Fetch XML file paths from Workbook Relationships

src/Spout/Reader/XLSX/Manager/WorkbookRelationshipsManager.php

@@ -0,0 +1,136 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX\Manager;
+
+use Box\Spout\Common\Exception\IOException;
+use Box\Spout\Reader\Wrapper\XMLReader;
+use Box\Spout\Reader\XLSX\Creator\EntityFactory;
+
+/**
+ * Class WorkbookRelationshipsManager
+ * This class manages the workbook relationships defined in the associated XML file
+ */
+class WorkbookRelationshipsManager
+{
+    const BASE_PATH = 'xl/';
+
+    /** Path of workbook relationships XML file inside the XLSX file */
+    const WORKBOOK_RELS_XML_FILE_PATH = 'xl/_rels/workbook.xml.rels';
+
+    /** Relationships types */
+    const RELATIONSHIP_TYPE_SHARED_STRINGS = 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/sharedStrings';
+    const RELATIONSHIP_TYPE_STYLES = 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles';
+    const RELATIONSHIP_TYPE_WORKSHEET = 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet';
+
+    /** Nodes and attributes used to find relevant information in the workbook relationships XML file */
+    const XML_NODE_RELATIONSHIP = 'Relationship';
+    const XML_ATTRIBUTE_TYPE = 'Type';
+    const XML_ATTRIBUTE_TARGET = 'Target';
+
+    /** @var string Path of the XLSX file being read */
+    private $filePath;
+
+    /** @var EntityFactory Factory to create entities */
+    private $entityFactory;
+
+    /** @var array Cache of the already read workbook relationships: [TYPE] => [FILE_NAME] */
+    private $cachedWorkbookRelationships;
+
+    /**
+     * @param string $filePath Path of the XLSX file being read
+     * @param EntityFactory $entityFactory Factory to create entities
+     */
+    public function __construct($filePath, $entityFactory)
+    {
+        $this->filePath = $filePath;
+        $this->entityFactory = $entityFactory;
+    }
+
+    /**
+     * @return string The path of the shared string XML file
+     */
+    public function getSharedStringsXMLFilePath()
+    {
+        $workbookRelationships = $this->getWorkbookRelationships();
+        $sharedStringsXMLFilePath = $workbookRelationships[self::RELATIONSHIP_TYPE_SHARED_STRINGS];
+
+        // the file path can be relative (e.g. "styles.xml") or absolute (e.g. "/xl/styles.xml")
+        $doesContainBasePath = (strpos($sharedStringsXMLFilePath, self::BASE_PATH) !== false);
+        if (!$doesContainBasePath) {
+            // make sure we return an absolute file path
+            $sharedStringsXMLFilePath = self::BASE_PATH . $sharedStringsXMLFilePath;
+        }
+
+        return $sharedStringsXMLFilePath;
+    }
+
+    /**
+     * @return bool Whether the XLSX file contains a shared string XML file
+     */
+    public function hasSharedStringsXMLFile()
+    {
+        $workbookRelationships = $this->getWorkbookRelationships();
+
+        return isset($workbookRelationships[self::RELATIONSHIP_TYPE_SHARED_STRINGS]);
+    }
+
+    /**
+     * @return string|null The path of the styles XML file
+     */
+    public function getStylesXMLFilePath()
+    {
+        $workbookRelationships = $this->getWorkbookRelationships();
+        $stylesXMLFilePath = $workbookRelationships[self::RELATIONSHIP_TYPE_STYLES];
+
+        // the file path can be relative (e.g. "styles.xml") or absolute (e.g. "/xl/styles.xml")
+        $doesContainBasePath = (strpos($stylesXMLFilePath, self::BASE_PATH) !== false);
+        if (!$doesContainBasePath) {
+            // make sure we return a full path
+            $stylesXMLFilePath = self::BASE_PATH . $stylesXMLFilePath;
+        }
+
+        return $stylesXMLFilePath;
+    }
+
+    /**
+     * Reads the workbook.xml.rels and extracts the filename associated to the different types.
+     * It caches the result so that the file is read only once.
+     *
+     * @throws \Box\Spout\Common\Exception\IOException If workbook.xml.rels can't be read
+     * @return array
+     */
+    private function getWorkbookRelationships()
+    {
+        if (!isset($this->cachedWorkbookRelationships)) {
+            $xmlReader = $this->entityFactory->createXMLReader();
+
+            if ($xmlReader->openFileInZip($this->filePath, self::WORKBOOK_RELS_XML_FILE_PATH) === false) {
+                throw new IOException('Could not open "' . self::WORKBOOK_RELS_XML_FILE_PATH . '".');
+            }
+
+            $this->cachedWorkbookRelationships = [];
+
+            while ($xmlReader->readUntilNodeFound(self::XML_NODE_RELATIONSHIP)) {
+                $this->processWorkbookRelationship($xmlReader);
+            }
+        }
+
+        return $this->cachedWorkbookRelationships;
+    }
+
+    /**
+     * Extracts and store the data of the current workbook relationship.
+     *
+     * @param XMLReader $xmlReader
+     * @return void
+     */
+    private function processWorkbookRelationship($xmlReader)
+    {
+        $type = $xmlReader->getAttribute(self::XML_ATTRIBUTE_TYPE);
+        $target = $xmlReader->getAttribute(self::XML_ATTRIBUTE_TARGET);
+
+        // @NOTE: if a type is defined more than once, we overwrite the previous value
+        // To be changed if we want to get the file paths of sheet XML files for instance.
+        $this->cachedWorkbookRelationships[$type] = $target;
+    }
+}