✏️ Editing: XLSXWriter.php Writable

<?php // phpcs:ignore SlevomatCodingStandard.TypeHints.DeclareStrictTypes.DeclareStrictTypesMissing

namespace MailPoetVendor;

if (!defined('ABSPATH')) exit;

/*
 * @license MIT License
 * */

if (!class_exists('ZipArchive')) { throw new \Exception('ZipArchive not found'); 
}

class XLSXWriter
{
  //------------------------------------------------------------------
  //http://office.microsoft.com/en-us/excel-help/excel-specifications-and-limits-HP010073849.aspx
  const EXCEL_2007_MAX_ROW = 1048576;
  const EXCEL_2007_MAX_COL = 16384;
  //------------------------------------------------------------------
  protected $author = 'MailPoet';
  protected $sheets = [];
  protected $shared_strings = [];//unique set
  protected $shared_string_count = 0;//count of non-unique references to the unique set
  protected $temp_files = [];
  protected $current_sheet = '';
  public $rtl = false;

public function __construct() {
    if (!ini_get('date.timezone'))
    {
      //using date functions can kick out warning if this isn't set
      date_default_timezone_set('UTC');
    }
  }

public function setAuthor($author='') {
    $this->author = $author; 
  }

public function __destruct() {
    if (!empty($this->temp_files)) {
      foreach ($this->temp_files as $temp_file) {
        @unlink($temp_file);
      }
    }
  }

protected function tempFilename() {
    $filename = tempnam(sys_get_temp_dir(), "xlsx_writer_");
    $this->temp_files[] = $filename;
    return $filename;
  }

public function writeToStdOut() {
    $temp_file = $this->tempFilename();
    self::writeToFile($temp_file);
    readfile($temp_file);
  }

public function writeToString() {
    $temp_file = $this->tempFilename();
    self::writeToFile($temp_file);
    $string = file_get_contents($temp_file);
    return $string;
  }

public function writeToFile($filename) {
    foreach ($this->sheets as $sheet_name => $sheet) {
      self::finalizeSheet($sheet_name);//making sure all footers have been written
    }

@unlink($filename);//if the zip already exists, overwrite it
    $zip = new \ZipArchive();
    if (empty($this->sheets))                       { self::log("Error in " . __CLASS__ . "::" . __FUNCTION__ . ", no worksheets defined.");
      return; 
    }
    if (!$zip->open($filename, \ZipArchive::CREATE)) { self::log("Error in " . __CLASS__ . "::" . __FUNCTION__ . ", unable to create zip.");
      return; 
    }

$zip->addEmptyDir("docProps/");
    $zip->addFromString("docProps/app.xml", self::buildAppXML() );
    $zip->addFromString("docProps/core.xml", self::buildCoreXML());

$zip->addEmptyDir("_rels/");
    $zip->addFromString("_rels/.rels", self::buildRelationshipsXML());

$zip->addEmptyDir("xl/worksheets/");
    foreach ($this->sheets as $sheet) {
      $zip->addFile($sheet->filename, "xl/worksheets/" . $sheet->xmlname );
    }
    if (!empty($this->shared_strings)) {
      $zip->addFile($this->writeSharedStringsXML(), "xl/sharedStrings.xml" );  //$zip->addFromString("xl/sharedStrings.xml",     self::buildSharedStringsXML() );
    }
    $zip->addFromString("xl/workbook.xml", self::buildWorkbookXML() );
    $zip->addFile($this->writeStylesXML(), "xl/styles.xml" );  //$zip->addFromString("xl/styles.xml"           , self::buildStylesXML() );
    $zip->addFromString("[Content_Types].xml", self::buildContentTypesXML() );

$zip->addEmptyDir("xl/_rels/");
    $zip->addFromString("xl/_rels/workbook.xml.rels", self::buildWorkbookRelsXML() );
    $zip->close();
  }

protected function initializeSheet($sheet_name) {
    //if already initialized
    if ($this->current_sheet == $sheet_name || isset($this->sheets[$sheet_name]))
      return;

$sheet_filename = $this->tempFilename();
 $sheet_xmlname = 'sheet' . (count($this->sheets) + 1) . ".xml";
 $this->sheets[$sheet_name] = (object)[
 'filename' => $sheet_filename,
 'sheetname' => $sheet_name,
 'xmlname' => $sheet_xmlname,
 'row_count' => 0,
 'file_writer' => new XLSXWriter_BuffererWriter($sheet_filename),
 'cell_formats' => [],
 'max_cell_tag_start' => 0,
 'max_cell_tag_end' => 0,
 'finalized' => false,
 ];
 $sheet = &$this->sheets[$sheet_name];
 $tabselected = count($this->sheets) == 1 ? 'true' : 'false';//only first sheet is selected
 $max_cell = XLSXWriter::xlsCell(self::EXCEL_2007_MAX_ROW, self::EXCEL_2007_MAX_COL);//XFE1048577
 $sheet->file_writer->write('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n");
 $sheet->file_writer->write('<worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">');
 $sheet->file_writer->write( '<sheetPr filterMode="false">');
 $sheet->file_writer->write( '<pageSetUpPr fitToPage="false"/>');
 $sheet->file_writer->write( '</sheetPr>');
 $sheet->max_cell_tag_start = $sheet->file_writer->ftell();
 $sheet->file_writer->write('<dimension ref="A1:' . $max_cell . '"/>');
 $sheet->max_cell_tag_end = $sheet->file_writer->ftell();
 $sheet->file_writer->write( '<sheetViews>');
 $sheet->file_writer->write( '<sheetView colorId="64" defaultGridColor="true" rightToLeft="' . $this->rtl . '" showFormulas="false" showGridLines="true" showOutlineSymbols="true" showRowColHeaders="true" showZeros="true" tabSelected="' . $tabselected . '" topLeftCell="A1" view="normal" windowProtection="false" workbookViewId="0" zoomScale="100" zoomScaleNormal="100" zoomScalePageLayoutView="100">');
 $sheet->file_writer->write( '<selection activeCell="A1" activeCellId="0" pane="topLeft" sqref="A1"/>');
 $sheet->file_writer->write( '</sheetView>');
 $sheet->file_writer->write( '</sheetViews>');
 $sheet->file_writer->write( '<cols>');
 $sheet->file_writer->write( '<col collapsed="false" hidden="false" max="1025" min="1" style="0" width="11.5"/>');
 $sheet->file_writer->write( '</cols>');
 $sheet->file_writer->write( '<sheetData>');
 }

public function writeSheetHeader($sheet_name, array $header_types) {
    if (empty($sheet_name) || empty($header_types) || !empty($this->sheets[$sheet_name]))
      return;

self::initializeSheet($sheet_name);
    $sheet = &$this->sheets[$sheet_name];
    $sheet->cell_formats = array_values($header_types);
    $header_row = array_keys($header_types);

$sheet->file_writer->write('<row collapsed="false" customFormat="false" customHeight="false" hidden="false" ht="12.1" outlineLevel="0" r="' . (1) . '">');
 foreach ($header_row as $k => $v) {
 $this->writeCell($sheet->file_writer, 0, $k, $v, $cell_format = 'string');
 }
 $sheet->file_writer->write('</row>');
 $sheet->row_count++;
 $this->current_sheet = $sheet_name;
 }

public function writeSheetRow($sheet_name, array $row) {
    if (empty($sheet_name) || empty($row))
      return;

self::initializeSheet($sheet_name);
    $sheet = &$this->sheets[$sheet_name];
    if (empty($sheet->cell_formats))
    {
      $sheet->cell_formats = array_fill(0, count($row), 'string');
    }

$sheet->file_writer->write('<row collapsed="false" customFormat="false" customHeight="false" hidden="false" ht="12.1" outlineLevel="0" r="' . ($sheet->row_count + 1) . '">');
 foreach ($row as $k => $v) {
 $this->writeCell($sheet->file_writer, $sheet->row_count, $k, $v, $sheet->cell_formats[$k]);
 }
 $sheet->file_writer->write('</row>');
 $sheet->row_count++;
 $this->current_sheet = $sheet_name;
 }

protected function finalizeSheet($sheet_name) {
    if (empty($sheet_name) || $this->sheets[$sheet_name]->finalized)
      return;

$sheet = &$this->sheets[$sheet_name];

$sheet->file_writer->write( '</sheetData>');
 $sheet->file_writer->write( '<printOptions headings="false" gridLines="false" gridLinesSet="true" horizontalCentered="false" verticalCentered="false"/>');
 $sheet->file_writer->write( '<pageMargins left="0.5" right="0.5" top="1.0" bottom="1.0" header="0.5" footer="0.5"/>');
 $sheet->file_writer->write( '<pageSetup blackAndWhite="false" cellComments="none" copies="1" draft="false" firstPageNumber="1" fitToHeight="1" fitToWidth="1" horizontalDpi="300" orientation="portrait" pageOrder="downThenOver" paperSize="1" scale="100" useFirstPageNumber="true" usePrinterDefaults="false" verticalDpi="300"/>');
 $sheet->file_writer->write( '<headerFooter differentFirst="false" differentOddEven="false">');
 $sheet->file_writer->write( '<oddHeader>&amp;C&amp;&quot;Times New Roman,Regular&quot;&amp;12&amp;A</oddHeader>');
 $sheet->file_writer->write( '<oddFooter>&amp;C&amp;&quot;Times New Roman,Regular&quot;&amp;12Page &amp;P</oddFooter>');
 $sheet->file_writer->write( '</headerFooter>');
 $sheet->file_writer->write('</worksheet>');

$max_cell = self::xlsCell($sheet->row_count - 1, count($sheet->cell_formats) - 1);
 $max_cell_tag = '<dimension ref="A1:' . $max_cell . '"/>';
 $padding_length = $sheet->max_cell_tag_end - $sheet->max_cell_tag_start - strlen($max_cell_tag);
 $sheet->file_writer->fseek($sheet->max_cell_tag_start);
 $sheet->file_writer->write($max_cell_tag . str_repeat(" ", (int)$padding_length));
 $sheet->file_writer->close();
 $sheet->finalized = true;
 }

public function writeSheet(array $data, $sheet_name='', array $header_types=[] ) {
    $sheet_name = empty($sheet_name) ? 'Sheet1' : $sheet_name;
    $data = empty($data) ? [['']] : $data;
    if (!empty($header_types))
    {
      $this->writeSheetHeader($sheet_name, $header_types);
    }
    foreach ($data as $i => $row)
    {
      $this->writeSheetRow($sheet_name, $row);
    }
    $this->finalizeSheet($sheet_name);
  }

protected function writeCell(XLSXWriter_BuffererWriter &$file, $row_number, $column_number, $value, $cell_format) {
    static $styles = ['money' => 1,'dollar' => 1,'datetime' => 2,'date' => 3,'string' => 0];
    $cell = self::xlsCell($row_number, $column_number);
    $s = isset($styles[$cell_format]) ? $styles[$cell_format] : '0';

if (!is_scalar($value) || $value == '') { //objects, array, empty
 $file->write('<c r="' . $cell . '" s="' . $s . '"/>');
 } elseif ($cell_format == 'date') {
 $file->write('<c r="' . $cell . '" s="' . $s . '" t="n"><v>' . intval(self::convert_date_time($value)) . '</v></c>');
 } elseif ($cell_format == 'datetime') {
 $file->write('<c r="' . $cell . '" s="' . $s . '" t="n"><v>' . self::convert_date_time($value) . '</v></c>');
 } elseif (!is_string($value)) {
 $file->write('<c r="' . $cell . '" s="' . $s . '" t="n"><v>' . ($value * 1) . '</v></c>');//int,float, etc
 } elseif ($value[0] != '0' && filter_var($value, FILTER_VALIDATE_INT)){ //excel wants to trim leading zeros
 $file->write('<c r="' . $cell . '" s="' . $s . '" t="n"><v>' . ($value) . '</v></c>');//numeric string
 } elseif ($value[0] == '='){
 $file->write('<c r="' . $cell . '" s="' . $s . '" t="s"><f>' . self::xmlspecialchars($value) . '</f></c>');
 } elseif ($value !== ''){
 $file->write('<c r="' . $cell . '" s="' . $s . '" t="s"><v>' . self::xmlspecialchars($this->setSharedString($value)) . '</v></c>');
 }
 }

protected function writeStylesXML() {
 $temporary_filename = $this->tempFilename();
 $file = new XLSXWriter_BuffererWriter($temporary_filename);
 $file->write('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n");
 $file->write('<styleSheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">');
 $file->write('<numFmts count="4">');
 $file->write( '<numFmt formatCode="GENERAL" numFmtId="164"/>');
 $file->write( '<numFmt formatCode="[$$-1009]#,##0.00;[RED]\-[$$-1009]#,##0.00" numFmtId="165"/>');
 $file->write( '<numFmt formatCode="YYYY-MM-DD\ HH:MM:SS" numFmtId="166"/>');
 $file->write( '<numFmt formatCode="YYYY-MM-DD" numFmtId="167"/>');
 $file->write('</numFmts>');
 $file->write('<fonts count="4">');
 $file->write( '<name val="Arial"/><charset val="1"/><family val="2"/><sz val="10"/>');
 $file->write( '<name val="Arial"/><family val="0"/><sz val="10"/>');
 $file->write( '<name val="Arial"/><family val="0"/><sz val="10"/>');
 $file->write( '<name val="Arial"/><family val="0"/><sz val="10"/>');
 $file->write('</fonts>');
 $file->write('<fills count="2"><fill><patternFill patternType="none"/></fill><fill><patternFill patternType="gray125"/></fill></fills>');
 $file->write('<borders count="1"><border diagonalDown="false" diagonalUp="false"><left/><right/><top/><bottom/><diagonal/></border></borders>');
 $file->write( '<cellStyleXfs count="20">');
 $file->write( '<xf applyAlignment="true" applyBorder="true" applyFont="true" applyProtection="true" borderId="0" fillId="0" fontId="0" numFmtId="164">');
 $file->write( '<alignment horizontal="general" indent="0" shrinkToFit="false" textRotation="0" vertical="bottom" wrapText="false"/>');
 $file->write( '<protection hidden="false" locked="true"/>');
 $file->write( '</xf>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="2" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="2" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="43"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="41"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="44"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="42"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="true" applyProtection="false" borderId="0" fillId="0" fontId="1" numFmtId="9"/>');
 $file->write( '</cellStyleXfs>');
 $file->write( '<cellXfs count="4">');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="164" xfId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="165" xfId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="166" xfId="0"/>');
 $file->write( '<xf applyAlignment="false" applyBorder="false" applyFont="false" applyProtection="false" borderId="0" fillId="0" fontId="0" numFmtId="167" xfId="0"/>');
 $file->write( '</cellXfs>');
 $file->write( '<cellStyles count="6">');
 $file->write( '<cellStyle builtinId="0" customBuiltin="false" name="Normal" xfId="0"/>');
 $file->write( '<cellStyle builtinId="3" customBuiltin="false" name="Comma" xfId="15"/>');
 $file->write( '<cellStyle builtinId="6" customBuiltin="false" name="Comma [0]" xfId="16"/>');
 $file->write( '<cellStyle builtinId="4" customBuiltin="false" name="Currency" xfId="17"/>');
 $file->write( '<cellStyle builtinId="7" customBuiltin="false" name="Currency [0]" xfId="18"/>');
 $file->write( '<cellStyle builtinId="5" customBuiltin="false" name="Percent" xfId="19"/>');
 $file->write( '</cellStyles>');
 $file->write('</styleSheet>');
 $file->close();
 return $temporary_filename;
 }

protected function setSharedString($v) {
    if (isset($this->shared_strings[$v]))
    {
      $string_value = $this->shared_strings[$v];
    }
    else
    {
      $string_value = count($this->shared_strings);
      $this->shared_strings[$v] = $string_value;
    }
    $this->shared_string_count++;//non-unique count
    return $string_value;
  }

protected function writeSharedStringsXML() {
 $temporary_filename = $this->tempFilename();
 $file = new XLSXWriter_BuffererWriter($temporary_filename, $fd_flags = 'w', $check_utf8 = true);
 $file->write('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n");
 $file->write('<sst count="' . ($this->shared_string_count) . '" uniqueCount="' . count($this->shared_strings) . '" xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">');
 foreach ($this->shared_strings as $s => $c)
 {
 $file->write('<si><t>' . self::xmlspecialchars($s) . '</t></si>');
 }
 $file->write('</sst>');
 $file->close();

return $temporary_filename;
  }

protected function buildAppXML() {
 $app_xml = "";
 $app_xml .= '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n";
 $app_xml .= '<Properties xmlns="http://schemas.openxmlformats.org/officeDocument/2006/extended-properties" xmlns:vt="http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes"><TotalTime>0</TotalTime></Properties>';
 return $app_xml;
 }

protected function buildCoreXML() {
 $core_xml = "";
 $core_xml .= '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n";
 $core_xml .= '<cp:coreProperties xmlns:cp="http://schemas.openxmlformats.org/package/2006/metadata/core-properties" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcmitype="http://purl.org/dc/dcmitype/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">';
 $core_xml .= '<dcterms:created xsi:type="dcterms:W3CDTF">' . date("Y-m-d\TH:i:s.00\Z") . '</dcterms:created>';//$date_time = '2014-10-25T15:54:37.00Z';
 $core_xml .= '<dc:creator>' . self::xmlspecialchars($this->author) . '</dc:creator>';
 $core_xml .= '<cp:revision>0</cp:revision>';
 $core_xml .= '</cp:coreProperties>';
 return $core_xml;
 }

protected function buildRelationshipsXML() {
 $rels_xml = "";
 $rels_xml .= '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
 $rels_xml .= '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">';
 $rels_xml .= '<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/>';
 $rels_xml .= '<Relationship Id="rId2" Type="http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties" Target="docProps/core.xml"/>';
 $rels_xml .= '<Relationship Id="rId3" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/extended-properties" Target="docProps/app.xml"/>';
 $rels_xml .= "\n";
 $rels_xml .= '</Relationships>';
 return $rels_xml;
 }

protected function buildWorkbookXML() {
 $i = 0;
 $workbook_xml = "";
 $workbook_xml .= '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>' . "\n";
 $workbook_xml .= '<workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">';
 $workbook_xml .= '<fileVersion appName="Calc"/><workbookPr backupFile="false" showObjects="all" date1904="false"/><workbookProtection/>';
 $workbook_xml .= '<bookViews><workbookView activeTab="0" firstSheet="0" showHorizontalScroll="true" showSheetTabs="true" showVerticalScroll="true" tabRatio="212" windowHeight="8192" windowWidth="16384" xWindow="0" yWindow="0"/></bookViews>';
 $workbook_xml .= '<sheets>';
 foreach ($this->sheets as $sheet_name => $sheet) {
 $workbook_xml .= '<sheet name="' . self::xmlspecialchars($sheet->sheetname) . '" sheetId="' . ($i + 1) . '" state="visible" r:id="rId' . ($i + 2) . '"/>';
 $i++;
 }
 $workbook_xml .= '</sheets>';
 $workbook_xml .= '<calcPr iterateCount="100" refMode="A1" iterate="false" iterateDelta="0.001"/></workbook>';
 return $workbook_xml;
 }

protected function buildWorkbookRelsXML() {
 $i = 0;
 $wkbkrels_xml = "";
 $wkbkrels_xml .= '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
 $wkbkrels_xml .= '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">';
 $wkbkrels_xml .= '<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/>';
 foreach ($this->sheets as $sheet_name => $sheet) {
 $wkbkrels_xml .= '<Relationship Id="rId' . ($i + 2) . '" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/' . ($sheet->xmlname) . '"/>';
 $i++;
 }
 if (!empty($this->shared_strings)) {
 $wkbkrels_xml .= '<Relationship Id="rId' . (count($this->sheets) + 2) . '" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/sharedStrings" Target="sharedStrings.xml"/>';
 }
 $wkbkrels_xml .= "\n";
 $wkbkrels_xml .= '</Relationships>';
 return $wkbkrels_xml;
 }

protected function buildContentTypesXML() {
 $content_types_xml = "";
 $content_types_xml .= '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
 $content_types_xml .= '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">';
 $content_types_xml .= '<Override PartName="/_rels/.rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>';
 $content_types_xml .= '<Override PartName="/xl/_rels/workbook.xml.rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>';
 foreach ($this->sheets as $sheet_name => $sheet) {
 $content_types_xml .= '<Override PartName="/xl/worksheets/' . ($sheet->xmlname) . '" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml"/>';
 }
 if (!empty($this->shared_strings)) {
 $content_types_xml .= '<Override PartName="/xl/sharedStrings.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml"/>';
 }
 $content_types_xml .= '<Override PartName="/xl/workbook.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml"/>';
 $content_types_xml .= '<Override PartName="/xl/styles.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml"/>';
 $content_types_xml .= '<Override PartName="/docProps/app.xml" ContentType="application/vnd.openxmlformats-officedocument.extended-properties+xml"/>';
 $content_types_xml .= '<Override PartName="/docProps/core.xml" ContentType="application/vnd.openxmlformats-package.core-properties+xml"/>';
 $content_types_xml .= "\n";
 $content_types_xml .= '</Types>';
 return $content_types_xml;
 }

//------------------------------------------------------------------
 /*
 * @param $row_number int, zero based
 * @param $column_number int, zero based
 * @return Cell label/coordinates, ex: A1, C3, AA42
 * */
 public static function xlsCell($row_number, $column_number) {
 $n = $column_number;
 for ($r = ""; $n >= 0; $n = intval($n / 26) - 1) {
 $r = chr($n % 26 + 0x41) . $r;
 }
 return $r . ($row_number + 1);
 }
 //------------------------------------------------------------------
 public static function log($string) {
 file_put_contents("php://stderr", date("Y-m-d H:i:s:") . rtrim(is_array($string) ? json_encode($string) : $string) . "\n");
 }
 //------------------------------------------------------------------
 public static function sanitize_filename($filename) {
 //http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx
 $nonprinting = array_map('chr', range(0, 31));
 $invalid_chars = ['<', '>', '?', '"', ':', '|', '\\', '/', '*', '&'];
 $all_invalids = array_merge($nonprinting, $invalid_chars);
 return str_replace($all_invalids, "", $filename);
 }
 //------------------------------------------------------------------
 public static function xmlspecialchars($val) {
 return str_replace("'", "&#39;", htmlspecialchars($val));
 }
 //------------------------------------------------------------------
 public static function array_first_key(array $arr) {
 reset($arr);
 $first_key = key($arr);
 return $first_key;
 }
 //------------------------------------------------------------------
 public static function convert_date_time($date_input) {
 //thanks to Excel::Writer::XLSX::Worksheet.pm (perl)
 $days = 0; # Number of days since epoch
 $seconds = 0; # Time expressed as fraction of 24h hours in seconds
 $year = $month = $day = 0;
 $hour = $min = $sec = 0;

$date_time = $date_input;
    if (preg_match("/(\d{4})\-(\d{2})\-(\d{2})/", $date_time, $matches))
    {
      list($junk,$year,$month,$day) = $matches;
    }
    if (preg_match("/(\d{2}):(\d{2}):(\d{2})/", $date_time, $matches))
    {
      list($junk,$hour,$min,$sec) = $matches;
      $seconds = ( $hour * 60 * 60 + $min * 60 + $sec ) / ( 24 * 60 * 60 );
    }

//using 1900 as epoch, not 1904, ignoring 1904 special case

# Special cases for Excel.
    if ("$year-$month-$day" == '1899-12-31')  return $seconds      ;    # Excel 1900 epoch
    if ("$year-$month-$day" == '1900-01-00')  return $seconds      ;    # Excel 1900 epoch
    if ("$year-$month-$day" == '1900-02-29')  return 60 + $seconds ;    # Excel false leapday

# We calculate the date by calculating the number of days since the epoch
    # and adjust for the number of leap days. We calculate the number of leap
    # days by normalising the year in relation to the epoch. Thus the year 2000
    # becomes 100 for 4 and 100 year leapdays and 400 for 400 year leapdays.
    $epoch  = 1900;
    $offset = 0;
    $norm   = 300;
    $range  = $year - $epoch;

# Set month days and check for leap year.
    $leap = (($year % 400 == 0) || (($year % 4 == 0) && ($year % 100)) ) ? 1 : 0;
    $mdays = [ 31, ($leap ? 29 : 28), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];

# Some boundary checks
 if ($year < $epoch || $year > 9999) return 0;
 if ($month < 1 || $month > 12) return 0;
 if ($day < 1 || $day > $mdays[$month - 1]) return 0;

# Accumulate the number of days since the epoch.
    $days = $day;    # Add days for current month
    $days += array_sum( array_slice($mdays, 0, $month - 1 ) );    # Add days for past months
    $days += $range * 365;                      # Add days for past years
    $days += intval( ( $range ) / 4 );             # Add leapdays
    $days -= intval( ( $range + $offset ) / 100 ); # Subtract 100 year leapdays
    $days += intval( ( $range + $offset + $norm ) / 400 );  # Add 400 year leapdays
    $days -= $leap;                                      # Already counted above

# Adjust for Excel erroneously treating 1900 as a leap year.
    if ($days > 59) { $days++;
    }

return $days + $seconds;
  }
  //------------------------------------------------------------------
}

class XLSXWriter_BuffererWriter
{
  protected $fd = null;
  protected $buffer = '';
  protected $check_utf8 = false;

public function __construct($filename, $fd_fopen_flags='w', $check_utf8=false) {
    $this->check_utf8 = $check_utf8;
    $this->fd = fopen($filename, $fd_fopen_flags);
    if ($this->fd === false) {
      XLSXWriter::log("Unable to open $filename for writing.");
    }
  }

public function write($string) {
    $this->buffer .= $string;
    if (isset($this->buffer[8191])) {
      $this->purge();
    }
  }

protected function purge() {
    if ($this->fd) {
      if ($this->check_utf8 && !self::isValidUTF8($this->buffer)) {
        XLSXWriter::log("Error, invalid UTF8 encoding detected.");
        $this->check_utf8 = false;
      }
      fwrite($this->fd, $this->buffer);
      $this->buffer = '';
    }
  }

public function close() {
    $this->purge();
    if ($this->fd) {
      fclose($this->fd);
      $this->fd = null;
    }
  }

public function __destruct() {
    $this->close();
  }

public function ftell() {
    if ($this->fd) {
      $this->purge();
      return ftell($this->fd);
    }
    return -1;
  }

public function fseek($pos) {
    if ($this->fd) {
      $this->purge();
      return fseek($this->fd, $pos);
    }
    return -1;
  }

protected static function isValidUTF8($string) {
    if (function_exists('mb_check_encoding'))
    {
      return mb_check_encoding($string, 'UTF-8') ? true : false;
    }
    return preg_match("//u", $string) ? true : false;
  }
}

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