xREL.v3

<?php
define("CALLBACK_URL", "XXX");
define("AUTH_URL", "https://api.xrel.to/v2/oauth2/auth");
define("ACCESS_TOKEN_URL", "https://api.xrel.to/v2/oauth2/token");
define("CLIENT_ID", "XXX");
define("CLIENT_SECRET", "XXX");
define("SCOPE", ""); // optional

	$url = AUTH_URL."?"
   ."response_type=code"
   ."&client_id=". urlencode(CLIENT_ID)
   ."&scope=". urlencode(SCOPE)
   ."&redirect_uri=". urlencode(CALLBACK_URL)
	;
if($_GET['code']) 
{ 
	$code = $_GET['code'];
	
	function getToken($code)
	{
		$curl = curl_init();
		$params = array(
		CURLOPT_URL =>  ACCESS_TOKEN_URL."?"
                    ."code=".$code
                    ."&grant_type=client_credentials"
                    ."&client_id=". urlencode(CLIENT_ID)
                    ."&client_secret=". urlencode(SCOPE)
                    ."&redirect_uri=". urlencode(CALLBACK_URL)
					."&scope=",
		CURLOPT_RETURNTRANSFER => true,
		CURLOPT_MAXREDIRS => 10,
		CURLOPT_TIMEOUT => 30,
		CURLOPT_HEADER => false,
		CURLOPT_RETURNTRANSFER => true,
		CURLOPT_FOLLOWLOCATION => true,
		CURLOPT_CUSTOMREQUEST => "POST",
		CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
		CURLOPT_NOBODY => false, 
		CURLOPT_HTTPHEADER => array(
			"cache-control: no-cache",
			"content-type: application/x-www-form-urlencoded",
			"accept: *",
			"accept-encoding: gzip, deflate",
			),
	    
		);
 
		curl_setopt_array($curl, $params);
 
		$response = curl_exec($curl);
                         print_r($response);
		$response = json_decode($response, true);   	
			print_r($response);
		curl_close($curl);
 
	}

getToken($code);	

} else {
header('Location:'.$url); 
}
?>

CURLOPT_HTTPHEADER => array(
			"cache-control: no-cache",
			"content-type: application/x-www-form-urlencoded",
			"accept: *",
			"accept-encoding: gzip, deflate",
			),