<?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\HttpCache;

use Symfony\Component\HttpFoundation\Request;

use Symfony\Component\HttpFoundation\Response;

use Symfony\Component\HttpKernel\HttpKernelInterface;

/**

 * Esi implements the ESI capabilities to Request and Response instances.

 *

 * For more information, read the following W3C notes:

 *

 *  * ESI Language Specification 1.0 (http://www.w3.org/TR/esi-lang)

 *

 *  * Edge Architecture Specification (http://www.w3.org/TR/edge-arch)

 *

 * @author Fabien Potencier <fabien@symfony.com>

 */

class Esi

{

    private $contentTypes;

    /**

     * Constructor.

     *

     * @param array $contentTypes An array of content-type that should be parsed for ESI information.

     *                           (default: text/html, text/xml, and application/xml)

     */

    public function __construct(array $contentTypes = array('text/html', 'text/xml', 'application/xml'))

    {

        $this->contentTypes = $contentTypes;

    }

    /**

     * Returns a new cache strategy instance.

     *

     * @return EsiResponseCacheStrategyInterface A EsiResponseCacheStrategyInterface instance

     */

    public function createCacheStrategy()

    {

        return new EsiResponseCacheStrategy();

    }

    /**

     * Checks that at least one surrogate has ESI/1.0 capability.

     *

     * @param Request $request A Request instance

     *

     * @return Boolean true if one surrogate has ESI/1.0 capability, false otherwise

     */

    public function hasSurrogateEsiCapability(Request $request)

    {

        if (null === $value = $request->headers->get('Surrogate-Capability')) {

            return false;

        }

        return (Boolean) preg_match('#ESI/1.0#', $value);

    }

    /**

     * Adds ESI/1.0 capability to the given Request.

     *

     * @param Request $request A Request instance

     */

    public function addSurrogateEsiCapability(Request $request)

    {

        $current = $request->headers->get('Surrogate-Capability');

        $new = 'symfony2="ESI/1.0"';

        $request->headers->set('Surrogate-Capability', $current ? $current.', '.$new : $new);

    }

    /**

     * Adds HTTP headers to specify that the Response needs to be parsed for ESI.

     *

     * This method only adds an ESI HTTP header if the Response has some ESI tags.

     *

     * @param Response $response A Response instance

     */

    public function addSurrogateControl(Response $response)

    {

        if (false !== strpos($response->getContent(), '<esi:include')) {

            $response->headers->set('Surrogate-Control', 'content="ESI/1.0"');

        }

    }

    /**

     * Checks that the Response needs to be parsed for ESI tags.

     *

     * @param Response $response A Response instance

     *

     * @return Boolean true if the Response needs to be parsed, false otherwise

     */

    public function needsEsiParsing(Response $response)

    {

        if (!$control = $response->headers->get('Surrogate-Control')) {

            return false;

        }

        return (Boolean) preg_match('#content="[^"]*ESI/1.0[^"]*"#', $control);

    }

    /**

     * Renders an ESI tag.

     *

     * @param string  $uri          A URI

     * @param string  $alt          An alternate URI

     * @param Boolean $ignoreErrors Whether to ignore errors or not

     * @param string  $comment      A comment to add as an esi:include tag

     */

    public function renderIncludeTag($uri, $alt = null, $ignoreErrors = true, $comment = '')

    {

        $html = sprintf('<esi:include src="%s"%s%s />',

            $uri,

            $ignoreErrors ? ' onerror="continue"' : '',

            $alt ? sprintf(' alt="%s"', $alt) : ''

        );

        if (!empty($comment)) {

            return sprintf("<esi:comment text=\"%s\" />\n%s", $comment, $html);

        }

        return $html;

    }

    /**

     * Replaces a Response ESI tags with the included resource content.

     *

     * @param Request  $request  A Request instance

     * @param Response $response A Response instance

     */

    public function process(Request $request, Response $response)

    {

        $this->request = $request;

        $type = $response->headers->get('Content-Type');

        if (empty($type)) {

            $type = 'text/html';

        }

        $parts = explode(';', $type);

        if (!in_array($parts[0], $this->contentTypes)) {

            return $response;

        }

        // we don't use a proper XML parser here as we can have ESI tags in a plain text response

        $content = $response->getContent();

        $content = preg_replace_callback('#<esi\:include\s+(.*?)\s*/>#', array($this, 'handleEsiIncludeTag'), $content);

        $content = preg_replace('#<esi\:comment[^>]*/>#', '', $content);

        $content = preg_replace('#<esi\:remove>.*?</esi\:remove>#', '', $content);

        $response->setContent($content);

        $response->headers->set('X-Body-Eval', 'ESI');

        // remove ESI/1.0 from the Surrogate-Control header

        if ($response->headers->has('Surrogate-Control')) {

            $value = $response->headers->get('Surrogate-Control');

            if ('content="ESI/1.0"' == $value) {

                $response->headers->remove('Surrogate-Control');

            } elseif (preg_match('#,\s*content="ESI/1.0"#', $value)) {

                $response->headers->set('Surrogate-Control', preg_replace('#,\s*content="ESI/1.0"#', '', $value));

            } elseif (preg_match('#content="ESI/1.0",\s*#', $value)) {

                $response->headers->set('Surrogate-Control', preg_replace('#content="ESI/1.0",\s*#', '', $value));

            }

        }

    }

    /**

     * Handles an ESI from the cache.

     *

     * @param HttpCache $cache        An HttpCache instance

     * @param string    $uri          The main URI

     * @param string    $alt          An alternative URI

     * @param Boolean   $ignoreErrors Whether to ignore errors or not

     */

    public function handle(HttpCache $cache, $uri, $alt, $ignoreErrors)

    {

        $subRequest = Request::create($uri, 'get', array(), $cache->getRequest()->cookies->all(), array(), $cache->getRequest()->server->all());

        try {

            $response = $cache->handle($subRequest, HttpKernelInterface::SUB_REQUEST, true);

            if (!$response->isSuccessful()) {

                throw new \RuntimeException(sprintf('Error when rendering "%s" (Status code is %s).', $subRequest->getUri(), $response->getStatusCode()));

            }

            return $response->getContent();

        } catch (\Exception $e) {

            if ($alt) {

                return $this->handle($cache, $alt, '', $ignoreErrors);

            }

            if (!$ignoreErrors) {

                throw $e;

            }

        }

    }

    /**

     * Handles an ESI include tag (called internally).

     *

     * @param array $attributes An array containing the attributes.

     *

     * @return string The response content for the include.

     */

    private function handleEsiIncludeTag($attributes)

    {

        $options = array();

        preg_match_all('/(src|onerror|alt)="([^"]*?)"/', $attributes[1], $matches, PREG_SET_ORDER);

        foreach ($matches as $set) {

            $options[$set[1]] = $set[2];

        }

        if (!isset($options['src'])) {

            throw new \RuntimeException('Unable to process an ESI tag without a "src" attribute.');

        }

        return sprintf('<?php echo $this->esi->handle($this, \'%s\', \'%s\', %s) ?>'."\n",

            $options['src'],

            isset($options['alt']) ? $options['alt'] : null,

            isset($options['onerror']) && 'continue' == $options['onerror'] ? 'true' : 'false'

        );

    }

}