public static function validateCompletion()
 {
     // Read POST data
     // reading posted data directly from $_POST causes serialization
     // issues with array data in POST. Reading raw POST data from input stream instead.
     $raw_post_data = file_get_contents('php://input');
     $raw_post_array = explode('&', $raw_post_data);
     $myPost = array();
     foreach ($raw_post_array as $keyval) {
         $keyval = explode('=', $keyval);
         if (count($keyval) == 2) {
             $myPost[$keyval[0]] = urldecode($keyval[1]);
         }
     }
     // read the post from PayPal system and add 'cmd'
     $req = 'cmd=_notify-validate';
     if (function_exists('get_magic_quotes_gpc')) {
         $get_magic_quotes_exists = true;
     }
     foreach ($myPost as $key => $value) {
         if ($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) {
             $value = urlencode(stripslashes($value));
         } else {
             $value = urlencode($value);
         }
         $req .= "&{$key}={$value}";
     }
     // Post IPN data back to PayPal to validate the IPN data is genuine
     // Without this step anyone can fake IPN data
     if (Config::get('vividstore.paypalTestMode') == true) {
         $paypal_url = "https://www.sandbox.paypal.com/cgi-bin/webscr";
     } else {
         $paypal_url = "https://www.paypal.com/cgi-bin/webscr";
     }
     $ch = curl_init($paypal_url);
     if ($ch == FALSE) {
         return FALSE;
     }
     curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
     curl_setopt($ch, CURLOPT_POST, 1);
     curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
     curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
     curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
     curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
     curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
     if (DEBUG == true) {
         curl_setopt($ch, CURLOPT_HEADER, 1);
         curl_setopt($ch, CURLINFO_HEADER_OUT, 1);
     }
     // CONFIG: Optional proxy configuration
     //curl_setopt($ch, CURLOPT_PROXY, $proxy);
     //curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, 1);
     // Set TCP timeout to 30 seconds
     curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
     curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
     // CONFIG: Please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set the directory path
     // of the certificate as shown below. Ensure the file is readable by the webserver.
     // This is mandatory for some environments.
     //$cert = __DIR__ . "./cacert.pem";
     //curl_setopt($ch, CURLOPT_CAINFO, $cert);
     $res = curl_exec($ch);
     if (curl_errno($ch) != 0) {
         Log::addEntry("Can't connect to PayPal to validate IPN message: " . curl_error($ch));
         curl_close($ch);
         exit;
     } else {
         //if we want to log more stuff
         //Log::addEntry("HTTP request of validation request:". curl_getinfo($ch, CURLINFO_HEADER_OUT) ." for IPN payload: $req");
         //Log::addEntry("HTTP response of validation request: $res");
         curl_close($ch);
     }
     // Inspect IPN validation result and act accordingly
     // Split response headers and payload, a better way for strcmp
     $tokens = explode("\r\n\r\n", trim($res));
     $res = trim(end($tokens));
     if (strcmp($res, "VERIFIED") == 0) {
         $order = VividOrder::getByID($_POST['invoice']);
         $order->completeOrder();
         $order->updateStatus(OrderStatus::getStartingStatus()->getHandle());
     } elseif (strcmp($res, "INVALID") == 0) {
         // log for manual investigation
         // Add business logic here which deals with invalid IPN messages
         Log::addEntry("Invalid IPN: {$req}");
     }
 }