veraPDF validation feature added, #265

pom.xml

@@ -282,5 +282,15 @@
 			<artifactId>webp-imageio</artifactId>
 			<version>0.1.6</version>
 		</dependency>
+		<dependency>
+			<groupId>org.verapdf</groupId>
+			<artifactId>validation-model</artifactId>
+			<version>1.26.1</version>
+		</dependency>
+		<dependency>
+			<groupId>org.verapdf</groupId>
+			<artifactId>validation-model-jakarta</artifactId>
+			<version>1.26.1</version>
+		</dependency>
 	</dependencies>
 </project>

src/main/java/org/metanorma/fop/PDFGenerator.java

@@ -490,6 +490,11 @@ private void convertmn2pdf(fontConfig fontcfg, XSLTconverter xsltConverter, File
                 logger.info(WARNING_NONPDFUA);
             }
 
+            // validate PDF by veraPDF
+            VeraPDFValidator veraPDFValidator = new VeraPDFValidator();
+            veraPDFValidator.validate(pdf);
+
+
             fontcfg.printMessages();
 
         } catch (Exception e) {

src/main/java/org/metanorma/fop/VeraPDFValidator.java

@@ -0,0 +1,48 @@
+package org.metanorma.fop;
+
+import org.metanorma.utils.LoggerHelper;
+import org.verapdf.core.EncryptedPdfException;
+import org.verapdf.core.ModelParsingException;
+import org.verapdf.core.ValidationException;
+import org.verapdf.gf.foundry.VeraGreenfieldFoundryProvider;
+import org.verapdf.pdfa.Foundries;
+import org.verapdf.pdfa.PDFAParser;
+import org.verapdf.pdfa.results.ValidationResult;
+import org.verapdf.pdfa.PDFAValidator;
+import org.verapdf.pdfa.flavours.PDFAFlavour;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.logging.Logger;
+
+import static org.metanorma.Constants.PDF_A_MODE;
+
+public class VeraPDFValidator {
+
+    protected static final Logger logger = Logger.getLogger(LoggerHelper.LOGGER_NAME);
+
+    // see https://docs.verapdf.org/develop/
+    public void validate(File filePDF) {
+        VeraGreenfieldFoundryProvider.initialise();
+        String sPDFAmode = PDF_A_MODE.substring(PDF_A_MODE.indexOf("-"));
+        PDFAFlavour flavour = PDFAFlavour.fromString(sPDFAmode);
+        try (PDFAParser parser = Foundries.defaultInstance().createParser(new FileInputStream(filePDF), flavour)) {
+            PDFAValidator validator = Foundries.defaultInstance().createValidator(flavour, false);
+            ValidationResult result = validator.validate(parser);
+
+            if (result.isCompliant()) {
+                // File is a valid PDF/A  PDF_A_MODE
+                return;
+            } else {
+                // it isn't
+                logger.severe("PDF isn't valid " + PDF_A_MODE + ":");
+                logger.severe(result.toString());
+            }
+        } catch (IOException | ValidationException | ModelParsingException | EncryptedPdfException exception) {
+            // Exception during validation
+            logger.severe(exception.toString());
+        }
+        return;
+    }
+
+}