResponseAr['ACK'] ) ) {
				
				$success = true;

				$morder->status = 'refunded';

				global $current_user;

				// translators: %1$s is the Transaction ID. %2$s is the user display name that initiated the refund.
				$morder->notes = trim( $morder->notes . ' ' . sprintf( __('Admin: Order successfully refunded on %1$s for transaction ID %2$s by %3$s.', 'paid-memberships-pro' ), date_i18n('Y-m-d H:i:s'), $transaction_id, $current_user->display_name ) );

				$user = get_user_by( 'id', $morder->user_id );
				//send an email to the member
				$myemail = new PMProEmail();
				$myemail->sendRefundedEmail( $user, $morder );

				//send an email to the admin
				$myemail = new PMProEmail();
				$myemail->sendRefundedAdminEmail( $user, $morder );

			} else {
				//The refund failed, so lets return the gateway message
				
				// translators: %1$s is the Transaction ID. %1$s is the Gateway Error
				$morder->notes = trim( $morder->notes .' '. sprintf( __( 'Admin: There was a problem processing a refund for transaction ID %1$s. Gateway Error: %2$s.', 'paid-memberships-pro' ), $transaction_id, $httpParsedResponseAr['L_LONGMESSAGE0'] ) );
			}

			$morder->SaveOrder();

			return $success;
			
		}
    
    /**
		 * PAYPAL Function
		 * Send HTTP POST Request with uuid
		 *
		 * @param	string	The API method name
		 * @param	string	The POST Message fields in &name=value pair format
		 * @return	array|\WP_Error	Parsed HTTP Response body
		 */
		function PPHttpPost_DontDieOnError($methodName_, $nvpStr_, $uuid) {
			global $gateway_environment;
			$environment = $gateway_environment;

			$API_UserName = pmpro_getOption("apiusername");
			$API_Password = pmpro_getOption("apipassword");
			$API_Signature = pmpro_getOption("apisignature");
			$API_Endpoint = "https://api-3t.paypal.com/nvp";
			if("sandbox" === $environment || "beta-sandbox" === $environment) {
				$API_Endpoint = "https://api-3t.$environment.paypal.com/nvp";
			}

			$version = urlencode('72.0');

			//NVPRequest for submitting to server
			$nvpreq = "METHOD=" . urlencode($methodName_) . "&VERSION=" . urlencode($version) . "&PWD=" . urlencode($API_Password) . "&USER=" . urlencode($API_UserName) . "&SIGNATURE=" . urlencode($API_Signature) . "&BUTTONSOURCE=" . urlencode(PAYPAL_BN_CODE) . $nvpStr_;

			//post to PayPal
			$response = wp_remote_post( $API_Endpoint, array(
					'timeout' => 60,
					'sslverify' => FALSE,
					'httpversion' => '1.1',
					'body' => $nvpreq,
					'headers'     => array(
						'content-type'      => 'application/json',
						'PayPal-Request-Id' => $uuid,
					),
			    )
			);

			if ( is_wp_error( $response ) ) {
                return $response;
			}

            //extract the response details
            $httpParsedResponseAr = array();
            parse_str(wp_remote_retrieve_body($response), $httpParsedResponseAr);

            //check for valid response
            if((0 == sizeof($httpParsedResponseAr)) || !array_key_exists('ACK', $httpParsedResponseAr)) {
	            return new WP_Error( 1, "Invalid HTTP Response for POST request($nvpreq) to $API_Endpoint." );
            }

			return $httpParsedResponseAr;
		}

		/**
		 * Provides the number of seconds to wait before retrying a request.
		 * Inspired by Stripe\HttpClient\CurlClient::sleepTime
		 *
		 * @param int $numRetries
		 *
		 * @return int
		 */
		public static function sleepTime( $numRetries ) {
			// Apply exponential backoff with $initialNetworkRetryDelay on the
			// number of $numRetries so far as inputs. Do not allow the number to exceed
			// $maxNetworkRetryDelay.
			$sleepSeconds = \min(
				self::$maxNetworkRetryDelay * 1.0 * 2 ** ( $numRetries - 1 ),
				self::$maxNetworkRetryDelay
			);

			// Apply some jitter by randomizing the value in the range of
			// ($sleepSeconds / 2) to ($sleepSeconds).
			$sleepSeconds *= 0.5 * ( 1 + self::randFloat() );

			// But never sleep less than the base sleep seconds.
			$sleepSeconds = \max( self::$initialNetworkRetryDelay, $sleepSeconds );

			return $sleepSeconds;
		}

		/**
		 * Returns a random value between 0 and $max.
		 * From Stripe\Util\RandomGenerator::randFloat()
		 *
		 * @param float $max (optional)
		 *
		 * @return float
		 */
		public static function randFloat( $max = 1.0 ) {
			return \mt_rand() / \mt_getrandmax() * $max;
		}

		/**
		 * Returns a v4 UUID.
		 * From Stripe\Util\RandomGenerator::uuid()
		 *
		 * @return string
		 */
		public static function RandomGenerator_uuid() {
			$arr    = \array_values( \unpack( 'N1a/n4b/N1c', \openssl_random_pseudo_bytes( 16 ) ) );
			$arr[2] = ( $arr[2] & 0x0fff ) | 0x4000;
			$arr[3] = ( $arr[3] & 0x3fff ) | 0x8000;

			return \vsprintf( '%08x-%04x-%04x-%04x-%04x%08x', $arr );
		}
	}
