<?php
/**
 * AmazonSimpleAdmin - Wordpress Plugin
 * 
 * @author Timo Reith
 * @copyright Copyright (c) 2007-2011 Timo Reith (http://www.wp-amazon-plugin.com)
 * 
 * 
 */

require_once ASA_LIB_DIR . 'Asa/Service/Amazon/Request/Exception.php';

abstract class Asa_Service_Amazon_Request_Abstract
{
    /**
     * Asa_Service_Amazon object
     * @var Asa_Service_Amazon
     */
    protected $_asa;
    
    /**
     * The request url
     * @var string
     */
    protected $_request_url;
    
    /**
     * The response object
     * @var AsaZend_Http_Response
     */
    protected $_response;
    
    
    /**
     * Constructor
     * @param Asa_Service_Amazon $asa
     */
    public function __construct(Asa_Service_Amazon $asa) 
    {
        $this->_asa = $asa;        
    }

    /**
     * Sends the built request url and fetches the result
     * @param array
     * @return string
     * @throws Asa_Service_Amazon_Request_Exception
     * @throws Asa_Service_Exception
     */
    public function send(array $url_params)
    {
        $this->build($url_params);
        
        if (!$request_url = $this->getRequestUrl()) {
            throw new Asa_Service_Amazon_Request_Exception('Error in building request url');
        }

        //asa_debug('#### ASA API request ' . $request_url . '####', true);
        $this->_response = $this->_send($request_url); 

        if ($this->_response->isError()) {
            require_once ASA_LIB_DIR . 'Asa/Service/Amazon/Request/Exception.php';

            $body = utf8_encode(html_entity_decode($this->_response->getBody()));
            $xml_response = new SimpleXMLElement($body);
            
            $error = $xml_response->Error->Code . ': '. $xml_response->Error->Message;
            throw new Asa_Service_Amazon_Request_Exception($error);
        }
 
        
        if ($this->_response->isSuccessful()) {
            $response_body = $this->_response->getBody();
            return $response_body;
        }
        
        return null;
    }
    
    /**
     * Must be implemented by the concrete request class, sends the request
     * @param string
     * @return AsaZend_Http_Response|null
     */
    abstract protected function _send($request_url);
    
    /**
     * Builds the request url
     * @param array $url_params
     * @throws Asa_Service_Exception
     */    
    public function build(array $url_params)
    {
        if (empty($url_params) && !is_array($url_params)) {
            throw new Asa_Service_Exception('Invalid URL params');
        }

        if ($this->_asa->getLocale() == null) {
            throw new Asa_Service_Exception('Missing locale');
        }        
        
        $this->_request_url = '';
        
        $url_parts = array();
        foreach (array_keys($url_params) as $key) {
            $url_parts[] = $key .'='. $url_params[$key];
        }
        sort($url_parts);
        
        $base_url = $this->_asa->getEndpoint() .
            '?Service=AWSECommerceService&AWSAccessKeyId=%s&Version=%s&AssociateTag=%s&';
            
        $base_url = sprintf($base_url, $this->_asa->getAccessKeyId(), 
            Asa_Service_Amazon::$api_version, $this->_asa->getAssociateTag());

        // append params to base url
        $url = $base_url . implode('&', $url_parts);
        
        // get the host
        $host = parse_url($url, PHP_URL_HOST);
        
        // add timestamp
        $timestamp = gmstrftime('%Y-%m-%dT%H:%M:%S.000Z');
        $url .= '&Timestamp='. $timestamp;

        // sort the params
        $paramstart = strpos($url, '?');
        $workurl = substr($url, $paramstart+1);
        $workurl = str_replace(',', '%2C', $workurl);
        $workurl = str_replace(':', '%3A', $workurl);
        $params = explode('&', $workurl);
        sort($params);
        
        // prepare the sign string
        $signstr = "GET\n". $host ."\n/onca/xml\n". implode('&', $params);
        $signstr = base64_encode(
            hash_hmac('sha256', $signstr, $this->_asa->getAccessKeySecret(), true));
        $signstr = urlencode($signstr);
        
        // add the signature to the url
        $signurl = $url . '&Signature='. $signstr;
        
        // set the request
        $this->_request_url = $signurl;
        
        return true;                    
    }

    /**
     * @return string
     * @obsolete
     */
    public function getRequest()
    {
        return $this->_request_url;
    }

    /**
     * Retrieves the request url
     * @return string
     */
    public function getRequestUrl()
    {
        return $this->_request_url;
    }

    /**
     * Retrieves AsaZend_Http_Response object
     * @return AsaZend_Http_Response
     */
    public function getResponse()
    {
        return $this->_response;
    }
    
    /**
     * 
     */
    public function getResponseBody()
    {
        return $this->_response->getBody();
    }
}


?>