HyperlinkBase Property, and Html Handling of Properties (#3589)

* HyperlinkBase Property, and Html Handling of Properties

Fix #3573. The original issue concerned non-support of Document Properties in Xml spreadsheets. However, most of the Properties mentioned there were already supported. But the investigation revealed some gaps in Html coverage.

HyperlinkBase is the one property mentioned in the issue that was not supported for Xml, nor indeed for any other format. All the other document properties are 'meta'; but HyperlinkBase is functional - if you supply a relative address for a link, Excel will use HyperlinkBase, if supplied, to convert to an absolute address. (Default is directory where spreadsheet is located.) Here's a summary of how this PR will handle this property for various formats:
- Support is added for Xlsx read and write.
- Support is added for Xml read (there is no Xml writer). Ironically, Excel messes up this processing when reading an Xml spreadsheet; however, PhpSpreadsheet will get it right.
- HyperlinkBase is supported for Xls, but I have no idea how to read or write this property. For now, when writing hyperlinked cells, PhpSpreadsheet will be changed to convert any relative addresses that it can detect to absolute references by adding HyperlinkBase to the relative address. In a similar vein, Xls supports custom properties, but PhpSpreadsheet does not know how to read or write those.
- Gnumeric has no equivalent property, so nothing needs to be done to its reader. Since we don't have a Gnumeric writer, that's not really a problem for us.
- Odt has no equivalent property, so nothing needs to be done to its reader. The Odt writer does not have any special logic for hyperlinks, so, at least for now, will remain unchanged.
- Csv has no equivalent property, so nothing needs to be done to its reader. The Csv writer does not have any special logic for hyperlinks, so, at least for now, will remain unchanged.
- Html allows for an equivalent `base` tag in the head section. Support for this is added to Html reader and writer.

Html Writer was only handling 8 of the 11 'core' properties. Support is added for `created`, `modified`, and `lastModifiedBy`. Custom properties were not supported at all, and now are.

Html Reader did not support any properties. It will now support all of them.

* Scrutinizer

Remove one dead reference.

src/PhpSpreadsheet/Document/Properties.php

@@ -107,6 +107,8 @@ class Properties
      */
     private $customProperties = [];
 
+    private string $hyperlinkBase = '';
+
     /**
      * Create a new Document Properties instance.
      */
@@ -534,4 +536,16 @@ class Properties
     {
         return self::PROPERTY_TYPE_ARRAY[$propertyType] ?? self::PROPERTY_TYPE_UNKNOWN;
     }
+
+    public function getHyperlinkBase(): string
+    {
+        return $this->hyperlinkBase;
+    }
+
+    public function setHyperlinkBase(string $hyperlinkBase): self
+    {
+        $this->hyperlinkBase = $hyperlinkBase;
+
+        return $this;
+    }
 }

src/PhpSpreadsheet/Reader/Html.php

@@ -8,6 +8,7 @@ use DOMNode;
 use DOMText;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
+use PhpOffice\PhpSpreadsheet\Document\Properties;
 use PhpOffice\PhpSpreadsheet\Helper\Dimension as CssDimension;
 use PhpOffice\PhpSpreadsheet\Reader\Security\XmlScanner;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
@@ -685,10 +686,94 @@ class Html extends BaseReader
         if ($loaded === false) {
             throw new Exception('Failed to load ' . $filename . ' as a DOM Document', 0, $e ?? null);
         }
+        self::loadProperties($dom, $spreadsheet);
 
         return $this->loadDocument($dom, $spreadsheet);
     }
 
+    private static function loadProperties(DOMDocument $dom, Spreadsheet $spreadsheet): void
+    {
+        $properties = $spreadsheet->getProperties();
+        foreach ($dom->getElementsByTagName('meta') as $meta) {
+            $metaContent = (string) $meta->getAttribute('content');
+            if ($metaContent !== '') {
+                $metaName = (string) $meta->getAttribute('name');
+                switch ($metaName) {
+                    case 'author':
+                        $properties->setCreator($metaContent);
+
+                        break;
+                    case 'category':
+                        $properties->setCategory($metaContent);
+
+                        break;
+                    case 'company':
+                        $properties->setCompany($metaContent);
+
+                        break;
+                    case 'created':
+                        $properties->setCreated($metaContent);
+
+                        break;
+                    case 'description':
+                        $properties->setDescription($metaContent);
+
+                        break;
+                    case 'keywords':
+                        $properties->setKeywords($metaContent);
+
+                        break;
+                    case 'lastModifiedBy':
+                        $properties->setLastModifiedBy($metaContent);
+
+                        break;
+                    case 'manager':
+                        $properties->setManager($metaContent);
+
+                        break;
+                    case 'modified':
+                        $properties->setModified($metaContent);
+
+                        break;
+                    case 'subject':
+                        $properties->setSubject($metaContent);
+
+                        break;
+                    case 'title':
+                        $properties->setTitle($metaContent);
+
+                        break;
+                    default:
+                        if (preg_match('/^custom[.](bool|date|float|int|string)[.](.+)$/', $metaName, $matches) === 1) {
+                            switch ($matches[1]) {
+                                case 'bool':
+                                    $properties->setCustomProperty($matches[2], (bool) $metaContent, Properties::PROPERTY_TYPE_BOOLEAN);
+
+                                    break;
+                                case 'float':
+                                    $properties->setCustomProperty($matches[2], (float) $metaContent, Properties::PROPERTY_TYPE_FLOAT);
+
+                                    break;
+                                case 'int':
+                                    $properties->setCustomProperty($matches[2], (int) $metaContent, Properties::PROPERTY_TYPE_INTEGER);
+
+                                    break;
+                                case 'date':
+                                    $properties->setCustomProperty($matches[2], $metaContent, Properties::PROPERTY_TYPE_DATE);
+
+                                    break;
+                                default: // string
+                                    $properties->setCustomProperty($matches[2], $metaContent, Properties::PROPERTY_TYPE_STRING);
+                            }
+                        }
+                }
+            }
+        }
+        if (!empty($dom->baseURI)) {
+            $properties->setHyperlinkBase($dom->baseURI);
+        }
+    }
+
     private static function replaceNonAscii(array $matches): string
     {
         return '&#' . mb_ord($matches[0], 'UTF-8') . ';';
@@ -719,8 +804,10 @@ class Html extends BaseReader
         if ($loaded === false) {
             throw new Exception('Failed to load content as a DOM Document', 0, $e ?? null);
         }
+        $spreadsheet = $spreadsheet ?? new Spreadsheet();
+        self::loadProperties($dom, $spreadsheet);
 
-        return $this->loadDocument($dom, $spreadsheet ?? new Spreadsheet());
+        return $this->loadDocument($dom, $spreadsheet);
     }
 
     /**

src/PhpSpreadsheet/Reader/Xlsx/Properties.php

@@ -73,6 +73,9 @@ class Properties
             if (isset($xmlCore->Manager)) {
                 $this->docProps->setManager((string) $xmlCore->Manager);
             }
+            if (isset($xmlCore->HyperlinkBase)) {
+                $this->docProps->setHyperlinkBase((string) $xmlCore->HyperlinkBase);
+            }
         }
     }
 

src/PhpSpreadsheet/Reader/Xml/Properties.php

@@ -92,6 +92,10 @@ class Properties
             case 'Manager':
                 $docProps->setManager($stringValue);
 
+                break;
+            case 'HyperlinkBase':
+                $docProps->setHyperlinkBase($stringValue);
+
                 break;
             case 'Keywords':
                 $docProps->setKeywords($stringValue);
@@ -110,17 +114,10 @@ class Properties
         ?SimpleXMLElement $propertyValue,
         SimpleXMLElement $propertyAttributes
     ): void {
-        $propertyType = DocumentProperties::PROPERTY_TYPE_UNKNOWN;
-
         switch ((string) $propertyAttributes) {
-            case 'string':
-                $propertyType = DocumentProperties::PROPERTY_TYPE_STRING;
-                $propertyValue = trim((string) $propertyValue);
-
-                break;
             case 'boolean':
                 $propertyType = DocumentProperties::PROPERTY_TYPE_BOOLEAN;
-                $propertyValue = (bool) $propertyValue;
+                $propertyValue = (bool) (string) $propertyValue;
 
                 break;
             case 'integer':
@@ -134,9 +131,15 @@ class Properties
 
                 break;
             case 'dateTime.tz':
+            case 'dateTime.iso8601tz':
                 $propertyType = DocumentProperties::PROPERTY_TYPE_DATE;
                 $propertyValue = trim((string) $propertyValue);
 
+                break;
+            default:
+                $propertyType = DocumentProperties::PROPERTY_TYPE_STRING;
+                $propertyValue = trim((string) $propertyValue);
+
                 break;
         }
 

src/PhpSpreadsheet/Writer/Html.php

@@ -7,9 +7,11 @@ use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Chart\Chart;
+use PhpOffice\PhpSpreadsheet\Document\Properties;
 use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PhpOffice\PhpSpreadsheet\RichText\Run;
 use PhpOffice\PhpSpreadsheet\Settings;
+use PhpOffice\PhpSpreadsheet\Shared\Date;
 use PhpOffice\PhpSpreadsheet\Shared\Drawing as SharedDrawing;
 use PhpOffice\PhpSpreadsheet\Shared\File;
 use PhpOffice\PhpSpreadsheet\Shared\Font as SharedFont;
@@ -342,13 +344,21 @@ class Html extends BaseWriter
 
     private static function generateMeta(?string $val, string $desc): string
     {
-        return $val
+        return ($val || $val === '0')
             ? ('      <meta name="' . $desc . '" content="' . htmlspecialchars($val, Settings::htmlEntityFlags()) . '" />' . PHP_EOL)
             : '';
     }
 
     public const BODY_LINE = '  <body>' . PHP_EOL;
 
+    private const CUSTOM_TO_META = [
+        Properties::PROPERTY_TYPE_BOOLEAN => 'bool',
+        Properties::PROPERTY_TYPE_DATE => 'date',
+        Properties::PROPERTY_TYPE_FLOAT => 'float',
+        Properties::PROPERTY_TYPE_INTEGER => 'int',
+        Properties::PROPERTY_TYPE_STRING => 'string',
+    ];
+
     /**
      * Generate HTML header.
      *
@@ -374,6 +384,36 @@ class Html extends BaseWriter
         $html .= self::generateMeta($properties->getCategory(), 'category');
         $html .= self::generateMeta($properties->getCompany(), 'company');
         $html .= self::generateMeta($properties->getManager(), 'manager');
+        $html .= self::generateMeta($properties->getLastModifiedBy(), 'lastModifiedBy');
+        $date = Date::dateTimeFromTimestamp((string) $properties->getCreated());
+        $date->setTimeZone(Date::getDefaultOrLocalTimeZone());
+        $html .= self::generateMeta($date->format(DATE_W3C), 'created');
+        $date = Date::dateTimeFromTimestamp((string) $properties->getModified());
+        $date->setTimeZone(Date::getDefaultOrLocalTimeZone());
+        $html .= self::generateMeta($date->format(DATE_W3C), 'modified');
+
+        $customProperties = $properties->getCustomProperties();
+        foreach ($customProperties as $customProperty) {
+            $propertyValue = $properties->getCustomPropertyValue($customProperty);
+            $propertyType = $properties->getCustomPropertyType($customProperty);
+            $propertyQualifier = self::CUSTOM_TO_META[$propertyType] ?? null;
+            if ($propertyQualifier !== null) {
+                if ($propertyType === Properties::PROPERTY_TYPE_BOOLEAN) {
+                    $propertyValue = $propertyValue ? '1' : '0';
+                } elseif ($propertyType === Properties::PROPERTY_TYPE_DATE) {
+                    $date = Date::dateTimeFromTimestamp((string) $propertyValue);
+                    $date->setTimeZone(Date::getDefaultOrLocalTimeZone());
+                    $propertyValue = $date->format(DATE_W3C);
+                } else {
+                    $propertyValue = (string) $propertyValue;
+                }
+                $html .= self::generateMeta($propertyValue, "custom.$propertyQualifier.$customProperty");
+            }
+        }
+
+        if (!empty($properties->getHyperlinkBase())) {
+            $html .= '      <base href="' . $properties->getHyperlinkBase() . '" />' . PHP_EOL;
+        }
 
         $html .= $includeStyles ? $this->generateStyles(true) : $this->generatePageDeclarations(true);
 

src/PhpSpreadsheet/Writer/Xls/Worksheet.php

@@ -503,6 +503,8 @@ class Worksheet extends BIFFwriter
         $this->writeMergedCells();
 
         // Hyperlinks
+        $phpParent = $phpSheet->getParent();
+        $hyperlinkbase = ($phpParent === null) ? '' : $phpParent->getProperties()->getHyperlinkBase();
         foreach ($phpSheet->getHyperLinkCollection() as $coordinate => $hyperlink) {
             [$column, $row] = Coordinate::indexesFromString($coordinate);
 
@@ -513,6 +515,11 @@ class Worksheet extends BIFFwriter
                 $url = str_replace('sheet://', 'internal:', $url);
             } elseif (preg_match('/^(http:|https:|ftp:|mailto:)/', $url)) {
                 // URL
+            } elseif (!empty($hyperlinkbase) && preg_match('~^([A-Za-z]:)?[/\\\\]~', $url) !== 1) {
+                $url = "$hyperlinkbase$url";
+                if (preg_match('/^(http:|https:|ftp:|mailto:)/', $url) !== 1) {
+                    $url = 'external:' . $url;
+                }
             } else {
                 // external (local file)
                 $url = 'external:' . $url;

src/PhpSpreadsheet/Writer/Xlsx/DocProps.php

@@ -93,6 +93,9 @@ class DocProps extends WriterPart
         // SharedDoc
         $objWriter->writeElement('SharedDoc', 'false');
 
+        // HyperlinkBase
+        $objWriter->writeElement('HyperlinkBase', $spreadsheet->getProperties()->getHyperlinkBase());
+
         // HyperlinksChanged
         $objWriter->writeElement('HyperlinksChanged', 'false');
 

tests/PhpSpreadsheetTests/Reader/Xml/XmlPropertiesTest.php

@@ -0,0 +1,187 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xml;
+
+use DateTimeImmutable;
+use PhpOffice\PhpSpreadsheet\Reader\Xml;
+use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
+
+class XmlPropertiesTest extends AbstractFunctional
+{
+    /** @var string */
+    private $filename = 'tests/data/Reader/Xml/hyperlinkbase.xml';
+
+    public function testProperties(): void
+    {
+        $reader = new Xml();
+        $spreadsheet = $reader->load($this->filename);
+
+        $properties = $spreadsheet->getProperties();
+        self::assertSame('title', $properties->getTitle());
+        self::assertSame('topic', $properties->getSubject());
+        self::assertSame('author', $properties->getCreator());
+        self::assertSame('keyword1, keyword2', $properties->getKeywords());
+        self::assertSame('no comment', $properties->getDescription());
+        self::assertSame('last author', $properties->getLastModifiedBy());
+        $expected = self::timestampToInt('2023-05-18T11:21:43Z');
+        self::assertEquals($expected, $properties->getCreated());
+        $expected = self::timestampToInt('2023-05-18T11:30:00Z');
+        self::assertEquals($expected, $properties->getModified());
+        self::assertSame('category', $properties->getCategory());
+        self::assertSame('manager', $properties->getManager());
+        self::assertSame('company', $properties->getCompany());
+
+        self::assertSame('https://phpspreadsheet.readthedocs.io/en/latest/', $properties->getHyperlinkBase());
+
+        self::assertSame('TheString', $properties->getCustomPropertyValue('StringProperty'));
+        self::assertSame(12345, $properties->getCustomPropertyValue('NumberProperty'));
+        $expected = self::timestampToInt('2023-05-18T10:00:00Z');
+        self::assertEquals($expected, $properties->getCustomPropertyValue('DateProperty'));
+        $expected = self::timestampToInt('2023-05-19T11:00:00Z');
+        self::assertEquals($expected, $properties->getCustomPropertyValue('DateProperty2'));
+        self::assertTrue($properties->getCustomPropertyValue('BooleanPropertyTrue'));
+        self::assertFalse($properties->getCustomPropertyValue('BooleanPropertyFalse'));
+        self::assertEqualsWithDelta(1.2345, $properties->getCustomPropertyValue('FloatProperty'), 1E-8);
+
+        $sheet = $spreadsheet->getActiveSheet();
+        // Note that relative links don't actually work in XML format.
+        // It will, however, work just fine in the Xlsx and Html copies.
+        $hyperlink = $sheet->getCell('A1')->getHyperlink();
+        self::assertSame('references/features-cross-reference/', $hyperlink->getUrl());
+        // Same comment as for cell above.
+        self::assertSame('topics/accessing-cells/', $sheet->getCell('A2')->getCalculatedValue());
+        // No problem for absolute links.
+        $hyperlink = $sheet->getCell('A3')->getHyperlink();
+        self::assertSame('https://www.google.com/', $hyperlink->getUrl());
+        self::assertSame('https://www.yahoo.com', $sheet->getCell('A4')->getCalculatedValue());
+
+        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, 'Xlsx');
+        $spreadsheet->disconnectWorksheets();
+
+        $properties = $reloadedSpreadsheet->getProperties();
+        self::assertSame('title', $properties->getTitle());
+        self::assertSame('topic', $properties->getSubject());
+        self::assertSame('author', $properties->getCreator());
+        self::assertSame('keyword1, keyword2', $properties->getKeywords());
+        self::assertSame('no comment', $properties->getDescription());
+        self::assertSame('last author', $properties->getLastModifiedBy());
+        $expected = self::timestampToInt('2023-05-18T11:21:43Z');
+        self::assertEquals($expected, $properties->getCreated());
+        $expected = self::timestampToInt('2023-05-18T11:30:00Z');
+        self::assertEquals($expected, $properties->getModified());
+        self::assertSame('category', $properties->getCategory());
+        self::assertSame('manager', $properties->getManager());
+        self::assertSame('company', $properties->getCompany());
+
+        self::assertSame('https://phpspreadsheet.readthedocs.io/en/latest/', $properties->getHyperlinkBase());
+
+        self::assertSame('TheString', $properties->getCustomPropertyValue('StringProperty'));
+        self::assertSame(12345, $properties->getCustomPropertyValue('NumberProperty'));
+        // Note that Xlsx will ignore the time part when displaying
+        // the property.
+        $expected = self::timestampToInt('2023-05-18T10:00:00Z');
+        self::assertEquals($expected, $properties->getCustomPropertyValue('DateProperty'));
+        $expected = self::timestampToInt('2023-05-19T11:00:00Z');
+        self::assertEquals($expected, $properties->getCustomPropertyValue('DateProperty2'));
+        self::assertTrue($properties->getCustomPropertyValue('BooleanPropertyTrue'));
+        self::assertFalse($properties->getCustomPropertyValue('BooleanPropertyFalse'));
+        self::assertEqualsWithDelta(1.2345, $properties->getCustomPropertyValue('FloatProperty'), 1E-8);
+
+        $sheet = $reloadedSpreadsheet->getActiveSheet();
+        // Note that relative links don't actually work in XML format.
+        // It will, however, work just fine in the Xlsx and Html copies.
+        $hyperlink = $sheet->getCell('A1')->getHyperlink();
+        self::assertSame('references/features-cross-reference/', $hyperlink->getUrl());
+        // Same comment as for cell above.
+        self::assertSame('topics/accessing-cells/', $sheet->getCell('A2')->getCalculatedValue());
+        // No problem for absolute links.
+        $hyperlink = $sheet->getCell('A3')->getHyperlink();
+        self::assertSame('https://www.google.com/', $hyperlink->getUrl());
+        self::assertSame('https://www.yahoo.com', $sheet->getCell('A4')->getCalculatedValue());
+
+        $reloadedSpreadsheet->disconnectWorksheets();
+    }
+
+    public function testPropertiesHtml(): void
+    {
+        $reader = new Xml();
+        $spreadsheet = $reader->load($this->filename);
+
+        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, 'Html');
+        $spreadsheet->disconnectWorksheets();
+
+        $properties = $reloadedSpreadsheet->getProperties();
+        self::assertSame('https://phpspreadsheet.readthedocs.io/en/latest/', $properties->getHyperlinkBase());
+
+        self::assertSame('title', $properties->getTitle());
+        self::assertSame('topic', $properties->getSubject());
+        self::assertSame('author', $properties->getCreator());
+        self::assertSame('keyword1, keyword2', $properties->getKeywords());
+        self::assertSame('no comment', $properties->getDescription());
+        self::assertSame('last author', $properties->getLastModifiedBy());
+        $expected = self::timestampToInt('2023-05-18T11:21:43Z');
+        self::assertEquals($expected, $properties->getCreated());
+        $expected = self::timestampToInt('2023-05-18T11:30:00Z');
+        self::assertEquals($expected, $properties->getModified());
+        self::assertSame('category', $properties->getCategory());
+        self::assertSame('manager', $properties->getManager());
+        self::assertSame('company', $properties->getCompany());
+
+        self::assertSame('TheString', $properties->getCustomPropertyValue('StringProperty'));
+        self::assertSame(12345, $properties->getCustomPropertyValue('NumberProperty'));
+        $expected = self::timestampToInt('2023-05-18T10:00:00Z');
+        self::assertEquals($expected, $properties->getCustomPropertyValue('DateProperty'));
+        $expected = self::timestampToInt('2023-05-19T11:00:00Z');
+        self::assertEquals($expected, $properties->getCustomPropertyValue('DateProperty2'));
+        self::assertTrue($properties->getCustomPropertyValue('BooleanPropertyTrue'));
+        self::assertFalse($properties->getCustomPropertyValue('BooleanPropertyFalse'));
+        self::assertEqualsWithDelta(1.2345, $properties->getCustomPropertyValue('FloatProperty'), 1E-8);
+
+        $sheet = $reloadedSpreadsheet->getActiveSheet();
+        // Note that relative links don't actually work in XML format.
+        // It will, however, work just fine in the Xlsx and Html copies.
+        $hyperlink = $sheet->getCell('A1')->getHyperlink();
+        self::assertSame('references/features-cross-reference/', $hyperlink->getUrl());
+        // Same comment as for cell above.
+        self::assertSame('topics/accessing-cells/', $sheet->getCell('A2')->getCalculatedValue());
+        // No problem for absolute links.
+        $hyperlink = $sheet->getCell('A3')->getHyperlink();
+        self::assertSame('https://www.google.com/', $hyperlink->getUrl());
+        self::assertSame('https://www.yahoo.com', $sheet->getCell('A4')->getCalculatedValue());
+
+        $reloadedSpreadsheet->disconnectWorksheets();
+    }
+
+    public function testHyperlinksXls(): void
+    {
+        $reader = new Xml();
+        $spreadsheet = $reader->load($this->filename);
+
+        $reloadedSpreadsheet = $this->writeAndReload($spreadsheet, 'Xls');
+        $spreadsheet->disconnectWorksheets();
+
+        $sheet = $reloadedSpreadsheet->getActiveSheet();
+        // Note that relative links don't actually work in XML format.
+        // However, Xls Writer will convert relative to absolute.
+        $hyperlink = $sheet->getCell('A1')->getHyperlink();
+        self::assertSame('https://phpspreadsheet.readthedocs.io/en/latest/references/features-cross-reference/', $hyperlink->getUrl());
+        // Xls writer does not get involved in function call.
+        // However, hyperlink does get updated somewhere.
+        //self::assertSame('topics/accessing-cells/', $sheet->getCell('A2')->getCalculatedValue());
+        $hyperlink = $sheet->getCell('A2')->getHyperlink();
+        self::assertSame('https://phpspreadsheet.readthedocs.io/en/latest/topics/accessing-cells/', $hyperlink->getUrl());
+        // No problem for absolute links.
+        $hyperlink = $sheet->getCell('A3')->getHyperlink();
+        self::assertSame('https://www.google.com/', $hyperlink->getUrl());
+        self::assertSame('https://www.yahoo.com', $sheet->getCell('A4')->getCalculatedValue());
+
+        $reloadedSpreadsheet->disconnectWorksheets();
+    }
+
+    private static function timestampToInt(string $timestamp): string
+    {
+        $dto = new DateTimeImmutable($timestamp);
+
+        return $dto->format('U');
+    }
+}

tests/data/Reader/Xml/hyperlinkbase.xml

@@ -0,0 +1,91 @@
+<?xml version="1.0"?>
+<?mso-application progid="Excel.Sheet"?>
+<Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
+ xmlns:o="urn:schemas-microsoft-com:office:office"
+ xmlns:x="urn:schemas-microsoft-com:office:excel"
+ xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882"
+ xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
+ xmlns:html="http://www.w3.org/TR/REC-html40">
+ <DocumentProperties xmlns="urn:schemas-microsoft-com:office:office">
+  <Title>title</Title>
+  <Subject>topic</Subject>
+  <Author>author</Author>
+  <Keywords>keyword1, keyword2</Keywords>
+  <Description>no comment</Description>
+  <LastAuthor>last author</LastAuthor>
+  <Created>2023-05-18T11:21:43Z</Created>
+  <LastSaved>2023-05-18T11:30:00Z</LastSaved>
+  <Category>category</Category>
+  <Manager>manager</Manager>
+  <Company>company</Company>
+  <HyperlinkBase>https://phpspreadsheet.readthedocs.io/en/latest/</HyperlinkBase>
+  <Version>16.00</Version>
+ </DocumentProperties>
+ <CustomDocumentProperties xmlns="urn:schemas-microsoft-com:office:office">
+  <StringProperty dt:dt="string">TheString</StringProperty>
+  <NumberProperty dt:dt="integer">12345</NumberProperty>
+  <DateProperty dt:dt="dateTime.tz">2023-05-18T10:00:00Z</DateProperty>
+  <DateProperty2 dt:dt="dateTime.iso8601tz">2023-05-19T11:00:00Z</DateProperty2>
+  <BooleanPropertyTrue dt:dt="boolean">1</BooleanPropertyTrue>
+  <BooleanPropertyFalse dt:dt="boolean">0</BooleanPropertyFalse>
+  <FloatProperty dt:dt="float">1.2345</FloatProperty>
+ </CustomDocumentProperties>
+ <OfficeDocumentSettings xmlns="urn:schemas-microsoft-com:office:office">
+  <AllowPNG/>
+ </OfficeDocumentSettings>
+ <ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel">
+  <WindowHeight>6820</WindowHeight>
+  <WindowWidth>19200</WindowWidth>
+  <WindowTopX>32767</WindowTopX>
+  <WindowTopY>32767</WindowTopY>
+  <ProtectStructure>False</ProtectStructure>
+  <ProtectWindows>False</ProtectWindows>
+ </ExcelWorkbook>
+ <Styles>
+  <Style ss:ID="Default" ss:Name="Normal">
+   <Alignment ss:Vertical="Bottom"/>
+   <Borders/>
+   <Font ss:FontName="Calibri" x:Family="Swiss" ss:Size="11" ss:Color="#000000"/>
+   <Interior/>
+   <NumberFormat/>
+   <Protection/>
+  </Style>
+  <Style ss:ID="s62" ss:Name="Hyperlink">
+   <Font ss:FontName="Calibri" x:Family="Swiss" ss:Size="11" ss:Color="#0066CC"
+    ss:Underline="Single"/>
+  </Style>
+ </Styles>
+ <Worksheet ss:Name="Tabelle1">
+  <Table ss:ExpandedColumnCount="1" ss:ExpandedRowCount="4" x:FullColumns="1"
+   x:FullRows="1" ss:DefaultRowHeight="14.5">
+   <Row ss:AutoFitHeight="0">
+    <Cell ss:StyleID="s62" ss:HRef="references/features-cross-reference/"><Data
+      ss:Type="String">references/features-cross-reference/</Data></Cell>
+   </Row>
+   <Row ss:AutoFitHeight="0">
+    <Cell ss:StyleID="s62" ss:Formula="=HYPERLINK(&quot;topics/accessing-cells/&quot;)"
+     ss:HRef="topics/accessing-cells/topics/accessing-cells/topics/accessing-cells/topics/accessing-cells/"><Data
+      ss:Type="String">topics/accessing-cells/</Data></Cell>
+   </Row>
+   <Row ss:AutoFitHeight="0">
+    <Cell ss:StyleID="s62" ss:HRef="https://www.google.com/"><Data ss:Type="String">https://www.google.com</Data></Cell>
+   </Row>
+   <Row ss:AutoFitHeight="0">
+    <Cell ss:StyleID="s62" ss:Formula="=HYPERLINK(&quot;https://www.yahoo.com&quot;)"
+     ss:HRef="https://www.yahoo.com/"><Data ss:Type="String">https://www.yahoo.com</Data></Cell>
+   </Row>
+  </Table>
+  <WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel">
+   <Unsynced/>
+   <Selected/>
+   <Panes>
+    <Pane>
+     <Number>3</Number>
+     <ActiveRow>3</ActiveRow>
+    </Pane>
+   </Panes>
+   <ProtectObjects>False</ProtectObjects>
+   <ProtectScenarios>False</ProtectScenarios>
+  </WorksheetOptions>
+ </Worksheet>
+</Workbook>