/**
 * <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.web.servlets;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import at.gv.egiz.pdfas.web.FormFields;
import at.gv.egiz.pdfas.web.PDFContainer;
import at.gv.egiz.pdfas.web.servlets.SignServlet;
import at.gv.egiz.pdfas.web.helper.SignServletHelper;
import at.gv.egiz.pdfas.web.session.SessionAttributes;
import at.gv.egiz.pdfas.web.session.SignSessionInformation;
import at.knowcenter.wag.egov.egiz.exceptions.PresentableException;

public class ProvidePDFServlet extends HttpServlet {

   /**
    * SVUID.
    */
   private static final long serialVersionUID = 1L;

   /**
    * The log.
    */
   private static Log log = LogFactory.getLog(ProvidePDFServlet.class);

   public static Set signedDocuments = Collections.synchronizedSet(new HashSet());

   public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      
      String pdfIdString = request.getParameter(FormFields.FIELD_PDF_ID);
      String plainPDFDigest = request.getParameter(FormFields.FIELD_ORIGINAL_DIGEST);
      
      HttpSession session = request.getSession();
      
      if (pdfIdString == null) {
         log.debug("No " + FormFields.FIELD_PDF_ID + " provided. Trying to retrieve PDF from session (" + session.getId() + ").");
         SignSessionInformation si = (SignSessionInformation) session.getAttribute(SessionAttributes.SIGNED_PDF_DOCUMENT);
         if (si == null) {
            log.warn("Unable to find signed pdf in session (" + session.getId() + ").");
            SignServlet.prepareDispatchToErrorPage(new PresentableException(600, "Das signierte Dokument konnte nicht gefunden werden."), request);
            response.setContentType("text/html");
            response.setCharacterEncoding("UTF-8");
            RequestDispatcher disp = super.getServletContext().getRequestDispatcher("/jsp/error.jsp");
            disp.forward(request, response);
            return;
         } else {
            log.debug("Signed pdf found.");
            // do NOT remove signed pdf document from session since IE9 loads this page/servlet twice...)
            // Popup-Blocker, Link-Prefetching, IE 9 SmartScreen-Filter...???
            // session.removeAttribute(SessionAttributes.SIGNED_PDF_DOCUMENT);
            log.debug("Returning signed pdf to browser.");
            if(plainPDFDigest != null) {
        		if(!plainPDFDigest.equalsIgnoreCase(si.plainPDFDigest)) {
        			log.error("PDF Digests don't match!");
        			log.error("Requested digest: " + plainPDFDigest);
        			log.error("Saved digest: " + si.plainPDFDigest);
                    return;
        		}
        	}
            SignServletHelper.returnSignResponse(si, request, response);
            log.debug("Removing free text (if any) from session.");
            session.removeAttribute(UpdateFormServlet.UPLOADFORM_FREETEXT_KEY);
            return;
         }
      } else {
         long pdfId = Long.parseLong(pdfIdString);

         PDFContainer pdf = null;
         synchronized (signedDocuments) {
            Iterator it = signedDocuments.iterator();

            while (it.hasNext() && pdf == null) {
               PDFContainer current = (PDFContainer) it.next();
               if (current.id == pdfId) {
                  pdf = current;
                  signedDocuments.remove(current);
               }
            }
         }
         
         if (pdf != null && pdf.pdf != null) {
            try {
            	if(plainPDFDigest != null) {
            		if(!plainPDFDigest.equalsIgnoreCase(pdf.originalDigest)) {
            			log.error("PDF Digests don't match! 1");
            			log.error("Requested digest: " + plainPDFDigest);
            			log.error("Saved digest: " + pdf.originalDigest);
                        return;
            		}
            	}
               SignServletHelper.disableBrowserCacheForResponse(response);
               response.setContentType("application/pdf");
               response.setContentLength(pdf.pdf.length);
               //SignSessionInformation si = (SignSessionInformation)session.getAttribute(SessionAttributes.ATTRIBUTE_SESSION_INFORMATION);
               String filename = (String)session.getAttribute(SignServlet.SUBMITFORM_FILENAME_KEY);
               
               response.setHeader("Content-disposition", "attachment; filename=\""+filename+"\"");
               
               InputStream is = new ByteArrayInputStream(pdf.pdf);
               final int bufferSize = 1024;
               byte[] buffer = new byte[bufferSize];
               int len = -1;
               while ((len = is.read(buffer)) != -1) {
            	  response.getOutputStream().write(buffer, 0, len);
               }
               response.getOutputStream().flush();
               log.debug("File sent. Invalidating session.");
               session.invalidate();
            } catch (IOException e) {
               log.error("IO excepton while providing pdf document: " + e.getMessage(), e);
            }
         } else {
            log.error("Unable to find signed pdf (id=" + pdfId + ") in session (" + session.getId() + ").");
            return;
         }
         
      }

   }

   public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      doPost(request, response);
   }

}