<?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;

/**
 * ResponseHeaderBag is a container for Response HTTP headers.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class ResponseHeaderBag extends HeaderBag
{
    protected $computedCacheControl = array();

    /**
     * Constructor.
     *
     * @param array $headers An array of HTTP headers
     */
    public function __construct(array $headers = array())
    {
        parent::__construct($headers);

        if (!isset($this->headers['cache-control'])) {
            $this->set('cache-control', '');
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function __toString()
    {
        $cookies = '';
        foreach ($this->cookies as $cookie) {
            $cookies .= 'Set-Cookie: '.$cookie."\r\n";
        }

        return parent::__toString().$cookies;
    }

    /**
     * {@inheritdoc}
     */
    public function replace(array $headers = array())
    {
        parent::replace($headers);

        if (!isset($this->headers['cache-control'])) {
            $this->set('cache-control', '');
        }
    }

    /**
     * {@inheritdoc}
     */
    public function set($key, $values, $replace = true)
    {
        parent::set($key, $values, $replace);

        // ensure the cache-control header has sensible defaults
        if (in_array(strtr(strtolower($key), '_', '-'), array('cache-control', 'etag', 'last-modified', 'expires'))) {
            $computed = $this->computeCacheControlValue();
            $this->headers['cache-control'] = array($computed);
            $this->computedCacheControl = $this->parseCacheControl($computed);
        }
    }

    /**
     * {@inheritdoc}
     */
    public function remove($key)
    {
        parent::remove($key);

        if ('cache-control' === strtr(strtolower($key), '_', '-')) {
            $this->computedCacheControl = array();
        }
    }

    /**
     * {@inheritdoc}
     */
    public function hasCacheControlDirective($key)
    {
        return array_key_exists($key, $this->computedCacheControl);
    }

    /**
     * {@inheritdoc}
     */
    public function getCacheControlDirective($key)
    {
        return array_key_exists($key, $this->computedCacheControl) ? $this->computedCacheControl[$key] : null;
    }

    /**
     * Clears a cookie in the browser
     *
     * @param string $name
     * @param string $path
     * @param string $domain
     * @return void
     */
    public function clearCookie($name, $path = null, $domain = null)
    {
        $this->setCookie(new Cookie($name, null, 1, $path, $domain));
    }

    /**
     * Returns the calculated value of the cache-control header.
     *
     * This considers several other headers and calculates or modifies the
     * cache-control header to a sensible, conservative value.
     *
     * @return string
     */
    protected function computeCacheControlValue()
    {
        if (!$this->cacheControl && !$this->has('ETag') && !$this->has('Last-Modified') && !$this->has('Expires')) {
            return 'no-cache';
        }

        if (!$this->cacheControl) {
            // conservative by default
            return 'private, must-revalidate';
        }

        $header = $this->getCacheControlHeader();
        if (isset($this->cacheControl['public']) || isset($this->cacheControl['private'])) {
            return $header;
        }

        // public if s-maxage is defined, private otherwise
        if (!isset($this->cacheControl['s-maxage'])) {
            return $header.', private';
        }

        return $header;
    }
}