/**
 * 
 */
package at.knowcenter.wag.egov.egiz.web.servlets;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;

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

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import at.gv.egiz.pdfas.exceptions.framework.SignatorException;
import at.gv.egiz.pdfas.framework.SignatorFactory;
import at.gv.egiz.pdfas.framework.signator.Signator;
import at.gv.egiz.pdfas.web.SignSessionInformation;
import at.gv.egiz.pdfas.web.VerifySessionInformation;
import at.gv.egiz.pdfas.web.helper.SessionHelper;
import at.gv.egiz.pdfas.web.helper.SignServletHelper;
import at.gv.egiz.pdfas.web.helper.SigningTimeHelper;
import at.gv.egiz.pdfas.web.helper.TempDirHelper;
import at.knowcenter.wag.egov.egiz.PdfASID;
import at.knowcenter.wag.egov.egiz.exceptions.ConnectorException;
import at.knowcenter.wag.egov.egiz.exceptions.InvalidIDException;
import at.knowcenter.wag.egov.egiz.exceptions.PresentableException;
import at.knowcenter.wag.egov.egiz.exceptions.SettingsException;
import at.knowcenter.wag.egov.egiz.exceptions.SignatorFactoryException;
import at.knowcenter.wag.egov.egiz.exceptions.SignatureException;
import at.knowcenter.wag.egov.egiz.pdf.SignatureHolder;
import at.knowcenter.wag.egov.egiz.sig.SignatureResponse;
import at.knowcenter.wag.egov.egiz.sig.connectors.ConnectorChooser;
import at.knowcenter.wag.egov.egiz.sig.connectors.LocalConnector;
import at.knowcenter.wag.egov.egiz.sig.connectors.bku.BKUHelper;
import at.knowcenter.wag.egov.egiz.sig.connectors.bku.BKUPostConnection;
import at.knowcenter.wag.egov.egiz.sig.signaturelayout.SignatureLayoutHandler;
import at.knowcenter.wag.egov.egiz.sig.signaturelayout.SignatureLayoutHandlerFactory;
import at.knowcenter.wag.egov.egiz.web.FormFields;
import at.knowcenter.wag.egov.egiz.web.LocalRequest;
import at.knowcenter.wag.egov.egiz.web.LocalRequestHelper;
import at.knowcenter.wag.egov.egiz.web.SessionAttributes;

/**
 * @author wprinz
 * 
 */
public class DataURLServlet extends HttpServlet
{

  /**
   * SVUID.
   */
  private static final long serialVersionUID = -5846618335843762752L;

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

  protected void dispatch(HttpServletRequest request,
      HttpServletResponse response, String resource) throws ServletException, IOException
  {
    dispatch(request, response, resource, getServletContext());
  }

  protected static void dispatch(HttpServletRequest request,
      HttpServletResponse response, String resource, ServletContext context) throws ServletException, IOException
  {
    response.setContentType("text/html");
    response.setCharacterEncoding("UTF-8");

    RequestDispatcher disp = context.getRequestDispatcher(resource);
    disp.forward(request, response);
  }

  protected void dispatchToResults(List results, HttpServletRequest request,
      HttpServletResponse response, String backToListURL) throws ServletException, IOException
  {
    request.setAttribute("results", results);
    request.setAttribute("btlurl", backToListURL);
    dispatch(request, response, "/jsp/results.jsp");
  }

  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     this.doPost(req, resp);
  }
  
  private static void temporaryRedirect(String redirectURL, HttpServletResponse response) throws IOException {
     String encodedRedirect = response.encodeRedirectURL(redirectURL);
     response.addHeader("Location", encodedRedirect);
     response.setContentType("text/xml");
     response.setStatus(HttpServletResponse.SC_TEMPORARY_REDIRECT);
     String nop = "<?xml version='1.0' encoding='UTF-8'?><NullOperationRequest xmlns='http://www.buergerkarte.at/namespaces/securitylayer/1.2#'/>";
     PrintWriter pw = response.getWriter();
     response.setCharacterEncoding("UTF-8");
     response.setContentLength(nop.getBytes("UTF-8").length);
     log.debug("Redirecting via NullOperationRequest to " + encodedRedirect + ".");
     pw.println(nop);
     pw.flush();
     pw.close();
  }

/**
   * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
   *      javax.servlet.http.HttpServletResponse)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
    log.debug("Data URL is accessed."); //$NON-NLS-1$

    try
    {
      Object sessionObject = SessionHelper.getSession(request);

      // obsolete since EncodingFilter is set in web.xml
      checkRequestCharacterEncoding(request);
      
      if (sessionObject instanceof SignSessionInformation)
      {
        SignSessionInformation si = (SignSessionInformation)sessionObject;
        processSign(request, response, si);
      }
      else
      {
        VerifySessionInformation si = (VerifySessionInformation) sessionObject;
        processVerify(request, response, si);
      }

    }
    catch (PresentableException e)
    {
      log.error(e.getMessage(), e);
      SignServlet.prepareDispatchToErrorPage(e, request);
      dispatch(request, response, "/jsp/error.jsp");
    }

    log.debug("DataURL access finished."); //$NON-NLS-1$
  }
  
  protected void checkRequestCharacterEncoding(HttpServletRequest request) throws UnsupportedEncodingException
  {
  if (request.getCharacterEncoding() == null || request.getCharacterEncoding().length() <= 0) //$NON-NLS-1$
  {
    log.info("The BKU didn't set a character encoding for the request."); //$NON-NLS-1$

    log.info("Manually setting character encoding to UTF-8"); //$NON-NLS-1$
    request.setCharacterEncoding("UTF-8"); //$NON-NLS-1$
  }
  }

  protected boolean isNullResponse(String xml_response)
  {
    return xml_response != null && xml_response.indexOf("NullOperationResponse") != -1;
  }
  
  private static String retrieveXMLResponse(HttpServletRequest request) throws ServletException {
     log.debug("Trying to fetch XMLResponse...");
     String xml_response = null;
     if (ServletFileUpload.isMultipartContent(request)) {
        log.debug("Response is multipart.");
        FileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);
        try {
          List items = upload.parseRequest(request);
          Iterator iter = items.iterator();
          while (iter.hasNext()) {
              FileItem item = (FileItem) iter.next();
               if (item.isFormField() && "XMLResponse".equals(item.getFieldName())) {
                  log.debug("XMLResponse part found.");
                  xml_response = item.getString();
                  break;
               }
          }
        } catch (FileUploadException e) {
           throw new ServletException(e);
        }
     } else {
        xml_response = request.getParameter("XMLResponse");
     }
     log.debug("XMLResponse = " + xml_response);
     return xml_response;
  }
  
  protected void processSign(HttpServletRequest request, HttpServletResponse response, SignSessionInformation si) throws ServletException, IOException, ConnectorException, SignatorException, SignatorFactoryException, SignatureException
  {
    log.trace("processSign");
    
    String xml_response = retrieveXMLResponse(request);
    Properties response_properties = BKUHelper.getBKUProperties(request);

    String bkuIdentifier = BKUHelper.getBKUIdentifier(response_properties);
    log.debug("BKU identifier: \"" + bkuIdentifier + "\"");
    
    try {
       SignatureLayoutHandlerFactory.verifyBKUSupport(bkuIdentifier);
    } catch (SettingsException e) {
       throw new ConnectorException(e.getErrorCode(), e.getMessage());
    }
    
    if (isNullResponse(xml_response))
    {
      log.debug("Received a NullOperationResponse -> answering with the first request."); //$NON-NLS-1$
      
      assert si.outputAvailable == false;
      assert si.response_properties == null;
      
      log.debug("There are still requests to be performed -> answering with request."); //$NON-NLS-1$

      LocalRequest local_request = si.localRequest;

      String request_string = local_request.getRequestString();

      log.debug("request = " + request_string);
      response.setContentType("text/xml");
      response.setCharacterEncoding("UTF-8");
      response.getWriter().println(request_string);
    }
    else if (xml_response != null)
    {
      log.debug("Received a normal response -> storing the response."); //$NON-NLS-1$

      response_properties.setProperty(BKUPostConnection.RESPONSE_STRING_KEY, xml_response);
      
      si.response_properties = response_properties;
      
      log.debug("All requests have been processed -> processing the responses."); //$NON-NLS-1$

      // Sign
      
      if (!si.outputAvailable)
      {
        LocalConnector c = ConnectorChooser.chooseLocalConnectorForSign(si.connector, si.type, "loc ref content not needed here"); //$NON-NLS-1$

        si.si.setSignSignatureObject(c.analyzeSignResponse(si.response_properties));

        // workaround for invalid signing time
        SigningTimeHelper.checkSigningTimeAgainstHostTime(si.si);

        PdfASID algorithm = FormFields.translateSignatureModeToPdfASID(si.mode);
        Signator signator = SignatorFactory.createSignator(algorithm);

        si.output = TempDirHelper.createTempDataSink(si.filename + "_signed.pdf"); 

        signator.finishSign(si.si, si.output);
        
        si.outputAvailable = true;
      }

      if (si.output.getMimeType().equals("text/xml") && si.outputAvailable)
      {
        // For "detached" signatures, the return value (data sink) is the response xml,
        // but when passed through the BKU it is interpreted as another request
        // which will generate a return code 1501
        // Then PDF-AS would answer with the response as well generating
        // another 1501 and so forth.
        // Therefor return it as TXT.
        response.setContentType("text/plain");
        response.setCharacterEncoding("UTF-8");
        response.getWriter().println("Das detached XML kann nicht direkt durch die BKU geschliffen werden, weil diese es als Request interpretieren würde. Daher das XML als Text:");
        response.getWriter().println(si.si.getSignSignatureObject().response_properties.getProperty(BKUPostConnection.RESPONSE_STRING_KEY));
      }
      else
      {
         // tzefferer: If PDF-AS has been called by an external web-application, we do not 
         //            redirect to download.jsp but return the sign-response immediately
         if (si.exappinf != null) {
            log.debug("Entering external application interface mode. Skipping redirection to download page.");
            SignServletHelper.returnSignResponse(si, request, response);
            
            // Not needed due to redirection of returnSignResponse.
            // Just to clarify that there must not be any code after returnSignResponse.
            return;
         } else {
            log.debug("Preparing download page.");
            HttpSession session = request.getSession(true);
            log.debug("Putting signed document into session (" + session.getId() + ").");
            session.setAttribute(SessionAttributes.SIGNED_PDF_DOCUMENT, si);
            String downloadURL = response.encodeRedirectURL(LocalRequestHelper.getLocalContextAddress(request, response) + "/ProvidePDF");
            log.debug("Creating download URL \"" + downloadURL + "\".");
            session.setAttribute(SessionAttributes.DOWNLOAD_URL_FOR_SIGNED_PDF_DOCUMENT, downloadURL);
            Cookie cookie = new Cookie("JSESSIONID", session.getId());
            response.addCookie(cookie);
            temporaryRedirect(response.encodeRedirectURL(LocalRequestHelper.getLocalContextAddress(request, response) + "/jsp/download.jsp") , response);

            // Not needed due to temporaryRedirect.
            // Just to clarify that there must not be any code after temporaryRedirect.
            return;
         }
         
         // do not insert any code within this else block !
      }
    } else {
        log.debug("No XMLResponse found. Do nothing.");
     }
  }
  
  protected void processVerify(HttpServletRequest request, HttpServletResponse response, VerifySessionInformation si) throws ServletException, IOException, ConnectorException, InvalidIDException
  {
    log.trace("processVerify");
    
    String xml_response = request.getParameter("XMLResponse"); //$NON-NLS-1$
    log.debug("xml_response = " + xml_response); //$NON-NLS-1$

    if (isNullResponse(xml_response))
    {
      log.debug("Received a NullOperationResponse -> answering with the first request."); //$NON-NLS-1$

      assert si.currentLocalOperation.current_operation == 0;
    }
    else
    {
      log.debug("Recieved a normal response -> storing the response."); //$NON-NLS-1$

      Properties response_properties = new Properties();
      response_properties.setProperty(BKUPostConnection.RESPONSE_STRING_KEY, xml_response);

      si.currentLocalOperation.finishCurrentOperation(response_properties);
    }

    if (!si.currentLocalOperation.isFinished())
    {
      log.debug("There are still requests to be performed -> answering with request #" + si.currentLocalOperation.current_operation); //$NON-NLS-1$

      LocalRequest local_request = si.currentLocalOperation.getCurrentLocalRequest();

      String request_string = local_request.getRequestString();

      response.setContentType("text/xml");
      response.setCharacterEncoding("UTF-8");
      response.getWriter().println(request_string);
    }
    else
    {
      log.debug("All requests have been processed -> processing the responses."); //$NON-NLS-1$

        
        List results = new ArrayList();

        for (int i = 0; i < si.currentLocalOperation.response_properties.length; i++)
        {
          SignatureHolder sh = (SignatureHolder) si.currentLocalOperation.holders_to_be_verified.get(i);
          
          PdfASID sig_kz = sh.getSignatureObject().getKZ();
          String sig_id = sh.getSignatureObject().getSignationIds();
          
          LocalConnector c = ConnectorChooser.chooseLocalConnectorForVerify(si.connector, sig_kz, sig_id, si.type, "loc ref content not needed here"); //$NON-NLS-1$

          SignatureResponse sig_resp = c.analyzeVerifyResponse(si.currentLocalOperation.response_properties[i]);
          results.add(sig_resp);
        }
        
        si.currentLocalOperation = null;

        URL btlURL = new URL(LocalRequestHelper.getLocalContextAddress(request, response) + "/jsp/verifylist.jsp");
        String backToListURL = response.encodeURL(btlURL.toString());

        dispatchToResults(results, request, response, backToListURL);
    }

  }
}