<?php
/**
 * My_Plugin_Xml component
 * Turns an Zend Framework MVC website into an XML webservice
 */
/**
 * My_Plugin_Xml class
 * 
 * @author Thijs Feryn <thijs@feryn.eu>
 */
class My_Plugin_Xml extends Zend_Controller_Plugin_Abstract 
{
    /**
     * Stores the front controller
     * 
     * @var Zend_Controller_Front
     */
    private $_front;
    /**
     * Stores the XML output in DOMDocument format
     * 
     * @var DOMDocument
     */
    private $_xml;
    /**
     * Class constructor
     */
    public function __construct()
    {
        $this->_front = Zend_Controller_Front::getInstance();
        $layout = Zend_Layout::getMvcInstance();
        $layout->disableLayout();
    }
    /**
     * Build DOMDocument to convert output to XML
     * 
     * @param mixed $return
     * @param Exception $exception
     * @return string
     */
    private function _getXML($return = null,Exception $exception = null)
    {    
        $this->_xml = new DOMDocument('1.0', 'UTF-8');
        $this->_xml->formatOutput = true;
 
        $responseNode = $this->_xml->createElement('response');
 
        $exceptionNode = $this->_xml->createElement('exception');    
        if(null !== $exception && $exception instanceof Exception ){
            $exceptionNode->appendChild(
                $this->_xml->createElement('message',
                    $exception->getMessage()
                )
            );
            $exceptionNode->appendChild(
                $this->_xml->createElement('code',
                    $exception->getCode()
                )
            );    
            $exceptionNode->appendChild(
                $this->_xml->createElement('type',
                    get_class($exception)
                )
            );    
        } 
 
        $responseNode->appendChild($exceptionNode);
        if(null !== $return){
            $responseNode->appendChild(
                $this->_serialize('return',$return)
            );
        } else {
            $responseNode->appendChild(
                $this->_xml->createElement('return')
            );
        }
 
        $this->_xml->appendChild($responseNode);
        return $this->_xml->saveXML();
    }
    /**
     * Modify the HTTP response object
     * Remove the HTML body, replace with XML and change the content-type
     * 
     * @param mixed $return
     * @param Exception $exception
     */
    private function _setResponse($return = false,Exception $exception = null)
    {
        $this->getResponse()->setHeader('Content-Type','text/xml; charset=UTF-8');
        $this->getResponse()->clearBody();
        $this->getResponse()->setBody(
            $this->_getXML($return,$exception)
        );            
    }
    /**
     * Serialize a mixed value to XML in DOMElement format
     * This method can be used recursively in case of objects and arrays
     *  
     * @param string $name
     * @param mixed $value
     * @return DOMElement
     */
    private function _serialize($name,$value)
    {
        if(is_array($value)){
            $element = $this->_xml->createElement($name);
            foreach ($value as $k=>$v){
                if(is_numeric($k)){
                    $k = 'item';
                } 
                $element->appendChild($this->_serialize($k,$v));
            }
        } elseif(is_object($value)){
            $element = $this->_xml->createElement($name);
            $reflection = new ReflectionObject($value);
            $properties = $reflection->getProperties();
            foreach ($properties as $property){
                if($property->isPublic()){
                    $element->appendChild(
                        $this->_serialize(
                            $property->getName(),
                            $property->getValue($value)
                        )
                    );
                }
            }
        }else{
            $element = $this->_xml->createElement(
                $name,
                (string)$value
            );
        }
        return $element;
    }
    /**
     * preDispatch hook that retrieves if an Exception was thrown in the application
     * If an exception is thrown, the exception is passed to the exception part of the XML output and script execution is terminated
     * 
     * @param Zend_Controller_Request_Abstract $request
     */
    public function preDispatch(Zend_Controller_Request_Abstract $request)
    {
        if($this->getResponse()->isException()){
            $exArray = $this->getResponse()->getException();
            $this->_setResponse(null,$exArray[0]);    
            $this->getResponse()->sendResponse();
            exit();    
        }
    }
    /**
     * postDispatch hook that serializes the view object to XML by modifying the HTTP response
     * If no exception was thrown script execution continues and the postDispatch method will be called
     * 
     * @param Zend_Controller_Request_Abstract $request
     */
    public function postDispatch(Zend_Controller_Request_Abstract $request)
    {
        $view = Zend_Controller_Action_HelperBroker::getExistingHelper('ViewRenderer')->view;
        $this->_setResponse($view);    
    }
}