Paypal Class

<?php
namespace Helpers;

use Helpers\HTTPRequest;
use Models\Payment_model;
class PP {

    const API_USERNAME = "";
    const API_PASSWORD = "";
    const API_SIGNATURE = "";
    const PP_RETURN = "http://hsfarm.myftp.org/splashwi-homepage/clientarea/pay_pingback";
    const PP_CANCEL = "http://hsfarm.myftp.org/splashwi-homepage/clientarea/pay_pingback";

    public $endpoint;
    public $host;
    public $gate;

    private $config;

    function __construct($config, $real = false) {
        $endpoint = '/nvp';

        $this->config = $config;
    }

    /**
     * @return HTTPRequest
     */
    public function response($data){
        $endpoint = '/nvp';

        $host = $this->config->pp_host;
        $gate = $this->config->pp_gate;

        /*$host = "api-3t.sandbox.paypal.com";
        $gate = 'https://www.sandbox.paypal.com/cgi-bin/webscr?';*/
        $r = new \Helpers\HTTPRequest($host, $endpoint, 'POST', true);
        $result = $r->connect($data);
        if ($result<400) return $r;
        return false;
    }

    public function buildQuery($data = array()){
        $data['USER'] = $this->config->username;
        $data['PWD'] = $this->config->publickey;
        $data['SIGNATURE'] = $this->config->privatekey;
        $data['VERSION'] = '52.0';
        $query = http_build_query($data);
        return $query;
    }


    /**
     * Main payment function
     *
     * If OK, the customer is redirected to PayPal gateway
     * If error, the error info is returned
     *
     * @param float $amount Amount (2 numbers after decimal point)
     * @param string $desc Item description
     * @param string $invoice Invoice number (can be omitted)
     * @param string $currency 3-letter currency code (USD, GBP, CZK etc.)
     *
     * @return array error info
     */
    public function doExpressCheckout($amount, $desc, $initial='', $invoice='', $currency='EUR'){
        if(!empty($initial) && $initial == "init") {
            $add = "_init";
        } else {
            $add = "";
        }

        $host = $_SERVER["HTTP_HOST"];
        $data = array(
        'PAYMENTACTION' =>'Sale',
        'AMT' =>$amount,
        'RETURNURL' => 'http://'.$host.DIR.'paypal_pingback',
        'CANCELURL'  => 'http://'.$host.DIR.'paypal_pingback',
        'DESC'=>$desc,
        'NOSHIPPING'=>"1",
        'ALLOWNOTE'=>"1",
        'CURRENCYCODE'=>$currency,
        'METHOD' =>'SetExpressCheckout');

        $data['CUSTOM'] = $amount.'|'.$currency.'|'.$invoice;
        if ($invoice) $data['INVNUM'] = $invoice;

        $query = PP::buildQuery($data);

        $result = PP::response($query);

        if (!$result) return false;
        $response = $result->getContent();
        $return = self::responseParse($response);

        if ($return['ACK'] == 'Success') {
            $gate = 'https://www.paypal.com/cgi-bin/webscr?';
            //$gate = 'https://www.sandbox.paypal.com/cgi-bin/webscr?';

            echo 'Du wirst zu PayPal weitergeleitet...';
            echo '<meta http-equiv="refresh" content="0; URL='.$gate.'cmd=_express-checkout&useraction=commit&token='.$return['TOKEN'].'">';
            //header('Location: '.$gate.'cmd=_express-checkout&useraction=commit&token='.$return['TOKEN'].'');
            die();
        }
        return($return);
    }

    public function getCheckoutDetails($token){
        $data = array(
        'TOKEN' => $token,
        'METHOD' =>'GetExpressCheckoutDetails');
        $query = $this->buildQuery($data);

        $result = $this->response($query);

        if (!$result) return false;
        $response = $result->getContent();
        $return = $this->responseParse($response);
        return($return);
    }
    public function doPayment(){
        $token = $_GET['token'];
        $payer = $_GET['PayerID'];
        $details = $this->getCheckoutDetails($token);
        if (!$details) return false;
        list($amount,$currency,$invoice) = explode('|',$details['CUSTOM']);
        $data = array(
        'PAYMENTACTION' => 'Sale',
        'PAYERID' => $payer,
        'TOKEN' =>$token,
        'AMT' => $amount,
        'CURRENCYCODE'=>$currency,
        'METHOD' =>'DoExpressCheckoutPayment');
        $query = $this->buildQuery($data);

        $result = $this->response($query);

        if (!$result) return false;
        $response = $result->getContent();
        $return = $this->responseParse($response);

        /*
         * [AMT] => 10.00
         * [CURRENCYCODE] => USD
         * [PAYMENTSTATUS] => Completed
         * [PENDINGREASON] => None
         * [REASONCODE] => None
         */

        return($return);
    }

    private function getScheme() {
        $scheme = 'http';
        if (isset($_SERVER['HTTPS']) and $_SERVER['HTTPS'] == 'on') {
            $scheme .= 's';
        }
        return $scheme;
    }

    private function responseParse($resp){
        $a=explode("&", $resp);
        $out = array();
        foreach ($a as $v){
            $k = strpos($v, '=');
            if ($k) {
                $key = trim(substr($v,0,$k));
                $value = trim(substr($v,$k+1));
                if (!$key) continue;
                $out[$key] = urldecode($value);
            } else {
                $out[] = $v;
            }
        }
        return $out;
    }
}