Simple PHP SDK for Amazon's Login and Pay Product

LoginAndPay.php

<?php

class LoginAndPayWithAmazon {
    private $sandbox; 
    private $merchantId; 
    private $accessKey; 
    private $secretKey; 
    
    // find your endpoint here: http://docs.developer.amazonservices.com/en_US/dev_guide/DG_Endpoints.html
    private $endpoint = 'https://mws.amazonservices.com'; 

    private $url;
    private $apiVersion = '2013-01-01';
    private $sigAlgorithm = "HmacSHA256";

    private $lastResponse;

    private $paramList;

    public function __construct( $merchantId , $accessKey , $secretKey , $sandbox ) {
        $this->sandbox = $sandbox;
        $this->merchantId = $merchantId;
        $this->accessKey = $accessKey;
        $this->secretKey = $secretKey;
        $this->url = ($this->sandbox ? '/OffAmazonPayments_Sandbox' : '/OffAmazonPayments') . "/" . $this->apiVersion;
        $this->paramList = array();
    }

    public function getOrderReferenceDetails ( $amazonOrderReferenceId ) {
        $mwsResponse = $this->apiRequest ("GetOrderReferenceDetails" , "POST" , array("Action"=>"GetOrderReferenceDetails","AmazonOrderReferenceId"=>$amazonOrderReferenceId));
        $this->lastResponse = $mwsResponse;
        return $mwsResponse->getResponse();
    }

    public function setOrderReferenceDetails ( $amazonOrderReferenceId , $orderAmount ) {
        $mwsResponse = $this->apiRequest("SetOrderReferenceDetails","POST",array("Action"=>"SetOrderReferenceDetails","AmazonOrderReferenceId"=>$amazonOrderReferenceId,"OrderReferenceAttributes.OrderTotal.Amount"=>$orderAmount,"OrderReferenceAttributes.OrderTotal.CurrencyCode"=>"USD"));
        $this->lastResponse = $mwsResponse;
        if($mwsResponse->getHttpCode() == "200") {
                        return true;
                } else {
                        return false;
                }
    }

    /* confirmOrderReference
     * returns boolean 
     */
    public function confirmOrderReference( $amazonOrderReferenceId ) {
        $mwsResponse = $this->apiRequest ("ConfirmOrderReference" , "POST" , array("Action"=>"ConfirmOrderReference","AmazonOrderReferenceId"=>$amazonOrderReferenceId));
        $this->lastResponse = $mwsResponse;
        if($mwsResponse->getHttpCode() == "200") {
            return true;
        } else {
            return false;
        }
    }


    /* authorize
     * Docs - http://docs.developer.amazonservices.com/en_US/off_amazon_payments/OffAmazonPayments_Authorize.html
     */
    public function authorize ( $amazonOrderReferenceId , $orderAmount , $sellerAuthNote , $captureNow = false , $syncAuth = false) {
        // AuthorizationReferenceId
        // The identifier for this authorization transaction that you specify. This identifier MUST BE unique for all your authorization transactions.
        $authRefID = $amazonOrderReferenceId . '-' . substr(md5($amazonOrderReferenceId . time()),0,4);
        
        // TransactionTimeout
        // The number of minutes to allow the authorization to come back with a Successful response - if hit without a positive determination, authorization is declined.
        if($syncAuth) {
            $transactionTimeout = 0;
        } else {
            $transactionTimeout = 1440; // API Default
        }

        // CaptureNow
        // Automagically capture funds upon successful Authorization
        $captureNow = ($captureNow) ? "true" : "false";    

        $mwsResponse = $this->apiRequest("Authorize","POST",array("AmazonOrderReferenceId"=>$amazonOrderReferenceId,"AuthorizationAmount.Amount"=>$orderAmount,"AuthorizationAmount.CurrencyCode"=>"USD","AuthorizationReferenceId"=>$authRefID,"SellerAuthorizationNote"=>$sellerAuthNote,"CaptureNow"=>$captureNow,"TransactionTimeout"=>$transactionTimeout));
        $this->lastResponse = $mwsResponse;
        if($mwsResponse->getHttpCode() == "200") {
            return true;
        } else {
            return false;
        }
    }

    /* authorizeAndCapture
     * default the sync auth and capture now values to true
     */
    public function authorizeAndCapture($amazonOrderReferenceId , $orderAmount , $sellerAuthNote) {
        return authorize($amazonOrderReferenceId , $orderAmount , $sellerAuthNote , true , true);
    }

    public function getLastResponse () {
        return $this->lastResponse->getResponse();
    }

    public function apiRequest ($apiAction , $method , array $requestParams) {
        $requestParams["Action"] = $apiAction;
        $this->buildRequest($method,$requestParams);
        error_log("requestParams to be submitted to MWS: " . print_r($requestParams,true));
        return $this->httpPost();
    }

    private function buildRequest ($method , array $requestParams) {

        $requestParams["AWSAccessKeyId"] = $this->accessKey;
        $requestParams["SellerId"] = $this->merchantId;
        $requestParams["SignatureVersion"] = "2";
        $requestParams["SignatureMethod"] = $this->sigAlgorithm;
        $requestParams["Version"] = $this->apiVersion;
        $requestParams["Timestamp"] = date("c");

        // add on request params
        $this->paramList = $requestParams;

        error_log("params: " . print_r($this->paramList,true));

        // gen string to sign
        $stringToSign = $this->getStringToSign($method);

        // gen signature
        $signature = $this->getSignature($stringToSign);

        // add signature to request parameters
        $this->paramList["Signature"] = $signature;

        error_log("params: " . print_r($this->paramList,true));
    }

    private function getStringToSign ( $method) {
        $endpoint = parse_url ($this->endpoint);
        $stringToSign = $method . "\n" . $endpoint['host'] . "\n" . $this->url . "\n" . $this->buildQueryString();
        error_log("string to sign: \n" . $stringToSign);
        return $stringToSign;
    }

    private function buildQueryString () {
        uksort($this->paramList, 'strcmp');
        return $this->getParametersAsString();
    }

    private function getParametersAsString() {
        $queryParameters = array();
        foreach ($this->paramList as $key => $value) {
            $queryParameters[] = $key . '=' . $this->customUrlEncode($value);
        }
        return implode('&', $queryParameters);
    }

    private function customUrlEncode($value) {
        return str_replace('%7E', '~', rawurlencode($value));
    }

    private function getSignature($data) {
        if ($this->sigAlgorithm === 'HmacSHA1') {
            $hash = 'sha1';
        } else if ($this->sigAlgorithm === 'HmacSHA256') {
            $hash = 'sha256';
        } else {
            throw new Exception ("Non-supported signing method specified");
        }
        return base64_encode(
            hash_hmac($hash, $data, $this->secretKey, true)
        );
    }

    private function httpPost () {

        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->endpoint . $this->url);
        curl_setopt($ch, CURLOPT_PORT, "443");
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        
        # if a ca bundle is configured, use it as opposed to the default ca 
        # configured for the server
        #if (!is_null($this->_merchantValues->getCaBundleFile())) {
        #    curl_setopt($ch, CURLOPT_CAINFO, $this->_merchantValues->getCaBundleFile());
        #}

        curl_setopt($ch, CURLOPT_USERAGENT, "PHP SDK/ Custom");
        curl_setopt($ch, CURLOPT_POST, true);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $this->getParametersAsString());
        curl_setopt($ch, CURLOPT_HEADER, true);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        #if ($this->_config['ProxyHost'] != null && $this->_config['ProxyPort'] != -1)
        #{
        #    curl_setopt($ch, CURLOPT_PROXY, $this->_config['ProxyHost'] . ':' . $this->_config['ProxyPort']);
        #} 

        $response = curl_exec($ch);
        if ($response === false) {
            $error_msg = "Unable to post request, underlying exception of: (". curl_errno($ch) . ") " . curl_error($ch);
            error_log("ERROR - " . $error_msg);
            curl_close($ch);
            throw new Exception($error_msg);    
        }

        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE );

        $headers = substr($response,0,strpos($response,"\r\n\r\n"));
        $body = substr($response,strpos($response,"\r\n\r\n")+4);

        $responseObj = new MWSResponse( $httpCode, $headers, $body );

        error_log("response: " . $response);
        curl_close($ch);
        return $responseObj;
    }

}

class MWSResponse {
    private $httpCode;
    private $headers;
    private $response;

    public function __construct($code,$headers,$response) {
        $this->httpCode = $code;
        $this->headers = $headers;
        $this->response = $response;
    }

    public function getHttpCode () { return $this->httpCode; }
    public function getHeaders () { return $this->headers; }
    public function getResponse () { return $this->response; }
}