/mvc/components/amazon

<?php
/**
 * Interface to Amazon Web Services
 */
class amazonComponent {
    /**
     * Cache storing the last response from AWS
     * @var object
     */
    public $lastResponse;

    /**
     * Response group as defined by the AWS API (item types that you want to get back from their web service)
     * @var array
     */
    public $responseGroup = array('ItemAttributes', 'Images');

    /**
     * Connects to Amazon Web Services to get products by ASIN/ISBN
     *
     * @param string $asin
     * @param boolean $isbn13
     * @return string XML response
     */
    public function getProductByAsin($asin, $isbn13 = false) {
        $params = array('Service' => 'AWSECommerceService',
                        'ResponseGroup' => implode(',', $this->responseGroup),
                        'AWSAccessKeyId' => get::$config->AMAZON['accessKey'],
                        'Operation' => 'ItemLookup',
                        'AssociateTag' => get::$config->AMAZON['id'],
                        'Timestamp' => gmdate('Y-m-d\TH:i:s') . '.000Z',
                        'Version' => '2009-03-31',
                        'ItemId' => (!is_array($asin) ? $asin : implode(',', $asin)));
        if ($isbn13) {
            $params['IdType'] = 'EAN';
            $params['SearchIndex'] = 'Books';
        }
        ksort($params);
        foreach ($params as $key => $val) {
            $encoded[] = str_replace('%7E', '~', rawurlencode($key))
                       . '=' . str_replace('%7E', '~', rawurlencode($val));
        }
        $request = implode('&', $encoded);
        $host = 'ecs.amazonaws.com';
        $path = '/onca/xml';
        $signature = "GET\n" . $host . "\n" . $path . "\n" . $request;
        $signature = urlencode(base64_encode(hash_hmac('sha256', $signature, get::$config->AMAZON['secretKey'],
 true)));
        $url = 'http://' . $host . $path . '?' . $request . '&Signature=' . $signature;
        $this->lastResponse = simplexml_load_string(file_get_contents($url));
        return $this->lastResponse;
    }

    /**
     * Internal sorting function to properly alphabetize the combined results of Amazon Web Services and cache
 response
     *
     * @param string $a
     * @param string $b
     * @return int
     */
    protected static function _titleSort($a, $b) {
        return strcasecmp($a['title'], $b['title']);
    }

    /**
     * Pass in one string or an array of ASIN or ISBN and get the items returned back
     * This is a wrapper method that simplifies the access and return data to $this->getProductByAsin
     *
     * @param string $asin
     * @param boolean $isbn13
     * @param boolean $getErrors
     * @return array
     */
    public function getTitlesByAsin($asin, $isbn13 = false, $getErrors = false) {
        $amazon = get::model('amazon');
        $titles = $amazon->getCache($asin);
        if (!is_array($asin)) {
            $asin = (isset($titles[$asin]) ? false : $asin);
        } else {
            $asin = array_diff($asin, array_keys($titles));
        }
        if ($asin) {
            $xml = $this->getProductByAsin($asin, $isbn13);
            if ($xml && property_exists($xml->Items, 'Item')) {
                foreach ($xml->Items->Item as $item) {
                    $thisAsin = (string) $item->ASIN;
                    $titles[$thisAsin]['title'] = $item->ItemAttributes->Title;
                    $titles[$thisAsin]['url'] = $item->DetailPageURL;
                    $titles[$thisAsin]['thumbnail'] = array('src' => $item->SmallImage->URL,
                                                            'height' => $item->SmallImage->Height,
                                                            'width' => $item->SmallImage->Width,
                                                            'alt' => $titles[$thisAsin]['title']);
                }
            }
            if ($getErrors && property_exists($xml->Items->Request, 'Errors')) {
                foreach ($xml->Items->Request->Errors->Error as $Error) {
                    if ($Error->Code == 'AWS.InvalidParameterValue') {
                        $asin = substr($Error->Message, 0, strpos($Error->Message, ' '));
                        $titles[(string) $asin]['error'] = $Error->Message;
                    }
                }
            } else {
                $amazon->updateCache($titles);
            }
            uasort($titles, array('self', '_titleSort'));
        }
        return $titles;
    }
}