Esi.php

<?php

/**
 * Nexcess.net Turpentine Extension for Magento
 * Copyright (C) 2012  Nexcess.net L.L.C.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

class Nexcessnet_Turpentine_Helper_Esi extends Mage_Core_Helper_Abstract {
    const ESI_DATA_PARAM            = 'data';
    const ESI_TTL_PARAM             = 'ttl';
    const ESI_CACHE_TYPE_PARAM      = 'access';
    const ESI_SCOPE_PARAM           = 'scope';
    const ESI_METHOD_PARAM          = 'method';
    const ESI_HMAC_PARAM            = 'hmac';
    const MAGE_CACHE_NAME           = 'turpentine_esi_blocks';

    /**
     * Cache for layout XML
     *
     * @var Mage_Core_Model_Layout_Element|SimpleXMLElement
     */
    protected $_layoutXml = null;

    /**
     * Get whether ESI includes are enabled or not
     *
     * @return bool
     */
    public function getEsiEnabled() {
        return Mage::app()->useCache($this->getMageCacheName());
    }

    /**
     * Get if ESI should be used for this request
     *
     * @return bool
     */
    public function shouldResponseUseEsi() {
        return Mage::helper('turpentine/varnish')->shouldResponseUseVarnish() &&
            $this->getEsiEnabled();
    }

    /**
     * Check if ESI includes are enabled and throw an exception if not
     *
     * @return null
     */
    public function ensureEsiEnabled() {
        if ( ! $this->shouldResponseUseEsi()) {
            Mage::throwException('ESI includes are not enabled');
        }
    }

    /**
     * Get the name of the URL param that holds the ESI block hash
     *
     * @return string
     */
    public function getEsiDataParam() {
        return self::ESI_DATA_PARAM;
    }

    /**
     * Get the URL param name for the ESI block cache type
     *
     * @return string
     */
    public function getEsiCacheTypeParam() {
        return self::ESI_CACHE_TYPE_PARAM;
    }

    /**
     * Get the URL param name for the ESI block scope
     *
     * @return string
     */
    public function getEsiScopeParam() {
        return self::ESI_SCOPE_PARAM;
    }

    /**
     * Get the URL param name for the ESI block TTL
     *
     * @return string
     */
    public function getEsiTtlParam() {
        return self::ESI_TTL_PARAM;
    }

    /**
     * Get the URL param name for the ESI inclusion method
     *
     * @return string
     */
    public function getEsiMethodParam() {
        return self::ESI_METHOD_PARAM;
    }

    /**
     * Get the URL param name for the ESI HMAC
     *
     * @return string
     */
    public function getEsiHmacParam() {
        return self::ESI_HMAC_PARAM;
    }

    /**
     * Get referrer param
     *
     * @return string
     */
    public function getEsiReferrerParam() {
        return Mage_Core_Controller_Varien_Action::PARAM_NAME_BASE64_URL;
    }

    /**
     * Get whether ESI debugging is enabled or not
     *
     * @return bool
     */
    public function getEsiDebugEnabled() {
        return Mage::helper('turpentine/varnish')
            ->getVarnishDebugEnabled();
    }

    /**
     * Get whether block name logging is enabled or not
     *
     * @return bool
     */
    public function getEsiBlockLogEnabled() {
        return (bool) Mage::getStoreConfig(
            'turpentine_varnish/general/block_debug' );
    }

    /**
     * Check if the flash messages are enabled and we're not in the admin section
     *
     * @return bool
     */
    public function shouldFixFlashMessages() {
        return Mage::helper('turpentine/data')->useFlashMessagesFix() &&
            Mage::app()->getStore()->getCode() !== 'admin';
    }

    /**
     * Get URL for redirects and dummy requests
     *
     * @return string
     */
    public function getDummyUrl() {
        return Mage::getUrl('checkout/cart');
    }

    /**
     * Get mock request
     *
     * Used to pretend that the request was for the base URL instead of
     * turpentine/esi/getBlock while rendering ESI blocks. Not perfect, but may
     * be good enough
     *
     * @return Mage_Core_Controller_Request_Http
     */
    public function getDummyRequest($url = null) {
        if ($url === null) {
            $url = $this->getDummyUrl();
        }
        $request = Mage::getModel('turpentine/dummy_request', $url);
        $request->fakeRouterDispatch();
        return $request;
    }

    /**
     * Get the cache type Magento uses
     *
     * @return string
     */
    public function getMageCacheName() {
        return self::MAGE_CACHE_NAME;
    }

    /**
     * Get the list of cache clear events to include with every ESI block
     *
     * @return string[]
     */
    public function getDefaultCacheClearEvents() {
        $events = array(
            'customer_login',
            'customer_logout',
        );
        return $events;
    }

    /**
     * Get the list of events that should cause the ESI cache to be cleared
     *
     * @return string[]
     */
    public function getCacheClearEvents() {
        Varien_Profiler::start('turpentine::helper::esi::getCacheClearEvents');
        $cacheKey = $this->getCacheClearEventsCacheKey();
        $events = @unserialize(Mage::app()->loadCache($cacheKey));
        if (is_null($events) || $events === false) {
            $events = $this->_loadEsiCacheClearEvents();
            Mage::app()->saveCache(serialize($events), $cacheKey,
                array('LAYOUT_GENERAL_CACHE_TAG'));
        }
        Varien_Profiler::stop('turpentine::helper::esi::getCacheClearEvents');
        return array_merge($this->getDefaultCacheClearEvents(), $events);
    }

    /**
     * Get the default private ESI block TTL
     *
     * @return string
     */
    public function getDefaultEsiTtl() {
        return trim(Mage::getStoreConfig('web/cookie/cookie_lifetime'));
    }

    /**
     * Get the CORS origin field from the unsecure base URL
     *
     * If this isn't added to AJAX responses they won't load properly
     *
     * @return string
     */
    public function getCorsOrigin($url = null) {
        if (is_null($url)) {
            $baseUrl = Mage::getBaseUrl();
        } else {
            $baseUrl = $url;
        }
        $path = parse_url($baseUrl, PHP_URL_PATH);
        $domain = parse_url($baseUrl, PHP_URL_HOST);
        // there has to be a better way to just strip the path off
        return substr($baseUrl, 0,
            strpos($baseUrl, $path,
                strpos($baseUrl, $domain)));
    }

    /**
     * Get the layout's XML structure
     *
     * This is cached because it's expensive to load for each ESI'd block
     *
     * @return Mage_Core_Model_Layout_Element|SimpleXMLElement
     */
    public function getLayoutXml() {
        Varien_Profiler::start('turpentine::helper::esi::getLayoutXml');
        if (is_null($this->_layoutXml)) {
            if ($useCache = Mage::app()->useCache('layout')) {
                $cacheKey = $this->getFileLayoutUpdatesXmlCacheKey();
                $this->_layoutXml = simplexml_load_string(
                    Mage::app()->loadCache($cacheKey) );
            }
            // this check is redundant if the layout cache is disabled
            if ( ! $this->_layoutXml) {
                $this->_layoutXml = $this->_loadLayoutXml();
                if ($useCache) {
                    Mage::app()->saveCache($this->_layoutXml->asXML(),
                        $cacheKey, array('LAYOUT_GENERAL_CACHE_TAG'));
                }
            }
        }
        Varien_Profiler::stop('turpentine::helper::esi::getLayoutXml');
        return $this->_layoutXml;
    }

    /**
     * Get the cache key for the cache clear events
     *
     * @return string
     */
    public function getCacheClearEventsCacheKey() {
        $design = Mage::getDesign();
        return Mage::helper('turpentine/data')
            ->getCacheKeyHash(array(
                'FILE_LAYOUT_ESI_CACHE_EVENTS',
                $design->getArea(),
                $design->getPackageName(),
                $design->getTheme('layout'),
                Mage::app()->getStore()->getId(),
            ));
    }

    /**
     * Get the cache key for the file layouts xml
     *
     * @return string
     */
    public function getFileLayoutUpdatesXmlCacheKey() {
        $design = Mage::getDesign();
        return Mage::helper('turpentine/data')
            ->getCacheKeyHash(array(
                'FILE_LAYOUT_UPDATES_XML',
                $design->getArea(),
                $design->getPackageName(),
                $design->getTheme('layout'),
                Mage::app()->getStore()->getId(),
            ));
    }

    /**
     * Generate an ESI tag to be replaced by the content from the given URL
     *
     * Generated tag looks like:
     *     <esi:include src="$url" />
     *
     * @param  string $url url to pull content from
     * @return string
     */
    public function buildEsiIncludeFragment($url) {
        return sprintf('<esi:include src="%s" />', $url);
    }

    /**
     * Generate an ESI tag with content that is removed when ESI processed, and
     * visible when not
     *
     * Generated tag looks like:
     *     <esi:remove>$content</esi>
     *
     * @param  string $content content to be removed
     * @return string
     */
    public function buildEsiRemoveFragment($content) {
        return sprintf('<esi:remove>%s</esi>', $content);
    }

    /**
     * Get URL for grabbing form key via ESI
     *
     * @return string
     */
    public function getFormKeyEsiUrl() {
        $urlOptions = array(
            $this->getEsiTtlParam()         => $this->getDefaultEsiTtl(),
            $this->getEsiMethodParam()      => 'esi',
            $this->getEsiScopeParam()       => 'global',
            $this->getEsiCacheTypeParam()   => 'private',
        );
        $esiUrl = Mage::getUrl('turpentine/esi/getFormKey', $urlOptions);
        // setting [web/unsecure/base_url] can be https://... but ESI can never be HTTPS
        $esiUrl = preg_replace('|^https://|i', 'http:https://', $esiUrl);
        return $esiUrl;
    }

    /**
     * Grab a block node by name from the layout XML.
     *
     * Multiple blocks with the same name may exist in the layout, because some themes
     * use 'unsetChild' to remove a block and create it with the same name somewhere
     * else. For example Ultimo does this.
     *
     * @param Mage_Core_Model_Layout $layout
     * @param string $blockName value of name= attribute in layout XML
     * @return Mage_Core_Model_Layout_Element
     */
    public function getEsiLayoutBlockNode($layout, $blockName) {
        // first try very specific by checking for action setEsiOptions inside block
        $blockNode = current($layout->getNode()->xpath(
            sprintf('//block[@name=\'%s\'][action[@method=\'setEsiOptions\']]',
                $blockName)
        ));
        // fallback: only match name
        if ( ! ($blockNode instanceof Mage_Core_Model_Layout_Element)) {
            $blockNode = current($layout->getNode()->xpath(
                sprintf('//block[@name=\'%s\']', $blockName)
            ));
        }
        return $blockNode;
    }

    /**
     * Load the ESI cache clear events from the layout
     *
     * @return array
     */
    protected function _loadEsiCacheClearEvents() {
        Varien_Profiler::start('turpentine::helper::esi::_loadEsiCacheClearEvents');
        $layoutXml = $this->getLayoutXml();
        $events = $layoutXml->xpath(
            '//action[@method=\'setEsiOptions\']/params/flush_events/*' );
        if ($events) {
            $events = array_unique(array_map(
                create_function('$e',
                    'return (string)$e->getName();'),
                $events ));
        } else {
            $events = array();
        }
        Varien_Profiler::stop('turpentine::helper::esi::_loadEsiCacheClearEvents');
        return $events;
    }

    /**
     * Load the layout's XML structure, bypassing any caching
     *
     * @return Mage_Core_Model_Layout_Element
     */
    protected function _loadLayoutXml() {
        Varien_Profiler::start('turpentine::helper::esi::_loadLayoutXml');
        $design = Mage::getDesign();
        $layoutXml = Mage::getSingleton('core/layout')
            ->getUpdate()
            ->getFileLayoutUpdatesXml(
                $design->getArea(),
                $design->getPackageName(),
                $design->getTheme('layout'),
                Mage::app()->getStore()->getId() );
        Varien_Profiler::stop('turpentine::helper::esi::_loadLayoutXml');
        return $layoutXml;
    }
}