ApachePreflightParser.java

/**
 * 
 */
package uk.bl.wa.parsers;

/*
 * #%L
 * warc-indexer
 * $Id:$
 * $HeadURL:$
 * %%
 * Copyright (C) 2013 - 2014 The UK Web Archive
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 2 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/gpl-2.0.html>.
 * #L%
 */

import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import org.apache.pdfbox.preflight.PreflightDocument;
import org.apache.pdfbox.preflight.ValidationResult;
import org.apache.pdfbox.preflight.ValidationResult.ValidationError;
import org.apache.pdfbox.preflight.exception.SyntaxValidationException;
import org.apache.pdfbox.preflight.parser.PreflightParser;
import org.apache.tika.exception.TikaException;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.metadata.Property;
import org.apache.tika.mime.MediaType;
import org.apache.tika.parser.AbstractParser;
import org.apache.tika.parser.ParseContext;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;

import uk.bl.wa.util.InputStreamDataSource;

/**
 * @author Andrew Jackson <Andrew.Jackson@bl.uk>
 *
 */
public class ApachePreflightParser extends AbstractParser {

    /** */
	private static final long serialVersionUID = 710873621129254338L;

	/** */
	private static final Set<MediaType> SUPPORTED_TYPES =
            Collections.unmodifiableSet(new HashSet<MediaType>(Arrays.asList(
                  MediaType.application("pdf")
            )));

	public static final Property PDF_PREFLIGHT_VALID = Property.internalBoolean("PDF-A-PREFLIGHT-VALID");

	public static final Property PDF_PREFLIGHT_ERRORS = Property.internalTextBag("PDF-A-PREFLIGHT-ERRORS");

	
	
	/* (non-Javadoc)
	 * @see org.apache.tika.parser.Parser#getSupportedTypes(org.apache.tika.parser.ParseContext)
	 */
	@Override
	public Set<MediaType> getSupportedTypes(ParseContext context) {
		return SUPPORTED_TYPES;
	}

	/* (non-Javadoc)
	 * @see org.apache.tika.parser.Parser#parse(java.io.InputStream, org.xml.sax.ContentHandler, org.apache.tika.metadata.Metadata, org.apache.tika.parser.ParseContext)
	 */
	@Override
	public void parse(InputStream stream, ContentHandler handler,
			Metadata metadata, ParseContext context) throws IOException,
			SAXException, TikaException {
		
		// Attempt to reduce logging of stacktraces:
		//System.setProperty("log4j.logger.org.apache.pdfbox","");

		// Set up the validation result:
		ValidationResult result = null;

		InputStreamDataSource isds = new InputStreamDataSource(stream);
		PreflightParser parser = new PreflightParser(isds);
		PreflightDocument document = null;
		try {

		  /* Parse the PDF file with PreflightParser that inherits from the NonSequentialParser.
		   * Some additional controls are present to check a set of PDF/A requirements. 
		   * (Stream length consistency, EOL after some Keyword...)
		   */
			parser.parse();

		  /* Once the syntax validation is done, 
		   * the parser can provide a PreflightDocument 
		   * (that inherits from PDDocument) 
		   * This document process the end of PDF/A validation.
		   */
			document = parser.getPreflightDocument();
			document.validate();
		  
			// Get validation result
			result = document.getResult();

		} catch (SyntaxValidationException e) {
			/*
			 * the parse method can throw a SyntaxValidationExceptionif the PDF
			 * file can't be parsed.
			 * 
			 * In this case, the exception contains an instance of
			 * ValidationResult
			 */
			result = e.getResult();
		} catch (Exception e) {
			// Otherwise, a NULL result:
			result = null;

		} finally {
			// Ensure the document is always closed:
			if (document != null)
				document.close();
		}

		// display validation result
		Set<String> rs = new HashSet<String>();
		if (result != null && result.isValid()) {
		  //System.out.println("The resource is not a valid PDF/A-1b file");
		  metadata.set( PDF_PREFLIGHT_VALID, Boolean.TRUE.toString() );
		} else {
		  //System.out.println("The resource is not valid, error(s) :");
		  metadata.set( PDF_PREFLIGHT_VALID, Boolean.FALSE.toString() );
			if (result != null) {
				for (ValidationError error : result.getErrorsList()) {
					// System.out.println(error.getErrorCode() + " : " +
					// error.getDetails());
					rs.add(error.getErrorCode() + " : " + error.getDetails());
				}
			}
		}

	    metadata.set( PDF_PREFLIGHT_ERRORS , rs.toArray( new String[] {} ));

	}

}