<?php
/* --------------------------------------------------------------
   AMPifyGMMeta.php 2018-08-30
   meco media & communication GmbH
   http://www.meco-media.com
   Copyright (c) 2018 meco media & communication GmbH
   Released under the GNU General Public License (Version 2)
   [http://www.gnu.org/licenses/gpl-2.0.html]
  --------------------------------------------------------------
 */

/*
 * 	class GMMeta 	
 */

class AMPifyGMMeta extends AMPifyGMMeta_parent
{
    /**
     * @var DataCache
     */
    protected $dataCache;
    
    /**
     * @var string
     */
    protected $cacheKey = 'accelerated-mobile-pages';
    
    /**
     * @var string
     */
    protected $ampifyUrl = 'https://ampify.it/';
    
    /**
     * @var boolean
     */
    protected $installed;
    
    /**
     * @var boolean
     */
    protected $active;
    
    /**
     * @var string
     */
    protected $key;
    
    
    public function __construct($p_output = true)
    {
        parent::__construct(false);
        $this->dataCache = DataCache::get_instance();
        
        $this->installed = gm_get_conf('MODULE_CENTER_AMPIFY_INSTALLED');
        $this->active    = gm_get_conf('AMPIFY_ACTIVE');
        $this->key       = gm_get_conf('AMPIFY_KEY');
    }
    
    
    /**
     * Extend meta-tags if AMP page available
     *
     * @return bool|string Returns the JSON string or false if the cache is outdated.
     */
    public function get_base_meta()
    {
        
        // Check if module is active
        if (empty($this->installed) || empty($this->active) || empty($this->key)) {
            return parent::get_base_meta();
        }
        
        $meta = '';
        
        // Get data from cache or via webservice
        $jsonString = $this->_getCacheResponse();
        if ($jsonString === false) {
            $jsonString = $this->_requestAmpUrls();
        }
        $ampUrlMap = @json_decode($jsonString, true);
        
        // Remove XTCsid from query string in requested url
        $requestUrl = GM_HTTP_SERVER . gm_get_env_info('REQUEST_URI');
        list($requestUrl, $query) = explode('?', $requestUrl);
        if (!empty($query)) {
            
            $queryParts = explode('&', $query);
            if (!empty($queryParts)) {
                foreach ($queryParts as $key => $queryPart) {
                    list($var, $value) = explode('=', $queryPart);
                    if ($var === xtc_session_name()) {
                        unset($queryParts[$key]);
                    }
                }
            }
            if (!empty($queryParts)) {
                $requestUrl .= '?' . implode('&', $queryParts);
            }
        }
        
        // Compare requested url with AMP map
        if (!empty($ampUrlMap) && is_array($ampUrlMap) && !empty($ampUrlMap[$requestUrl])) {
            $ampUrl = $ampUrlMap[$requestUrl];
            $meta   = sprintf('<link rel="amphtml" href="%s">', $ampUrl);
        }
        
        return $meta . PHP_EOL . parent::get_base_meta();
    }
    
    
    /**
     * Get the cached response
     *
     * @return bool|string Returns the JSON string or false if the cache is outdated.
     */
    protected function _getCacheResponse()
    {
        // Clear cache via GET-variable
        if (!empty($_GET['clear-amp-cache']) && $_GET['clear-amp-cache'] == $this->key) {
            return false;
        }
        
        // Cache is not created
        if (!$this->dataCache->key_exists($this->cacheKey, true)) {
            return false;
        }
        
        // Read cache; break if older than 5 minutes
        $cacheData = $this->dataCache->get_persistent_data($this->cacheKey);
        if ($cacheData['timestamp'] <= mktime(date('H'),
                                              date('i') - (60 * 24),
                                              date('s'),
                                              date('m'),
                                              date('d'),
                                              date('Y'))) {
            return false;
        }
        
        return $cacheData['response'];
    }
    
    
    /**
     * Receive AMP-pages array from Ampify-Server
     *
     * @return bool|string Returns the JSON string or false if the cache is outdated.
     */
    protected function _requestAmpUrls()
    {
        
        // Rest request
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $this->ampifyUrl . 'de/amp-site-pages/sitemap/' . $this->key);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_HTTPHEADER, ['Accept: application/json']);
        $response = json_decode(curl_exec($ch));
        curl_close($ch);
        
        // Response data
        $urls = (array)$response->ampSitePages;
        
        // Change urls to shop internal
        $connectionType = GM_HTTP_SERVER === HTTPS_SERVER ? 'SSL' : 'NONSSL';
        foreach ($urls as $shopUrl => &$ampUrl) {
            $ampUrl = xtc_href_link('amp/' . str_replace($this->ampifyUrl, '', $ampUrl), '', $connectionType);
        }
        
        // save url array to session
        $jsonString = json_encode($urls);
        $cacheData  = [
            'timestamp' => time(),
            'response'  => $jsonString
        ];
        
        // Write data into cache file and return
        $this->dataCache->write_persistent_data($this->cacheKey, $cacheData);
        
        return $jsonString;
    }
}