<?php
/**
 * PageCache powered by Varnish
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to support@phoenix-media.eu so we can send you a copy immediately.
 *
 * @category   Phoenix
 * @package    Phoenix_VarnishCache
 * @copyright  Copyright (c) 2011 PHOENIX MEDIA GmbH & Co. KG (http://www.phoenix-media.de)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

class Phoenix_VarnishCache_Helper_Cache extends Mage_Core_Helper_Abstract
{
    const XML_PATH_VARNISH_CACHE_DISABLE_CACHING      = 'system/varnishcache/disable_caching';
    const XML_PATH_VARNISH_CACHE_DISABLE_CACHING_VARS = 'system/varnishcache/disable_caching_vars';
    const XML_PATH_VARNISH_CACHE_DISABLE_ROUTES       = 'system/varnishcache/disable_routes';
    const XML_PATH_VARNISH_CACHE_TTL                  = 'system/varnishcache/ttl';
    const XML_PATH_VARNISH_CACHE_ROUTES_TTL           = 'system/varnishcache/routes_ttl';

    /**
     * Cookie name for disabling external caching
     *
     * @var string
     */
    const NO_CACHE_COOKIE = 'EXTERNAL_NO_CACHE';

    /**
     * Header for debug flag
     *
     * @var string
     * @return void
     */
    const DEBUG_HEADER = 'X-Cache-Debug: 1';
    
    
    /**
     * Get Cookie object
     * 
     * @return Mage_Core_Model_Cookie
     */
    public static function getCookie()
    {
    	return Mage::getSingleton('core/cookie');
    }


    /**
     * Set appropriate cache control headers
     *
     * @return Phoenix_VarnishCache_Helper_Cache
     */
    public function setCacheControlHeaders()
    {
        $request = Mage::app()->getRequest();
        
        // set debug header
        if (Mage::helper('varnishcache')->isDebug()) {
            $this->setDebugHeader();
        }

        // check for disable caching vars
        if ($disableCachingVars = trim(Mage::getStoreConfig(self::XML_PATH_VARNISH_CACHE_DISABLE_CACHING_VARS))) {
            foreach (explode(',', $disableCachingVars) as $param) {
                if ($request->getParam(trim($param))) {
                    $this->setNoCacheHeader();
                    return $this->setNoCacheCookie();
                }
            }
        }

        // renew no-cache cookie
        $this->setNoCacheCookie(true);

        // disable page caching for POSTs and no_cache parameters
        if ($request->isPost() || $request->getParam('no_cache') ||
            !in_array(Mage::app()->getResponse()->getHttpResponseCode(), array(200, 301, 404))) {
            return $this->setNoCacheHeader();
        }

        // disable page caching because of configuration
        if (Mage::getStoreConfigFlag(self::XML_PATH_VARNISH_CACHE_DISABLE_CACHING)) {
            return $this->setNoCacheHeader();
        }


        /**
         * Check for ruleset depending on request path
         *
         * see: Mage_Core_Controller_Varien_Action::getFullActionName()
         */
        $fullActionName = $request->getRequestedRouteName().'_'.
            $request->getRequestedControllerName().'_'.
            $request->getRequestedActionName();
			
        Mage::app()->getResponse()->setHeader("PW-MageDebug-Route", $fullActionName, true);

        // check caching blacklist for request routes
        $disableRoutes = explode("\n", trim(Mage::getStoreConfig(self::XML_PATH_VARNISH_CACHE_DISABLE_ROUTES)));
        foreach ($disableRoutes as $route) {
            $route = trim($route);
            // if route is found at first position we have a hit
            if (!empty($route) && strpos($fullActionName, $route) === 0) {
                return $this->setNoCacheHeader();
            }
        }

        // set TTL header
        $regexp = null;
        $value = null;
        $routesTtl = unserialize(Mage::getStoreConfig(self::XML_PATH_VARNISH_CACHE_ROUTES_TTL));
        if (is_array($routesTtl)) {
            foreach ($routesTtl as $routeTtl) {
                extract($routeTtl, EXTR_OVERWRITE);
                $regexp = trim($regexp);
                if (!empty($regexp) && strpos($fullActionName, $regexp) === 0) {
                    break;
                }
                $value = null;
            }
        }
        if (!isset($value)) {
            $value = Mage::getStoreConfig(self::XML_PATH_VARNISH_CACHE_TTL);
        }
        Mage::app()->getResponse()->setHeader("PW-MageDebug-TTL", $value, true);
        $this->setTtlHeader(intval($value));

        return $this;
    }
    
    /**
     * Check for a NO_CACHE cookie and if found force a TTL=0 for this
     * page.
     * 
     *  @return void
     */
    public static function sanitizeCacheControlHeader()
    {
    	$cookie = self::getCookie();
    	if ($cookie->get(self::NO_CACHE_COOKIE)) {
    		self::setNoCacheHeader();
    	}
    }

    /**
     * Disable caching of this and all future request for this visitor
     *
     * @return Phoenix_VarnishCache_Helper_Cache
     */
    public function setNoCacheCookie($renewOnly = false)
    {
        if ($this->getCookie()->get(self::NO_CACHE_COOKIE)) {
            $this->getCookie()->renew(self::NO_CACHE_COOKIE);
        } elseif (!$renewOnly) {
            $this->getCookie()->set(self::NO_CACHE_COOKIE, 1);
        }
        return $this;
    }

    /**
     * Disable caching for this request
     *
     * @return Phoenix_VarnishCache_Helper_Cache
     */
    public static function setNoCacheHeader()
    {
        return self::setTtlHeader(0);
    }

    /**
     * Set debug flag in HTTP header
     *
     * @return Phoenix_VarnishCache_Helper_Cache
     */
    public function setDebugHeader()
    {
        $el = explode(':', self::DEBUG_HEADER, 2);
        Mage::app()->getResponse()->setHeader($el[0], $el[1], true);
        return $this;
    }

    /**
     * Set TTL HTTP header for cache
     *
     * For mod_expires it is important to have "Expires" header. However for
     * Varnish it is easier to deal with "Cache-Control: s-maxage=xx" as it
     * is relative to its system time and not depending on timezone settings.
     * 
     * Magento normaly doesn't set any Cache-Control or Expires headers. If they
     * appear the are set by PHP's setcookie() function.
     *
     * @param int   Time to life in seconds. Value greater than 0 means "cacheable".
     * @return void
     */
    public static function setTtlHeader($ttl)
    {
        Mage::app()->getResponse()->setHeader("X-VARNISH-TTL", $ttl, true);
        $maxAge = 's-maxage=' . (($ttl < 0) ? 0 : $ttl);
        $cacheControlValue = 'no-store, no-cache, must-revalidate, post-check=0, pre-check=0, '.$maxAge;

        // retrieve existing "Cache-Control" header
        $response = Mage::app()->getResponse();
        $headers = $response->getHeaders();

        foreach ($headers as $key => $header) {
            if ('Cache-Control' == $header['name'] && !empty($header['value'])) {
                // replace existing "max-age" value
                if (strpos($header['value'], 'age=') !== false) {
                    $cacheControlValue = preg_replace('/(s-)?max[-]?age=[0-9]+/', $maxAge, $header['value']);
					Mage::app()->getResponse()->setHeader("PW-MageDebug-cacheControl1", $cacheControlValue . ' -- ' . $maxAge . ' -- ' . $header['value'], true);
                } else {
                    $cacheControlValue .= $header['value'].', '.$maxAge;
					Mage::app()->getResponse()->setHeader("PW-MageDebug-cacheControl2", $cacheControlValue . ' -- ' . $maxAge . ' -- ' . $header['value'], true);
                }
				Mage::app()->getResponse()->setHeader("PW-MageDebug-cacheControl3", $header['name'], true);
            }
        }
		Mage::app()->getResponse()->setHeader("PW-MageDebug-cacheControl4", $cacheControlValue, true);

        // set "Cache-Control" header with "s-maxage" value
        $response->setHeader('Cache-Control', $cacheControlValue, true);

        // set "Expires" header in the past to keep mod_expires from applying it's ruleset
        $response->setHeader('Expires', 'Mon, 31 Mar 2008 10:00:00 GMT', true);
        
        // set "Pragma: no-cache" - just in case
        $response->setHeader('Pragma', 'no-cache', true);
    }

    /**
     * Find all domains for store
     *
     * @return string
     */
    public function getStoreDomainList($storeId = 0, $seperator = '|')
    {
        $storeIds = array($storeId);

        // if $store is empty or 0 get all store ids
        if (empty($storeId)) {
            $storeIds = Mage::getResourceModel('core/store_collection')->getAllIds();
        }

        $domains = array();
        $urlTypes = array(
            Mage_Core_Model_Store::URL_TYPE_LINK,
            Mage_Core_Model_Store::URL_TYPE_DIRECT_LINK,
            Mage_Core_Model_Store::URL_TYPE_WEB,
            Mage_Core_Model_Store::URL_TYPE_SKIN,
            Mage_Core_Model_Store::URL_TYPE_JS,
            Mage_Core_Model_Store::URL_TYPE_MEDIA
        );
        foreach ($storeIds as $storeId) {
            $store = Mage::getModel('core/store')->load($storeId);

            foreach ($urlTypes as $urlType) {
                // get non-secure store domain
                $domains[] = Zend_Uri::factory($store->getBaseUrl($urlType, false))->getHost();
                // get secure store domain
                $domains[] = Zend_Uri::factory($store->getBaseUrl($urlType, true))->getHost();
            }
        }

        // get only unique values
        $domains = array_unique($domains);

        return implode($seperator, $domains);
    }
}