/**
* Get a cache control directive from a message.
*
* @param MessageInterface $message Message to retrieve
* @param string $part Cache directive to retrieve
*
* @return mixed|bool|null
*/
public static function getDirective(MessageInterface $message, $part)
{
$parts = AbstractMessage::parseHeader($message, 'Cache-Control');
foreach ($parts as $line) {
if (isset($line[$part])) {
return $line[$part];
} elseif (in_array($part, $line)) {
return true;
}
}
return null;
}
/**
* Gets the number of seconds from the current time in which a response
* is still considered fresh.
*
* @param ResponseInterface $response
*
* @return int|null Returns the number of seconds
*/
public static function getMaxAge(ResponseInterface $response)
{
$parts = AbstractMessage::parseHeader($response, 'Cache-Control');
if (isset($parts['s-maxage'])) {
return $parts['s-maxage'];
} elseif (isset($parts['max-age'])) {
return $parts['max-age'];
} elseif ($response->hasHeader('Expires')) {
return strtotime($response->getHeader('Expires')) - time();
}
return null;
}
