/**
 * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
 * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
 * joint initiative of the Federal Chancellery Austria and Graz University of
 * Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.knowcenter.wag.egov.egiz.pdf;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Logger;
import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObjectImage;
import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotation;

import at.gv.egiz.pdfas.api.analyze.NonTextObjectInfo;
import at.gv.egiz.pdfas.framework.input.PdfDataSource;

/**
 * Method for object extraction from pdf documents.
 * This uses pdf-box 0.8.0, not 0.7.2. Packages org.apache.pdfbox instead org.pdfbox!
 * @author dferbas
 *
 */
public class ObjectExtractor {
   private static Logger log = Logger.getLogger(ObjectExtractor.class);
   
   /*
    * If set <code>true</code> signature annotations are not extracted otherwise
    * all signatures except PDF-AS signatures are extracted.
    */
   private final static boolean SKIP_NON_PDFAS_SIGNATURES = false;

   /**
    * Find annotation objects in pdf documents
    * @param objectInfos
    * @param pageNr
    * @param page
    */
   private static void doExtractAnnotations(List objectInfos, int pageNr, PDPage page) {
        List annotations; 
        try {
           annotations = page.getAnnotations();
        } catch (IOException e) {
           log.error("Error extracting annotations from pdf. No NonTextObjectInfo-annotations available.", e);
           return;
        }
        for (Iterator it = annotations.iterator(); it.hasNext();) {
           try {              
              PDAnnotation anno = (PDAnnotation) it.next();
              log.debug("found annotation: " +anno);
              if (log.isTraceEnabled()) {
                 log.trace("annotation def: " + dictToString(anno.getDictionary()));
              }
              String ft = anno.getDictionary().getNameAsString("FT");
              if (ft != null && ft.equals("Sig")) {  // skip signature widgets
                 if (SKIP_NON_PDFAS_SIGNATURES) {
                    log.debug("found signature widged, skip extraction");
                    continue;
                 } else {
                    COSDictionary sigDict = (COSDictionary) anno.getDictionary().getDictionaryObject("V");
                    if (sigDict != null && AdobeSignatureHelper.ADOBE_SIG_FILTER.equals(sigDict.getNameAsString("Filter"))) {
                       log.debug("found PDF-AS signature widged, skip extraction");
                       continue;
                    }
                 }
              }

              NonTextObjectInfo objInfo = new NonTextObjectInfo();
              objInfo.setName(anno.getDictionary().getString( "NM" ));
              objInfo.setObjectType(NonTextObjectInfo.TYPE_ANNOTATION);

              String subtype = anno.getDictionary().getNameAsString("Subtype");
              String subj = anno.getDictionary().getString("Subj");
              if (subj != null) {
                subtype+= "/" + subj; 
              }
              objInfo.setSubType(subtype);
              
              objInfo.setPageNr(pageNr);
              objInfo.setHeight(anno.getRectangle().getHeight());
              objInfo.setWidth(anno.getRectangle().getWidth());
              objectInfos.add(objInfo);              
           } catch (Exception ex) {
              log.info("error reading non text object info key " + ex);
           }
        }   
     }
   
   /**
    * Create string representation from COSDictionary
    * @param dict
    * @return
    */
   public static String dictToString(COSDictionary dict)
   {
       try {
         String retVal = "COSDictionary{";
          for (int i = 0; i<dict.size(); i++)
          {
              COSName key = (COSName)dict.keyList().get(i);           
              retVal = retVal + "(" + key + ":" + dict.getItem(key) + ") ";
          }
          retVal = retVal + "}";
          return retVal;
      } catch (Exception e) {
         return "no detail available";
      }
   }

   /**
    * Find resources (images) in pdf documents
    * @param objectInfos
    * @param pageNr
    * @param page
    */
   private static void doExtractFromResources(List objectInfos, int pageNr, PDPage page) {
        PDResources resources = page.getResources();
    
        Map images;
        try {
           images = resources.getImages();
        } catch (IOException e) {
           log.error("Error extracting images from pdf. No NonTextObjectInfo-Images available.", e);
           return;
        }
        if (images != null) {
           Iterator imageIter = images.keySet().iterator();
           while (imageIter.hasNext()) {
              NonTextObjectInfo objInfo = new NonTextObjectInfo();
              String key = (String) imageIter.next();
              PDXObjectImage image = (PDXObjectImage) images.get(key);
              
              objInfo.setHeight(image.getHeight());
              objInfo.setWidth(image.getWidth());
              objInfo.setName(key + image.getSuffix());
              objInfo.setObjectType(NonTextObjectInfo.TYPE_IMAGE);
              objInfo.setPageNr(pageNr);
              objectInfos.add(objInfo);
              objInfo.setSubType(image.getSuffix());
              
              if (log.isDebugEnabled()) {
                 log.debug("Found non text object: " + objInfo.toString());
              }
           }
        }     
     }

   /**
      * Extract non textual data from pdf. 
      * 
      * @see org.pdfbox.ExtractImages
      * 
      * @param document
      * @return List of {@link NonTextObjectInfo}
      */
     public static List extractNonTextInfo(PDDocument document) {         
        // extraction does not work with the normalized pdf from extractTextTextual
        log.debug("going to extract non text objects");
        List objectInfos = new ArrayList();
        List pages = document.getDocumentCatalog().getAllPages();
        Iterator iter = pages.iterator();
        int pageNr = 0;
        while (iter.hasNext()) {
           pageNr++;
           PDPage page = (PDPage) iter.next();
           doExtractFromResources(objectInfos, pageNr, page);
           doExtractAnnotations(objectInfos, pageNr, page); // does not work with pdf-box 0.7.2 -> 0.8.0 needed
        }
        if (log.isDebugEnabled()) {
           log.debug("extracted non textual objects count: " + objectInfos.size());
        }
        return objectInfos;
   
     }

   /**
      * Extract non textual data from pdf. 
    * @param pdfDataSource 
      * 
      * @see org.pdfbox.ExtractImages
      * 
      * @return List of {@link NonTextObjectInfo}
      */
      public static List extractNonTextInfo(PdfDataSource pdfDataSource) {
   
         PDDocument doc = null;
         try {
            doc = PDDocument.load(pdfDataSource.createInputStream());
            List res = extractNonTextInfo(doc);
            doc.close();
            return res;
         } catch (IOException e) {
            log.error("Error extracting images from pdf. No NonTextObjectInfo available.", e);
            return new ArrayList();
         } finally {
            if (doc != null) {
               try {
                  doc.close();
               } catch (IOException e) {
                  log.error("error closing pddocument", e);
               }            
            }
         }
         
      }

}