<?php
/**
 * Random Include Plugin:
 * Randomly select a page from a namespace and include it the current page.
 *
 * Action plugin component, for cache validity determination
 * 
 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author     Christopher Smith <chris@jalakai.co.uk>  
 */
if(!defined('DOKU_INC')) die();  // no Dokuwiki, no go
 
if(!defined('DOKU_PLUGIN')) define('DOKU_PLUGIN',DOKU_INC.'lib/plugins/');
require_once(DOKU_PLUGIN.'action.php');

/**
 * All DokuWiki plugins to extend the parser/rendering mechanism
 * need to inherit from this class
 */
class action_plugin_randominc extends DokuWiki_Action_Plugin {

    protected $supportedModes = array('xhtml');
    
    /**
     * plugin should use this method to register its handlers with the dokuwiki's event controller
     */
    function register(Doku_Event_Handler $controller) {
        $controller->register_hook('PARSER_CACHE_USE','BEFORE', $this, '_cache_prepare');
        // debugging only
        //$controller->register_hook('PARSER_CACHE_USE','AFTER', $this, '_cache_result');
    }

    /**
     * prepare the cache object for default _useCache action
     */
    function _cache_prepare(&$event, $param) {
        $cache =& $event->data;

        // we're only interested in wiki pages and supported render modes
        if (!isset($cache->page)) return;
        if (!isset($cache->mode) || !in_array($cache->mode, $this->supportedModes)) return;
 
        $key = '';
        $depends = array();    
        $expire = $this->_inclusion_check($cache->page, $key, $depends);
 
        //global $debug;
        //$debug[] = compact('key','expire','depends','cache');
 
        // empty $key implies no includes, so nothing to do
        if (empty($key)) return;

        // mark the cache as being modified by the include plugin
        $cache->include = true;

        // set new cache key & cache name - now also dependent on included page ids and their ACL_READ status
        $cache->key .= $key;
        $cache->cache = getCacheName($cache->key, $cache->ext);

        // inclusion check was able to determine the cache must be invalid
        if ($expire) {
            $event->preventDefault();
            $event->stopPropagation();
            $event->result = false;
            return;
        }

        // update depends['files'] array to include all included files
        $cache->depends['files'] = !empty($cache->depends['files']) ? array_merge($cache->depends['files'], $depends) : $depends;
    }
 
    /**
     * carry out included page checks:
     * - to establish proper cache name, its dependent on the read status of included pages
     * - to establish file dependencies, the included raw wiki pages
     *
     * @param   string    $id         wiki page name
     * @param   string    $key        (reference) cache key
     * @param   array     $depends    array of include file dependencies
     *
     * @return  bool                  expire the cache
     */
    function _inclusion_check($id, &$key, &$depends) {
        $hasPart = p_get_metadata($id, 'relation haspart');
        if (empty($hasPart)) return false;

        $expire = false;
        foreach ($hasPart as $page => $exists) {
            // ensure its a wiki page
            if (strpos($page,'/') ||  cleanID($page) != $page) continue;
 
            $file = wikiFN($page);
 
            // file existence state is different from state recorded in metadata
            if (@file_exists($file) != $exists) {
                if (($acl = $this->_acl_read_check($page)) != 'NONE') { $expire = true;  }
            } else if ($exists) {
                // carry out an inclusion check on the included page, that will update $key & $depends
                if ($this->_inclusion_check($page, $key, $depends)) { $expire = true; }
                if (($acl = $this->_acl_read_check($page)) != 'NONE') { $depends[] = $file;  }
            } else {
                $acl = 'NONE';
            }

            // add this page and acl status to the key
            $key .= '#'.$page.'|'.$acl;
        }

        return $expire;
    }
 
    function _acl_read_check($id) {
        return (AUTH_READ <= auth_quickaclcheck($id)) ? 'READ' : 'NONE';
    }

    function _cache_result(&$event, $param) {
        $cache =& $event->data;
        if (empty($cache->include)) return;

        //global $debug;
        //$debug['cache_result'][] = $event->result ? 'true' : 'false';
    }
}

//Setup VIM: ex: et ts=4 enc=utf-8 :