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<?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\HttpFoundation;

/**
* Response represents an HTTP response.
*
* @author Fabien Potencier <fabien@symfony.com>
*
* @api
*/
class Response
{
    const HTTP_CONTINUE = 100;
    const HTTP_SWITCHING_PROTOCOLS = 101;
    const HTTP_PROCESSING = 102; // RFC2518
    const HTTP_OK = 200;
    const HTTP_CREATED = 201;
    const HTTP_ACCEPTED = 202;
    const HTTP_NON_AUTHORITATIVE_INFORMATION = 203;
    const HTTP_NO_CONTENT = 204;
    const HTTP_RESET_CONTENT = 205;
    const HTTP_PARTIAL_CONTENT = 206;
    const HTTP_MULTI_STATUS = 207; // RFC4918
    const HTTP_ALREADY_REPORTED = 208; // RFC5842
    const HTTP_IM_USED = 226; // RFC3229
    const HTTP_MULTIPLE_CHOICES = 300;
    const HTTP_MOVED_PERMANENTLY = 301;
    const HTTP_FOUND = 302;
    const HTTP_SEE_OTHER = 303;
    const HTTP_NOT_MODIFIED = 304;
    const HTTP_USE_PROXY = 305;
    const HTTP_RESERVED = 306;
    const HTTP_TEMPORARY_REDIRECT = 307;
    const HTTP_PERMANENTLY_REDIRECT = 308; // RFC-reschke-http-status-308-07
    const HTTP_BAD_REQUEST = 400;
    const HTTP_UNAUTHORIZED = 401;
    const HTTP_PAYMENT_REQUIRED = 402;
    const HTTP_FORBIDDEN = 403;
    const HTTP_NOT_FOUND = 404;
    const HTTP_METHOD_NOT_ALLOWED = 405;
    const HTTP_NOT_ACCEPTABLE = 406;
    const HTTP_PROXY_AUTHENTICATION_REQUIRED = 407;
    const HTTP_REQUEST_TIMEOUT = 408;
    const HTTP_CONFLICT = 409;
    const HTTP_GONE = 410;
    const HTTP_LENGTH_REQUIRED = 411;
    const HTTP_PRECONDITION_FAILED = 412;
    const HTTP_REQUEST_ENTITY_TOO_LARGE = 413;
    const HTTP_REQUEST_URI_TOO_LONG = 414;
    const HTTP_UNSUPPORTED_MEDIA_TYPE = 415;
    const HTTP_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
    const HTTP_EXPECTATION_FAILED = 417;
    const HTTP_I_AM_A_TEAPOT = 418; // RFC2324
    const HTTP_UNPROCESSABLE_ENTITY = 422; // RFC4918
    const HTTP_LOCKED = 423; // RFC4918
    const HTTP_FAILED_DEPENDENCY = 424; // RFC4918
    const HTTP_RESERVED_FOR_WEBDAV_ADVANCED_COLLECTIONS_EXPIRED_PROPOSAL = 425; // RFC2817
    const HTTP_UPGRADE_REQUIRED = 426; // RFC2817
    const HTTP_PRECONDITION_REQUIRED = 428; // RFC6585
    const HTTP_TOO_MANY_REQUESTS = 429; // RFC6585
    const HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE = 431; // RFC6585
    const HTTP_INTERNAL_SERVER_ERROR = 500;
    const HTTP_NOT_IMPLEMENTED = 501;
    const HTTP_BAD_GATEWAY = 502;
    const HTTP_SERVICE_UNAVAILABLE = 503;
    const HTTP_GATEWAY_TIMEOUT = 504;
    const HTTP_VERSION_NOT_SUPPORTED = 505;
    const HTTP_VARIANT_ALSO_NEGOTIATES_EXPERIMENTAL = 506; // RFC2295
    const HTTP_INSUFFICIENT_STORAGE = 507; // RFC4918
    const HTTP_LOOP_DETECTED = 508; // RFC5842
    const HTTP_NOT_EXTENDED = 510; // RFC2774
    const HTTP_NETWORK_AUTHENTICATION_REQUIRED = 511; // RFC6585

    /**
* @var \Symfony\Component\HttpFoundation\ResponseHeaderBag
*/
    public $headers;

    /**
* @var string
*/
    protected $content;

    /**
* @var string
*/
    protected $version;

    /**
* @var int
*/
    protected $statusCode;

    /**
* @var string
*/
    protected $statusText;

    /**
* @var string
*/
    protected $charset;

    /**
* Status codes translation table.
*
* The list of codes is complete according to the
* {@link http://www.iana.org/assignments/http-status-codes/ Hypertext Transfer Protocol (HTTP) Status Code Registry}
* (last updated 2012-02-13).
*
* Unless otherwise noted, the status code is defined in RFC2616.
*
* @var array
*/
    public static $statusTexts = array(
        100 => 'Continue',
        101 => 'Switching Protocols',
        102 => 'Processing', // RFC2518
        200 => 'OK',
        201 => 'Created',
        202 => 'Accepted',
        203 => 'Non-Authoritative Information',
        204 => 'No Content',
        205 => 'Reset Content',
        206 => 'Partial Content',
        207 => 'Multi-Status', // RFC4918
        208 => 'Already Reported', // RFC5842
        226 => 'IM Used', // RFC3229
        300 => 'Multiple Choices',
        301 => 'Moved Permanently',
        302 => 'Found',
        303 => 'See Other',
        304 => 'Not Modified',
        305 => 'Use Proxy',
        306 => 'Reserved',
        307 => 'Temporary Redirect',
        308 => 'Permanent Redirect', // RFC-reschke-http-status-308-07
        400 => 'Bad Request',
        401 => 'Unauthorized',
        402 => 'Payment Required',
        403 => 'Forbidden',
        404 => 'Not Found',
        405 => 'Method Not Allowed',
        406 => 'Not Acceptable',
        407 => 'Proxy Authentication Required',
        408 => 'Request Timeout',
        409 => 'Conflict',
        410 => 'Gone',
        411 => 'Length Required',
        412 => 'Precondition Failed',
        413 => 'Request Entity Too Large',
        414 => 'Request-URI Too Long',
        415 => 'Unsupported Media Type',
        416 => 'Requested Range Not Satisfiable',
        417 => 'Expectation Failed',
        418 => 'I\'m a teapot', // RFC2324
        422 => 'Unprocessable Entity', // RFC4918
        423 => 'Locked', // RFC4918
        424 => 'Failed Dependency', // RFC4918
        425 => 'Reserved for WebDAV advanced collections expired proposal', // RFC2817
        426 => 'Upgrade Required', // RFC2817
        428 => 'Precondition Required', // RFC6585
        429 => 'Too Many Requests', // RFC6585
        431 => 'Request Header Fields Too Large', // RFC6585
        500 => 'Internal Server Error',
        501 => 'Not Implemented',
        502 => 'Bad Gateway',
        503 => 'Service Unavailable',
        504 => 'Gateway Timeout',
        505 => 'HTTP Version Not Supported',
        506 => 'Variant Also Negotiates (Experimental)', // RFC2295
        507 => 'Insufficient Storage', // RFC4918
        508 => 'Loop Detected', // RFC5842
        510 => 'Not Extended', // RFC2774
        511 => 'Network Authentication Required', // RFC6585
    );

    /**
* Constructor.
*
* @param mixed $content The response content, see setContent()
* @param int $status The response status code
* @param array $headers An array of response headers
*
* @throws \InvalidArgumentException When the HTTP status code is not valid
*
* @api
*/
    public function __construct($content = '', $status = 200, $headers = array())
    {
        $this->headers = new ResponseHeaderBag($headers);
        $this->setContent($content);
        $this->setStatusCode($status);
        $this->setProtocolVersion('1.0');
        if (!$this->headers->has('Date')) {
            $this->setDate(new \DateTime(null, new \DateTimeZone('UTC')));
        }
    }

    /**
* Factory method for chainability
*
* Example:
*
* return Response::create($body, 200)
* ->setSharedMaxAge(300);
*
* @param mixed $content The response content, see setContent()
* @param int $status The response status code
* @param array $headers An array of response headers
*
* @return Response
*/
    public static function create($content = '', $status = 200, $headers = array())
    {
        return new static($content, $status, $headers);
    }

    /**
* Returns the Response as an HTTP string.
*
* The string representation of the Response is the same as the
* one that will be sent to the client only if the prepare() method
* has been called before.
*
* @return string The Response as an HTTP string
*
* @see prepare()
*/
    public function __toString()
    {
        return
            sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText)."\r\n".
            $this->headers."\r\n".
            $this->getContent();
    }

    /**
* Clones the current Response instance.
*/
    public function __clone()
    {
        $this->headers = clone $this->headers;
    }

    /**
* Prepares the Response before it is sent to the client.
*
* This method tweaks the Response to ensure that it is
* compliant with RFC 2616. Most of the changes are based on
* the Request that is "associated" with this Response.
*
* @param Request $request A Request instance
*
* @return Response The current response.
*/
    public function prepare(Request $request)
    {
        $headers = $this->headers;

        if ($this->isInformational() || in_array($this->statusCode, array(204, 304))) {
            $this->setContent(null);
        }

        // Content-type based on the Request
        if (!$headers->has('Content-Type')) {
            $format = $request->getRequestFormat();
            if (null !== $format && $mimeType = $request->getMimeType($format)) {
                $headers->set('Content-Type', $mimeType);
            }
        }

        // Fix Content-Type
        $charset = $this->charset ?: 'UTF-8';
        if (!$headers->has('Content-Type')) {
            $headers->set('Content-Type', 'text/html; charset='.$charset);
        } elseif (0 === stripos($headers->get('Content-Type'), 'text/') && false === stripos($headers->get('Content-Type'), 'charset')) {
            // add the charset
            $headers->set('Content-Type', $headers->get('Content-Type').'; charset='.$charset);
        }

        // Fix Content-Length
        if ($headers->has('Transfer-Encoding')) {
            $headers->remove('Content-Length');
        }

        if ($request->isMethod('HEAD')) {
            // cf. RFC2616 14.13
            $length = $headers->get('Content-Length');
            $this->setContent(null);
            if ($length) {
                $headers->set('Content-Length', $length);
            }
        }

        // Fix protocol
        if ('HTTP/1.0' != $request->server->get('SERVER_PROTOCOL')) {
            $this->setProtocolVersion('1.1');
        }

        // Check if we need to send extra expire info headers
        if ('1.0' == $this->getProtocolVersion() && 'no-cache' == $this->headers->get('Cache-Control')) {
            $this->headers->set('pragma', 'no-cache');
            $this->headers->set('expires', -1);
        }

        $this->ensureIEOverSSLCompatibility($request);

        return $this;
    }

    /**
* Sends HTTP headers.
*
* @return Response
*/
    public function sendHeaders()
    {
        // headers have already been sent by the developer
        if (headers_sent()) {
            return $this;
        }

        // status
        header(sprintf('HTTP/%s %s %s', $this->version, $this->statusCode, $this->statusText), true, $this->statusCode);

        // headers
        foreach ($this->headers->allPreserveCase() as $name => $values) {
            foreach ($values as $value) {
                header($name.': '.$value, false, $this->statusCode);
            }
        }

        // cookies
        foreach ($this->headers->getCookies() as $cookie) {
            setcookie($cookie->getName(), $cookie->getValue(), $cookie->getExpiresTime(), $cookie->getPath(), $cookie->getDomain(), $cookie->isSecure(), $cookie->isHttpOnly());
        }

        return $this;
    }

    /**
* Sends content for the current web response.
*
* @return Response
*/
    public function sendContent()
    {
        echo $this->content;

        return $this;
    }

    /**
* Sends HTTP headers and content.
*
* @return Response
*
* @api
*/
    public function send()
    {
        $this->sendHeaders();
        $this->sendContent();

        if (function_exists('fastcgi_finish_request')) {
            fastcgi_finish_request();
        } elseif ('cli' !== PHP_SAPI) {
            static::closeOutputBuffers(0, true);
            flush();
        }

        return $this;
    }

    /**
* Sets the response content.
*
* Valid types are strings, numbers, null, and objects that implement a __toString() method.
*
* @param mixed $content Content that can be cast to string
*
* @return Response
*
* @throws \UnexpectedValueException
*
* @api
*/
    public function setContent($content)
    {
        if (null !== $content && !is_string($content) && !is_numeric($content) && !is_callable(array($content, '__toString'))) {
            throw new \UnexpectedValueException(sprintf('The Response content must be a string or object implementing __toString(), "%s" given.', gettype($content)));
        }

        $this->content = (string) $content;

        return $this;
    }

    /**
* Gets the current response content.
*
* @return string Content
*
* @api
*/
    public function getContent()
    {
        return $this->content;
    }

    /**
* Sets the HTTP protocol version (1.0 or 1.1).
*
* @param string $version The HTTP protocol version
*
* @return Response
*
* @api
*/
    public function setProtocolVersion($version)
    {
        $this->version = $version;

        return $this;
    }

    /**
* Gets the HTTP protocol version.
*
* @return string The HTTP protocol version
*
* @api
*/
    public function getProtocolVersion()
    {
        return $this->version;
    }

    /**
* Sets the response status code.
*
* @param int $code HTTP status code
* @param mixed $text HTTP status text
*
* If the status text is null it will be automatically populated for the known
* status codes and left empty otherwise.
*
* @return Response
*
* @throws \InvalidArgumentException When the HTTP status code is not valid
*
* @api
*/
    public function setStatusCode($code, $text = null)
    {
        $this->statusCode = $code = (int) $code;
        if ($this->isInvalid()) {
            throw new \InvalidArgumentException(sprintf('The HTTP status code "%s" is not valid.', $code));
        }

        if (null === $text) {
            $this->statusText = isset(self::$statusTexts[$code]) ? self::$statusTexts[$code] : '';

            return $this;
        }

        if (false === $text) {
            $this->statusText = '';

            return $this;
        }

        $this->statusText = $text;

        return $this;
    }

    /**
* Retrieves the status code for the current web response.
*
* @return int Status code
*
* @api
*/
    public function getStatusCode()
    {
        return $this->statusCode;
    }

    /**
* Sets the response charset.
*
* @param string $charset Character set
*
* @return Response
*
* @api
*/
    public function setCharset($charset)
    {
        $this->charset = $charset;

        return $this;
    }

    /**
* Retrieves the response charset.
*
* @return string Character set
*
* @api
*/
    public function getCharset()
    {
        return $this->charset;
    }

    /**
* Returns true if the response is worth caching under any circumstance.
*
* Responses marked "private" with an explicit Cache-Control directive are
* considered uncacheable.
*
* Responses with neither a freshness lifetime (Expires, max-age) nor cache
* validator (Last-Modified, ETag) are considered uncacheable.
*
* @return bool true if the response is worth caching, false otherwise
*
* @api
*/
    public function isCacheable()
    {
        if (!in_array($this->statusCode, array(200, 203, 300, 301, 302, 404, 410))) {
            return false;
        }

        if ($this->headers->hasCacheControlDirective('no-store') || $this->headers->getCacheControlDirective('private')) {
            return false;
        }

        return $this->isValidateable() || $this->isFresh();
    }

    /**
* Returns true if the response is "fresh".
*
* Fresh responses may be served from cache without any interaction with the
* origin. A response is considered fresh when it includes a Cache-Control/max-age
* indicator or Expires header and the calculated age is less than the freshness lifetime.
*
* @return bool true if the response is fresh, false otherwise
*
* @api
*/
    public function isFresh()
    {
        return $this->getTtl() > 0;
    }

    /**
* Returns true if the response includes headers that can be used to validate
* the response with the origin server using a conditional GET request.
*
* @return bool true if the response is validateable, false otherwise
*
* @api
*/
    public function isValidateable()
    {
        return $this->headers->has('Last-Modified') || $this->headers->has('ETag');
    }

    /**
* Marks the response as "private".
*
* It makes the response ineligible for serving other clients.
*
* @return Response
*
* @api
*/
    public function setPrivate()
    {
        $this->headers->removeCacheControlDirective('public');
        $this->headers->addCacheControlDirective('private');

        return $this;
    }

    /**
* Marks the response as "public".
*
* It makes the response eligible for serving other clients.
*
* @return Response
*
* @api
*/
    public function setPublic()
    {
        $this->headers->addCacheControlDirective('public');
        $this->headers->removeCacheControlDirective('private');

        return $this;
    }

    /**
* Returns true if the response must be revalidated by caches.
*
* This method indicates that the response must not be served stale by a
* cache in any circumstance without first revalidating with the origin.
* When present, the TTL of the response should not be overridden to be
* greater than the value provided by the origin.
*
* @return bool true if the response must be revalidated by a cache, false otherwise
*
* @api
*/
    public function mustRevalidate()
    {
        return $this->headers->hasCacheControlDirective('must-revalidate') || $this->headers->has('proxy-revalidate');
    }

    /**
* Returns the Date header as a DateTime instance.
*
* @return \DateTime A \DateTime instance
*
* @throws \RuntimeException When the header is not parseable
*
* @api
*/
    public function getDate()
    {
        return $this->headers->getDate('Date', new \DateTime());
    }

    /**
* Sets the Date header.
*
* @param \DateTime $date A \DateTime instance
*
* @return Response
*
* @api
*/
    public function setDate(\DateTime $date)
    {
        $date->setTimezone(new \DateTimeZone('UTC'));
        $this->headers->set('Date', $date->format('D, d M Y H:i:s').' GMT');

        return $this;
    }

    /**
* Returns the age of the response.
*
* @return int The age of the response in seconds
*/
    public function getAge()
    {
        if (null !== $age = $this->headers->get('Age')) {
            return (int) $age;
        }

        return max(time() - $this->getDate()->format('U'), 0);
    }

    /**
* Marks the response stale by setting the Age header to be equal to the maximum age of the response.
*
* @return Response
*
* @api
*/
    public function expire()
    {
        if ($this->isFresh()) {
            $this->headers->set('Age', $this->getMaxAge());
        }

        return $this;
    }

    /**
* Returns the value of the Expires header as a DateTime instance.
*
* @return \DateTime|null A DateTime instance or null if the header does not exist
*
* @api
*/
    public function getExpires()
    {
        try {
            return $this->headers->getDate('Expires');
        } catch (\RuntimeException $e) {
            // according to RFC 2616 invalid date formats (e.g. "0" and "-1") must be treated as in the past
            return \DateTime::createFromFormat(DATE_RFC2822, 'Sat, 01 Jan 00 00:00:00 +0000');
        }
    }

    /**
* Sets the Expires HTTP header with a DateTime instance.
*
* Passing null as value will remove the header.
*
* @param \DateTime|null $date A \DateTime instance or null to remove the header
*
* @return Response
*
* @api
*/
    public function setExpires(\DateTime $date = null)
    {
        if (null === $date) {
            $this->headers->remove('Expires');
        } else {
            $date = clone $date;
            $date->setTimezone(new \DateTimeZone('UTC'));
            $this->headers->set('Expires', $date->format('D, d M Y H:i:s').' GMT');
        }

        return $this;
    }

    /**
* Returns the number of seconds after the time specified in the response's Date
* header when the response should no longer be considered fresh.
*
* First, it checks for a s-maxage directive, then a max-age directive, and then it falls
* back on an expires header. It returns null when no maximum age can be established.
*
* @return int|null Number of seconds
*
* @api
*/
    public function getMaxAge()
    {
        if ($this->headers->hasCacheControlDirective('s-maxage')) {
            return (int) $this->headers->getCacheControlDirective('s-maxage');
        }

        if ($this->headers->hasCacheControlDirective('max-age')) {
            return (int) $this->headers->getCacheControlDirective('max-age');
        }

        if (null !== $this->getExpires()) {
            return $this->getExpires()->format('U') - $this->getDate()->format('U');
        }
    }

    /**
* Sets the number of seconds after which the response should no longer be considered fresh.
*
* This methods sets the Cache-Control max-age directive.
*
* @param int $value Number of seconds
*
* @return Response
*
* @api
*/
    public function setMaxAge($value)
    {
        $this->headers->addCacheControlDirective('max-age', $value);

        return $this;
    }

    /**
* Sets the number of seconds after which the response should no longer be considered fresh by shared caches.
*
* This methods sets the Cache-Control s-maxage directive.
*
* @param int $value Number of seconds
*
* @return Response
*
* @api
*/
    public function setSharedMaxAge($value)
    {
        $this->setPublic();
        $this->headers->addCacheControlDirective('s-maxage', $value);

        return $this;
    }

    /**
* Returns the response's time-to-live in seconds.
*
* It returns null when no freshness information is present in the response.
*
* When the responses TTL is <= 0, the response may not be served from cache without first
* revalidating with the origin.
*
* @return int|null The TTL in seconds
*
* @api
*/
    public function getTtl()
    {
        if (null !== $maxAge = $this->getMaxAge()) {
            return $maxAge - $this->getAge();
        }
    }

    /**
* Sets the response's time-to-live for shared caches.
*
* This method adjusts the Cache-Control/s-maxage directive.
*
* @param int $seconds Number of seconds
*
* @return Response
*
* @api
*/
    public function setTtl($seconds)
    {
        $this->setSharedMaxAge($this->getAge() + $seconds);

        return $this;
    }

    /**
* Sets the response's time-to-live for private/client caches.
*
* This method adjusts the Cache-Control/max-age directive.
*
* @param int $seconds Number of seconds
*
* @return Response
*
* @api
*/
    public function setClientTtl($seconds)
    {
        $this->setMaxAge($this->getAge() + $seconds);

        return $this;
    }

    /**
* Returns the Last-Modified HTTP header as a DateTime instance.
*
* @return \DateTime|null A DateTime instance or null if the header does not exist
*
* @throws \RuntimeException When the HTTP header is not parseable
*
* @api
*/
    public function getLastModified()
    {
        return $this->headers->getDate('Last-Modified');
    }

    /**
* Sets the Last-Modified HTTP header with a DateTime instance.
*
* Passing null as value will remove the header.
*
* @param \DateTime|null $date A \DateTime instance or null to remove the header
*
* @return Response
*
* @api
*/
    public function setLastModified(\DateTime $date = null)
    {
        if (null === $date) {
            $this->headers->remove('Last-Modified');
        } else {
            $date = clone $date;
            $date->setTimezone(new \DateTimeZone('UTC'));
            $this->headers->set('Last-Modified', $date->format('D, d M Y H:i:s').' GMT');
        }

        return $this;
    }

    /**
* Returns the literal value of the ETag HTTP header.
*
* @return string|null The ETag HTTP header or null if it does not exist
*
* @api
*/
    public function getEtag()
    {
        return $this->headers->get('ETag');
    }

    /**
* Sets the ETag value.
*
* @param string|null $etag The ETag unique identifier or null to remove the header
* @param bool $weak Whether you want a weak ETag or not
*
* @return Response
*
* @api
*/
    public function setEtag($etag = null, $weak = false)
    {
        if (null === $etag) {
            $this->headers->remove('Etag');
        } else {
            if (0 !== strpos($etag, '"')) {
                $etag = '"'.$etag.'"';
            }

            $this->headers->set('ETag', (true === $weak ? 'W/' : '').$etag);
        }

        return $this;
    }

    /**
* Sets the response's cache headers (validation and/or expiration).
*
* Available options are: etag, last_modified, max_age, s_maxage, private, and public.
*
* @param array $options An array of cache options
*
* @return Response
*
* @throws \InvalidArgumentException
*
* @api
*/
    public function setCache(array $options)
    {
        if ($diff = array_diff(array_keys($options), array('etag', 'last_modified', 'max_age', 's_maxage', 'private', 'public'))) {
            throw new \InvalidArgumentException(sprintf('Response does not support the following options: "%s".', implode('", "', array_values($diff))));
        }

        if (isset($options['etag'])) {
            $this->setEtag($options['etag']);
        }

        if (isset($options['last_modified'])) {
            $this->setLastModified($options['last_modified']);
        }

        if (isset($options['max_age'])) {
            $this->setMaxAge($options['max_age']);
        }

        if (isset($options['s_maxage'])) {
            $this->setSharedMaxAge($options['s_maxage']);
        }

        if (isset($options['public'])) {
            if ($options['public']) {
                $this->setPublic();
            } else {
                $this->setPrivate();
            }
        }

        if (isset($options['private'])) {
            if ($options['private']) {
                $this->setPrivate();
            } else {
                $this->setPublic();
            }
        }

        return $this;
    }

    /**
* Modifies the response so that it conforms to the rules defined for a 304 status code.
*
* This sets the status, removes the body, and discards any headers
* that MUST NOT be included in 304 responses.
*
* @return Response
*
* @see http://tools.ietf.org/html/rfc2616#section-10.3.5
*
* @api
*/
    public function setNotModified()
    {
        $this->setStatusCode(304);
        $this->setContent(null);

        // remove headers that MUST NOT be included with 304 Not Modified responses
        foreach (array('Allow', 'Content-Encoding', 'Content-Language', 'Content-Length', 'Content-MD5', 'Content-Type', 'Last-Modified') as $header) {
            $this->headers->remove($header);
        }

        return $this;
    }

    /**
* Returns true if the response includes a Vary header.
*
* @return bool true if the response includes a Vary header, false otherwise
*
* @api
*/
    public function hasVary()
    {
        return null !== $this->headers->get('Vary');
    }

    /**
* Returns an array of header names given in the Vary header.
*
* @return array An array of Vary names
*
* @api
*/
    public function getVary()
    {
        if (!$vary = $this->headers->get('Vary', null, false)) {
            return array();
        }

        $ret = array();
        foreach ($vary as $item) {
            $ret = array_merge($ret, preg_split('/[\s,]+/', $item));
        }

        return $ret;
    }

    /**
* Sets the Vary header.
*
* @param string|array $headers
* @param bool $replace Whether to replace the actual value of not (true by default)
*
* @return Response
*
* @api
*/
    public function setVary($headers, $replace = true)
    {
        $this->headers->set('Vary', $headers, $replace);

        return $this;
    }

    /**
* Determines if the Response validators (ETag, Last-Modified) match
* a conditional value specified in the Request.
*
* If the Response is not modified, it sets the status code to 304 and
* removes the actual content by calling the setNotModified() method.
*
* @param Request $request A Request instance
*
* @return bool true if the Response validators match the Request, false otherwise
*
* @api
*/
    public function isNotModified(Request $request)
    {
        if (!$request->isMethodSafe()) {
            return false;
        }

        $lastModified = $request->headers->get('If-Modified-Since');
        $notModified = false;
        if ($etags = $request->getEtags()) {
            $notModified = (in_array($this->getEtag(), $etags) || in_array('*', $etags)) && (!$lastModified || $this->headers->get('Last-Modified') == $lastModified);
        } elseif ($lastModified) {
            $notModified = $lastModified == $this->headers->get('Last-Modified');
        }

        if ($notModified) {
            $this->setNotModified();
        }

        return $notModified;
    }

    // http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
    /**
* Is response invalid?
*
* @return bool
*
* @api
*/
    public function isInvalid()
    {
        return $this->statusCode < 100 || $this->statusCode >= 600;
    }

    /**
* Is response informative?
*
* @return bool
*
* @api
*/
    public function isInformational()
    {
        return $this->statusCode >= 100 && $this->statusCode < 200;
    }

    /**
* Is response successful?
*
* @return bool
*
* @api
*/
    public function isSuccessful()
    {
        return $this->statusCode >= 200 && $this->statusCode < 300;
    }

    /**
* Is the response a redirect?
*
* @return bool
*
* @api
*/
    public function isRedirection()
    {
        return $this->statusCode >= 300 && $this->statusCode < 400;
    }

    /**
* Is there a client error?
*
* @return bool
*
* @api
*/
    public function isClientError()
    {
        return $this->statusCode >= 400 && $this->statusCode < 500;
    }

    /**
* Was there a server side error?
*
* @return bool
*
* @api
*/
    public function isServerError()
    {
        return $this->statusCode >= 500 && $this->statusCode < 600;
    }

    /**
* Is the response OK?
*
* @return bool
*
* @api
*/
    public function isOk()
    {
        return 200 === $this->statusCode;
    }

    /**
* Is the response forbidden?
*
* @return bool
*
* @api
*/
    public function isForbidden()
    {
        return 403 === $this->statusCode;
    }

    /**
* Is the response a not found error?
*
* @return bool
*
* @api
*/
    public function isNotFound()
    {
        return 404 === $this->statusCode;
    }

    /**
* Is the response a redirect of some form?
*
* @param string $location
*
* @return bool
*
* @api
*/
    public function isRedirect($location = null)
    {
        return in_array($this->statusCode, array(201, 301, 302, 303, 307, 308)) && (null === $location ?: $location == $this->headers->get('Location'));
    }

    /**
* Is the response empty?
*
* @return bool
*
* @api
*/
    public function isEmpty()
    {
        return in_array($this->statusCode, array(204, 304));
    }

    /**
* Cleans or flushes output buffers up to target level.
*
* Resulting level can be greater than target level if a non-removable buffer has been encountered.
*
* @param int $targetLevel The target output buffering level
* @param bool $flush Whether to flush or clean the buffers
*/
    public static function closeOutputBuffers($targetLevel, $flush)
    {
        $status = ob_get_status(true);
        $level = count($status);

        while ($level-- > $targetLevel
            && (!empty($status[$level]['del'])
                || (isset($status[$level]['flags'])
                    && ($status[$level]['flags'] & PHP_OUTPUT_HANDLER_REMOVABLE)
                    && ($status[$level]['flags'] & ($flush ? PHP_OUTPUT_HANDLER_FLUSHABLE : PHP_OUTPUT_HANDLER_CLEANABLE))
                )
            )
        ) {
            if ($flush) {
                ob_end_flush();
            } else {
                ob_end_clean();
            }
        }
    }

    /**
* Checks if we need to remove Cache-Control for SSL encrypted downloads when using IE < 9
*
* @link http://support.microsoft.com/kb/323308
*/
    protected function ensureIEOverSSLCompatibility(Request $request)
    {
        if (false !== stripos($this->headers->get('Content-Disposition'), 'attachment') && preg_match('/MSIE (.*?);/i', $request->server->get('HTTP_USER_AGENT'), $match) == 1 && true === $request->isSecure()) {
            if (intval(preg_replace("/(MSIE )(.*?);/", "$2", $match[0])) < 9) {
                $this->headers->remove('Cache-Control');
            }
        }
    }
}
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