<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @link      http://github.com/zendframework/zf2 for the canonical source repository
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   http://framework.zend.com/license/new-bsd New BSD License
 * @package   Zend_Mvc
 */

namespace Zend\Mvc\View\Http;

use Zend\EventManager\EventManagerInterface;
use Zend\EventManager\ListenerAggregateInterface;
use Zend\Http\Response as HttpResponse;
use Zend\Mvc\Application;
use Zend\Mvc\MvcEvent;
use Zend\Stdlib\ResponseInterface as Response;
use Zend\View\Model\ViewModel;

/**
 * @category   Zend
 * @package    Zend_Mvc
 * @subpackage View
 */
class ExceptionStrategy implements ListenerAggregateInterface
{
    /**
     * Display exceptions?
     * @var bool
     */
    protected $displayExceptions = false;

    /**
     * Name of exception template
     * @var string
     */
    protected $exceptionTemplate = 'error';

    /**
     * @var \Zend\Stdlib\CallbackHandler[]
     */
    protected $listeners = array();

    /**
     * Attach the aggregate to the specified event manager
     *
     * @param  EventManagerInterface $events
     * @return void
     */
    public function attach(EventManagerInterface $events)
    {
        $this->listeners[] = $events->attach(MvcEvent::EVENT_DISPATCH_ERROR, array($this, 'prepareExceptionViewModel'));
    }

    /**
     * Detach aggregate listeners from the specified event manager
     *
     * @param  EventManagerInterface $events
     * @return void
     */
    public function detach(EventManagerInterface $events)
    {
        foreach ($this->listeners as $index => $listener) {
            if ($events->detach($listener)) {
                unset($this->listeners[$index]);
            }
        }
    }

    /**
     * Flag: display exceptions in error pages?
     *
     * @param  bool $displayExceptions
     * @return ExceptionStrategy
     */
    public function setDisplayExceptions($displayExceptions)
    {
        $this->displayExceptions = (bool) $displayExceptions;
        return $this;
    }

    /**
     * Should we display exceptions in error pages?
     *
     * @return bool
     */
    public function displayExceptions()
    {
        return $this->displayExceptions;
    }

    /**
     * Set the exception template
     *
     * @param  string $exceptionTemplate
     * @return ExceptionStrategy
     */
    public function setExceptionTemplate($exceptionTemplate)
    {
        $this->exceptionTemplate = (string) $exceptionTemplate;
        return $this;
    }

    /**
     * Retrieve the exception template
     *
     * @return string
     */
    public function getExceptionTemplate()
    {
        return $this->exceptionTemplate;
    }

    /**
     * Create an exception view model, and set the HTTP status code
     *
     * @todo   dispatch.error does not halt dispatch unless a response is
     *         returned. As such, we likely need to trigger rendering as a low
     *         priority dispatch.error event (or goto a render event) to ensure
     *         rendering occurs, and that munging of view models occurs when
     *         expected.
     * @param  MvcEvent $e
     * @return void
     */
    public function prepareExceptionViewModel(MvcEvent $e)
    {
        // Do nothing if no error in the event
        $error = $e->getError();
        if (empty($error)) {
            return;
        }

        // Do nothing if the result is a response object
        $result = $e->getResult();
        if ($result instanceof Response) {
            return;
        }

        switch ($error) {
            case Application::ERROR_CONTROLLER_NOT_FOUND:
            case Application::ERROR_CONTROLLER_INVALID:
            case Application::ERROR_ROUTER_NO_MATCH:
                // Specifically not handling these
                return;

            case Application::ERROR_EXCEPTION:
            default:
                $model = new ViewModel(array(
                    'message'            => 'An error occurred during execution; please try again later.',
                    'exception'          => $e->getParam('exception'),
                    'display_exceptions' => $this->displayExceptions(),
                ));
                $model->setTemplate($this->getExceptionTemplate());
                $e->setResult($model);

                $response = $e->getResponse();
                if (!$response) {
                    $response = new HttpResponse();
                    $e->setResponse($response);
                }
                $response->setStatusCode(500);
                break;
        }
    }
}
