package stirling.software.SPDF.controller.api.converters; import java.awt.Color; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.nio.file.Files; import java.nio.file.Path; import java.util.ArrayList; import java.util.Arrays; import java.util.Calendar; import java.util.Collections; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Optional; import java.util.Set; import java.util.TimeZone; import org.apache.commons.io.FileUtils; import org.apache.pdfbox.Loader; import org.apache.pdfbox.cos.COSArray; import org.apache.pdfbox.cos.COSBase; import org.apache.pdfbox.cos.COSDictionary; import org.apache.pdfbox.cos.COSName; import org.apache.pdfbox.pdfwriter.compress.CompressParameters; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDDocumentCatalog; import org.apache.pdfbox.pdmodel.PDDocumentInformation; import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.PDPageContentStream; import org.apache.pdfbox.pdmodel.PDResources; import org.apache.pdfbox.pdmodel.common.PDMetadata; import org.apache.pdfbox.pdmodel.common.PDStream; import org.apache.pdfbox.pdmodel.font.PDFont; import org.apache.pdfbox.pdmodel.font.PDFontDescriptor; import org.apache.pdfbox.pdmodel.font.PDTrueTypeFont; import org.apache.pdfbox.pdmodel.font.PDType0Font; import org.apache.pdfbox.pdmodel.graphics.PDXObject; import org.apache.pdfbox.pdmodel.graphics.color.PDOutputIntent; import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject; import org.apache.pdfbox.pdmodel.graphics.image.LosslessFactory; import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject; import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotation; import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotationTextMarkup; import org.apache.pdfbox.pdmodel.interactive.viewerpreferences.PDViewerPreferences; import org.apache.xmpbox.XMPMetadata; import org.apache.xmpbox.schema.AdobePDFSchema; import org.apache.xmpbox.schema.DublinCoreSchema; import org.apache.xmpbox.schema.PDFAIdentificationSchema; import org.apache.xmpbox.schema.XMPBasicSchema; import org.apache.xmpbox.xml.DomXmpParser; import org.apache.xmpbox.xml.XmpSerializer; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.multipart.MultipartFile; import io.github.pixee.security.Filenames; import io.swagger.v3.oas.annotations.Operation; import io.swagger.v3.oas.annotations.tags.Tag; import lombok.extern.slf4j.Slf4j; import stirling.software.SPDF.model.api.converters.PdfToPdfARequest; import stirling.software.common.util.ProcessExecutor; import stirling.software.common.util.ProcessExecutor.ProcessExecutorResult; import stirling.software.common.util.WebResponseUtils; @RestController @RequestMapping("/api/v1/convert") @Slf4j @Tag(name = "Convert", description = "Convert APIs") public class ConvertPDFToPDFA { @PostMapping(consumes = "multipart/form-data", value = "/pdf/pdfa") @Operation( summary = "Convert a PDF to a PDF/A", description = "This endpoint converts a PDF file to a PDF/A file using LibreOffice. PDF/A is a format designed for long-term archiving of digital documents. Input:PDF Output:PDF Type:SISO") public ResponseEntity pdfToPdfA(@ModelAttribute PdfToPdfARequest request) throws Exception { MultipartFile inputFile = request.getFileInput(); String outputFormat = request.getOutputFormat(); // Validate input file type if (!"application/pdf".equals(inputFile.getContentType())) { log.error("Invalid input file type: {}", inputFile.getContentType()); throw new IllegalArgumentException("Input file must be a PDF"); } // Get the original filename without extension String originalFileName = Filenames.toSimpleFileName(inputFile.getOriginalFilename()); if (originalFileName == null || originalFileName.trim().isEmpty()) { originalFileName = "output.pdf"; } String baseFileName = originalFileName.contains(".") ? originalFileName.substring(0, originalFileName.lastIndexOf('.')) : originalFileName; Path tempInputFile = null; byte[] fileBytes; Path loPdfPath = null; // Used for LibreOffice conversion output File preProcessedFile = null; int pdfaPart = 2; try { // Save uploaded file to temp location tempInputFile = Files.createTempFile("input_", ".pdf"); inputFile.transferTo(tempInputFile); // Branch conversion based on desired output PDF/A format if ("pdfa".equals(outputFormat)) { preProcessedFile = tempInputFile.toFile(); } else { pdfaPart = 1; preProcessedFile = preProcessHighlights(tempInputFile.toFile()); } Set missingFonts = new HashSet<>(); boolean needImgs = false; try (PDDocument doc = Loader.loadPDF(preProcessedFile)) { missingFonts = findUnembeddedFontNames(doc); needImgs = (pdfaPart == 1) && hasTransparentImages(doc); if (!missingFonts.isEmpty() || needImgs) { // Run LibreOffice conversion to get flattened images and embedded fonts loPdfPath = runLibreOfficeConversion(preProcessedFile.toPath(), pdfaPart); } } fileBytes = convertToPdfA( preProcessedFile.toPath(), loPdfPath, pdfaPart, missingFonts, needImgs); String outputFilename = baseFileName + "_PDFA.pdf"; return WebResponseUtils.bytesToWebResponse( fileBytes, outputFilename, MediaType.APPLICATION_PDF); } finally { // Clean up temporary files if (tempInputFile != null) { Files.deleteIfExists(tempInputFile); } if (loPdfPath != null && loPdfPath.getParent() != null) { FileUtils.deleteDirectory(loPdfPath.getParent().toFile()); } if (preProcessedFile != null) { Files.deleteIfExists(preProcessedFile.toPath()); } } } /** * Merge fonts & flattened images from loPdfPath into basePdfPath, then run the standard * PDFBox/A pipeline. * * @param basePdfPath Path to the original (or highlight‐preprocessed) PDF * @param loPdfPath Path to the LibreOffice–flattened PDF/A, or null if not used * @param pdfaPart 1 (PDF/A-1B) or 2 (PDF/A-2B) * @return the final PDF/A bytes */ private byte[] convertToPdfA( Path basePdfPath, Path loPdfPath, int pdfaPart, Set missingFonts, boolean importImages) throws Exception { try (PDDocument baseDoc = Loader.loadPDF(basePdfPath.toFile())) { if (loPdfPath != null) { try (PDDocument loDoc = Loader.loadPDF(loPdfPath.toFile())) { if (!missingFonts.isEmpty()) { embedMissingFonts(loDoc, baseDoc, missingFonts); } if (importImages) { importFlattenedImages(loDoc, baseDoc); } } } return processWithPDFBox(baseDoc, pdfaPart); } } private byte[] processWithPDFBox(PDDocument document, int pdfaPart) throws Exception { removeElementsForPdfA(document, pdfaPart); mergeAndAddXmpMetadata(document, pdfaPart); addICCProfileIfNotPresent(document); // Mark the document as PDF/A PDDocumentCatalog catalog = document.getDocumentCatalog(); catalog.setMetadata( document.getDocumentCatalog().getMetadata()); // Ensure metadata is linked catalog.setViewerPreferences( new PDViewerPreferences(catalog.getCOSObject())); // PDF/A best practice document.getDocument().setVersion(pdfaPart == 1 ? 1.4f : 1.7f); ByteArrayOutputStream baos = new ByteArrayOutputStream(); if (pdfaPart == 1) { document.save(baos, CompressParameters.NO_COMPRESSION); } else { document.save(baos); } return baos.toByteArray(); } private Path runLibreOfficeConversion(Path tempInputFile, int pdfaPart) throws Exception { // Create temp output directory Path tempOutputDir = Files.createTempDirectory("output_"); // Determine PDF/A filter based on requested format String pdfFilter = pdfaPart == 2 ? "pdf:writer_pdf_Export:{\"SelectPdfVersion\":{\"type\":\"long\",\"value\":\"2\"}}" : "pdf:writer_pdf_Export:{\"SelectPdfVersion\":{\"type\":\"long\",\"value\":\"1\"}}"; // Prepare LibreOffice command List command = new ArrayList<>( Arrays.asList( "soffice", "--headless", "--nologo", "--convert-to", pdfFilter, "--outdir", tempOutputDir.toString(), tempInputFile.toString())); ProcessExecutorResult returnCode = ProcessExecutor.getInstance(ProcessExecutor.Processes.LIBRE_OFFICE) .runCommandWithOutputHandling(command); if (returnCode.getRc() != 0) { log.error("PDF/A conversion failed with return code: {}", returnCode.getRc()); throw new RuntimeException("PDF/A conversion failed"); } // Get the output file File[] outputFiles = tempOutputDir.toFile().listFiles(); if (outputFiles == null || outputFiles.length != 1) { throw new RuntimeException( "Expected one output PDF, found " + (outputFiles == null ? "none" : outputFiles.length)); } return outputFiles[0].toPath(); } private void embedMissingFonts(PDDocument loDoc, PDDocument baseDoc, Set missingFonts) throws IOException { List loPages = new ArrayList<>(); loDoc.getPages().forEach(loPages::add); List basePages = new ArrayList<>(); baseDoc.getPages().forEach(basePages::add); for (int i = 0; i < loPages.size(); i++) { PDResources loRes = loPages.get(i).getResources(); PDResources baseRes = basePages.get(i).getResources(); for (COSName fontKey : loRes.getFontNames()) { PDFont loFont = loRes.getFont(fontKey); if (loFont == null) continue; String psName = loFont.getName(); if (!missingFonts.contains(psName)) continue; PDFontDescriptor desc = loFont.getFontDescriptor(); if (desc == null) continue; PDStream fontStream = null; if (desc.getFontFile() != null) { fontStream = desc.getFontFile(); } else if (desc.getFontFile2() != null) { fontStream = desc.getFontFile2(); } else if (desc.getFontFile3() != null) { fontStream = desc.getFontFile3(); } if (fontStream == null) continue; try (InputStream in = fontStream.createInputStream()) { PDFont newFont = null; try { newFont = PDType0Font.load(baseDoc, in, false); } catch (IOException e1) { try { newFont = PDTrueTypeFont.load(baseDoc, in, null); } catch (IOException | IllegalArgumentException e2) { log.error("Could not embed font {}: {}", psName, e2.getMessage()); continue; } } if (newFont != null) { baseRes.put(fontKey, newFont); } } } } } private Set findUnembeddedFontNames(PDDocument doc) throws IOException { Set missing = new HashSet<>(); for (PDPage page : doc.getPages()) { PDResources res = page.getResources(); for (COSName name : res.getFontNames()) { PDFont font = res.getFont(name); if (font != null && !font.isEmbedded()) { missing.add(font.getName()); } } } return missing; } private void importFlattenedImages(PDDocument loDoc, PDDocument baseDoc) throws IOException { List loPages = new ArrayList<>(); loDoc.getPages().forEach(loPages::add); List basePages = new ArrayList<>(); baseDoc.getPages().forEach(basePages::add); for (int i = 0; i < loPages.size(); i++) { PDPage loPage = loPages.get(i); PDPage basePage = basePages.get(i); PDResources loRes = loPage.getResources(); PDResources baseRes = basePage.getResources(); Set toReplace = detectTransparentXObjects(basePage); for (COSName name : toReplace) { PDXObject loXo = loRes.getXObject(name); if (!(loXo instanceof PDImageXObject img)) continue; PDImageXObject newImg = LosslessFactory.createFromImage(baseDoc, img.getImage()); // replace the resource under the same name baseRes.put(name, newImg); } } } private Set detectTransparentXObjects(PDPage page) { Set transparentObjects = new HashSet<>(); PDResources res = page.getResources(); if (res == null) return transparentObjects; for (COSName name : res.getXObjectNames()) { try { PDXObject xo = res.getXObject(name); if (xo instanceof PDImageXObject img) { COSDictionary d = img.getCOSObject(); if (d.containsKey(COSName.SMASK) || isTransparencyGroup(d) || d.getBoolean(COSName.INTERPOLATE, false)) { transparentObjects.add(name); } } } catch (IOException ioe) { log.error("Error processing XObject {}: {}", name.getName(), ioe.getMessage()); } } return transparentObjects; } private boolean isTransparencyGroup(COSDictionary dict) { COSBase g = dict.getDictionaryObject(COSName.GROUP); return g instanceof COSDictionary gd && COSName.TRANSPARENCY.equals(gd.getCOSName(COSName.S)); } private boolean hasTransparentImages(PDDocument doc) { for (PDPage page : doc.getPages()) { PDResources res = page.getResources(); if (res == null) continue; for (COSName name : res.getXObjectNames()) { try { PDXObject xo = res.getXObject(name); if (xo instanceof PDImageXObject img) { COSDictionary dict = img.getCOSObject(); if (dict.containsKey(COSName.SMASK)) return true; COSBase g = dict.getDictionaryObject(COSName.GROUP); if (g instanceof COSDictionary gd && COSName.TRANSPARENCY.equals(gd.getCOSName(COSName.S))) { return true; } if (dict.getBoolean(COSName.INTERPOLATE, false)) return true; } } catch (IOException ioe) { log.error("Error processing XObject {}: {}", name.getName(), ioe.getMessage()); } } } return false; } private void sanitizePdfA(COSBase base, PDResources resources, int pdfaPart) { if (base instanceof COSDictionary dict) { if (pdfaPart == 1) { // Remove transparency-related elements COSBase group = dict.getDictionaryObject(COSName.GROUP); if (group instanceof COSDictionary gDict && COSName.TRANSPARENCY.equals(gDict.getCOSName(COSName.S))) { dict.removeItem(COSName.GROUP); } dict.removeItem(COSName.SMASK); // Transparency blending constants (/CA, /ca) — disallowed in PDF/A-1 dict.removeItem(COSName.CA); dict.removeItem(COSName.getPDFName("ca")); } // Interpolation (non-deterministic image scaling) — required to be false if (dict.containsKey(COSName.INTERPOLATE) && dict.getBoolean(COSName.INTERPOLATE, true)) { dict.setBoolean(COSName.INTERPOLATE, false); } // Remove common forbidden features (for PDF/A 1 and 2) dict.removeItem(COSName.JAVA_SCRIPT); dict.removeItem(COSName.getPDFName("JS")); dict.removeItem(COSName.getPDFName("RichMedia")); dict.removeItem(COSName.getPDFName("Movie")); dict.removeItem(COSName.getPDFName("Sound")); dict.removeItem(COSName.getPDFName("Launch")); dict.removeItem(COSName.URI); dict.removeItem(COSName.getPDFName("GoToR")); dict.removeItem(COSName.EMBEDDED_FILES); dict.removeItem(COSName.FILESPEC); // Recurse through all entries in the dictionary for (Map.Entry entry : dict.entrySet()) { sanitizePdfA(entry.getValue(), resources, pdfaPart); } } else if (base instanceof COSArray arr) { // Recursively sanitize each item in the array for (COSBase item : arr) { sanitizePdfA(item, resources, pdfaPart); } } } private void removeElementsForPdfA(PDDocument doc, int pdfaPart) { if (pdfaPart == 1) { // Remove Optional Content (Layers) - not allowed in PDF/A-1 doc.getDocumentCatalog().getCOSObject().removeItem(COSName.getPDFName("OCProperties")); } for (PDPage page : doc.getPages()) { if (pdfaPart == 1) { page.setAnnotations(Collections.emptyList()); } PDResources res = page.getResources(); // Clean page-level dictionary sanitizePdfA(page.getCOSObject(), res, pdfaPart); // sanitize each Form XObject if (res != null) { for (COSName name : res.getXObjectNames()) { try { PDXObject xo = res.getXObject(name); if (xo instanceof PDFormXObject form) { sanitizePdfA(form.getCOSObject(), res, pdfaPart); } else if (xo instanceof PDImageXObject img) { sanitizePdfA(img.getCOSObject(), res, pdfaPart); } } catch (IOException ioe) { log.error("Cannot load XObject {}: {}", name.getName(), ioe.getMessage()); } } } } } /** Embbeds the XMP metadata required for PDF/A compliance. */ private void mergeAndAddXmpMetadata(PDDocument document, int pdfaPart) throws Exception { PDMetadata existingMetadata = document.getDocumentCatalog().getMetadata(); XMPMetadata xmp; // Load existing XMP if available if (existingMetadata != null) { try (InputStream xmpStream = existingMetadata.createInputStream()) { DomXmpParser parser = new DomXmpParser(); parser.setStrictParsing(false); xmp = parser.parse(xmpStream); } catch (Exception e) { xmp = XMPMetadata.createXMPMetadata(); } } else { xmp = XMPMetadata.createXMPMetadata(); } PDDocumentInformation docInfo = document.getDocumentInformation(); if (docInfo == null) { docInfo = new PDDocumentInformation(); } String originalCreator = Optional.ofNullable(docInfo.getCreator()).orElse("Unknown"); String originalProducer = Optional.ofNullable(docInfo.getProducer()).orElse("Unknown"); // Only keep the original creator so it can match xmp creator tool for compliance DublinCoreSchema dcSchema = xmp.getDublinCoreSchema(); if (dcSchema != null) { List existingCreators = dcSchema.getCreators(); if (existingCreators != null) { for (String creator : new ArrayList<>(existingCreators)) { dcSchema.removeCreator(creator); } } } else { dcSchema = xmp.createAndAddDublinCoreSchema(); } dcSchema.addCreator(originalCreator); PDFAIdentificationSchema pdfaSchema = (PDFAIdentificationSchema) xmp.getSchema(PDFAIdentificationSchema.class); if (pdfaSchema == null) { pdfaSchema = xmp.createAndAddPDFAIdentificationSchema(); } pdfaSchema.setPart(pdfaPart); pdfaSchema.setConformance("B"); XMPBasicSchema xmpBasicSchema = xmp.getXMPBasicSchema(); if (xmpBasicSchema == null) { xmpBasicSchema = xmp.createAndAddXMPBasicSchema(); } AdobePDFSchema adobePdfSchema = xmp.getAdobePDFSchema(); if (adobePdfSchema == null) { adobePdfSchema = xmp.createAndAddAdobePDFSchema(); } docInfo.setCreator(originalCreator); xmpBasicSchema.setCreatorTool(originalCreator); docInfo.setProducer(originalProducer); adobePdfSchema.setProducer(originalProducer); String originalAuthor = docInfo.getAuthor(); if (originalAuthor != null && !originalAuthor.isBlank()) { docInfo.setAuthor(null); // If the author is set, we keep it in the XMP metadata if (!originalCreator.equals(originalAuthor)) { dcSchema.addCreator(originalAuthor); } } String title = docInfo.getTitle(); if (title != null && !title.isBlank()) { dcSchema.setTitle(title); } String subject = docInfo.getSubject(); if (subject != null && !subject.isBlank()) { dcSchema.addSubject(subject); } String keywords = docInfo.getKeywords(); if (keywords != null && !keywords.isBlank()) { adobePdfSchema.setKeywords(keywords); } // Set creation and modification dates Calendar now = Calendar.getInstance(TimeZone.getTimeZone("UTC")); Calendar originalCreationDate = docInfo.getCreationDate(); if (originalCreationDate == null) { originalCreationDate = now; } docInfo.setCreationDate(originalCreationDate); xmpBasicSchema.setCreateDate(originalCreationDate); docInfo.setModificationDate(now); xmpBasicSchema.setModifyDate(now); xmpBasicSchema.setMetadataDate(now); // Serialize the created metadata so it can be attached to the existent metadata ByteArrayOutputStream xmpOut = new ByteArrayOutputStream(); new XmpSerializer().serialize(xmp, xmpOut, true); PDMetadata newMetadata = new PDMetadata(document); newMetadata.importXMPMetadata(xmpOut.toByteArray()); document.getDocumentCatalog().setMetadata(newMetadata); } private void addICCProfileIfNotPresent(PDDocument document) throws Exception { if (document.getDocumentCatalog().getOutputIntents().isEmpty()) { try (InputStream colorProfile = getClass().getResourceAsStream("/icc/sRGB2014.icc")) { PDOutputIntent outputIntent = new PDOutputIntent(document, colorProfile); outputIntent.setInfo("sRGB IEC61966-2.1"); outputIntent.setOutputCondition("sRGB IEC61966-2.1"); outputIntent.setOutputConditionIdentifier("sRGB IEC61966-2.1"); outputIntent.setRegistryName("http://www.color.org"); document.getDocumentCatalog().addOutputIntent(outputIntent); } catch (Exception e) { log.error("Failed to load ICC profile: {}", e.getMessage()); } } } private File preProcessHighlights(File inputPdf) throws Exception { try (PDDocument document = Loader.loadPDF(inputPdf)) { for (PDPage page : document.getPages()) { // Retrieve the annotations on the page. List annotations = page.getAnnotations(); for (PDAnnotation annot : annotations) { // Process only highlight annotations. if ("Highlight".equals(annot.getSubtype()) && annot instanceof PDAnnotationTextMarkup highlight) { // Create a new appearance stream with the same bounding box. float[] colorComponents = highlight.getColor() != null ? highlight.getColor().getComponents() : new float[] {1f, 1f, 0f}; Color highlightColor = new Color( colorComponents[0], colorComponents[1], colorComponents[2]); float[] quadPoints = highlight.getQuadPoints(); if (quadPoints != null) { try (PDPageContentStream cs = new PDPageContentStream( document, page, PDPageContentStream.AppendMode.PREPEND, true, true)) { cs.setStrokingColor(highlightColor); cs.setLineWidth(0.05f); float spacing = 2f; // Draw diagonal lines across the highlight area to simulate // transparency. for (int i = 0; i < quadPoints.length; i += 8) { float minX = Math.min( Math.min(quadPoints[i], quadPoints[i + 2]), Math.min(quadPoints[i + 4], quadPoints[i + 6])); float maxX = Math.max( Math.max(quadPoints[i], quadPoints[i + 2]), Math.max(quadPoints[i + 4], quadPoints[i + 6])); float minY = Math.min( Math.min(quadPoints[i + 1], quadPoints[i + 3]), Math.min(quadPoints[i + 5], quadPoints[i + 7])); float maxY = Math.max( Math.max(quadPoints[i + 1], quadPoints[i + 3]), Math.max(quadPoints[i + 5], quadPoints[i + 7])); float width = maxX - minX; float height = maxY - minY; for (float y = minY; y <= maxY; y += spacing) { float len = Math.min(width, maxY - y); cs.moveTo(minX, y); cs.lineTo(minX + len, y + len); } for (float x = minX + spacing; x <= maxX; x += spacing) { float len = Math.min(maxX - x, height); cs.moveTo(x, minY); cs.lineTo(x + len, minY + len); } } cs.stroke(); } } page.getAnnotations().remove(highlight); COSDictionary pageDict = page.getCOSObject(); if (pageDict.containsKey(COSName.GROUP)) { COSDictionary groupDict = (COSDictionary) pageDict.getDictionaryObject(COSName.GROUP); if (groupDict != null) { if (COSName.TRANSPARENCY .getName() .equalsIgnoreCase(groupDict.getNameAsString(COSName.S))) { pageDict.removeItem(COSName.GROUP); } } } } } } // Save the modified document to a temporary file. File preProcessedFile = Files.createTempFile("preprocessed_", ".pdf").toFile(); document.save(preProcessedFile); return preProcessedFile; } } }