<?php
if(!defined('sugarEntry') || !sugarEntry) die('Not A Valid Entry Point');
/*********************************************************************************
 * SugarCRM is a customer relationship management program developed by
 * SugarCRM, Inc. Copyright (C) 2004-2010 SugarCRM Inc.
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License version 3 as published by the
 * Free Software Foundation with the addition of the following permission added
 * to Section 15 as permitted in Section 7(a): FOR ANY PART OF THE COVERED WORK
 * IN WHICH THE COPYRIGHT IS OWNED BY SUGARCRM, SUGARCRM DISCLAIMS THE WARRANTY
 * OF NON INFRINGEMENT OF THIRD PARTY RIGHTS.
 * 
 * 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 Affero General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Affero General Public License along with
 * this program; if not, see http://www.gnu.org/licenses or write to the Free
 * Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 * 
 * You can contact SugarCRM, Inc. headquarters at 10050 North Wolfe Road,
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 * 
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License version 3.
 * 
 * In accordance with Section 7(b) of the GNU Affero General Public License version 3,
 * these Appropriate Legal Notices must retain the display of the "Powered by
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 * technical reasons, the Appropriate Legal Notices must display the words
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require_once 'modules/ModuleBuilder/parsers/constants.php' ;

class History
{
    
    private $_dirname ; // base directory for the history files
    private $_basename ; // base name for a history file, for example, listviewdef.php
    private $_list ; // the history - a list of history files
    
    private $_previewFilename ; // the location of a file for preview

    /*
     * Constructor
     * @param string $previewFilename The filename which the caller expects for a preview file
     */
    function __construct ($previewFilename )
    {
        $GLOBALS [ 'log' ]->debug ( get_class ( $this ) . "->__construct( {$previewFilename} )" ) ;
        $this->_previewFilename = $previewFilename ;
        $this->_list = array ( ) ;
        
        $this->_dirname = dirname ( $this->_previewFilename ) ;
        // create the history directory if it does not already exist
        if (! is_dir ( $this->_dirname ))
        {
            mkdir_recursive ( $this->_dirname ) ;
        }
        $this->_basename = basename ( $this->_previewFilename ) ;
        // Reconstruct the history from the saved files
        foreach ( scandir ( $this->_dirname ) as $filename )
        {
            if ($filename != "." && $filename != "..")
            {
                // history files are of the form {$basename}_{$timestamp}
                if (preg_match ( '/(' . $this->_basename . ')_(.*)/', $filename, $matches ) == 1)
                {
                    $this->_list [ $matches [ 2 ] ] = $matches [ 2 ] ;
                }
            }
        }
        // now sort the files, oldest first
        if (count ( $this->_list ) > 0)
        {
            ksort ( $this->_list ) ;
        }
    }


 /*
     * Get the most recent item in the history
     * @return timestamp of the first item
     */
    function getCount ()
    {
        return count ( $this->_list ) ;
    }
    
    /*
     * Get the most recent item in the history
     * @return timestamp of the first item
     */
    function getFirst ()
    {
        return end ( $this->_list ) ;
    }
    
/*
     * Get the oldest item in the history (the default layout)
     * @return timestamp of the last item
     */
    function getLast ()
    {
        return reset ( $this->_list ) ;
    }

    /*
     * Get the next oldest item in the history
     * @return timestamp of the next item
     */
    function getNext ()
    {
        return prev ( $this->_list ) ;
    }

    /*
     * Get the nth item in the history (where the zeroeth record is the most recent)
     * @return timestamp of the nth item
     */
    function getNth ($index)
    {
        $value = end ( $this->_list ) ;
        $i = 0 ;
        while ( $i < $index )
        {
            $value = prev ( $this->_list ) ;
            $i ++ ;
        }
        return $value ;
    }

    /*
     * Add an item to the history
     * @return String   A GMT Unix timestamp for this newly added item
     */
    function append ($path)
    {
        // make sure we don't have a duplicate filename - highly unusual as two people should not be using Studio/MB concurrently, but when testing quite possible to do two appends within one second...
        // because so unlikely in normal use we handle this the naive way by waiting a second so our naming scheme doesn't get overelaborated
        $retries = 0 ;
        
        $time = strtotime ( gmdate ( 'r' ) ) ;
        while ( (file_exists ( $this->_previewFilename . "_" . $time ) && $retries < 5) )
        
        {
            sleep ( 1 ) ;
            $time = strtotime ( gmdate ( 'r' ) ) ;
            $retries ++ ;
        }
        // now we have a unique filename, copy the file into the history
        copy ( $path, $this->_previewFilename . "_" . $time ) ;
        $this->_list [ $time ] = $time ;
        
        // finally, trim the number of files we're holding in the history to that specified in the configuration
        $max_history = (isset ( $GLOBALS [ 'sugar_config' ] [ 'studio_max_history' ] )) ? $GLOBALS [ 'sugar_config' ] [ 'studio_max_history' ] : 50 ;
        $count = count ( $this->_list ) ;
        // truncate the oldest files, keeping only the most recent $GLOBALS['sugar_config']['studio_max_history'] files (zero=keep them all)
        if (($max_history != 0) && ($count > $max_history))
        {
            // most recent files are at the end of the list, so we strip out the first count-max_history records
            // can't just use array_shift because it renumbers numeric keys (our timestamp keys) to start from zero...
            for ( $i = 0 ; $i < $count - $max_history ; $i ++ )
            {
                $timestamp = reset ( $this->_list ) ;
                unset ( $this->_list [ $timestamp ] ) ;
                if (! unlink ( $this->_dirname . "/" . $this->_basename . "_" . $timestamp ))
                {
                    $GLOBALS [ 'log' ]->warn ( "History.php: unable to remove history file {$this->_basename}_$timestamp from directory {$this->_dirname} - permissions problem?" ) ;
                }
            }
        }
        
        // finally, remove any history preview file that might be lurking around - as soon as we append a new record it supercedes any old preview, so that must be removed (bug 20130)
        if (file_exists($this->_previewFilename))
        {
            $GLOBALS [ 'log' ]->debug( get_class($this)."->append(): removing old history file at {$this->_previewFilename}");
            unlink ( $this->_previewFilename);
        }
        
        return $time ;
    }

    /*
     * Restore the historical layout identified by timestamp
     * @param Unix timestamp $timestamp GMT Timestamp of the layout to recover
     * @return GMT Timestamp if successful, null if failure (if the file could not be copied for some reason)
     */
    function restoreByTimestamp ($timestamp)
    {
        $filename = $this->_previewFilename . "_" . $timestamp ;
        $GLOBALS [ 'log' ]->debug ( get_class ( $this ) . ": restoring from $filename to {$this->_previewFilename}" ) ;
        
        if (file_exists ( $filename ))
        {
            copy ( $filename, $this->_previewFilename ) ;
            return $timestamp ;
        }
        return null ;
    }

    /*
     * Undo the restore - revert back to the layout before the restore
     */
    function undoRestore ()
    {
        if (file_exists ( $this->_previewFilename ))
        {
            unlink ( $this->_previewFilename ) ;
        }
    }

}