<?php
/**
 * The Strangecode Codebase - a general application development framework for PHP
 * For details visit the project site: <http://trac.strangecode.com/codebase/>
 * Copyright 2001-2012 Strangecode, LLC
 *
 * This file is part of The Strangecode Codebase.
 *
 * The Strangecode Codebase 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 3 of the License, or (at your option)
 * any later version.
 *
 * The Strangecode Codebase 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
 * The Strangecode Codebase. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * PEdit.inc.php
 *
 * PEdit provides a mechanism to store text in php variables
 * which will be printed to the client browser under normal
 * circumstances, but an authenticated user can 'edit' the document--
 * data stored in vars will be shown in html form elements to be edited
 * and saved. Posted data is stored in XML format in a specified data dir.
 * A copy of the previous version is saved with the unix
 * timestamp as part of the filename. This allows reverting to previous versions.
 *
 * To use, include this file, initialize variables,
 * and call printing/editing functions where you want data and forms to
 * show up.
 *
 * @author  Quinn Comendant <quinn@strangecode.com>
 * @concept Beau Smith <beau@beausmith.com>
 * @version 2.0
 *
 * Example of use:

 // Initialize PEdit object.
 require_once 'codebase/lib/PEdit.inc.php';
 $pedit = new PEdit(array(
     'data_dir' => COMMON_BASE . '/html/_pedit_data',
     'authorized' => true,
 ));

 // Setup content data types.
 $pedit->set('title');
 $pedit->set('content', array('type' => 'textarea'));

 // After setting all parameters and data, load the data.
 $pedit->start();

 // Print content.
 echo $pedit->get('title');
 echo $pedit->get('content');

 // Print additional PEdit functionality.
 $pedit->formBegin();
 $pedit->printAllForms();
 $pedit->printVersions();
 $pedit->formEnd();

 */
class PEdit
{

    // PEdit object parameters.
    protected $_params = array(
        'data_dir' => '',
        'character_set' => 'utf-8',
        'versions_min_qty' => 20,
        'versions_min_days' => 10,
    );

    protected $_data = array(); // Array to store loaded data.
    protected $_data_file = ''; // Full file path to the pedit data file.
    protected $_authorized = false; // User is authenticated to see extended functions.
    protected $_data_loaded = false;
    public $op = '';

    /**
     * Constructs a new PEdit object. Initializes what file is being operated with
     * (PHP_SELF) and what that operation is. The two
     * operations that actually modify data (save, restore) are treated differently
     * than view operations (versions, view, default). They die redirect so you see
     * the page you just modified.
     *
     * @access public
     * @param optional array $params  A hash containing connection parameters.
     */
    public function __construct($params)
    {
        $this->setParam($params);

        if ($this->getParam('authorized') === true) {
            $this->_authorized = true;
        }

        // Setup PEAR XML libraries.
        require_once 'XML/Serializer.php';
        $this->xml_serializer = new XML_Serializer(array(
            XML_SERIALIZER_OPTION_INDENT => '',
            XML_SERIALIZER_OPTION_LINEBREAKS => '',
            XML_SERIALIZER_OPTION_RETURN_RESULT => true,
            XML_SERIALIZER_OPTION_TYPEHINTS => true,
        ));
        require_once 'XML/Unserializer.php';
        $this->xml_unserializer = new XML_Unserializer(array(
            XML_UNSERIALIZER_OPTION_COMPLEXTYPE => 'array',
        ));
    }

    /**
     * Set (or overwrite existing) parameters by passing an array of new parameters.
     *
     * @access public
     * @param  array    $params     Array of parameters (key => val pairs).
     */
    public function setParam($params)
    {
        $app =& App::getInstance();

        if (isset($params) && is_array($params)) {
            // Merge new parameters with old overriding only those passed.
            $this->_params = array_merge($this->_params, $params);
        } else {
            $app->logMsg(sprintf('Parameters are not an array: %s', $params), LOG_WARNING, __FILE__, __LINE__);
        }
    }

    /**
     * Return the value of a parameter, if it exists.
     *
     * @access public
     * @param string $param        Which parameter to return.
     * @return mixed               Configured parameter value.
     */
    public function getParam($param)
    {
        $app =& App::getInstance();

        if (array_key_exists($param, $this->_params)) {
            return $this->_params[$param];
        } else {
            $app->logMsg(sprintf('Parameter is not set: %s', $param), LOG_DEBUG, __FILE__, __LINE__);
            return null;
        }
    }

    /*
    * Load the pedit data and run automatic functions.
    *
    * @access   public
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    12 Apr 2006 12:43:47
    */
    public function start($initialize_data_file=false)
    {
        $app =& App::getInstance();

        if (!is_dir($this->getParam('data_dir'))) {
            trigger_error(sprintf('PEdit data directory not found: %s', $this->getParam('data_dir')), E_USER_WARNING);
        }

        // The location of the data file. (i.e.: "COMMON_DIR/html/_pedit_data/news/index.xml")
        $this->_data_file = sprintf('%s%s.xml', $this->getParam('data_dir'), $_SERVER['SCRIPT_NAME']);

        // Make certain the evaluated path matches the assumed path (realpath will expand /../../);
        // if realpath returns FALSE we're not concerned because it means the file doesn't exist (_initializeDataFile() will create it).
        if (false !== realpath($this->_data_file) && $this->_data_file !== realpath($this->_data_file)) {
            $app->logMsg(sprintf('PEdit data file not a real path: %s', $this->_data_file), LOG_CRIT, __FILE__, __LINE__);
            trigger_error(sprintf('PEdit data file not a real path: %s', $this->_data_file), E_USER_ERROR);
        }

        // op is used throughout the script to determine state.
        $this->op = getFormData('op');

        // Automatic functions based on state.
        switch ($this->op) {
        case 'Save' :
            if ($this->_writeData()) {
                $app->dieURL($_SERVER['PHP_SELF']);
            }
            break;

        case 'Restore' :
            if ($this->_restoreVersion(getFormData('version'))) {
                $app->dieURL($_SERVER['PHP_SELF']);
            }
            break;

        case 'View' :
            $this->_data_file = sprintf('%s%s__%s.xml', $this->getParam('data_dir'), $_SERVER['PHP_SELF'], getFormData('version'));
            $app->raiseMsg(sprintf(_("This is <em><strong>only a preview</strong></em> of version %s."), getFormData('version')), MSG_NOTICE, __FILE__, __LINE__);
            break;
        }

        // Load data.
        $this->_loadDataFile();

        if ($initialize_data_file === true) {
            $this->_createVersion();
            $this->_initializeDataFile();
        }
    }

    /**
     * Stores a variable in the pedit data array with the content name, and type of form.
     *
     * @access public
     *
     * @param string    $content         The variable containing the text to store.
     * @param array     $options         Additional options to store with this data.
     */
    public function set($name, $options=array())
    {
        $app =& App::getInstance();

        $name = preg_replace('/\s/', '_', $name);
        if (!isset($this->_data[$name])) {
            $this->_data[$name] = array_merge(array('content' => ''), $options);
        } else {
            $app->logMsg(sprintf('Duplicate set data: %s', $name), LOG_NOTICE, __FILE__, __LINE__);
        }
    }

    /**
     * Returns the contents of a data variable. The variable must first be 'set'.
     *
     * @access public
     * @param string $name   The name of the variable to return.
     * @return string        The trimmed content of the named data.
     */
    public function get($name)
    {
        $name = preg_replace('/\s/', '_', $name);
        if ($this->op != 'Edit' && $this->op != 'Versions' && isset($this->_data[$name]['content'])) {
            return $this->_data[$name]['content'];
        } else {
            return '';
        }
    }

    /**
     * Prints the beginning <form> HTML tag, as well as hidden input forms.
     *
     * @return bool  False if unauthorized or current page is a version.
     */
    public function formBegin()
    {
        $app =& App::getInstance();

        if (!$this->_authorized || empty($this->_data)) {
            return false;
        }
        ?>
        <form action="<?php echo oTxt($_SERVER['PHP_SELF']); ?>" method="post" id="sc-pedit-form">
        <input type="hidden" name="filename" value="<?php echo oTxt($_SERVER['PHP_SELF']); ?>" />
        <input type="hidden" name="file_hash" value="<?php echo $this->_fileHash(); ?>" />
        <?php
        $app->printHiddenSession();
        switch ($this->op) {
        case 'Edit' :
            ?>
            <div class="sc-pedit-buttons">
                <input type="submit" name="op" value="<?php echo _("Save"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Save"))?>" accesskey="<?php echo mb_substr(_("Save"), 0, 1) ?>" />
                <input type="submit" name="op" value="<?php echo _("Cancel"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Cancel"))?>" accesskey="<?php echo mb_substr(_("Cancel"), 0, 1) ?>" />
            </div>
            <?php
            break;

        case 'View' :
            ?>
            <input type="hidden" name="version" value="<?php echo getFormData('version'); ?>" />
            <?php
            break;
        }
    }

    /**
     * Loops through the PEdit data array and prints all the HTML forms corresponding
     * to all pedit variables, in the order in which they were 'set'.
     *
     * @access public
     */
    public function printAllForms()
    {
        if ($this->_authorized && $this->op == 'Edit' && is_array($this->_data) && $this->_data_loaded) {
            foreach ($this->_data as $name=>$d) {
                $this->printForm($name);
            }
        }
    }

    /**
     * Prints the HTML forms corresponding to pedit variables. Each variable
     * must first be 'set'.
     *
     * @access public
     * @param string $name      The name of the variable.
     * @param string $type      Type of form to print. Currently only 'text' and 'textarea' supported.
     */
    public function printForm($name, $type='text')
    {
        if ($this->_authorized && $this->op == 'Edit' && $this->_data_loaded) {
            ?>
            <div class="sc-pedit-item">
            <?php
            $type = (isset($this->_data[$name]['type'])) ? $this->_data[$name]['type'] : $type;
            // Print edit form.
            switch ($type) {
            case 'text' :
            default :
                ?>
                <label>
                <?php echo ucfirst(str_replace('_', ' ', $name)); ?>
                <input type="text" name="_pedit_data[<?php echo $name; ?>]" id="sc-pedit-field-<?php echo $name; ?>" value="<?php echo oTxt($this->_data[$name]['content']); ?>" class="sc-full" />
                </label>
                <?php
                break;

            case 'textarea' :
                ?>
                <label>
                <?php echo ucfirst(str_replace('_', ' ', $name)); ?>
                <textarea name="_pedit_data[<?php echo $name; ?>]" id="sc-pedit-field-<?php echo $name; ?>" rows="" cols="" class="sc-full sc-tall"><?php echo oTxt($this->_data[$name]['content']); ?></textarea>
                </label>
                <?php
                break;
            }
            ?>
            </div>
            <?php
        }
    }

    /**
     * Prints the ending </form> HTML tag, as well as buttons used during
     * different operations.
     *
     * @return bool  False if unauthorized or current page is a version.
     */
    public function formEnd()
    {
        if (!$this->_authorized || empty($this->_data)) {
            // Don't show form elements for versioned documents.
            return false;
        }
        switch ($this->op) {
        case 'Edit' :
            ?>
            <div class="sc-pedit-buttons">
                <input type="submit" name="op" value="<?php echo _("Save"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Save"))?>" accesskey="<?php echo mb_substr(_("Save"), 0, 1) ?>" />
                <input type="submit" name="op" value="<?php echo _("Cancel"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Cancel"))?>" accesskey="<?php echo mb_substr(_("Cancel"), 0, 1) ?>" />
            </div>
            </form>
            <?php
            break;

        case 'Versions' :
            ?>
            <div class="sc-pedit-buttons">
                <input type="submit" name="op" value="<?php echo _("Cancel"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Cancel"))?>" accesskey="<?php echo mb_substr(_("Cancel"), 0, 1) ?>" />
            </div>
            </form>
            <?php
            break;

        case 'View' :
            ?>
            <div class="sc-pedit-buttons">
                <input type="submit" name="op" value="<?php echo _("Restore"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Restore"))?>" accesskey="<?php echo mb_substr(_("Restore"), 0, 1) ?>" />
                <input type="submit" name="op" value="<?php echo _("Versions"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Versions"))?>" accesskey="<?php echo mb_substr(_("Versions"), 0, 1) ?>" />
                <input type="submit" name="op" value="<?php echo _("Cancel"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Cancel"))?>" accesskey="<?php echo mb_substr(_("Cancel"), 0, 1) ?>" />
            </div>
            </form>
            <?php
            break;

        default :
            ?>
            <div class="sc-pedit-buttons">
                <input type="submit" name="op" value="<?php echo _("Edit"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Edit"))?>" accesskey="<?php echo mb_substr(_("Edit"), 0, 1) ?>" />
                <input type="submit" name="op" value="<?php echo _("Versions"); ?>" title="<?php echo preg_replace('/^(\w)/i', '($1)', _("Versions"))?>" accesskey="<?php echo mb_substr(_("Versions"), 0, 1) ?>" />
            </div>
            </form>
            <?php
        }
    }

    /**
     * Prints an HTML list of versions of current file, with the filesize
     * and links to view and restore the file.
     *
     * @access public
     */
    public function printVersions()
    {
        $app =& App::getInstance();

        if ($this->_authorized && $this->op == 'Versions') {
            // Print versions and commands to view/restore.
            $version_files = $this->_getVersions();
            ?><h1><?php printf(_("%s saved versions of %s"), sizeof($version_files), basename($_SERVER['PHP_SELF'])); ?></h1><?php
            if (is_array($version_files) && !empty($version_files)) {
                ?>
                <table id="sc-pedit-versions-table">
                <tr>
                    <th><?php echo _("Date"); ?></th>
                    <th><?php echo _("Time"); ?></th>
                    <th><?php echo _("File size"); ?></th>
                    <th><?php echo _("Version options"); ?></th>
                </tr>
                <?php
                foreach ($version_files as $v) {
                    ?>
                    <tr>
                        <td><?php echo date($app->getParam('date_format'), $v['unixtime']); ?></td>
                        <td><?php echo date($app->getParam('time_format'), $v['unixtime']); ?></td>
                        <td><?php echo humanFileSize($v['filesize']); ?></td>
                        <td class="sc-nowrap"><a href="<?php echo $app->oHREF($_SERVER['PHP_SELF'] . '?op=View&version=' . $v['unixtime'] . '&file_hash=' . $this->_fileHash()); ?>"><?php echo _("View"); ?></a> <?php echo _("or"); ?> <a href="<?php echo $app->oHREF($_SERVER['PHP_SELF'] . '?op=Restore&version=' . $v['unixtime'] . '&file_hash=' . $this->_fileHash()); ?>"><?php echo _("Restore"); ?></a></td>
                    </tr>
                    <?php
                }
                ?>
                </table>
                <div class="sc-help"><?php printf(_("When there are more than %s versions, those over %s days old are deleted."), $this->getParam('versions_min_qty'), $this->getParam('versions_min_days')); ?></div>
                <?php
            }
        }
    }

    /*
    * Returns a secret hash for the current file.
    *
    * @access   public
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    12 Apr 2006 10:52:35
    */
    protected function _fileHash()
    {
        $app =& App::getInstance();

        return md5($app->getParam('signing_key') . $_SERVER['PHP_SELF']);
    }

    /*
    * Load the XML data file into $this->_data.
    *
    * @access   public
    * @return   bool    false on error
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    11 Apr 2006 20:36:26
    */
    protected function _loadDataFile()
    {
        $app =& App::getInstance();

        if (!file_exists($this->_data_file)) {
            if (!$this->_initializeDataFile()) {
                $app->logMsg(sprintf('Initializing content file failed: %s', $this->_data_file), LOG_WARNING, __FILE__, __LINE__);
                return false;
            }
        }
        $xml_file_contents = file_get_contents($this->_data_file);
        $status = $this->xml_unserializer->unserialize($xml_file_contents, false);
        if (PEAR::isError($status)) {
            $app->logMsg(sprintf('XML_Unserialize error: %s', $status->getMessage()), LOG_WARNING, __FILE__, __LINE__);
            return false;
        }
        $xml_file_data = $this->xml_unserializer->getUnserializedData();

        // Only load data specified with set(), even though there may be more in the xml file.
        foreach ($this->_data as $name => $initial_data) {
            if (isset($xml_file_data[$name])) {
                $this->_data[$name] = array_merge($initial_data, $xml_file_data[$name]);
            } else {
                $this->_data[$name] = $initial_data;
            }
        }

        $this->_data_loaded = true;
        return true;
    }

    /*
    * Start a new data file.
    *
    * @access   public
    * @return   The success value of both xml_serializer->serialize() and _filePutContents()
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    11 Apr 2006 20:53:42
    */
    protected function _initializeDataFile()
    {
        $app =& App::getInstance();

        $app->logMsg(sprintf('Initializing data file: %s', $this->_data_file), LOG_INFO, __FILE__, __LINE__);
        $xml_file_contents = $this->xml_serializer->serialize($this->_data);
        return $this->_filePutContents($this->_data_file, $xml_file_contents);
    }

    /**
     * Saves the POSTed data by overwriting the pedit variables in the
     * current file.
     *
     * @access private
     * @return bool  False if unauthorized or on failure. True on success.
     */
    protected function _writeData()
    {
        $app =& App::getInstance();

        if (!$this->_authorized) {
            return false;
        }
        if ($this->_fileHash() != getFormData('file_hash')) {
            // Posted data is NOT for this file!
            $app->logMsg(sprintf('File_hash does not match current file.', null), LOG_WARNING, __FILE__, __LINE__);
            return false;
        }

        // Scrub incoming data. Escape tags?
        $new_data = getFormData('_pedit_data');

        if (is_array($new_data) && !empty($new_data)) {
            // Make certain a version is created.
            $this->_deleteOldVersions();
            if (!$this->_createVersion()) {
                $app->logMsg(sprintf('Failed creating new version of file.', null), LOG_NOTICE, __FILE__, __LINE__);
                return false;
            }

            // Collect posted data that is already specified in _data (by set()).
            foreach ($new_data as $name => $content) {
                if (isset($this->_data[$name])) {
                    $this->_data[$name]['content'] = $content;
                }
            }

            if (is_array($this->_data) && !empty($this->_data)) {
                $xml_file_contents = $this->xml_serializer->serialize($this->_data);
                return $this->_filePutContents($this->_data_file, $xml_file_contents);
            }
        }
    }

    /*
    * Writes content to the specified file.
    *
    * @access   public
    * @param    string  $filename   Path to file.
    * @param    string  $content    Data to write into file.
    * @return   bool                Success or failure.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    11 Apr 2006 22:48:30
    */
    protected function _filePutContents($filename, $content)
    {
        $app =& App::getInstance();

        // Ensure requested filename is within the pedit data dir.
        if (mb_strpos($filename, $this->getParam('data_dir')) === false) {
            $app->logMsg(sprintf('Failed writing file outside pedit data_dir: %s', $filename), LOG_ERR, __FILE__, __LINE__);
            return false;
        }

        // Recursively create directories.
        $subdirs = preg_split('!/!', str_replace($this->getParam('data_dir'), '', dirname($filename)), -1, PREG_SPLIT_NO_EMPTY);
        // Start with the pedit data_dir base.
        $curr_path = $this->getParam('data_dir');
        while (!empty($subdirs)) {
            $curr_path .= '/' . array_shift($subdirs);
            if (!is_dir($curr_path)) {
                if (!mkdir($curr_path)) {
                    $app->logMsg(sprintf('Failed mkdir: %s', $curr_path), LOG_ERR, __FILE__, __LINE__);
                    return false;
                }
            }
        }

        // Open file for writing and truncate to zero length.
        if ($fp = fopen($filename, 'w')) {
            if (flock($fp, LOCK_EX)) {
                fwrite($fp, $content);
                flock($fp, LOCK_UN);
            } else {
                $app->logMsg(sprintf('Could not lock file for writing: %s', $filename), LOG_ERR, __FILE__, __LINE__);
                return false;
            }
            fclose($fp);
            // Success!
            $app->logMsg(sprintf('Wrote to file: %s', $filename), LOG_DEBUG, __FILE__, __LINE__);
            return true;
        } else {
            $app->logMsg(sprintf('Could not open file for writing: %s', $filename), LOG_ERR, __FILE__, __LINE__);
            return false;
        }
    }

    /**
     * Makes a copy of the current file with the unix timestamp appended to the
     * filename.
     *
     * @access private
     * @return bool  False on failure. True on success.
     */
    protected function _createVersion()
    {
        $app =& App::getInstance();

        if (!$this->_authorized) {
            return false;
        }
        if ($this->_fileHash() != getFormData('file_hash')) {
            // Posted data is NOT for this file!
            $app->logMsg(sprintf('File_hash does not match current file.', null), LOG_ERR, __FILE__, __LINE__);
            return false;
        }

        // Ensure current data file exists.
        if (!file_exists($this->_data_file)) {
            $app->logMsg(sprintf('Data file does not yet exist: %s', $this->_data_file), LOG_NOTICE, __FILE__, __LINE__);
            return false;
        }

        // Do the actual copy. File naming scheme must be consistent!
        // filename.php.xml becomes filename.php__1124124128.xml
        $version_file = sprintf('%s__%s.xml', preg_replace('/\.xml$/', '', $this->_data_file), time());
        if (!copy($this->_data_file, $version_file)) {
            $app->logMsg(sprintf('Failed copying new version: %s -> %s', $this->_data_file, $version_file), LOG_ERR, __FILE__, __LINE__);
            return false;
        }

        return true;
    }

    /*
    * Delete all versions older than versions_min_days if there are more than versions_min_qty or 100.
    *
    * @access   public
    * @return bool  False on failure. True on success.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @since    12 Apr 2006 11:08:11
    */
    protected function _deleteOldVersions()
    {
        $app =& App::getInstance();

        $version_files = $this->_getVersions();
        if (is_array($version_files) && sizeof($version_files) > $this->getParam('versions_min_qty')) {
            // Pop oldest ones off bottom of array.
            $oldest = array_pop($version_files);
            // Loop while minimum X qty && minimum X days worth but never more than 100 qty.
            while ((sizeof($version_files) > $this->getParam('versions_min_qty')
            && $oldest['unixtime'] < mktime(date('H'), date('i'), date('s'), date('m'), date('d') - $this->getParam('versions_min_days'), date('Y')))
            || sizeof($version_files) > 100) {
                $del_file = dirname($this->_data_file) . '/' . $oldest['filename'];
                if (!unlink($del_file)) {
                    $app->logMsg(sprintf('Failed deleting version: %s', $del_file), LOG_ERR, __FILE__, __LINE__);
                }
                $oldest = array_pop($version_files);
            }
        }
    }

    /**
     * Returns an array of all archived versions of the current file,
     * sorted with newest versions at the top of the array.
     *
     * @access private
     * @return array  Array of versions.
     */
    protected function _getVersions()
    {
        $version_files = array();
        $dir_handle = opendir(dirname($this->_data_file));
        $curr_file_preg_pattern = sprintf('/^%s__(\d+).xml$/', preg_quote(basename($_SERVER['PHP_SELF'])));
        while ($dir_handle && ($version_file = readdir($dir_handle)) !== false) {
            if (!preg_match('/^\./', $version_file) && !is_dir($version_file) && preg_match($curr_file_preg_pattern, $version_file, $time)) {
                $version_files[] = array(
                    'filename' => $version_file,
                    'unixtime' => $time[1],
                    'filesize' => filesize(dirname($this->_data_file) . '/' . $version_file)
                );
            }
        }

        if (is_array($version_files) && !empty($version_files)) {
            array_multisort($version_files, SORT_DESC);
            return $version_files;
        } else {
            return array();
        }
    }

    /**
     * Makes a version backup of the current file, then copies the specified
     * archived version over the current file.
     *
     * @access private
     * @param string $version    Unix timestamp of archived version to restore.
     * @return bool  False on failure. True on success.
     */
    protected function _restoreVersion($version)
    {
        $app =& App::getInstance();

        if (!$this->_authorized) {
            return false;
        }

        // The file to restore.
        $version_file = sprintf('%s__%s.xml', preg_replace('/\.xml$/', '', $this->_data_file), $version);

        // Ensure specified version exists.
        if (!file_exists($version_file)) {
            $app->logMsg(sprintf('Cannot restore non-existent file: %s', $version_file), LOG_NOTICE, __FILE__, __LINE__);
            return false;
        }

        // Make certain a version is created.
        if (!$this->_createVersion()) {
            $app->logMsg(sprintf('Failed creating new version of file.', null), LOG_ERR, __FILE__, __LINE__);
            return false;
        }

        // Do the actual copy.
        if (!copy($version_file, $this->_data_file)) {
            $app->logMsg(sprintf('Failed copying old version: %s -> %s', $version_file, $this->_data_file), LOG_ERR, __FILE__, __LINE__);
            return false;
        }

        // Success!
        $app->raiseMsg(sprintf(_("Page has been restored to version %s."), $version), MSG_SUCCESS, __FILE__, __LINE__);
        return true;
    }

} // End class.