Get Amazon ASIN By SKU PHP example

GetAsinBySku.php

    /**
     * Get Amazon ASIN by SKU
     * 
     * @param  string $sku 
     * @return string      Amazon ASIN
     * @link http://docs.developer.amazonservices.com/en_UK/products/Products_GetMatchingProductForId.html
     */
    public function getAsinBySku($sku)
    {
        // append the real SKU ending
        $sku = $sku.'-XL-F-CUSTOM';

        /*
        https://mws.amazonservices.com/Products/2011-10-01
        ?AWSAccessKeyId=AKIAEXAMPLEFWR4TJ7ZQ
        &Action=GetMatchingProductForId
        &SellerId=A1IMEXAMPLEWRC
        &SignatureVersion=2
        &Timestamp=2012-12-04T21%3A09%3A02Z
        &Version=2011-10-01
        &Signature=ZhhdEXAMPLEiTy6k5etzw%2BIOCvbDrGop5u9EXAMPLE8%3D
        &SignatureMethod=HmacSHA256
        &MarketplaceId=ATVPDKIKX0DER
        &IdType=ISBN
        &IdList.Id.1=9781933988665
        &IdList.Id.2=0439708184
        */
        
        $amazonUrl = 'https://mws.amazonservices.co.uk/Products/2011-10-01';

        $marketplaceIds = $this->getContainer()->getParameter('amazon.sites.uk.marketplace_ids');

        $urlParams = array(
            'AWSAccessKeyId'    => $this->getContainer()->getParameter('amazon.sites.uk.aws_access_key_id'),
            'Action'            => 'GetMatchingProductForId',
            'SellerId'          => $this->getContainer()->getParameter('amazon.sites.uk.merchant_id'),
            'SignatureVersion'  => '2',
            'Timestamp'         => gmdate("Y-m-d\TH:i:s\Z"),
            'Version'           => '2011-10-01',
            // 'Signature'         => $signature,
            'SignatureMethod'   => 'HmacSHA256',
            'MarketplaceId'     => $marketplaceIds[0],
            'IdType'            => 'SellerSKU',
            'IdList.Id.1'       => $sku
        );

        ksort($urlParams);

        // @todo http://docs.developer.amazonservices.com/en_UK/dev_guide/DG_ClientLibraries.html#DG_OwnClientLibrary__Signatures
        // @todo AWS Client line 1283

        $stringToSign = "POST\n"
                      . "mws.amazonservices.co.uk\n"
                      . "/Products/2011-10-01\n"
                      . http_build_query($urlParams);

        $secret = $this->getContainer()->getParameter('amazon.sites.uk.aws_secret_access_key');

        $hmacSignature = hash_hmac('sha256', $stringToSign, $secret);

        echo "stringToSign: $stringToSign".PHP_EOL;
        echo "HmacSHA256: ".$hmacSignature.PHP_EOL;
        echo "Base64HMAC: ".base64_encode(hash_hmac('sha256', $stringToSign, $secret, true)).PHP_EOL;

        $urlParams['Signature'] = base64_encode(hash_hmac('sha256', $stringToSign, $secret, true));

        $ch = curl_init();

        //set the url, number of POST vars, POST data
        curl_setopt($ch, CURLOPT_URL, $amazonUrl);
        curl_setopt($ch, CURLOPT_POST, count($urlParams));
        curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($urlParams));
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION,    true);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER,    true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST,    false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER,    false);
        // curl_setopt($ch, CURLOPT_USERAGENT, 'Aardvark-Admin/0.1 (Language=PHP; Host=iconwallstickers.co.uk)');

        //execute post
        $result = curl_exec($ch);
        // print $result;

        if (preg_match('/\<ASIN\>([A-Z0-9])\<\/ASIN\>/', $result, $match)) {
            echo __METHOD__."(sku=$sku): Found ASIN: ".$match[1].PHP_EOL;
            return $match[1];
        } else {
            echo __METHOD__."(sku=$sku): ASIN Not found. Does the product exist?".PHP_EOL;
            return null;
        }
    }