<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\HttpKernel\Fragment;

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;
use Symfony\Component\HttpFoundation\RequestStack;
use Symfony\Component\HttpKernel\Controller\ControllerReference;

/**
 * Renders a URI that represents a resource fragment.
 *
 * This class handles the rendering of resource fragments that are included into
 * a main resource. The handling of the rendering is managed by specialized renderers.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 *
 * @see FragmentRendererInterface
 */
class FragmentHandler
{
    private $debug;
    private $renderers = array();
    private $requestStack;

    /**
     * Constructor.
     *
     * @param RequestStack                $requestStack The Request stack that controls the lifecycle of requests
     * @param FragmentRendererInterface[] $renderers    An array of FragmentRendererInterface instances
     * @param bool                        $debug        Whether the debug mode is enabled or not
     */
    public function __construct(RequestStack $requestStack, array $renderers = array(), $debug = false)
    {
        $this->requestStack = $requestStack;
        foreach ($renderers as $renderer) {
            $this->addRenderer($renderer);
        }
        $this->debug = $debug;
    }

    /**
     * Adds a renderer.
     *
     * @param FragmentRendererInterface $renderer A FragmentRendererInterface instance
     */
    public function addRenderer(FragmentRendererInterface $renderer)
    {
        $this->renderers[$renderer->getName()] = $renderer;
    }

    /**
     * Renders a URI and returns the Response content.
     *
     * Available options:
     *
     *  * ignore_errors: true to return an empty string in case of an error
     *
     * @param string|ControllerReference $uri      A URI as a string or a ControllerReference instance
     * @param string                     $renderer The renderer name
     * @param array                      $options  An array of options
     *
     * @return string|null The Response content or null when the Response is streamed
     *
     * @throws \InvalidArgumentException when the renderer does not exist
     * @throws \LogicException           when no master request is being handled
     */
    public function render($uri, $renderer = 'inline', array $options = array())
    {
        if (!isset($options['ignore_errors'])) {
            $options['ignore_errors'] = !$this->debug;
        }

        if (!isset($this->renderers[$renderer])) {
            throw new \InvalidArgumentException(sprintf('The "%s" renderer does not exist.', $renderer));
        }

        if (!$request = $this->requestStack->getCurrentRequest()) {
            throw new \LogicException('Rendering a fragment can only be done when handling a Request.');
        }

        return $this->deliver($this->renderers[$renderer]->render($uri, $request, $options));
    }

    /**
     * Delivers the Response as a string.
     *
     * When the Response is a StreamedResponse, the content is streamed immediately
     * instead of being returned.
     *
     * @param Response $response A Response instance
     *
     * @return string|null The Response content or null when the Response is streamed
     *
     * @throws \RuntimeException when the Response is not successful
     */
    protected function deliver(Response $response)
    {
        if (!$response->isSuccessful()) {
            throw new \RuntimeException(sprintf('Error when rendering "%s" (Status code is %s).', $this->requestStack->getCurrentRequest()->getUri(), $response->getStatusCode()));
        }

        if (!$response instanceof StreamedResponse) {
            return $response->getContent();
        }

        $response->sendContent();
    }
}
