Add: Option to remove the digital signature when merging (#1424)

src/main/java/stirling/software/SPDF/controller/api/MergeController.java

@@ -10,11 +10,16 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.apache.pdfbox.Loader;
 import org.apache.pdfbox.multipdf.PDFMergerUtility;
 import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDDocumentCatalog;
 import org.apache.pdfbox.pdmodel.PDPage;
+import org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm;
+import org.apache.pdfbox.pdmodel.interactive.form.PDField;
+import org.apache.pdfbox.pdmodel.interactive.form.PDSignatureField;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.http.ResponseEntity;
@@ -38,6 +43,7 @@ public class MergeController {
 
     private static final Logger logger = LoggerFactory.getLogger(MergeController.class);
 
+    // Merges a list of PDDocument objects into a single PDDocument
     public PDDocument mergeDocuments(List<PDDocument> documents) throws IOException {
         PDDocument mergedDoc = new PDDocument();
         for (PDDocument doc : documents) {
@@ -48,6 +54,7 @@ public class MergeController {
         return mergedDoc;
     }
 
+    // Returns a comparator for sorting MultipartFile arrays based on the given sort type
     private Comparator<MultipartFile> getSortComparator(String sortType) {
         switch (sortType) {
             case "byFileName":
@@ -108,37 +115,78 @@ public class MergeController {
                     "This endpoint merges multiple PDF files into a single PDF file. The merged file will contain all pages from the input files in the order they were provided. Input:PDF Output:PDF Type:MISO")
     public ResponseEntity<byte[]> mergePdfs(@ModelAttribute MergePdfsRequest form)
             throws IOException {
-        List<File> filesToDelete = new ArrayList<File>();
+        List<File> filesToDelete = new ArrayList<>(); // List of temporary files to delete
+        ByteArrayOutputStream docOutputstream =
+                new ByteArrayOutputStream(); // Stream for the merged document
+        PDDocument mergedDocument = null;
+
+        boolean removeCertSign = form.isRemoveCertSign();
+
         try {
             MultipartFile[] files = form.getFileInput();
-            Arrays.sort(files, getSortComparator(form.getSortType()));
+            Arrays.sort(
-
+                    files,
-            PDFMergerUtility mergedDoc = new PDFMergerUtility();
+                    getSortComparator(
-            ByteArrayOutputStream docOutputstream = new ByteArrayOutputStream();
+                            form.getSortType())); // Sort files based on the given sort type
 
+            PDFMergerUtility mergerUtility = new PDFMergerUtility();
             for (MultipartFile multipartFile : files) {
-                File tempFile = GeneralUtils.convertMultipartFileToFile(multipartFile);
+                File tempFile =
-                filesToDelete.add(tempFile);
+                        GeneralUtils.convertMultipartFileToFile(
-                mergedDoc.addSource(tempFile);
+                                multipartFile); // Convert MultipartFile to File
+                filesToDelete.add(tempFile); // Add temp file to the list for later deletion
+                mergerUtility.addSource(tempFile); // Add source file to the merger utility
+            }
+            mergerUtility.setDestinationStream(
+                    docOutputstream); // Set the output stream for the merged document
+            mergerUtility.mergeDocuments(null); // Merge the documents
+
+            byte[] mergedPdfBytes = docOutputstream.toByteArray(); // Get merged document bytes
+
+            // Load the merged PDF document
+            mergedDocument = Loader.loadPDF(mergedPdfBytes);
+
+            // Remove signatures if removeCertSign is true
+            if (removeCertSign) {
+                PDDocumentCatalog catalog = mergedDocument.getDocumentCatalog();
+                PDAcroForm acroForm = catalog.getAcroForm();
+                if (acroForm != null) {
+                    List<PDField> fieldsToRemove =
+                            acroForm.getFields().stream()
+                                    .filter(field -> field instanceof PDSignatureField)
+                                    .collect(Collectors.toList());
+
+                    if (!fieldsToRemove.isEmpty()) {
+                        acroForm.flatten(
+                                fieldsToRemove,
+                                false); // Flatten the fields, effectively removing them
+                    }
+                }
             }
 
-            mergedDoc.setDestinationFileName(
+            // Save the modified document to a new ByteArrayOutputStream
-                    files[0].getOriginalFilename().replaceFirst("[.][^.]+$", "") + "_merged.pdf");
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
-            mergedDoc.setDestinationStream(docOutputstream);
+            mergedDocument.save(baos);
-
-            mergedDoc.mergeDocuments(null);
 
+            String mergedFileName =
+                    files[0].getOriginalFilename().replaceFirst("[.][^.]+$", "")
+                            + "_merged_unsigned.pdf";
             return WebResponseUtils.bytesToWebResponse(
-                    docOutputstream.toByteArray(), mergedDoc.getDestinationFileName());
+                    baos.toByteArray(), mergedFileName); // Return the modified PDF
+
         } catch (Exception ex) {
             logger.error("Error in merge pdf process", ex);
             throw ex;
         } finally {
             for (File file : filesToDelete) {
                 if (file != null) {
-                    Files.deleteIfExists(file.toPath());
+                    Files.deleteIfExists(file.toPath()); // Delete temporary files
                 }
             }
+            docOutputstream.close();
+            if (mergedDocument != null) {
+                mergedDocument.close(); // Close the merged document
+            }
         }
     }
 }

src/main/java/stirling/software/SPDF/model/api/general/MergePdfsRequest.java

@@ -21,4 +21,10 @@ public class MergePdfsRequest extends MultiplePDFFiles {
             },
             defaultValue = "orderProvided")
     private String sortType = "orderProvided";
+
+    @Schema(
+            description =
+                    "Flag indicating whether to remove certification signatures from the merged PDF. If true, all certification signatures will be removed from the final merged document.",
+            example = "true")
+    private boolean isRemoveCertSign;
 }

src/main/resources/messages_ar_AR.properties

@@ -803,6 +803,7 @@ merge.title=دمج
 merge.header=دمج ملفات PDF متعددة (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=دمج
 
 

src/main/resources/messages_bg_BG.properties

@@ -803,6 +803,7 @@ merge.title=Обединяване
 merge.header=Обединяване на множество PDF файлове (2+)
 merge.sortByName=Сортиране по име
 merge.sortByDate=Сортиране по дата
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Обединяване
 
 

src/main/resources/messages_ca_CA.properties

@@ -803,6 +803,7 @@ merge.title=Fusiona
 merge.header=Fusiona múltiples PDFs (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Fusiona
 
 

src/main/resources/messages_cs_CZ.properties

@@ -803,6 +803,7 @@ merge.title=Sloučit
 merge.header=Sloučit více PDF (2+)
 merge.sortByName=Seřadit podle názvu
 merge.sortByDate=Seřadit podle data
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Sloučit
 
 

src/main/resources/messages_de_DE.properties

@@ -803,6 +803,7 @@ merge.title=Zusammenführen
 merge.header=Mehrere PDFs zusammenführen (2+)
 merge.sortByName=Nach Namen sortieren
 merge.sortByDate=Nach Datum sortieren
+merge.removeCertSign=Digitale Signatur in der zusammengeführten Datei entfernen?
 merge.submit=Zusammenführen
 
 

src/main/resources/messages_el_GR.properties

@@ -803,6 +803,7 @@ merge.title=Συγχώνευση
 merge.header=Συγχώνευση πολλαπλών PDFs (2+)
 merge.sortByName=Ταξινόμηση με βάση το Όνομα
 merge.sortByDate=Ταξινόμηση με βάση την Ημερομηνία
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Συγχώνευση
 
 

src/main/resources/messages_en_GB.properties

@@ -803,6 +803,7 @@ merge.title=Merge
 merge.header=Merge multiple PDFs (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Merge
 
 

src/main/resources/messages_en_US.properties

@@ -803,6 +803,7 @@ merge.title=Merge
 merge.header=Merge multiple PDFs (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Merge
 
 

src/main/resources/messages_es_ES.properties

@@ -803,6 +803,7 @@ merge.title=Unir
 merge.header=Unir múltiples PDFs (2+)
 merge.sortByName=Ordenar por nombre
 merge.sortByDate=Ordenar por fecha
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Unir
 
 

src/main/resources/messages_eu_ES.properties

@@ -803,6 +803,7 @@ merge.title=Elkartu
 merge.header=Elkartu zenbait PDF  (2+)
 merge.sortByName=Sort by nameOrdenatu izenaren arabera
 merge.sortByDate=Ordenatu dataren arabera
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Elkartu
 
 

src/main/resources/messages_fr_FR.properties

@@ -803,6 +803,7 @@ merge.title=Fusionner
 merge.header=Fusionner plusieurs PDF
 merge.sortByName=Trier par nom
 merge.sortByDate=Trier par date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Fusionner
 
 

src/main/resources/messages_hi_IN.properties

@@ -803,6 +803,7 @@ merge.title=मर्ज
 merge.header=एक से अधिक PDF एक साथ मर्ज करें (2+)
 merge.sortByName=नाम से क्रमबद्ध करें
 merge.sortByDate=तारीख से क्रमबद्ध करें
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=मर्ज करें
 
 

src/main/resources/messages_hr_HR.properties

@@ -803,6 +803,7 @@ merge.title=Spajanje
 merge.header=Spajanje više PDF-ova (2+)
 merge.sortByName=Poredaj po imenu
 merge.sortByDate=Poredaj po datumu
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Spajanje
 
 

src/main/resources/messages_hu_HU.properties

@@ -803,6 +803,7 @@ merge.title=Összevonás
 merge.header=Több PDF összevonása (2+)
 merge.sortByName=Név szerinti rendezés
 merge.sortByDate=Dátum szerinti rendezés
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Összevonás
 
 

src/main/resources/messages_id_ID.properties

@@ -803,6 +803,7 @@ merge.title=Gabungkan
 merge.header=Gabungkan beberapa PDFs (2+)
 merge.sortByName=Sortir berdasarkan nama
 merge.sortByDate=Sortir berdasrkan tanggal
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Gabungkan
 
 

src/main/resources/messages_it_IT.properties

@@ -803,6 +803,7 @@ merge.title=Unisci
 merge.header=Unisci 2 o più PDF
 merge.sortByName=Ordina per nome
 merge.sortByDate=Ordina per data
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Unisci
 
 

src/main/resources/messages_ja_JP.properties

@@ -803,6 +803,7 @@ merge.title=結合
 merge.header=複数のPDFを結合 (2ファイル以上)
 merge.sortByName=名前で並べ替え
 merge.sortByDate=日付で並べ替え
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=結合
 
 

src/main/resources/messages_ko_KR.properties

@@ -803,6 +803,7 @@ merge.title=병합
 merge.header=여러 개의 PDF 병합 (2개 이상)
 merge.sortByName=이름순 정렬
 merge.sortByDate=날짜순 정렬
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=병합
 
 

src/main/resources/messages_nl_NL.properties

@@ -803,6 +803,7 @@ merge.title=Samenvoegen
 merge.header=Meerdere PDF's samenvoegen (2+)
 merge.sortByName=Sorteer op naam
 merge.sortByDate=Sorteer op datum
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Samenvoegen
 
 

src/main/resources/messages_no_NB.properties

@@ -803,6 +803,7 @@ merge.title=Slå sammen
 merge.header=Slå sammen flere PDF-er (2+)
 merge.sortByName=Sorter etter navn
 merge.sortByDate=Sorter etter dato
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Slå sammen
 
 

src/main/resources/messages_pl_PL.properties

@@ -803,6 +803,7 @@ merge.title=Połącz
 merge.header=Połącz wiele dokumentów PDF (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Połącz
 
 

src/main/resources/messages_pt_BR.properties

@@ -803,6 +803,7 @@ merge.title=Mesclar
 merge.header=Mesclar Vários PDFs (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Mesclar
 
 

src/main/resources/messages_pt_PT.properties

@@ -803,6 +803,7 @@ merge.title=Juntar
 merge.header=Juntar Vários PDFs (2+)
 merge.sortByName=Ordenar por nome
 merge.sortByDate=Ordenar por data
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Juntar
 
 

src/main/resources/messages_ro_RO.properties

@@ -803,6 +803,7 @@ merge.title=Unire
 merge.header=Unirea mai multor PDF-uri (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Unire
 
 

src/main/resources/messages_ru_RU.properties

@@ -803,6 +803,7 @@ merge.title=Объединить
 merge.header=Объединение нескольких PDF-файлов (2+)
 merge.sortByName=Сортировка по имени
 merge.sortByDate=Сортировка по дате
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Объединить
 
 

src/main/resources/messages_sk_SK.properties

@@ -803,6 +803,7 @@ merge.title=Zlúčiť
 merge.header=Zlúčiť viacero PDF (2+)
 merge.sortByName=Zoradiť podľa názvu
 merge.sortByDate=Zoradiť podľa dátumu
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Zlúčiť
 
 

src/main/resources/messages_sr_LATN_RS.properties

@@ -803,6 +803,7 @@ merge.title=Spajanje
 merge.header=Spajanje više PDF fajlova (2+)
 merge.sortByName=Sortiraj po imenu
 merge.sortByDate=Sortiraj po datumu
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Spajanje
 
 

src/main/resources/messages_sv_SE.properties

@@ -803,6 +803,7 @@ merge.title=Sammanfoga
 merge.header=Slå samman flera PDF-filer (2+)
 merge.sortByName=Sort by name
 merge.sortByDate=Sort by date
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Slå samman
 
 

src/main/resources/messages_tr_TR.properties

@@ -803,6 +803,7 @@ merge.title=Birleştir
 merge.header=Çoklu PDF'leri Birleştir (2+)
 merge.sortByName=İsme göre sırala
 merge.sortByDate=Tarihe göre sırala
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Birleştir
 
 

src/main/resources/messages_uk_UA.properties

@@ -803,6 +803,7 @@ merge.title=Об'єднати
 merge.header=Об'єднання кількох PDF-файлів (2+)
 merge.sortByName=Сортування за ім'ям
 merge.sortByDate=Сортування за датою
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=Об'єднати
 
 

src/main/resources/messages_zh_CN.properties

@@ -803,6 +803,7 @@ merge.title=合并
 merge.header=合并多个PDF（2个以上）。
 merge.sortByName=按名称排序
 merge.sortByDate=按日期排序
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=合并
 
 

src/main/resources/messages_zh_TW.properties

@@ -803,6 +803,7 @@ merge.title=合併
 merge.header=合併多個 PDF
 merge.sortByName=依名稱排序
 merge.sortByDate=依日期排序
+merge.removeCertSign=Remove digital signature in the merged file?
 merge.submit=合併
 
 

src/main/resources/templates/merge-pdfs.html

@@ -19,9 +19,13 @@
               </div>
               <form action="api/v1/general/merge-pdfs" method="post" enctype="multipart/form-data">
                 <div class="mb-3">
-                  <label th:text="#{multiPdfDropPrompt}"></label>
+                  <label th:text="#{multiPdfDropPrompt}" for="fileInput-input"></label>
                   <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=true, accept='application/pdf')}"></div>
                 </div>
+                <div class="mb-3">
+                  <input type="checkbox" name="removeCertSign" id="removeCertSign">
+                  <label for="removeCertSign" th:text="#{merge.removeCertSign}">Remove digital signature in the merged file?</label>
+                </div>
                 <div class="mb-3">
                   <ul id="selectedFiles" class="list-group"></ul>
                 </div>