/**
* Retrieves data from cache, if it's there. If it is, but it's expired,
* it performs a conditional GET to see if the data is updated. If it
* isn't, it down updates the modification time of the cache file and
* returns the data. If the cache is not there, or the remote file has been
* modified, it is downloaded and cached.
*
* @param string URL of remote file to retrieve
* @param int Length of time to cache file locally before asking the server
* if it changed.
* @return string File contents
*/
function retrieveFile($url, $cacheLength, $cacheDir)
{
$cacheID = md5($url);
$cache = new Cache_Lite(array("cacheDir" => $cacheDir, "lifeTime" => $cacheLength));
if ($data = $cache->get($cacheID)) {
return $data;
} else {
// we need to perform a request, so include HTTP_Request
include_once 'HTTP/Request.php';
// HTTP_Request has moronic redirect "handling", turn that off (Alexey Borzov)
$req = new HTTP_Request($url, array('allowRedirects' => false));
// if $cache->get($cacheID) found the file, but it was expired,
// $cache->_file will exist
if (isset($cache->_file) && file_exists($cache->_file)) {
$req->addHeader('If-Modified-Since', gmdate("D, d M Y H:i:s", filemtime($cache->_file)) . " GMT");
}
$req->sendRequest();
if (!($req->getResponseCode() == 304)) {
// data is changed, so save it to cache
$data = $req->getResponseBody();
$cache->save($data, $cacheID);
return $data;
} else {
// retrieve the data, since the first time we did this failed
if ($data = $cache->get($cacheID, 'default', true)) {
return $data;
}
}
}
Services_ExchangeRates::raiseError("Unable to retrieve file {$url} (unknown reason)", SERVICES_EXCHANGERATES_ERROR_RETRIEVAL_FAILED);
return false;
}
function _retrieveFile($url, $cacheLength, $cacheDir)
{
$cacheID = md5($url);
$cache = new Cache_Lite(array("cacheDir" => $cacheDir, "lifeTime" => $cacheLength));
if ($data = $cache->get($cacheID)) {
return $data;
} else {
$fp = fopen($url, 'r');
$data = stream_get_contents($fp);
if (strlen($data) > 10) {
// data is changed, so save it to cache
$cache->save($data, $cacheID);
return $data;
} else {
// retrieve the data, since the first time we did this failed
if ($data = $cache->get($cacheID, 'default', true)) {
return $data;
}
}
}
Services_ExchangeRates::raiseError("Unable to retrieve file {$url} (unknown reason)", SERVICES_EXCHANGERATES_ERROR_RETRIEVAL_FAILED);
return false;
}
/**
* Downloads exchange rates in terms of the PLN from the National Bank of
* Poland (NBP). This information is updated daily, and is cached by default for 1 hour.
*
* Returns a multi-dimensional array containing:
* 'rates' => associative array of currency codes to exchange rates
* 'source' => URL of feed
* 'date' => date feed last updated, pulled from the feed (more reliable than file mod time)
*
* @link http://www.nbp.pl/Kursy/RatesA.html English HTML version
* @link http://www.nbp.pl/Kursy/KursyA.html Polish HTML version (with link to XML)
*
* @param int Length of time to cache (in seconds)
* @return array
*/
function retrieve($cacheLength, $cacheDir)
{
$return['rates'] = array('PLN' => 1.0);
// retrieve XML address
$htmlpage = $this->retrieveFile($this->feedHTMLUrl, $cacheLength, $cacheDir);
// Example line is:
// <div class="file"><a href="xml/a055z020319.xml">powysza tabela w formacie .xml</a></div>
if (!preg_match('#href="(xml/a\\d+z\\d+\\.xml)"#', $htmlpage, $match)) {
Services_ExchangeRates::raiseError("Retrieved url " . $this->feedHTMLUrl . " has no link to XML page", SERVICES_EXCHANGERATES_RETRIEVAL_FAILED);
return false;
}
$this->feedXMLUrl = $this->feedDir . $match[1];
$return['source'] = $this->_feedXMLUrl;
// retrieve the feed from the server or cache
$root = $this->retrieveXML($this->feedXMLUrl, $cacheLength, $cacheDir);
// get down to array of exchange rates
foreach ($root->children as $rateinfo) {
if ($rateinfo->name == 'pozycja') {
$rateinfo->children[4]->content = strtr($rateinfo->children[4]->content, ',', '.');
$value = $rateinfo->children[2]->content / $rateinfo->children[4]->content;
// currency rate
$return['rates'][$rateinfo->children[3]->content] = $value;
} elseif ($rateinfo->name == 'data_publikacji') {
// set date published
$return['date'] = $rateinfo->content;
}
}
return $return;
}
