Convert excel file to csv

/**
        Convert excel file to csv
     */
    public function excel_to_csv()
    {
        ini_set('max_execution_time','0');
        ini_set('memory_limit', '1G');
        
        $xls_file = storage_path('excel_file') . '\\' . '1w.xls';
        $file_info = pathinfo($xls_file);

        Log::debug('文件路径：' . $xls_file);
        if (!file_exists($xls_file)) {
            Log::debug('文件不存在！');
        }
        $file_size = (filesize($xls_file) / 1024 / 1024) . "MB";
        if ($file_size) {
            Log::debug('Excel file size: '.$file_size);
        }

        // valide the file type
        if (strtolower($file_info['extension']) == 'xls') {
            $reader = new Xls();
        }else{
            $reader = new Xlsx();
        }

        $memonry = '【开始执行内存：'.(memory_get_usage()/1024/1024)."MB， ";
        $memonry .= '峰值内存：'.(memory_get_peak_usage()/1024/1024)."MB】\r\n";
        Log::debug($memonry);
        
        $spreadsheet = $reader->load($xls_file);
        $loadedSheetNames = $spreadsheet->getSheetNames();
        $writer = new Csv($spreadsheet);
        
        foreach($loadedSheetNames as $sheetIndex => $loadedSheetName) {
            Log::debug($sheetIndex);
            $writer->setSheetIndex($sheetIndex);
            $csv_path = storage_path('new_csv') . '\\' . $file_info['filename'] . '_' . $loadedSheetName . '.csv';
//            $writer->save($loadedSheetName.'.csv');
            $writer->save($csv_path);
        }
        $memonry = '【结束执行内存：'.(memory_get_usage()/1024/1024)."MB， ";
        $memonry .= '峰值内存：'.(memory_get_peak_usage()/1024/1024)."MB】\r\n";
        Log::debug($memonry);
        Log::debug('All End!');
        
    }