<?php

// phpcs:disable PSR1.Classes.ClassDeclaration.MissingNamespace
// phpcs:disable PSR1.Files.SideEffects
defined('SYSPATH') or die('No direct access allowed.');
// phpcs:enable PSR1.Files.SideEffects
// phpcs:disable Squiz.Classes.ValidClassName.NotCamelCaps

/**
 * Controls headers that effect client caching of pages
 *
 * $Id: expires.php 4272 2009-04-25 21:47:26Z zombor $
 *
 * @package    Core
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
class expires_Core
{
    /**
     * Sets the amount of time before a page expires
     *
     * @param  integer Seconds before the page expires
     * @return boolean
     */
    public static function set($seconds = 60)
    {
        if (expires::check_headers()) {
            $now = $expires = time();

            // Set the expiration timestamp
            $expires += $seconds;

            // Send headers
            header('Last-Modified: ' . gmdate('D, d M Y H:i:s T', $now));
            header('Expires: ' . gmdate('D, d M Y H:i:s T', $expires));
            header('Cache-Control: max-age=' . $seconds);

            return $expires;
        }

        return false;
    }

    /**
     * Checks to see if a page should be updated or send Not Modified status
     *
     * @param   integer  Seconds added to the modified time received to calculate what should be sent
     * @return  bool     FALSE when the request needs to be updated
     */
    public static function check($seconds = 60)
    {
        if (! empty($_SERVER['HTTP_IF_MODIFIED_SINCE']) and expires::check_headers()) {
            if (($strpos = strpos($_SERVER['HTTP_IF_MODIFIED_SINCE'], ';')) !== false) {
                // IE6 and perhaps other IE versions send length too, compensate here
                $mod_time = substr($_SERVER['HTTP_IF_MODIFIED_SINCE'], 0, $strpos);
            } else {
                $mod_time = $_SERVER['HTTP_IF_MODIFIED_SINCE'];
            }

            $mod_time = strtotime($mod_time);
            $mod_time_diff = $mod_time + $seconds - time();

            if ($mod_time_diff > 0) {
                // Re-send headers
                header('Last-Modified: ' . gmdate('D, d M Y H:i:s T', $mod_time));
                header('Expires: ' . gmdate('D, d M Y H:i:s T', time() + $mod_time_diff));
                header('Cache-Control: max-age=' . $mod_time_diff);
                header('Status: 304 Not Modified', true, 304);

                // Prevent any output
                Event::add('system.display', array('expires', 'prevent_output'));

                // Exit to prevent other output
                exit;
            }
        }

        return false;
    }

    /**
     * Check headers already created to not step on download or Img_lib's feet
     *
     * @return boolean
     */
    public static function check_headers()
    {
        foreach (headers_list() as $header) {
            if (
                (session_cache_limiter() == '' and stripos($header, 'Last-Modified:') === 0)
                or stripos($header, 'Expires:') === 0
            ) {
                return false;
            }
        }

        return true;
    }

    /**
     * Prevent any output from being displayed. Executed during system.display.
     *
     * @return  void
     */
    public static function prevent_output()
    {
        Kohana::$output = '';
    }
}
// End expires