curlcurl --location --request POST 'https://cp.kassa.flamix.solutions/api/cashbox/:CODE:/getPaymentRequest' \
--data-urlencode 'type=form' \
--data-urlencode 'amount=100' \
--data-urlencode 'currency=UAH' \
--data-urlencode 'order_id=432'

<?php
  use \Flamix\Kassa\API as Kassa;
  try {
        $kassa = new Kassa('cashbox_public_id');
        $kassa->setSecretKey('cashbox_secret');

        //Check
        if(!$kassa->isPaymentSuccess($_POST))
            exit();

        //If OK you can use
        $kassa->amount;
        $kassa->cashbox_currency;
        $kassa->order_id;
        $kassa->custom_info;
    } catch (Exception $e) {
        echo $e->getMessage();
        exit();
    }
?>