feat(ZUGFERD): Add dedicated ZUGFERD v1/v2 support and refine invoice format detection logic
This commit is contained in:
@ -1,30 +1,54 @@
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import { PDFDocument, PDFDict, PDFName, PDFRawStream, PDFArray, PDFString } from 'pdf-lib';
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import * as pako from 'pako';
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import {
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BaseXMLExtractor,
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StandardXMLExtractor,
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AssociatedFilesExtractor,
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TextXMLExtractor
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} from './extractors/index.js';
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/**
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* Class for extracting XML from PDF files
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* Main PDF extractor class that orchestrates the extraction process
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* Uses multiple specialized extractors in sequence to maximize success rate
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*/
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export class PDFExtractor {
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private extractors: BaseXMLExtractor[] = [];
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/**
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* Extracts XML from a PDF buffer
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* Constructor initializes the chain of extractors
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*/
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constructor() {
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// Add extractors in order of preference/likelihood of success
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this.extractors.push(
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new StandardXMLExtractor(), // Standard PDF/A-3 embedded files
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new AssociatedFilesExtractor(), // Associated files (ZUGFeRD v1, some Factur-X)
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new TextXMLExtractor() // Text-based extraction (fallback)
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);
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}
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/**
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* Extract XML from a PDF buffer
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* Tries multiple extraction methods in sequence
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* @param pdfBuffer PDF buffer
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* @returns XML content or null if not found
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*/
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public async extractXml(pdfBuffer: Uint8Array | Buffer): Promise<string | null> {
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try {
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// First try the standard extraction
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const standardXml = await this.standardExtraction(pdfBuffer);
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if (standardXml && this.isValidXml(standardXml)) {
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return standardXml;
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console.log('Starting XML extraction from PDF...');
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// Try each extractor in sequence
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for (const extractor of this.extractors) {
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const extractorName = extractor.constructor.name;
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console.log(`Trying extraction with ${extractorName}...`);
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const xml = await extractor.extractXml(pdfBuffer);
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if (xml) {
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console.log(`Successfully extracted XML using ${extractorName}`);
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return xml;
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}
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console.log(`Extraction with ${extractorName} failed, trying next method...`);
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}
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// If standard extraction fails, try alternative methods
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const alternativeXml = await this.alternativeExtraction(pdfBuffer);
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if (alternativeXml && this.isValidXml(alternativeXml)) {
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return alternativeXml;
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}
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// If all extraction methods fail, return null
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// If all extractors fail, return null
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console.warn('All extraction methods failed, no valid XML found in PDF');
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return null;
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} catch (error) {
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@ -33,255 +57,7 @@ export class PDFExtractor {
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}
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}
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/**
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* Standard extraction method using PDF-lib
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* @param pdfBuffer PDF buffer
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* @returns XML content or null if not found
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*/
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private async standardExtraction(pdfBuffer: Uint8Array | Buffer): Promise<string | null> {
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try {
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const pdfDoc = await PDFDocument.load(pdfBuffer);
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// Get the document's metadata dictionary
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const namesDictObj = pdfDoc.catalog.lookup(PDFName.of('Names'));
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if (!(namesDictObj instanceof PDFDict)) {
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console.warn('No Names dictionary found in PDF! This PDF does not contain embedded files.');
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return null;
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}
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const embeddedFilesDictObj = namesDictObj.lookup(PDFName.of('EmbeddedFiles'));
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if (!(embeddedFilesDictObj instanceof PDFDict)) {
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console.warn('No EmbeddedFiles dictionary found! This PDF does not contain embedded files.');
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return null;
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}
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const filesSpecObj = embeddedFilesDictObj.lookup(PDFName.of('Names'));
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if (!(filesSpecObj instanceof PDFArray)) {
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console.warn('No files specified in EmbeddedFiles dictionary!');
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return null;
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}
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// Try to find an XML file in the embedded files
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let xmlFile: PDFRawStream | undefined;
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let xmlFileName: string | undefined;
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for (let i = 0; i < filesSpecObj.size(); i += 2) {
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const fileNameObj = filesSpecObj.lookup(i);
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const fileSpecObj = filesSpecObj.lookup(i + 1);
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if (!(fileNameObj instanceof PDFString)) {
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continue;
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}
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if (!(fileSpecObj instanceof PDFDict)) {
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continue;
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}
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// Get the filename as string
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const fileName = fileNameObj.toString();
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// Check if it's an XML file (checking both extension and known standard filenames)
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if (fileName.toLowerCase().includes('.xml') ||
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fileName.toLowerCase().includes('factur-x') ||
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fileName.toLowerCase().includes('zugferd') ||
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fileName.toLowerCase().includes('xrechnung')) {
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const efDictObj = fileSpecObj.lookup(PDFName.of('EF'));
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if (!(efDictObj instanceof PDFDict)) {
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continue;
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}
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const maybeStream = efDictObj.lookup(PDFName.of('F'));
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if (maybeStream instanceof PDFRawStream) {
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// Found an XML file - save it
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xmlFile = maybeStream;
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xmlFileName = fileName;
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break;
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}
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}
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}
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// If no XML file was found, return null
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if (!xmlFile) {
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console.warn('No embedded XML file found in the PDF!');
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return null;
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}
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// Decompress and decode the XML content
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try {
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// Try to decompress with pako
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const xmlCompressedBytes = xmlFile.getContents().buffer;
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const xmlBytes = pako.inflate(xmlCompressedBytes);
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const xmlContent = new TextDecoder('utf-8').decode(xmlBytes);
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// Check if the XML content is valid
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if (this.isValidXml(xmlContent)) {
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console.log(`Successfully extracted XML from PDF file. File name: ${xmlFileName}`);
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return xmlContent;
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}
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// If we get here, the XML content is not valid, try without decompression
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console.log('Decompression succeeded but XML is not valid, trying without decompression...');
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const rawXmlBytes = xmlFile.getContents();
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const rawXmlContent = new TextDecoder('utf-8').decode(rawXmlBytes);
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if (this.isValidXml(rawXmlContent)) {
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console.log(`Successfully extracted uncompressed XML from PDF file. File name: ${xmlFileName}`);
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return rawXmlContent;
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}
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// If we get here, neither the decompressed nor the raw XML content is valid
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console.log('Neither decompressed nor raw XML content is valid');
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return null;
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} catch (decompressError) {
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// Decompression failed, try without decompression
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console.log('Decompression failed, trying without decompression...');
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try {
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const xmlBytes = xmlFile.getContents();
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const xmlContent = new TextDecoder('utf-8').decode(xmlBytes);
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if (this.isValidXml(xmlContent)) {
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console.log(`Successfully extracted uncompressed XML from PDF file. File name: ${xmlFileName}`);
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return xmlContent;
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}
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// If we get here, the XML content is not valid
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console.log('Uncompressed XML content is not valid');
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return null;
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} catch (decodeError) {
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console.error('Error decoding XML content:', decodeError);
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return null;
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}
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}
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} catch (error) {
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console.error('Error in standard extraction:', error);
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return null;
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}
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}
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/**
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* Alternative extraction method using string search
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* @param pdfBuffer PDF buffer
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* @returns XML content or null if not found
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*/
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private async alternativeExtraction(pdfBuffer: Uint8Array | Buffer): Promise<string | null> {
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try {
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// Convert buffer to string and look for XML patterns
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const pdfString = Buffer.from(pdfBuffer).toString('utf8', 0, Math.min(pdfBuffer.length, 10000));
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// Look for common XML patterns in the PDF
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const xmlPatterns = [
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/<\?xml[^>]*\?>/i,
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/<CrossIndustryInvoice[^>]*>/i,
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/<Invoice[^>]*>/i,
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/<CreditNote[^>]*>/i,
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/<rsm:CrossIndustryInvoice[^>]*>/i
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];
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for (const pattern of xmlPatterns) {
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const match = pdfString.match(pattern);
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if (match) {
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console.log(`Found XML pattern in PDF: ${match[0]}`);
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// Try to extract the XML content
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const xmlContent = this.extractXmlFromString(pdfString);
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if (xmlContent) {
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console.log('Successfully extracted XML from PDF string');
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return xmlContent;
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}
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}
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}
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return null;
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} catch (error) {
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console.error('Error in alternative extraction:', error);
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return null;
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}
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}
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/**
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* Extracts XML from a string
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* @param pdfString PDF string
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* @returns XML content or null if not found
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*/
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private extractXmlFromString(pdfString: string): string | null {
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try {
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// Look for XML start and end tags
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const xmlStartIndex = pdfString.indexOf('<?xml');
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if (xmlStartIndex === -1) {
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return null;
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}
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// Try to find the end of the XML document
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const possibleEndTags = [
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'</CrossIndustryInvoice>',
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'</Invoice>',
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'</CreditNote>',
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'</rsm:CrossIndustryInvoice>'
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];
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let xmlEndIndex = -1;
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for (const endTag of possibleEndTags) {
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const endIndex = pdfString.indexOf(endTag);
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if (endIndex !== -1) {
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xmlEndIndex = endIndex + endTag.length;
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break;
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}
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}
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if (xmlEndIndex === -1) {
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return null;
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}
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// Extract the XML content
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return pdfString.substring(xmlStartIndex, xmlEndIndex);
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} catch (error) {
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console.error('Error extracting XML from string:', error);
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return null;
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}
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}
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/**
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* Checks if an XML string is valid
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* @param xmlString XML string to check
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* @returns True if the XML is valid
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*/
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private isValidXml(xmlString: string): boolean {
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try {
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// Check if the XML string contains basic XML structure
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if (!xmlString.includes('<?xml')) {
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return false;
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}
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// Check if the XML string contains known invoice formats
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const knownFormats = [
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'CrossIndustryInvoice',
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'Invoice',
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'CreditNote',
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'ubl:Invoice',
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'ubl:CreditNote'
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];
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const hasKnownFormat = knownFormats.some(format => xmlString.includes(format));
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if (!hasKnownFormat) {
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return false;
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}
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// Check if the XML string contains binary data or invalid characters
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const invalidChars = ['\u0000', '\u0001', '\u0002', '\u0003', '\u0004', '\u0005'];
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const hasBinaryData = invalidChars.some(char => xmlString.includes(char));
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if (hasBinaryData) {
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return false;
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}
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// Check if the XML string is too short
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if (xmlString.length < 100) {
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return false;
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}
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return true;
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} catch (error) {
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console.error('Error validating XML:', error);
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return false;
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}
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}
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}
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