Logging changes to a text file in MATE

<?php
require_once('DBC.php');
require_once('Common.php');
require_once('php/lang/LangVars-en.php');
require_once('php/AjaxTableEditor.php');

/* http://www.mysqlajaxtableeditor.com */
// ========== Script Settings =============

$p = isAdmin() ? "ADEFHIUOQSVX" : "";
$str_admin = isAdmin() ? " - Logged in as Admin" : " - Not Admin - ";

define("tblMain", "fundflow");
define("primaryCol", "id");
define("sortOn", "id");
define("ascOrDesc", "ASC");

define("displayNum", 100);
define("displayNumInc", 100);
define("orderByColumn", "tr_date");
define("tableTitle", 'FundFlow ' . $str_admin);

define("permissions", $p);  //Available : ADEFHIOQSUVX
define("addRowTitle", "Add ".tbleMain);
define("editRowTitle", "Edit ".tbleMain);

define("addInPlace", true);
define("editInPlace", true);
define("viewQuery", false);
define("paginationLinks", true);

class Blank extends Common
{
    var $Editor;
    var $mateInstances = array('mate1_');

    protected function displayHtml()
    {
        $html = '
            <br />
                <div class="mateAjaxLoaderDiv">
                    <div id="ajaxLoader1"><img src="images/ajax_loader.gif" alt="Loading..." />
                    </div>
                </div>
            <br />
            <br />
                <div id="'.$this->mateInstances[0].'information"></div>
                <div id="mateTooltipErrorDiv" style="display: none;"></div>
                <div id="'.$this->mateInstances[0].'titleLayer" class="mateTitleDiv"></div>
                <div id="'.$this->mateInstances[0].'tableLayer" class="mateTableDiv"></div>
                <div id="'.$this->mateInstances[0].'updateInPlaceLayer" class="mateUpdateInPlaceDiv"></div>
                <div id="'.$this->mateInstances[0].'recordLayer" class="mateRecordLayerDiv"></div>
                <div id="'.$this->mateInstances[0].'searchButtonsLayer" class="mateSearchBtnsDiv"></div>
                <div style="align: center; valign: middle;"><div><center><a  href="http://mukeshdak.com/apps/fundflow/">FundFlow</a></center></div></div>
            ';

        echo $html;

        // Set default session configuration variables here
        $defaultSessionData['orderByColumn'] = orderByColumn;
        $defaultSessionData['ascOrDesc'] = ascOrDesc;
      //    $defaultSessionData['displayNum'] = displayNum;
        //$defaultSessionData['displayNumInc'] = displayNumInc;
        $defaultSessionData = base64_encode($this->Editor->jsonEncode($defaultSessionData));

        $javascript = '
            <script type="text/javascript">
                var ' . $this->mateInstances[0] . ' = new mate("' . $this->mateInstances[0] . '");
                ' . $this->mateInstances[0] . '.setAjaxInfo({url: "' . $_SERVER['PHP_SELF'] . '", history: true});
                ' . $this->mateInstances[0] . '.init("' . $defaultSessionData . '");
            </script>';
        echo $javascript;
    }


    function storeRow($col,$val,$row)
    {
       $_SESSION['old_row'] = $row;
       return $val;
    }

    function logEdit($val,$col,$row)
    {
       $changes = array();
       foreach($row as $col => $val)
       {
          if(isset($_SESSION['old_row'][$col]) && $_SESSION['old_row'][$col] != $val)
          {
             $changes[] = $col.' changed from '.$_SESSION['old_row'][$col].' to '.$val;
          }
       }
       if(count($changes) > 0)
       {
        // log changes
        $log_file_name = basename(__FILE__, ".php")."_".date("Y-m").".csv" ;
        $change_time = date("Y-m-d_H-i-s");
        $file = fopen($log_file_name, "a");
        $changes = "\n". $change_time." Changes by ".$_SESSION['oauth_user']['email']." for " . primaryCol . ": ". $_SESSION['old_row'][primaryCol] . " are ".implode(", ", $changes);
        fwrite ($file, $changes);
        fclose($file);// log changes
       }
    }

    protected function initiateEditor()
    {
        $tableColumns['id'] = array(
            'display_text' => 'ID',
            'perms' => 'TVQFSXO',
            'view_fun' => array(&$this,'showDeleteOnEdit')
        );

        $tableColumns['tr_name'] = array(
            'display_text' => 'Transaction Name',
            'perms' => 'AEVCTXQSHOF'
        );

        $tableColumns['tr_date'] = array(
            'display_text' => 'Tr Date',
            'perms' => 'AEFVCTXQSHO',
            'display_mask' => 'date_format(tr_date,"%d %M %Y")',
            'order_mask' => 'date_format(tr_date,"%Y-%m-%d %T")',
            'calendar' => array('js_format' => 'dd MM yy')
        );

        $tableColumns['tr_value'] = array(
            'display_text' => 'Value',
            'perms' => 'AEVCTAXQSHOF',
            'input_info' => 'size="32"',
            'table_fun' => array(&$this,'limit_characters'),
            'edit_fun' => array(&$this,'storeRow')
            );

        $tableColumns['notes'] = array(
            'display_text' => 'Notes',
            'perms' => 'EVCTAXQSFHO',
            'textarea' => array('cols' => 40, 'rows' => 3),
            'sub_str' => 30
        );

            $tableColumns['modified'] = array(
            'display_text' => 'Modified',
            'perms' => 'VCXQSHO',
            'display_mask' => 'date_format(modified,"%d %M %Y")',
            'calendar' => array('js_format' => 'dd MM yy')
        );

        $errorFun = array(&$this,'logError');

        $this->Editor = new AjaxTableEditor(tblMain, primaryCol, $errorFun, permissions, $tableColumns);
        $this->Editor->setConfig('tableInfo','cellpadding="1" cellspacing="1" align="center" class="mateTable"'); /* width="90%" */
        $this->Editor->setConfig('orderByColumn', orderByColumn);
        $this->Editor->setConfig('removeIcons', "CD");
        $this->Editor->setConfig('tableTitle', tableTitle);
        $this->Editor->setConfig('addRowTitle', addRowTitle);
        $this->Editor->setConfig('editRowTitle', editRowTitle);
        $this->Editor->setConfig('addInPlace', addInPlace);
        $this->Editor->setConfig('editInPlace', editInPlace);
        $this->Editor->setConfig('viewQuery', viewQuery);
        $this->Editor->setConfig('paginationLinks', paginationLinks);
        $this->Editor->setConfig('instanceName',$this->mateInstances[0]);
        $this->Editor->setConfig('afterDeleteFun', array(&$this, 'refreshAfterDelete'));
        $this->Editor->setConfig('afterEditFun',array(&$this,'logEdit'));
    //  $this->Editor->setConfig('modifyRowSets',array(&$this,'changeBgColor'));
        $this->Editor->setConfig('storageType','web');

    //  $userButtons[] = array('label' => 'Show Info', 'call_back_fun' => array(&$this,'testUserBtn'));
    //  $this->Editor->setConfig('userButtons',$userButtons);
        //$this->Editor->setConfig('escapeHtml',true);
    }

    function __construct()
    {
        session_start();
        ob_start();
        $this->initiateEditor();
        if(isset($_POST['json']))
        {
            if(ini_get('magic_quotes_gpc'))
            {
                $_POST['json'] = stripslashes($_POST['json']);
            }
            $this->Editor->data = $this->Editor->jsonDecode($_POST['json'],true);
            $this->Editor->setDefaults();
            $this->Editor->main();
        }
        else if(isset($_GET['mate_export']))
        {
            $this->Editor->data['sessionData'] = $_GET['session_data'];
            $this->Editor->setDefaults();
            ob_end_clean();
            header('Cache-Control: no-cache, must-revalidate');
            header('Pragma: no-cache');
            header('Content-type: application/x-msexcel');
            header('Content-Type: text/csv');
            header('Content-Disposition: attachment; filename="' . $this->Editor->tableName . '.csv"');
            // Add utf-8 signature for windows/excel
            echo chr(0xEF).chr(0xBB).chr(0xBF);
            echo $this->Editor->exportInfo();
            exit();
        }
        else
        {
            $this->allowIfLoggedIn();
            $this->displayHeaderHtml();
            $this->displayHtml();
            $this->displayFooterHtml();
        }
    }
}
$page = new Blank();
?>