MPG class for signature generation

mpg-sample.php

<?php

require_once 'mpg.php';

$mpg = new Mpg(array(
    'merchantId'          => '980xxxxxxx',
    'merchantResponseUrl' => 'https://example.com/response',
    'transactionPassword' => 'xxxxxxxx',
    'orderId'             => 'XXX12341234',
    'amount'              => '149.99'));

$mpg->generateSignature();

/**
 * In the HTML template use $mpg values as:
 * 
 * <input type="hidden" name="Version" value="<?php echo $mpg->version ?>" />
 * <input type="hidden" name="MerID" value="<?php echo $mpg->merchantId ?>" />
 * <input type="hidden" name="AcqID" value="<?php echo $mpg->acquirerId ?>" />
 * <input type="hidden" name="MerRespURL" value="<?php echo $mpg->merchantResponseUrl ?>" />
 * <input type="hidden" name="PurchaseCurrency" value="<?php echo $mpg->purchaseCurrency ?>" />
 * <input type="hidden" name="PurchaseCurrencyExponent" value="<?php echo $mpg->purchaseCurrencyExponent ?>" />
 * <input type="hidden" name="OrderID" value="<?php echo $mpg->orderId ?>" />
 * <input type="hidden" name="SignatureMethod" value="<?php echo $mpg->signatureMethod ?>" />
 * <input type="hidden" name="PurchaseAmt" value="<?php echo $mpg->amount ?>" />
 * <input type="hidden" name="Signature" value="<?php echo $mpg->requestSignature ?>" />
 * 
 */

mpg.php

<?php

/**
 * @author  Inash Zubair <inash@leptone.com>
 * @created Monday, July 05, 2010
 */

class Mpg
{
    private $_values = array(
        'version'                  => '1.0.0',
        'merchantId'               => null,
        'acquirerId'               => '407387',
        'merchantResponseUrl'      => null,
        'purchaseCurrency'         => '462',
        'purchaseCurrencyExponent' => '2',
        'orderId'                  => null,
        'signatureMethod'          => 'SHA1',
        'transactionPassword'      => null,
        'amount'                   => null,
        'requestSignature'         => null);

    private $_gatewayMethod = 'direct';

    public function __construct($config = array())
    {
        if (!is_array($config)) {
            throw new Exception('$config needs to be an array.');
        }

        $validParams = array(
            'version',
            'merchantId',
            'acquirerId',
            'merchantResponseUrl',
            'purchaseCurrency',
            'purchaseCurrencyExponent',
            'orderId',
            'signatureMethod',
            'transactionPassword',
            'amount',
            'requestSignature');

        foreach ($config as $key => $value) {
            if (!in_array($key, $validParams)) {
                throw new Exception("invalid config param '{$key}'.");
            } else {
                if ($key == 'amount') {
                    $this->setAmount($value);
                    continue;
                }
                $this->_values[$key] = $value;
            }
        }
    }

    public function setGatewayMethod($method = 'direct')
    {
        $validParams = array('direct', 'redirect');
        if (!in_array($method, $validParams)) {
            throw new Exception('invalid gateway method.');
        } else {
            $this->_gatewayMethod = $method;
        }
    }

    public function setTransactionPassword($password)
    {
        $this->_transactionPassword = $password;
    }

    public function setOrderId($orderId)
    {
        $this->_orderId = $orderId;
    }

    public function setAmount($amount)
    {
        $amount = number_format($amount, 2, '.', '');
        $amount = str_replace('.', '', $amount);
        $amount = str_pad($amount, 12, '0', STR_PAD_LEFT);
        $this->_values['amount'] = $amount;
    }

    public function generateSignature($regenerate = false)
    {
        if ($this->_values['requestSignature'] != null &&
            $regenerate == false) {
            return $this->_values['requestSignature'];
        }

        if ($this->_values['transactionPassword'] == null ||
            $this->_values['merchantId'] == null ||
            $this->_values['orderId'] == null ||
            $this->_values['amount'] == null) {
            throw new Exception('required params missing.');
        }

        $signature = $this->_values['transactionPassword']
                   . $this->_values['merchantId']
                   . $this->_values['acquirerId']
                   . $this->_values['orderId']
                   . $this->_values['amount']
                   . $this->_values['purchaseCurrency'];
        $this->_values['requestSignature'] = base64_encode(sha1($signature, true));
        return $this->_values['requestSignature'];
    }

    public function getRedirectFormData()
    {
        $formData = array(
            'Version'                  => $this->_version,
            'MerID'                    => $this->_merchantId,
            'AcqID'                    => $this->_acquirerId,
            'MerRespURL'               => $this->_merchantResponseUrl,
            'PurchaseCurrency'         => $this->_purchaseCurrency,
            'PurchaseCurrencyExponent' => $this->_purchaseCurrencyExponent,
            'OrderID'                  => $this->_orderId,
            'SignatureMethod'          => $this->_signatureMethod,
            'PurchaseAmt'              => $this->_purchaseAmt,
            'Signature'                => $this->generateSignature());

        return $formData;
    }

    public function __get($name)
    {
        return $this->_values[$name];
    }
}