/**
 * 
 */
package at.gv.egiz.pdfas.web.helper;

import java.io.FileInputStream;
import java.io.IOException;
import java.net.URL;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
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.api.commons.Constants;
import at.gv.egiz.pdfas.framework.SignatorFactory;
import at.gv.egiz.pdfas.framework.signator.Signator;
import at.gv.egiz.pdfas.impl.output.ByteArrayDataSink;
import at.gv.egiz.pdfas.impl.output.FileBasedDataSink;
import at.gv.egiz.pdfas.utils.WebUtils;
import at.gv.egiz.pdfas.web.SignSessionInformation;
import at.knowcenter.wag.egov.egiz.PdfASID;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;
import at.knowcenter.wag.egov.egiz.exceptions.PresentableException;
import at.knowcenter.wag.egov.egiz.framework.signators.DetachedSignator_1_0_0;
import at.knowcenter.wag.egov.egiz.sig.ConnectorFactory;
import at.knowcenter.wag.egov.egiz.sig.connectors.Connector;
import at.knowcenter.wag.egov.egiz.sig.connectors.ConnectorChooser;
import at.knowcenter.wag.egov.egiz.sig.connectors.bku.SignSignatureObject;
import at.knowcenter.wag.egov.egiz.web.FormFields;
import at.knowcenter.wag.egov.egiz.web.LocalRequestHelper;
import at.knowcenter.wag.egov.egiz.web.PDFContainer;
import at.knowcenter.wag.egov.egiz.web.SessionAttributes;
import at.knowcenter.wag.egov.egiz.web.servlets.ProvidePDFServlet;

/**
 * @author wprinz
 *
 */
public class SignServletHelper
{
  /**
   * The log.
   */
  private static Log log = LogFactory.getLog(SignServletHelper.class);

  public 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);
  }


  /**
   * Prepares the sign.
   * 
   * <p>
   * This prepares the data for both being signed or being previewed.
   * </p>
   * 
   * @param si
   *          The SessionInformation to be prepared.
   * @throws PresentableException
   *           f.e.
   */
  public static void prepareSign(SignSessionInformation si) throws PresentableException
  {
    log.debug("prepareSign:"); //$NON-NLS-1$

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

    // tzefferer: modified
    // si.iui = signator.prepareSign(si.pdf, si.type, null,
    // ConnectorFactory.needsSIG_ID(si.connector));
    si.si = signator.prepareSign(si.pdfDataSource, si.type, si.pos, null);
    // end modify
    log.debug("prepareSign finished."); //$NON-NLS-1$
  }
  
  /**
   * Finishes the sign.
   * 
   * <p>
   * For non local connectors this concludes the sign process, signs the
   * document and returns the result. For local connectors this initializes the
   * local sign process and redirects to following servlets.
   * </p>
   * 
   * @param si
   *          The SessionInformation.
   * @param request
   *          The servlet request for dispatching.
   * @param response
   *          The servlet response for dispatching.
   * @param context
   *          The servlet context for dispatching.
   * @throws PresentableException
   *           f.e.
   * @throws IOException
   *           f. e.
   * @throws ServletException
   *           f. e.
   */
  public static void finishSign(SignSessionInformation si, HttpServletRequest request, HttpServletResponse response, ServletContext context) throws PresentableException, IOException, ServletException
  {
    log.debug("finishSign:"); //$NON-NLS-1$

    // check if document is empty
    if (si.si.getSignatureData() == null || si.si.getSignatureData().getDataSource().getLength() == 0) {
       throw new PDFDocumentException(251, "Unable to extract and textual content.");
    }
    
    log.debug("connector = " + si.connector); //$NON-NLS-1$
    if (ConnectorFactory.isConnectorLocal(si.connector))
    {
      log.debug("Connector is local -> dispatching to local processing."); //$NON-NLS-1$

      String dispatch_to = LocalRequestHelper.processLocalSign(si, request, response);
      dispatch(request, response, dispatch_to, context);
      return;
    }
    log.debug("Connector is not local -> finishing the sign."); //$NON-NLS-1$

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

    log.debug("RequestURL = " + request.getRequestURL());
    log.debug("ContextPath = " + request.getContextPath());
    String host = request.getServerName();
    
    // TODO TR: Web-Applikation verwendet in Loc-Ref-Variante ext. Referenz, um performanter zu sein;
    // nachfolend auskommentieren, wenn anstatt SwA-Connector LocRef-Connector verwendet wird
//    URL signature_data_URL = new URL(WebUtils.addJSessionID(LocalRequestHelper.getLocalContextAddress(request, response) + "/RetrieveSignatureData", request));
    URL signature_data_URL = new URL(WebUtils.buildRetrieveSignatureDataURL(request, response));
    String signature_data_url = response.encodeURL(signature_data_URL.toString());

    Connector c = ConnectorChooser.chooseWebConnectorForSign(si.connector, si.type, signature_data_url);
    SignSignatureObject signSignatureObject = c.doSign(si.si.getSignatureData());
    
    si.si.setSignSignatureObject(signSignatureObject);

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

    returnSignResponse(si, request, response);
    log.debug("finishSign finished."); //$NON-NLS-1$
    
  }
  
  /**
   * Returns the data in the SignResult with proper content disposition.
   * 
   * @param si
   *          SessionInformation.
   * @parem request The servlet request.
   * @param response
   *          The servlet response.
   * @throws IOException
   *           The IO Exception.
   */
  public static void returnSignResponse(SignSessionInformation si, HttpServletRequest request, HttpServletResponse response) throws IOException
  {
//    SignResult sign_result = si.sign_result;

    String file_name = formatFileNameForSignResult(si.filename, si.output.getMimeType());

    // tzefferer: added condition
    if (si.exappinf == null)
    {

      // The name parameter is actually deprecated in favour of
      // Content-Disposition filename
      // Unfortunately Acrobat reader does recognize neither of these parameters
      // with its inline save-as. It always takes the page name.
      response.setContentType(si.output.getMimeType() + "; name=\"" + file_name + "\"");
      if (si.download_inline)
      {
        response.addHeader("Content-Disposition", "inline; filename=\"" + file_name + "\"");
      }
      else
      {
        response.addHeader("Content-Disposition", "attachment; filename=\"" + file_name + "\"");
      }
      
      TempDirHelper.writeDataSinkToHttpResponse(si.output, response);
      //response.getOutputStream().write(sign_result.getData());
      
      // tzefferer: added else-block
    }
    else
    {
      /**
       * The following code handles an external invocation of pdf-as. External invocation is done by
       * redirecting the user to the Sign-Servlet using the parameters defined in class
       * at.knowcenter.wag.egov.egiz.web.FormFields.
       * e.g. http://localhost:48080/pdf-as/Sign?preview=false&connector=bku&mode=textual&sig_type=SIGNATURBLOCK_DE&inline=false&filename=test.pdf&num-bytes=45916&pdf-url=http%3A%2F%2Flocalhost%3A8080%2Fmyapp%2FProvidePDF&pdf-id=1956507909008215134&invoke-app-url=https%3A%2F%2Flocalhost%3A8443%2Fmyapp%2FReturnSignedPDF&invoke-app-error-url=https%3A%2F%2Flocalhost%3A8443%2Fmyapp%2Fpdfaserror.do&session-id=9085B85B364BEC31E7D38047FE54577D&locale=de
       */
       log.debug("External webapp invocation detected.");
      byte [] signed_pdf = null;
      if (si.output instanceof FileBasedDataSink)
      {
        FileBasedDataSink fbds = (FileBasedDataSink)si.output;
        signed_pdf = new byte [(int)fbds.getFile().length()];
        FileInputStream fis = new FileInputStream(fbds.getFile());
        fis.read(signed_pdf);
        fis.close();
      }
      else
      {
        ByteArrayDataSink bads = (ByteArrayDataSink)si.output;
        signed_pdf = bads.getByteArray();
      }
      HttpSession session = request.getSession();
      
      PDFContainer entry = new PDFContainer(signed_pdf, si.exappinf.pdf_id);
      ProvidePDFServlet.signedDocuments.add(entry);

      // notify webapp...
      String invoke_url = si.exappinf.invoke_url;

      String providePDFServlet = "ProvidePDF";
      String pdf_id = String.valueOf(si.exappinf.pdf_id);
      String session_id = si.exappinf.session_id;

      log.debug("External application has to be notified. Building url from callback url \"" + invoke_url + "\".");
      
      // build URL
      int ind = invoke_url.indexOf("?");
      
      // fixed by tknall: must not presume that invoke_url contains "?"
      String sep = "&";
      if (ind == -1) {
      	ind = invoke_url.length();
      	sep = "?";
      }
      	
      String query = invoke_url.substring(0, ind) + ";jsessionid=" + session_id + invoke_url.substring(ind)
      	+ sep + FormFields.FIELD_PDF_URL + "=" + providePDFServlet + "&" + FormFields.FIELD_PDF_ID
         + "=" + pdf_id + "&" + FormFields.FIELD_FILE_LENGTH + "=" + signed_pdf.length
         + "&" + FormFields.FIELD_PDFAS_SESSION_ID + "=" + session.getId();

      /*
       *  Using the external web-interface of pdf-as (as described above) pdf-as should be run within
       *  an iframe. In case of a signature performed with a local citizen card software or with the
       *  server bku the result has to be provided outside the iframe. To break out of the iframe a
       *  helper jsp (redirect_to_parent) has to be used that redirects the user to the parent
       *  window.
       */
      disableBrowserCacheForResponse(response);
      if (Constants.SIGNATURE_DEVICE_BKU.equals(si.connector) || Constants.SIGNATURE_DEVICE_MOC.equals(si.connector)) {
         log.debug("Pdf-as is supposed to run within an iframe.");
         log.debug("Putting external application notify url (\"" + query + "\") in session (" + session.getId() + ") for later use.");
         session.setAttribute(SessionAttributes.PARENT_WEBAPP_REDIRECT_URL, query);
         String redirectHelper = response.encodeRedirectURL(request.getContextPath() + "/jsp/redirect_to_parent.jsp");
         
         log.debug("Redirecting to " + redirectHelper);
         log.debug("The browser will finally be redirected outside the iframe to " + query + " in order to notify the external application.");
         
         response.sendRedirect(redirectHelper);
         
      } else {
         log.debug("Notifying external application by redirecting to \"" + query + "\".");
         response.sendRedirect(query);
      }

    }

  }
  
  public static void disableBrowserCacheForResponse(HttpServletResponse response) {
     log.debug("Disabling browser cache for HttpServletResponse.");
     response.setHeader("Cache-Control", "no-cache");
     response.setHeader("Pragma","no-cache");
     response.setDateHeader("Expires", -1);
  }
  
  /**
   * Formats the file name according to the SignResult.
   * 
   * @param file_name
   *          The file name.
   * @param sign_result
   *          The sign result.
   * @return Returns the formatted file name.
   */
  public static String formatFileNameForSignResult(String file_name, String mimeType)
  {
    String output = file_name + "_signed";
    if (mimeType.equals(DetachedSignator_1_0_0.MIME_TYPE))
    {
      output += ".xml";
    }
    else
    {
      output += ".pdf";
    }

    return output;
  }
}