AcceptHandler.php

class Fdrop_Plugin_AcceptHandler extends Zend_Controller_Plugin_Abstract
{
	protected function getQuality($media)
	{
		$data = explode(";q=", $media);
		return isset($data[1]) ? $data[1] : 1.0;
	}

	protected function sortMediaByQuality($a, $b)
	{
		$q1 = $this->getQuality($a);
		$q2 = $this->getQuality($b);
		if ($q1 > $q2) {
			return -1;
		} elseif ($q1 < $q2) {
			return 1;
		}

		return 0;
	}

	public function dispatchLoopStartup(Zend_Controller_Request_Abstract $request)
	{
		$this->getResponse()->setHeader('Vary', 'Accept');
		$header = $request->getHeader('Accept');
		$accepts = explode(',', $header);
		usort($accepts, array($this, 'sortMediaByQuality')); 

		foreach($accepts as $accept) {
			if (substr($accept, 0, 9) == 'text/html') {
				break;
			} else if(substr($accept, 0, 31) == 'application/vnd.fdrop.xhtml+xml') {
				$request->setParam('format', 'xhtml');
				break;
			}
		}
	}
}