/**
 * <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.gv.egiz.pdfas.placeholder;

import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Vector;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.exceptions.WrappedIOException;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObject;
import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObjectImage;
import org.apache.pdfbox.util.Matrix;
import org.apache.pdfbox.util.PDFOperator;
import org.apache.pdfbox.util.PDFStreamEngine;
import org.apache.pdfbox.util.ResourceLoader;

import at.gv.egiz.pdfas.api.commons.Constants;
import at.gv.egiz.pdfas.exceptions.ErrorCode;
import at.gv.egiz.pdfas.exceptions.framework.PlaceholderExtractionException;
import at.gv.egiz.pdfas.utils.PDFASUtils;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;
import at.knowcenter.wag.egov.egiz.pdf.TablePos;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.LuminanceSource;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.NotFoundException;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.HybridBinarizer;

/**
 * Extract all relevant information from a placeholder image.
 * 
 * @author exthex
 *
 */
public class SignaturePlaceholderExtractor extends PDFStreamEngine {
   /**
    * The log.
    */
   private static Log log = LogFactory.getLog(SignaturePlaceholderExtractor.class);
   
   private List placeholders = new Vector();
   private int currentPage = 0;
   
   private SignaturePlaceholderExtractor(String placeholderId, int placeholderMatchMode) throws IOException {
      super(ResourceLoader.loadProperties("at/gv/egiz/pdfas/placeholder/pdfbox-reader.properties",
            true));
   }

   /**
    * Search the document for placeholder images and possibly included
    * additional info.<br/>
    * Searches only for the first placeholder page after page from top.
    * 
    * @param inputStream
    * @return all available info from the first found placeholder.
    * @throws PDFDocumentException if the document could not be read.
    * @throws PlaceholderExtractionException if STRICT matching mode was requested and no suitable placeholder could be found.
    */
   public static SignaturePlaceholderData extract(InputStream inputStream, String placeholderId, int matchMode)
         throws PDFDocumentException, PlaceholderExtractionException {
      SignaturePlaceholderContext.setSignaturePlaceholderData(null);
      PDDocument doc = null;
      try 
      {
         try {
            doc = PDDocument.load(inputStream);
         } catch (IOException e) {
            throw new PDFDocumentException(ErrorCode.DOCUMENT_CANNOT_BE_READ, e);
         }
         PDFASUtils.checkDocumentPermissions(doc);
   
         SignaturePlaceholderExtractor extractor;
         try
         {
            extractor = new SignaturePlaceholderExtractor(placeholderId, matchMode);
         } catch (IOException e2) {
            throw new PDFDocumentException(ErrorCode.DOCUMENT_CANNOT_BE_READ, e2);
         }
         List pages = doc.getDocumentCatalog().getAllPages();
         Iterator iter = pages.iterator();
         int pageNr = 0;
         while (iter.hasNext()) {
            pageNr++;
            PDPage page = (PDPage) iter.next();
            try {
               extractor.setCurrentPage(pageNr);
               extractor.processStream( page, page.findResources(), page.getContents().getStream() );
               SignaturePlaceholderData ret = matchPlaceholderPage(extractor.placeholders, placeholderId, matchMode);
               if (ret != null){
            	   SignaturePlaceholderContext.setSignaturePlaceholderData(ret);
                  return ret;
               }
            } catch (IOException e1) {
               throw new PDFDocumentException(ErrorCode.DOCUMENT_CANNOT_BE_READ, e1);
            }
   
         }
         if (extractor.placeholders.size() > 0){
            SignaturePlaceholderData ret = matchPlaceholderDocument(extractor.placeholders, placeholderId, matchMode);
            SignaturePlaceholderContext.setSignaturePlaceholderData(ret);
            return ret;
         }
         // no placeholders found, apply strict mode if set
         if (matchMode == Constants.PLACEHOLDER_MATCH_MODE_STRICT) {
            throw new PlaceholderExtractionException(ErrorCode.SIGNATURE_PLACEHOLDER_EXTRACTION_FAILED, "no suitable placeholder found and STRICT matching mode requested.");
         }
         
         return null;
      } finally {
         if (doc != null)
            try {
               doc.close();
            } catch (IOException e) {
               log.debug("Could not close document.", e);
            }
      }

   }
   
   private static SignaturePlaceholderData matchPlaceholderDocument(
         List placeholders, String placeholderId, int matchMode) throws PlaceholderExtractionException {
      
      if (matchMode == Constants.PLACEHOLDER_MATCH_MODE_STRICT)
         throw new PlaceholderExtractionException(ErrorCode.SIGNATURE_PLACEHOLDER_EXTRACTION_FAILED, "no suitable placeholder found and STRICT matching mode requested.");
      
      if (placeholders.size() == 0)
         return null;
      
      for (int i = 0; i < placeholders.size(); i++)
      {
         SignaturePlaceholderData spd = (SignaturePlaceholderData)placeholders.get(i);
         if (spd.getId() == null)
            return spd;
      }
      
      if (matchMode == Constants.PLACEHOLDER_MATCH_MODE_LENIENT)
         return (SignaturePlaceholderData)placeholders.get(0);

      return null;
   }

   private static SignaturePlaceholderData matchPlaceholderPage(List placeholders,
         String placeholderId, int matchMode) {
      if (placeholders.size() == 0)
         return null;
      for (int i = 0; i < placeholders.size(); i++)
      {
         SignaturePlaceholderData data = (SignaturePlaceholderData)placeholders.get(i);
         if (placeholderId != null && placeholderId.equals(data.getId()))
            return data;
         if (placeholderId == null && data.getId() == null)
            return data;
      }
      return null;
   }

   private void setCurrentPage(int pageNr) {
      this.currentPage = pageNr;
   }

   protected void processOperator( PDFOperator operator, List arguments ) throws IOException
   {
       String operation = operator.getOperation();
       if( operation.equals( "Do" ) )
       {
           COSName objectName = (COSName)arguments.get( 0 );
           Map xobjects = getResources().getXObjects();
           PDXObject xobject = (PDXObject)xobjects.get( objectName.getName() );
           if( xobject instanceof PDXObjectImage )
           {
               try
               {
                   PDXObjectImage image = (PDXObjectImage)xobject;
                   SignaturePlaceholderData data = checkImage(image);
                   if (data != null)
                   {
                      PDPage page = getCurrentPage();
                      Matrix ctm = getGraphicsState().getCurrentTransformationMatrix();
                      double rotationInRadians = (page.findRotation() * Math.PI)/180;
   
                      AffineTransform rotation = new AffineTransform();
                      rotation.setToRotation( rotationInRadians );
                      AffineTransform rotationInverse = rotation.createInverse();
                      Matrix rotationInverseMatrix = new Matrix();
                      rotationInverseMatrix.setFromAffineTransform( rotationInverse );
                      Matrix rotationMatrix = new Matrix();
                      rotationMatrix.setFromAffineTransform( rotation );
   
                      Matrix unrotatedCTM = ctm.multiply( rotationInverseMatrix );
   
                      float x = unrotatedCTM.getXPosition();
                      float y = unrotatedCTM.getYPosition() + unrotatedCTM.getYScale();
                      float w = unrotatedCTM.getXScale();
                      
                      String posString = "p:" + currentPage + ";x:" + x + ";y:" + y + ";w:" + w;
                      try
                      {
                         data.setTablePos(new TablePos(posString));
                         data.setPlaceholderName(objectName.getName());
                         placeholders.add(data);
                      } catch (PDFDocumentException e) {
                         throw new WrappedIOException(e);
                      }
                   }
               }
               catch( NoninvertibleTransformException e )
               {
                   throw new WrappedIOException( e );
               }
           }
       }
       else
       {
           super.processOperator( operator, arguments );
       }
   }

   /**
    * Checks an image if it is a placeholder for a signature.
    * 
    * @param image
    * @return
    * @throws IOException
    */
   private SignaturePlaceholderData checkImage(PDXObjectImage image) throws IOException {
      BufferedImage bimg = image.getRGBImage();
      if (bimg == null) {
         String type = image.getSuffix();
         if (type != null) {
            type = type.toUpperCase() + " images";
         } else {
            type = "Image type";
         }
         log.info("Unable to extract image for QRCode analysis. " + type + " not supported. Add additional JAI Image filters to your classpath. Refer to https://jai.dev.java.net. Skipping image.");
         return null;
      }
      if(bimg.getHeight() < 10 || bimg.getWidth() < 10) {
         log.debug("Image too small for QRCode. Skipping image.");
         return null;
      }

      LuminanceSource source = new BufferedImageLuminanceSource(bimg);
      BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
      Result result;
      long before = System.currentTimeMillis();
      try {
         Hashtable hints = new Hashtable();
         Vector formats = new Vector();
         formats.add(BarcodeFormat.QR_CODE);
         hints.put(DecodeHintType.POSSIBLE_FORMATS, formats);
         result = new MultiFormatReader().decode(bitmap, hints);
         String text = result.getText();
         String profile = null;
         String type = null;
         String sigKey = null;
         String id = null;
         if (text != null) {
            if (text.startsWith(Constants.QR_PLACEHOLDER_IDENTIFIER)) {
               String[] data = text.split(";");
               if (data.length > 1) {
                  for (int i = 1; i < data.length; i++) {
                     String kvPair = data[i];
                     String[] kv = kvPair.split("=");
                     if (kv.length != 2) {
                        log.debug("Invalid parameter in placeholder data: " + kvPair);
                     } else {
                        if (kv[0].equalsIgnoreCase(SignaturePlaceholderData.ID_KEY)) {
                           id = kv[1];
                        } else if (kv[0].equalsIgnoreCase(SignaturePlaceholderData.PROFILE_KEY)) {
                           profile = kv[1];
                        } else if (kv[0]
                              .equalsIgnoreCase(SignaturePlaceholderData.SIG_KEY_KEY)) {
                           sigKey = kv[1];
                        } else if (kv[0]
                              .equalsIgnoreCase(SignaturePlaceholderData.TYPE_KEY)) {
                           type = kv[1];
                        }
                     }
                  }
               }
               return new SignaturePlaceholderData(profile, type, sigKey, id);
            } else {
               log.warn("QR-Code found but does not start with \"" + Constants.QR_PLACEHOLDER_IDENTIFIER + "\". Ignoring QR placeholder.");
            }
         }
      } catch (ReaderException re) {
         if (log.isDebugEnabled()) {
            log.debug("Could not decode - not a placeholder. needed: "
                  + (System.currentTimeMillis() - before));
         }
         if (!(re instanceof NotFoundException)){
            if (log.isInfoEnabled()) {
               log.info("Failed to decode image", re);
            }
         }
      } catch(ArrayIndexOutOfBoundsException e){
         if (log.isInfoEnabled()) {
            log.info("Failed to decode image. Probably a zxing bug", e);
         }
      }
      return null;
   }

}