/gforge/plugins/wiki/www/lib/WikiDB.php

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<?php //-*-php-*-
rcs_id('$Id: WikiDB.php,v 1.135 2005/09/11 14:19:44 rurban Exp $');

require_once('lib/PageType.php');

/**
 * The classes in the file define the interface to the
 * page database.
 *
 * @package WikiDB
 * @author Geoffrey T. Dairiki <dairiki@dairiki.org>
 *         Reini Urban
 */

/**
 * Force the creation of a new revision.
 * @see WikiDB_Page::createRevision()
 */
if (!defined('WIKIDB_FORCE_CREATE'))
    define('WIKIDB_FORCE_CREATE', -1);

/** 
 * Abstract base class for the database used by PhpWiki.
 *
 * A <tt>WikiDB</tt> is a container for <tt>WikiDB_Page</tt>s which in
 * turn contain <tt>WikiDB_PageRevision</tt>s.
 *
 * Conceptually a <tt>WikiDB</tt> contains all possible
 * <tt>WikiDB_Page</tt>s, whether they have been initialized or not.
 * Since all possible pages are already contained in a WikiDB, a call
 * to WikiDB::getPage() will never fail (barring bugs and
 * e.g. filesystem or SQL database problems.)
 *
 * Also each <tt>WikiDB_Page</tt> always contains at least one
 * <tt>WikiDB_PageRevision</tt>: the default content (e.g. "Describe
 * [PageName] here.").  This default content has a version number of
 * zero.
 *
 * <tt>WikiDB_PageRevision</tt>s have read-only semantics. One can
 * only create new revisions or delete old ones --- one can not modify
 * an existing revision.
 */
class WikiDB {
    /**
     * Open a WikiDB database.
     *
     * This is a static member function. This function inspects its
     * arguments to determine the proper subclass of WikiDB to
     * instantiate, and then it instantiates it.
     *
     * @access public
     *
     * @param hash $dbparams Database configuration parameters.
     * Some pertinent paramters are:
     * <dl>
     * <dt> dbtype
     * <dd> The back-end type.  Current supported types are:
     *   <dl>
     *   <dt> SQL
     *     <dd> Generic SQL backend based on the PEAR/DB database abstraction
     *       library. (More stable and conservative)
     *   <dt> ADODB
     *     <dd> Another generic SQL backend. (More current features are tested here. Much faster)
     *   <dt> dba
     *     <dd> Dba based backend. The default and by far the fastest.
     *   <dt> cvs
     *     <dd> 
     *   <dt> file
     *     <dd> flat files
     *   </dl>
     *
     * <dt> dsn
     * <dd> (Used by the SQL and ADODB backends.)
     *      The DSN specifying which database to connect to.
     *
     * <dt> prefix
     * <dd> Prefix to be prepended to database tables (and file names).
     *
     * <dt> directory
     * <dd> (Used by the dba backend.)
     *      Which directory db files reside in.
     *
     * <dt> timeout
     * <dd> Used only by the dba backend so far. 
     *      And: When optimizing mysql it closes timed out mysql processes.
     *      otherwise only used for dba: Timeout in seconds for opening (and 
     *      obtaining lock) on the dbm file.
     *
     * <dt> dba_handler
     * <dd> (Used by the dba backend.)
     *
     *      Which dba handler to use. Good choices are probably either
     *      'gdbm' or 'db2'.
     * </dl>
     *
     * @return WikiDB A WikiDB object.
     **/
    function open ($dbparams) {
        $dbtype = $dbparams{'dbtype'};
        include_once("lib/WikiDB/$dbtype.php");
				
        $class = 'WikiDB_' . $dbtype;
        return new $class ($dbparams);
    }


    /**
     * Constructor.
     *
     * @access private
     * @see open()
     */
    function WikiDB (&$backend, $dbparams) {
        $this->_backend = &$backend;
        // don't do the following with the auth_dsn!
        if (isset($dbparams['auth_dsn'])) return;
        
        $this->_cache = new WikiDB_cache($backend);
        if (!empty($GLOBALS['request'])) $GLOBALS['request']->_dbi = $this;

        // If the database doesn't yet have a timestamp, initialize it now.
        if ($this->get('_timestamp') === false)
            $this->touch();
        
        //FIXME: devel checking.
        //$this->_backend->check();
    }
    
    /**
     * Close database connection.
     *
     * The database may no longer be used after it is closed.
     *
     * Closing a WikiDB invalidates all <tt>WikiDB_Page</tt>s,
     * <tt>WikiDB_PageRevision</tt>s and <tt>WikiDB_PageIterator</tt>s
     * which have been obtained from it.
     *
     * @access public
     */
    function close () {
        $this->_backend->close();
        $this->_cache->close();
    }
    
    /**
     * Get a WikiDB_Page from a WikiDB.
     *
     * A {@link WikiDB} consists of the (infinite) set of all possible pages,
     * therefore this method never fails.
     *
     * @access public
     * @param string $pagename Which page to get.
     * @return WikiDB_Page The requested WikiDB_Page.
     */
    function getPage($pagename) {
        static $error_displayed = false;
        $pagename = (string) $pagename;
        if (DEBUG) {
            if ($pagename === '') {
                if ($error_displayed) return false;
                $error_displayed = true;
                if (function_exists("xdebug_get_function_stack"))
                    var_dump(xdebug_get_function_stack());
                trigger_error("empty pagename", E_USER_WARNING);
                return false;
            }
        } else {
            assert($pagename != '');
        }
        return new WikiDB_Page($this, $pagename);
    }

    /**
     * Determine whether page exists (in non-default form).
     *
     * <pre>
     *   $is_page = $dbi->isWikiPage($pagename);
     * </pre>
     * is equivalent to
     * <pre>
     *   $page = $dbi->getPage($pagename);
     *   $current = $page->getCurrentRevision();
     *   $is_page = ! $current->hasDefaultContents();
     * </pre>
     * however isWikiPage may be implemented in a more efficient
     * manner in certain back-ends.
     *
     * @access public
     *
     * @param string $pagename string Which page to check.
     *
     * @return boolean True if the page actually exists with
     * non-default contents in the WikiDataBase.
     */
    function isWikiPage ($pagename) {
        $page = $this->getPage($pagename);
        return $page->exists();
    }

    /**
     * Delete page from the WikiDB. 
     *
     * Deletes the page from the WikiDB with the possibility to revert and diff.
     * //Also resets all page meta-data to the default values.
     *
     * Note: purgePage() effectively destroys all revisions of the page from the WikiDB. 
     *
     * @access public
     *
     * @param string $pagename Name of page to delete.
     */
    function deletePage($pagename) {
    	// don't create empty revisions of already purged pages.
        if ($this->_backend->get_latest_version($pagename))
            $result = $this->_cache->delete_page($pagename);
        else 
            $result = -1;

        /* Generate notification emails? */
        if (! $this->isWikiPage($pagename) and !isa($GLOBALS['request'],'MockRequest')) {
            $notify = $this->get('notify');
            if (!empty($notify) and is_array($notify)) {
                global $request;
                //TODO: deferr it (quite a massive load if you remove some pages).
                //TODO: notification class which catches all changes,
                //  and decides at the end of the request what to mail. 
                //  (type, page, who, what, users, emails)
                // could be used for PageModeration and RSS2 Cloud xml-rpc also.
                $page = new WikiDB_Page($this, $pagename);
                list($emails, $userids) = $page->getPageChangeEmails($notify);
                if (!empty($emails)) {
                    $from = $request->_user->getId();
                    $editedby = sprintf(_("Removed by: %s"), $from);
                    $emails = join(',', $emails);
        			$headers = "From: $from <nobody>\r\n" .
        				"Bcc: $emails\r\n" .
        				"MIME-Version: 1.0\r\n" .
        				"Content-Type: text/plain; charset=".CHARSET."; format=flowed\r\n" .
        				"Content-Transfer-Encoding: 8bit";
                    $subject = sprintf(_("Page removed %s"), urlencode($pagename));
                    if (mail("<undisclosed-recipients>","[".WIKI_NAME."] ".$subject, 
                             $subject."\n".
                             $editedby."\n\n".
                             "Deleted $pagename",
                             $headers))
                        trigger_error(sprintf(_("PageChange Notification of %s sent to %s"),
                                              $pagename, join(',',$userids)), E_USER_NOTICE);
                    else
                        trigger_error(sprintf(_("PageChange Notification Error: Couldn't send %s to %s"),
                                              $pagename, join(',',$userids)), E_USER_WARNING);
                }
            }
        }

        //How to create a RecentChanges entry with explaining summary? Dynamically
        /*
        $page = $this->getPage($pagename);
        $current = $page->getCurrentRevision();
        $meta = $current->_data;
        $version = $current->getVersion();
        $meta['summary'] = _("removed");
        $page->save($current->getPackedContent(), $version + 1, $meta);
        */
        return $result;
    }

    /**
     * Completely remove the page from the WikiDB, without undo possibility.
     */
    function purgePage($pagename) {
        $result = $this->_cache->purge_page($pagename);
        $this->deletePage($pagename); // just for the notification
        return $result;
    }
    
    /**
     * Retrieve all pages.
     *
     * Gets the set of all pages with non-default contents.
     *
     * @access public
     *
     * @param boolean $include_defaulted Normally pages whose most
     * recent revision has empty content are considered to be
     * non-existant. Unless $include_defaulted is set to true, those
     * pages will not be returned.
     *
     * @return WikiDB_PageIterator A WikiDB_PageIterator which contains all pages
     *     in the WikiDB which have non-default contents.
     */
    function getAllPages($include_empty=false, $sortby=false, $limit=false, 
                         $exclude=false) 
    {
        // HACK: memory_limit=8M will fail on too large pagesets. old php on unix only!
        if (USECACHE) {
            $mem = ini_get("memory_limit");
            if ($mem and !$limit and !isWindows() and !check_php_version(4,3)) {
                $limit = 450;
                $GLOBALS['request']->setArg('limit', $limit);
                $GLOBALS['request']->setArg('paging', 'auto');
            }
        }
        $result = $this->_backend->get_all_pages($include_empty, $sortby, $limit, 
                                                 $exclude);
        return new WikiDB_PageIterator($this, $result, 
                                       array('include_empty' => $include_empty, 
                                             'exclude' => $exclude,
                                             'limit' => $limit));
    }

    /**
     * $include_empty = true: include also empty pages
     * exclude: comma-seperated list pagenames: TBD: array of pagenames
     */
    function numPages($include_empty=false, $exclude='') {
    	if (method_exists($this->_backend, 'numPages'))
            // FIXME: currently are all args ignored.
            $count = $this->_backend->numPages($include_empty, $exclude);
        else {
            // FIXME: exclude ignored.
            $iter = $this->getAllPages($include_empty, false, false, $exclude);
            $count = $iter->count();
            $iter->free();
        }
        return (int)$count;
    }
    
    /**
     * Title search.
     *
     * Search for pages containing (or not containing) certain words
     * in their names.
     *
     * Pages are returned in alphabetical order whenever it is
     * practical to do so.
     *
     * FIXME: clarify $search syntax. provide glob=>TextSearchQuery converters
     *
     * @access public
     * @param TextSearchQuery $search A TextSearchQuery object
     * @return WikiDB_PageIterator A WikiDB_PageIterator containing the matching pages.
     * @see TextSearchQuery
     */
    function titleSearch($search, $sortby='pagename', $limit=false, $exclude=false) {
        $result = $this->_backend->text_search($search, false, $sortby, $limit, $exclude);
        return new WikiDB_PageIterator($this, $result,
                                       array('exclude' => $exclude,
                                             'limit' => $limit));
    }

    /**
     * Full text search.
     *
     * Search for pages containing (or not containing) certain words
     * in their entire text (this includes the page content and the
     * page name).
     *
     * Pages are returned in alphabetical order whenever it is
     * practical to do so.
     *
     * @access public
     *
     * @param TextSearchQuery $search A TextSearchQuery object.
     * @return WikiDB_PageIterator A WikiDB_PageIterator containing the matching pages.
     * @see TextSearchQuery
     */
    function fullSearch($search, $sortby='pagename', $limit=false, $exclude=false) {
        $result = $this->_backend->text_search($search, true, $sortby, $limit, $exclude);
        return new WikiDB_PageIterator($this, $result,
                                       array('exclude' => $exclude,
                                             'limit'   => $limit,
                                             'stoplisted' => $result->stoplisted
                                             ));
    }

    /**
     * Find the pages with the greatest hit counts.
     *
     * Pages are returned in reverse order by hit count.
     *
     * @access public
     *
     * @param integer $limit The maximum number of pages to return.
     * Set $limit to zero to return all pages.  If $limit < 0, pages will
     * be sorted in decreasing order of popularity.
     *
     * @return WikiDB_PageIterator A WikiDB_PageIterator containing the matching
     * pages.
     */
    function mostPopular($limit = 20, $sortby = '-hits') {
        $result = $this->_backend->most_popular($limit, $sortby);
        return new WikiDB_PageIterator($this, $result);
    }

    /**
     * Find recent page revisions.
     *
     * Revisions are returned in reverse order by creation time.
     *
     * @access public
     *
     * @param hash $params This hash is used to specify various optional
     *   parameters:
     * <dl>
     * <dt> limit 
     *    <dd> (integer) At most this many revisions will be returned.
     * <dt> since
     *    <dd> (integer) Only revisions since this time (unix-timestamp) will be returned. 
     * <dt> include_minor_revisions
     *    <dd> (boolean) Also include minor revisions.  (Default is not to.)
     * <dt> exclude_major_revisions
     *    <dd> (boolean) Don't include non-minor revisions.
     *         (Exclude_major_revisions implies include_minor_revisions.)
     * <dt> include_all_revisions
     *    <dd> (boolean) Return all matching revisions for each page.
     *         Normally only the most recent matching revision is returned
     *         for each page.
     * </dl>
     *
     * @return WikiDB_PageRevisionIterator A WikiDB_PageRevisionIterator containing the
     * matching revisions.
     */
    function mostRecent($params = false) {
        $result = $this->_backend->most_recent($params);
        return new WikiDB_PageRevisionIterator($this, $result);
    }

    /**
     * @access public
     *
     * @return Iterator A generic iterator containing rows of (duplicate) pagename, wantedfrom.
     */
    function wantedPages($exclude_from='', $exclude='', $sortby=false, $limit=false) {
        return $this->_backend->wanted_pages($exclude_from, $exclude, $sortby, $limit);
        //return new WikiDB_PageIterator($this, $result);
    }


    /**
     * Call the appropriate backend method.
     *
     * @access public
     * @param string $from Page to rename
     * @param string $to   New name
     * @param boolean $updateWikiLinks If the text in all pages should be replaced.
     * @return boolean     true or false
     */
    function renamePage($from, $to, $updateWikiLinks = false) {
        assert(is_string($from) && $from != '');
        assert(is_string($to) && $to != '');
        $result = false;
        if (method_exists($this->_backend, 'rename_page')) {
            $oldpage = $this->getPage($from);
            $newpage = $this->getPage($to);
            //update all WikiLinks in existing pages
            //non-atomic! i.e. if rename fails the links are not undone
            if ($updateWikiLinks) {
                require_once('lib/plugin/WikiAdminSearchReplace.php');
                $links = $oldpage->getBackLinks();
                while ($linked_page = $links->next()) {
                    WikiPlugin_WikiAdminSearchReplace::replaceHelper($this,
                                                                     $linked_page->getName(),
                                                                     $from, $to);
                }
// ape: Disabled to avoid recursive modification when renaming
//      a page like 'PageApe' to 'PageApeTwo'.
//
//                $links = $newpage->getBackLinks();
//                while ($linked_page = $links->next()) {
//                    WikiPlugin_WikiAdminSearchReplace::replaceHelper($this,
//                                                                     $linked_page->getName(),
//                                                                     $from, $to);
//                }
            }
            if ($oldpage->exists() and ! $newpage->exists()) {
                if ($result = $this->_backend->rename_page($from, $to)) {
                    //create a RecentChanges entry with explaining summary
                    $page = $this->getPage($to);
                    $current = $page->getCurrentRevision();
                    $meta = $current->_data;
                    $version = $current->getVersion();
                    $meta['summary'] = sprintf(_("renamed from %s"), $from);
                    $page->save($current->getPackedContent(), $version + 1, $meta);
                }
            } elseif (!$oldpage->getCurrentRevision(false) and !$newpage->exists()) {
                // if a version 0 exists try it also.
                $result = $this->_backend->rename_page($from, $to);
            }
        } else {
            trigger_error(_("WikiDB::renamePage() not yet implemented for this backend"),
                          E_USER_WARNING);
        }
        /* Generate notification emails? */
        if ($result and !isa($GLOBALS['request'], 'MockRequest')) {
            $notify = $this->get('notify');
            if (!empty($notify) and is_array($notify)) {
                list($emails, $userids) = $oldpage->getPageChangeEmails($notify);
                if (!empty($emails)) {
                    $oldpage->sendPageRenameNotification($to, $meta, $emails, $userids);
                }
            }
        }
        return $result;
    }

    /** Get timestamp when database was last modified.
     *
     * @return string A string consisting of two integers,
     * separated by a space.  The first is the time in
     * unix timestamp format, the second is a modification
     * count for the database.
     *
     * The idea is that you can cast the return value to an
     * int to get a timestamp, or you can use the string value
     * as a good hash for the entire database.
     */
    function getTimestamp() {
        $ts = $this->get('_timestamp');
        return sprintf("%d %d", $ts[0], $ts[1]);
    }
    
    /**
     * Update the database timestamp.
     *
     */
    function touch() {
        $ts = $this->get('_timestamp');
        $this->set('_timestamp', array(time(), $ts[1] + 1));
    }

        
    /**
     * Access WikiDB global meta-data.
     *
     * NOTE: this is currently implemented in a hackish and
     * not very efficient manner.
     *
     * @access public
     *
     * @param string $key Which meta data to get.
     * Some reserved meta-data keys are:
     * <dl>
     * <dt>'_timestamp' <dd> Data used by getTimestamp().
     * </dl>
     *
     * @return scalar The requested value, or false if the requested data
     * is not set.
     */
    function get($key) {
        if (!$key || $key[0] == '%')
            return false;
        /*
         * Hack Alert: We can use any page (existing or not) to store
         * this data (as long as we always use the same one.)
         */
        $gd = $this->getPage('global_data');
        $data = $gd->get('__global');

        if ($data && isset($data[$key]))
            return $data[$key];
        else
            return false;
    }

    /**
     * Set global meta-data.
     *
     * NOTE: this is currently implemented in a hackish and
     * not very efficient manner.
     *
     * @see get
     * @access public
     *
     * @param string $key  Meta-data key to set.
     * @param string $newval  New value.
     */
    function set($key, $newval) {
        if (!$key || $key[0] == '%')
            return;
        
        $gd = $this->getPage('global_data');
        $data = $gd->get('__global');
        if ($data === false)
            $data = array();

        if (empty($newval))
            unset($data[$key]);
        else
            $data[$key] = $newval;

        $gd->set('__global', $data);
    }

    /* TODO: these are really backend methods */

    // SQL result: for simple select or create/update queries
    // returns the database specific resource type
    function genericSqlQuery($sql, $args=false) {
        if (function_exists('debug_backtrace')) { // >= 4.3.0
            echo "<pre>", printSimpleTrace(debug_backtrace()), "</pre>\n";
        }
        trigger_error("no SQL database", E_USER_ERROR);
        return false;
    }

    // SQL iter: for simple select or create/update queries
    // returns the generic iterator object (count,next)
    function genericSqlIter($sql, $field_list = NULL) {
        if (function_exists('debug_backtrace')) { // >= 4.3.0
            echo "<pre>", printSimpleTrace(debug_backtrace()), "</pre>\n";
        }
        trigger_error("no SQL database", E_USER_ERROR);
        return false;
    }
    
    // see backend upstream methods
    // ADODB adds surrounding quotes, SQL not yet!
    function quote ($s) {
        return $s;
    }

    function isOpen () {
        global $request;
        if (!$request->_dbi) return false;
        else return false; /* so far only needed for sql so false it. 
                            later we have to check dba also */
    }

    function getParam($param) {
        global $DBParams;
        if (isset($DBParams[$param])) return $DBParams[$param];
        elseif ($param == 'prefix') return '';
        else return false;
    }

    function getAuthParam($param) {
        global $DBAuthParams;
        if (isset($DBAuthParams[$param])) return $DBAuthParams[$param];
        elseif ($param == 'USER_AUTH_ORDER') return $GLOBALS['USER_AUTH_ORDER'];
        elseif ($param == 'USER_AUTH_POLICY') return $GLOBALS['USER_AUTH_POLICY'];
        else return false;
    }
};


/**
 * An abstract base class which representing a wiki-page within a
 * WikiDB.
 *
 * A WikiDB_Page contains a number (at least one) of
 * WikiDB_PageRevisions.
 */
class WikiDB_Page 
{
    function WikiDB_Page(&$wikidb, $pagename) {
        $this->_wikidb = &$wikidb;
        $this->_pagename = $pagename;
        if (DEBUG) {
            if (!(is_string($pagename) and $pagename != '')) {
                if (function_exists("xdebug_get_function_stack")) {
                    echo "xdebug_get_function_stack(): "; var_dump(xdebug_get_function_stack());
                } elseif (function_exists("debug_backtrace")) { // >= 4.3.0
                    printSimpleTrace(debug_backtrace());
                }
                trigger_error("empty pagename", E_USER_WARNING);
                return false;
            }
        } else {
            assert(is_string($pagename) and $pagename != '');
        }
    }

    /**
     * Get the name of the wiki page.
     *
     * @access public
     *
     * @return string The page name.
     */
    function getName() {
        return $this->_pagename;
    }
    
    // To reduce the memory footprint for larger sets of pagelists,
    // we don't cache the content (only true or false) and 
    // we purge the pagedata (_cached_html) also
    function exists() {
        if (isset($this->_wikidb->_cache->_id_cache[$this->_pagename])) return true;
        $current = $this->getCurrentRevision(false);
        if (!$current) return false;
        return ! $current->hasDefaultContents();
    }

    /**
     * Delete an old revision of a WikiDB_Page.
     *
     * Deletes the specified revision of the page.
     * It is a fatal error to attempt to delete the current revision.
     *
     * @access public
     *
     * @param integer $version Which revision to delete.  (You can also
     *  use a WikiDB_PageRevision object here.)
     */
    function deleteRevision($version) {
        $backend = &$this->_wikidb->_backend;
        $cache = &$this->_wikidb->_cache;
        $pagename = &$this->_pagename;

        $version = $this->_coerce_to_version($version);
        if ($version == 0)
            return;

        $backend->lock(array('page','version'));
        $latestversion = $cache->get_latest_version($pagename);
        if ($latestversion && ($version == $latestversion)) {
            $backend->unlock(array('page','version'));
            trigger_error(sprintf("Attempt to delete most recent revision of '%s'",
                                  $pagename), E_USER_ERROR);
            return;
        }

        $cache->delete_versiondata($pagename, $version);
        $backend->unlock(array('page','version'));
    }

    /*
     * Delete a revision, or possibly merge it with a previous
     * revision.
     *
     * The idea is this:
     * Suppose an author make a (major) edit to a page.  Shortly
     * after that the same author makes a minor edit (e.g. to fix
     * spelling mistakes he just made.)
     *
     * Now some time later, where cleaning out old saved revisions,
     * and would like to delete his minor revision (since there's
     * really no point in keeping minor revisions around for a long
     * time.)
     *
     * Note that the text after the minor revision probably represents
     * what the author intended to write better than the text after
     * the preceding major edit.
     *
     * So what we really want to do is merge the minor edit with the
     * preceding edit.
     *
     * We will only do this when:
     * <ul>
     * <li>The revision being deleted is a minor one, and
     * <li>It has the same author as the immediately preceding revision.
     * </ul>
     */
    function mergeRevision($version) {
        $backend = &$this->_wikidb->_backend;
        $cache = &$this->_wikidb->_cache;
        $pagename = &$this->_pagename;

        $version = $this->_coerce_to_version($version);
        if ($version == 0)
            return;

        $backend->lock(array('version'));
        $latestversion = $cache->get_latest_version($pagename);
        if ($latestversion && $version == $latestversion) {
            $backend->unlock(array('version'));
            trigger_error(sprintf("Attempt to merge most recent revision of '%s'",
                                  $pagename), E_USER_ERROR);
            return;
        }

        $versiondata = $cache->get_versiondata($pagename, $version, true);
        if (!$versiondata) {
            // Not there? ... we're done!
            $backend->unlock(array('version'));
            return;
        }

        if ($versiondata['is_minor_edit']) {
            $previous = $backend->get_previous_version($pagename, $version);
            if ($previous) {
                $prevdata = $cache->get_versiondata($pagename, $previous);
                if ($prevdata['author_id'] == $versiondata['author_id']) {
                    // This is a minor revision, previous version is
                    // by the same author. We will merge the
                    // revisions.
                    $cache->update_versiondata($pagename, $previous,
                                               array('%content' => $versiondata['%content'],
                                                     '_supplanted' => $versiondata['_supplanted']));
                }
            }
        }

        $cache->delete_versiondata($pagename, $version);
        $backend->unlock(array('version'));
    }

    
    /**
     * Create a new revision of a {@link WikiDB_Page}.
     *
     * @access public
     *
     * @param int $version Version number for new revision.  
     * To ensure proper serialization of edits, $version must be
     * exactly one higher than the current latest version.
     * (You can defeat this check by setting $version to
     * {@link WIKIDB_FORCE_CREATE} --- not usually recommended.)
     *
     * @param string $content Contents of new revision.
     *
     * @param hash $metadata Metadata for new revision.
     * All values in the hash should be scalars (strings or integers).
     *
     * @param array $links List of pagenames which this page links to.
     *
     * @return WikiDB_PageRevision  Returns the new WikiDB_PageRevision object. If
     * $version was incorrect, returns false
     */
    function createRevision($version, &$content, $metadata, $links) {
        $backend = &$this->_wikidb->_backend;
        $cache = &$this->_wikidb->_cache;
        $pagename = &$this->_pagename;
        $cache->invalidate_cache($pagename);
        
        $backend->lock(array('version','page','recent','link','nonempty'));

        $latestversion = $backend->get_latest_version($pagename);
        $newversion = ($latestversion ? $latestversion : 0) + 1;
        assert($newversion >= 1);

        if ($version != WIKIDB_FORCE_CREATE and $version != $newversion) {
            $backend->unlock(array('version','page','recent','link','nonempty'));
            return false;
        }

        $data = $metadata;
        
        foreach ($data as $key => $val) {
            if (empty($val) || $key[0] == '_' || $key[0] == '%')
                unset($data[$key]);
        }
			
        assert(!empty($data['author']));
        if (empty($data['author_id']))
            @$data['author_id'] = $data['author'];
		
        if (empty($data['mtime']))
            $data['mtime'] = time();

        if ($latestversion and $version != WIKIDB_FORCE_CREATE) {
            // Ensure mtimes are monotonic.
            $pdata = $cache->get_versiondata($pagename, $latestversion);
            if ($data['mtime'] < $pdata['mtime']) {
                trigger_error(sprintf(_("%s: Date of new revision is %s"),
                                      $pagename,"'non-monotonic'"),
                              E_USER_NOTICE);
                $data['orig_mtime'] = $data['mtime'];
                $data['mtime'] = $pdata['mtime'];
            }
            
	    // FIXME: use (possibly user specified) 'mtime' time or
	    // time()?
            $cache->update_versiondata($pagename, $latestversion,
                                       array('_supplanted' => $data['mtime']));
        }

        $data['%content'] = &$content;

        $cache->set_versiondata($pagename, $newversion, $data);

        //$cache->update_pagedata($pagename, array(':latestversion' => $newversion,
        //':deleted' => empty($content)));
        
        $backend->set_links($pagename, $links);

        $backend->unlock(array('version','page','recent','link','nonempty'));

        return new WikiDB_PageRevision($this->_wikidb, $pagename, $newversion,
                                       $data);
    }

    /** A higher-level interface to createRevision.
     *
     * This takes care of computing the links, and storing
     * a cached version of the transformed wiki-text.
     *
     * @param string $wikitext  The page content.
     *
     * @param int $version Version number for new revision.  
     * To ensure proper serialization of edits, $version must be
     * exactly one higher than the current latest version.
     * (You can defeat this check by setting $version to
     * {@link WIKIDB_FORCE_CREATE} --- not usually recommended.)
     *
     * @param hash $meta  Meta-data for new revision.
     */
    function save($wikitext, $version, $meta) {
	$formatted = new TransformedText($this, $wikitext, $meta);
        $type = $formatted->getType();
	$meta['pagetype'] = $type->getName();
	$links = $formatted->getWikiPageLinks();

	$backend = &$this->_wikidb->_backend;
	$newrevision = $this->createRevision($version, $wikitext, $meta, $links);
	if ($newrevision and !WIKIDB_NOCACHE_MARKUP)
            $this->set('_cached_html', $formatted->pack());

	// FIXME: probably should have some global state information
	// in the backend to control when to optimize.
        //
        // We're doing this here rather than in createRevision because
        // postgresql can't optimize while locked.
        if ((DEBUG & _DEBUG_SQL)
	    or (DATABASE_OPTIMISE_FREQUENCY > 0 and 
                (time() % DATABASE_OPTIMISE_FREQUENCY == 0))) {
            if ($backend->optimize()) {
                if (DEBUG)
                    trigger_error(_("Optimizing database"), E_USER_NOTICE);
            }
        }

        /* Generate notification emails? */
        if (isa($newrevision, 'WikiDB_PageRevision')) {
            // Save didn't fail because of concurrent updates.
            $notify = $this->_wikidb->get('notify');
            if (!empty($notify) and is_array($notify) and !isa($GLOBALS['request'],'MockRequest')) {
                list($emails, $userids) = $this->getPageChangeEmails($notify);
                if (!empty($emails)) {
                    $this->sendPageChangeNotification($wikitext, $version, $meta, $emails, $userids);
                }
            }
            $newrevision->_transformedContent = $formatted;
        }

	return $newrevision;
    }

    function getPageChangeEmails($notify) {
        $emails = array(); $userids = array();
        foreach ($notify as $page => $users) {
            if (glob_match($page, $this->_pagename)) {
                foreach ($users as $userid => $user) {
                    if (!$user) { // handle the case for ModeratePage: no prefs, just userid's.
                        global $request;
                        $u = $request->getUser();
                        if ($u->UserName() == $userid) {
                            $prefs = $u->getPreferences();
                        } else {
                            // not current user
                            if (ENABLE_USER_NEW) {
                                $u = WikiUser($userid);
                                $u->getPreferences();
                                $prefs = &$u->_prefs;
                            } else {
                                $u = new WikiUser($GLOBALS['request'], $userid);
                                $prefs = $u->getPreferences();
                            }
                        }
                        $emails[] = $prefs->get('email');
                        $userids[] = $userid;
                    } else {
                      if (!empty($user['verified']) and !empty($user['email'])) {
                        $emails[]  = $user['email'];
                        $userids[] = $userid;
                      } elseif (!empty($user['email'])) {
                        global $request;
                        // do a dynamic emailVerified check update
                        $u = $request->getUser();
                        if ($u->UserName() == $userid) {
                            if ($request->_prefs->get('emailVerified')) {
                                $emails[] = $user['email'];
                                $userids[] = $userid;
                                $notify[$page][$userid]['verified'] = 1;
                                $request->_dbi->set('notify', $notify);
                            }
                        } else {
                            // not current user
                            if (ENABLE_USER_NEW) {
                                $u = WikiUser($userid);
                                $u->getPreferences();
                                $prefs = &$u->_prefs;
                            } else {
                                $u = new WikiUser($GLOBALS['request'], $userid);
                                $prefs = $u->getPreferences();
                            }
                            if ($prefs->get('emailVerified')) {
                                $emails[] = $user['email'];
                                $userids[] = $userid;
                                $notify[$page][$userid]['verified'] = 1;
                                $request->_dbi->set('notify', $notify);
                            }
                        }
                        // ignore verification
                        /*
                        if (DEBUG) {
                            if (!in_array($user['email'],$emails))
                                $emails[] = $user['email'];
                        }
                        */
                    }
                  }
                }
            }
        }
        $emails = array_unique($emails);
        $userids = array_unique($userids);
        return array($emails, $userids);
    }

    /**
     * Send udiff for a changed page to multiple users.
     * See rename and remove methods also
     */
    function sendPageChangeNotification(&$wikitext, $version, $meta, $emails, $userids) {
        global $request;
        if (@is_array($request->_deferredPageChangeNotification)) {
            // collapse multiple changes (loaddir) into one email
            $request->_deferredPageChangeNotification[] 
		= array($this->_pagename, $emails, $userids);
            return;
        }
        $backend = &$this->_wikidb->_backend;
        //$backend = &$request->_dbi->_backend;
        $subject = _("Page change").' '.urlencode($this->_pagename);
        $previous = $backend->get_previous_version($this->_pagename, $version);
        if (!isset($meta['mtime'])) $meta['mtime'] = time();
        if ($previous) {
            $difflink = WikiURL($this->_pagename, array('action'=>'diff'), true);
            $cache = &$this->_wikidb->_cache;
            //$cache = &$request->_dbi->_cache;
            $this_content = explode("\n", $wikitext);
            $prevdata = $cache->get_versiondata($this->_pagename, $previous, true);
            if (empty($prevdata['%content']))
                $prevdata = $backend->get_versiondata($this->_pagename, $previous, true);
            $other_content = explode("\n", $prevdata['%content']);
            
            include_once("lib/difflib.php");
            $diff2 = new Diff($other_content, $this_content);
            //$context_lines = max(4, count($other_content) + 1,
            //                     count($this_content) + 1);
            $fmt = new UnifiedDiffFormatter(/*$context_lines*/);
            $content  = $this->_pagename . " " . $previous . " " . 
                Iso8601DateTime($prevdata['mtime']) . "\n";
            $content .= $this->_pagename . " " . $version . " " .  
                Iso8601DateTime($meta['mtime']) . "\n";
            $content .= $fmt->format($diff2);
            
        } else {
            $difflink = WikiURL($this->_pagename,array(),true);
            $content = $this->_pagename . " " . $version . " " .  
                Iso8601DateTime($meta['mtime']) . "\n";
            $content .= _("New page");
        }
        $from = $request->_user->getId();
        $editedby = sprintf(_("Edited by: %s"), $from);
        $emails = join(',',$emails);
        $headers = "From: $from <nobody>\r\n" .
       		"Bcc: $emails\r\n" .
       		"MIME-Version: 1.0\r\n" .
       		"Content-Type: text/plain; charset=".CHARSET."; format=flowed\r\n" .
       		"Content-Transfer-Encoding: 8bit";
        if (mail("<undisclosed-recipients>",
                 "[".WIKI_NAME."] ".$subject, 
                 $subject."\n". $editedby."\n". $difflink."\n\n". $content,
                 $headers))
            trigger_error(sprintf(_("PageChange Notification of %s sent to %s"),
                                  $this->_pagename, join(',',$userids)), E_USER_NOTICE);
        else
            trigger_error(sprintf(_("PageChange Notification Error: Couldn't send %s to %s"),
                                  $this->_pagename, join(',',$userids)), E_USER_WARNING);
    }

    /** support mass rename / remove (not yet tested)
     */
    function sendPageRenameNotification($to, &$meta, $emails, $userids) {
        global $request;
        if (@is_array($request->_deferredPageRenameNotification)) {
            $request->_deferredPageRenameNotification[] = array($this->_pagename, 
                                                                $to, $meta, $emails, $userids);
        } else {
            $oldname = $this->_pagename;
            $from = $request->_user->getId();
            $editedby = sprintf(_("Edited by: %s"), $from);
            $emails = join(',',$emails);
            $subject = sprintf(_("Page rename %s to %s"), urlencode($oldname), urlencode($to));
            $link = WikiURL($to, true);
	        $headers = "From: $from <nobody>\r\n" .
       			"Bcc: $emails\r\n" .
       			"MIME-Version: 1.0\r\n" .
        		"Content-Type: text/plain; charset=".CHARSET."; format=flowed\r\n" .
        		"Content-Transfer-Encoding: 8bit";
            if (mail("<undisclosed-recipients>",
                     "[".WIKI_NAME."] ".$subject, 
                     $subject."\n".$editedby."\n".$link."\n\n"."Renamed $from to $to",
                     $headers))
                trigger_error(sprintf(_("PageChange Notification of %s sent to %s"),
                                      $oldname, join(',',$userids)), E_USER_NOTICE);
            else
                trigger_error(sprintf(_("PageChange Notification Error: Couldn't send %s to %s"),
                                      $oldname, join(',',$userids)), E_USER_WARNING);
        }
    }

    /**
     * Get the most recent revision of a page.
     *
     * @access public
     *
     * @return WikiDB_PageRevision The current WikiDB_PageRevision object. 
     */
    function getCurrentRevision ($need_content = true) {
        $backend = &$this->_wikidb->_backend;
        $cache = &$this->_wikidb->_cache;
        $pagename = &$this->_pagename;
        
        // Prevent deadlock in case of memory exhausted errors
        // Pure selection doesn't really need locking here.
        //   sf.net bug#927395
        // I know it would be better to lock, but with lots of pages this deadlock is more 
        // severe than occasionally get not the latest revision.
        // In spirit to wikiwiki: read fast, edit slower.
        //$backend->lock();
        $version = $cache->get_latest_version($pagename);
        // getRevision gets the content also!
        $revision = $this->getRevision($version, $need_content);
        //$backend->unlock();
        assert($revision);
        return $revision;
    }

    /**
     * Get a specific revision of a WikiDB_Page.
     *
     * @access public
     *
     * @param integer $version  Which revision to get.
     *
     * @return WikiDB_PageRevision The requested WikiDB_PageRevision object, or
     * false if the requested revision does not exist in the {@link WikiDB}.
     * Note that version zero of any page always exists.
     */
    function getRevision ($version, $need_content=true) {
        $cache = &$this->_wikidb->_cache;
        $pagename = &$this->_pagename;
        
        if (! $version or $version == -1) // 0 or false
            return new WikiDB_PageRevision($this->_wikidb, $pagename, 0);

        assert($version > 0);
        $vdata = $cache->get_versiondata($pagename, $version, $need_content);
        if (!$vdata) {
            return new WikiDB_PageRevision($this->_wikidb, $pagename, 0);
        }
        return new WikiDB_PageRevision($this->_wikidb, $pagename, $version,
                                       $vdata);
    }

    /**
     * Get previous page revision.
     *
     * This method find the most recent revision before a specified
     * version.
     *
     * @access public
     *
     * @param integer $version  Find most recent revision before this version.
     *  You can also use a WikiDB_PageRevision object to specify the $version.
     *
     * @return WikiDB_PageRevision The requested WikiDB_PageRevision object, or false if the
     * requested revision does not exist in the {@link WikiDB}.  Note that
     * unless $version is greater than zero, a revision (perhaps version zero,
     * the default revision) will always be found.
     */
    function getRevisionBefore ($version=false, $need_content=true) {
        $backend = &$this->_wikidb->_backend;
        $pagename = &$this->_pagename;
        if ($version === false)
            $version = $this->_wikidb->_cache->get_latest_version($pagename);
        else
            $version = $this->_coerce_to_version($version);

        if ($version == 0)
            return false;
        //$backend->lock();
        $previous = $backend->get_previous_version($pagename, $version);
        $revision = $this->getRevision($previous, $need_content);
        //$backend->unlock();
        assert($revision);
        return $revision;
    }

    /**
     * Get all revisions of the WikiDB_Page.
     *
     * This does not include the version zero (default) revision in the
     * returned revision set.
     *
     * @return WikiDB_PageRevisionIterator A
     *   WikiDB_PageRevisionIterator containing all revisions of this
     *   WikiDB_Page in reverse order by version number.
     */
    function getAllRevisions() {
        $backend = &$this->_wikidb->_backend;
        $revs = $backend->get_all_revisions($this->_pagename);
        return new WikiDB_PageRevisionIterator($this->_wikidb, $revs);
    }
    
    /**
     * Find pages which link to or are linked from a page.
     *
     * @access public
     *
     * @param boolean $reversed Which links to find: true for backlinks (default).
     *
     * @return WikiDB_PageIterator A WikiDB_PageIterator containing
     * all matching pages.
     */
    function getLinks ($reversed = true, $include_empty=false, $sortby=false, 
                       $limit=false, $exclude=false) {
        $backend = &$this->_wikidb->_backend;
        $result =  $backend->get_links($this->_pagename, $reversed, 
                                       $include_empty, $sortby, $limit, $exclude);
        return new WikiDB_PageIterator($this->_wikidb, $result, 
                                       array('include_empty' => $include_empty,
                                             'sortby' => $sortby, 
                                             'limit' => $limit, 
                                             'exclude' => $exclude));
    }

    /**
     * All Links from other pages to this page.
     */
    function getBackLinks($include_empty=false, $sortby=false, $limit=false, $exclude=false) {
        return $this->getLinks(true, $include_empty, $sortby, $limit, $exclude);
    }
    /**
     * Forward Links: All Links from this page to other pages.
     */
    function getPageLinks($include_empty=false, $sortby=false, $limit=false, $exclude=false) {
        return $this->getLinks(false, $include_empty, $sortby, $limit, $exclude);
    }
    
    /**
     * possibly faster link existance check. not yet accelerated.
     */
    function existLink($link, $reversed=false) {
        $backend = &$this->_wikidb->_backend;
        if (method_exists($backend,'exists_link'))
            return $backend->exists_link($this->_pagename, $link, $reversed);
        //$cache = &$this->_wikidb->_cache;
        // TODO: check cache if it is possible
        $iter = $this->getLinks($reversed, false);
        while ($page = $iter->next()) {
            if ($page->getName() == $link)
                return $page;
        }
        $iter->free();
        return false;
    }
            
    /**
     * Access WikiDB_Page non version-specific meta-data.
     *
     * @access public
     *
     * @param string $key Which meta data to get.
     * Some reserved meta-data keys are:
     * <dl>
     * <dt>'date'  <dd> Created as unixtime
     * <dt>'locked'<dd> Is page locked? 'yes' or 'no'
     * <dt>'hits'  <dd> Page hit counter.
     * <dt>'_cached_html' <dd> Transformed CachedMarkup object, serialized + optionally gzipped.
     *                         In SQL stored now in an extra column.
     * Optional data:
     * <dt>'pref'  <dd> Users preferences, stored only in homepages.
     * <dt>'owner' <dd> Default: first author_id. We might add a group with a dot here:
     *                  E.g. "owner.users"
     * <dt>'perm'  <dd> Permission flag to authorize read/write/execution of 
     *                  page-headers and content.
     + <dt>'moderation'<dd> ModeratedPage data
     * <dt>'score' <dd> Page score (not yet implement, do we need?)
     * </dl>
     *
     * @return scalar The requested value, or false if the requested data
     * is not set.
     */
    function get($key) {
        $cache = &$this->_wikidb->_cache;
        $backend = &$this->_wikidb->_backend;
        if (!$key || $key[0] == '%')
            return false;
        // several new SQL backends optimize this.
        if (!WIKIDB_NOCACHE_MARKUP
            and $key == '_cached_html' 
            and method_exists($backend, 'get_cached_html')) 
        {
            return $backend->get_cached_html($this->_pagename);
        }
        $data = $cache->get_pagedata($this->_pagename);
   …

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