how to recive HTTP POST request in php file

Question

This request sent to my specified url from payment gateway over http post request

POST https://mywebsite.com/checkout/?oid=12345
{
   "status":"SUCCESS",
   "notif_token":"dd497bda3b250e536186fc0663f32f40",
   "txnid": "MP150709.1341.A00073"
}

screenshot of payment gateway documentation

how to receive this request data in checkout.php file

i want to store this data into variable

// Get the JSON contents notif respone in varibale
$notif_response_body = file_get_contents('php://input');

// decode json respone
$notif_response_data = json_decode($notif_response_body, true);

switch ($notif_response_data['status']){
    case "PENDING":
        $sorder->add_order_note( __('The Transaction id ' . $notif_response_data['txnid'] . 'is in progress on Orange Money Payment Gateway ', 'orange_money'), true );
    $sorder->status = 'On hold';
    break;
    case "SUCCESS":
        $sorder->add_order_note( __('Order Paid via Orange Money Payment Gateway transaction id : ' . $notif_response_data['txnid'], 'orange_money'), true );
        $sorder->status = 'Processing';
    break;
    case "FAILED":
        $sorder->add_order_note( __('Payment Failed on Orange Money Payment Gateway transaction id : ' . $notif_response_data['txnid'], 'orange_money'), true );
        $sorder->status = 'Failed';
    break;
    case "EXPIRED":
        $sorder->add_order_note( __('Payment Expired on Orange Money Payment Gateway transaction id : ' . $notif_response_data['txnid'], 'orange_money'), true );
        $sorder->status = 'Failed';
    break;
    default:
    break;
}