/*
 * <copyright> Copyright (c) 2006 by Know-Center, Graz, Austria </copyright>
 * 
 * This software is the confidential and proprietary information of Know-Center,
 * Graz, Austria. You shall not disclose such Confidential Information and shall
 * use it only in accordance with the terms of the license agreement you entered
 * into with Know-Center.
 * 
 * KNOW-CENTER MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
 * NON-INFRINGEMENT. KNOW-CENTER SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
 * LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES.
 * 
 * $Id: Verify.java,v 1.7 2006/10/11 07:39:13 wprinz Exp $
 */
package at.knowcenter.wag.egov.egiz.web.servlets;

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

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

import org.apache.commons.fileupload.FileItem;
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.ErrorCode;
import at.gv.egiz.pdfas.framework.config.SettingsHelper;
import at.gv.egiz.pdfas.framework.input.DataSource;
import at.gv.egiz.pdfas.framework.input.ExtractionStage;
import at.gv.egiz.pdfas.framework.input.PdfDataSource;
import at.gv.egiz.pdfas.framework.input.TextDataSource;
import at.gv.egiz.pdfas.framework.vfilter.VerificationFilterParameters;
import at.gv.egiz.pdfas.web.VerifySessionInformation;
import at.gv.egiz.pdfas.web.helper.TempDirHelper;
import at.knowcenter.wag.egov.egiz.PdfAS;
import at.knowcenter.wag.egov.egiz.cfg.SettingsReader;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;
import at.knowcenter.wag.egov.egiz.exceptions.PresentableException;
import at.knowcenter.wag.egov.egiz.exceptions.SettingNotFoundException;
import at.knowcenter.wag.egov.egiz.pdf.NoSignatureHolder;
import at.knowcenter.wag.egov.egiz.pdf.SignatureHolder;
import at.knowcenter.wag.egov.egiz.sig.ConnectorFactory;
import at.knowcenter.wag.egov.egiz.sig.SignatureResponse;
import at.knowcenter.wag.egov.egiz.web.FormFields;
import at.knowcenter.wag.egov.egiz.web.LocalRequestHelper;
import at.knowcenter.wag.egov.egiz.web.SessionAttributes;

/**
 * This method is the verify servlet for the pdf-as web application. It takes
 * get and post requests fill out jsp templates and give the user feedback about
 * the results of the verify process.
 * 
 * @author wlackner
 * @author wprinz
 */
public class VerifyServlet extends HttpServlet
{

  /**
   * SVUID.
   */
  private static final long serialVersionUID = 309198792358636766L;

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

  protected void dispatch(HttpServletRequest request, HttpServletResponse response, String resource) throws ServletException, IOException
  {
    response.setContentType("text/html"); //$NON-NLS-1$
    response.setCharacterEncoding("UTF-8"); //$NON-NLS-1$

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

  protected void dispatchToResults(List results, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
    request.setAttribute("results", results); //$NON-NLS-1$
    dispatch(request, response, "/jsp/results.jsp"); //$NON-NLS-1$
  }

  /**
   * Processes the verify upload.
   * 
   * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
   *      javax.servlet.http.HttpServletResponse)
   */
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
	    // for performance measurement
	    long startTime = 0; 
	    long fileSize = 0;
	    if (log.isInfoEnabled()) {
	    	startTime = System.currentTimeMillis();    	
	    }
    try
    {
      UploadedData ud = retrieveUploadedDataFromRequest(request);

      VerifySessionInformation si = new VerifySessionInformation();
      si.connector = ud.sig_app;
      si.application = "verify";
      si.mode = null;
      si.inputDataSource = ud.dataSource;
      si.type = null;
//      si.user_name = null;
//      si.user_password = null;

      // List signature_holders = extractSignatureHoldersFromFile(ud.file_name,
      // ud.file_data);
      List signature_holders = extractSignatureHolders(ud.dataSource);
      
      TempDirHelper.storeTextSignatureHoldersIfApplicable(signature_holders, "_textholder.utf8.txt");

      si.signature_holders = signature_holders;

      request.getSession().setAttribute(SessionAttributes.ATTRIBUTE_SESSION_INFORMATION, si);

      if (ud.preview)
      {
        dispatch(request, response, "/jsp/verifylist.jsp");
        // VerifyPreview.formatPreview(signature_holders, connector, request,
        // response);
      }
      else
      {
        if (ConnectorFactory.isConnectorLocal(si.connector))
        {
          String dispatch_to = LocalRequestHelper.processLocalVerify(si, si.signature_holders, request, response);

          dispatch(request, response, dispatch_to);
          return;
        }

        String host = request.getServerName();
        // TODO still required for old communication with MOA-SS/SP
        URL loc_ref_URL = new URL(LocalRequestHelper.getLocalContextAddress(request, response) + "/RetrieveSignatureData");
        String loc_ref_url = response.encodeURL(loc_ref_URL.toString());

        List results = PdfAS.verifySignatureHoldersWeb(signature_holders, si, loc_ref_url);
        dispatchToResults(results, request, response);
        
        // for performance measurement
        if (log.isInfoEnabled()) {
        	long endTime = System.currentTimeMillis();
        	String toReport = "VERIFY;"+ ud.file_name + ";"+ 0 + ";" + (endTime - startTime) + ";" + debugVerifyResults(results); 
        	log.info(toReport);
        }
        
      }

    }
    catch (FileUploadException e)
    {
      request.setAttribute("error", "Fehler beim Upload der Daten");
      request.setAttribute("cause", "Beim Upload der Daten ist ein Fehler aufgetreten.");
      dispatch(request, response, "/jsp/error_verify.jsp");
    }
    catch (PresentableException e)
    {
      log.error(e.getMessage(), e);
      SignServlet.prepareDispatchToErrorPage(e, request);
      dispatch(request, response, "/jsp/error_verify.jsp");
    }

  }

  protected UploadedData retrieveUploadedDataFromRequest(HttpServletRequest request) throws ServletException, UnsupportedEncodingException, FileUploadException, PDFDocumentException
  {
    DiskFileItemFactory fif = new DiskFileItemFactory();
    fif.setRepository(SettingsReader.getTemporaryDirectory());
    ServletFileUpload sfu = new ServletFileUpload(fif);

    List items = sfu.parseRequest(request);

    FileItem upload_fi = null;
    FileItem connector_fi = null;
    // FileItem mode_fi = null;
    FileItem preview_fi = null;
    
    String characterEncoding = request.getCharacterEncoding();
    log.debug("request character encoding = " + characterEncoding);

    {
      Iterator it = items.iterator();
      while (it.hasNext())
      {
        FileItem item = (FileItem) it.next();
        log.debug("item = " + item.getFieldName()); //$NON-NLS-1$

        if (item.isFormField())
        {
          String item_string = item.getString("UTF-8"); //$NON-NLS-1$
          log.debug("  form field string = " + item_string); //$NON-NLS-1$
        }
        else
        {
          log.debug("  filename = " + item.getName()); //$NON-NLS-1$
          log.debug("  filesize = " + item.getSize()); //$NON-NLS-1$
        }

        if (item.getFieldName().equals(FormFields.FIELD_UPLOAD))
        {
          upload_fi = item;
          continue;
        }

        if (item.getFieldName().equals(FormFields.FIELD_CONNECTOR))
        {
          connector_fi = item;
          continue;
        }

        // if (item.getFieldName().equals(FormFields.FIELD_MODE))
        // {
        // mode_fi = item;
        // continue;
        // }

        if (item.getFieldName().equals(FormFields.FIELD_PREVIEW))
        {
          preview_fi = item;
          continue;
        }

        throw new ServletException("unrecognized POST data."); //$NON-NLS-1$
      }
    }

    if (upload_fi == null || connector_fi == null || /* mode_fi == null || */preview_fi == null)
    {
      throw new ServletException("Unsufficient data provided in request."); //$NON-NLS-1$
    }

    String connector = connector_fi.getString("UTF-8"); //$NON-NLS-1$

    // String mode = mode_fi.getString("UTF-8");
    // if (!mode.equals(FormFields.VALUE_MODE_BINARY) &&
    // !mode.equals(FormFields.VALUE_MODE_TEXTUAL))
    // {
    // throw new ServletException("The mode '" + mode + "' is unrecognized.");
    // }

    String preview_str = preview_fi.getString("UTF-8"); //$NON-NLS-1$
    if (!preview_str.equals(FormFields.VALUE_TRUE) && !preview_str.equals(FormFields.VALUE_FALSE))
    {
      throw new ServletException("The preview '" + preview_str + "' is unrecognized."); //$NON-NLS-1$//$NON-NLS-2$
    }
    boolean preview = false;
    if (preview_str.equals(FormFields.VALUE_TRUE))
    {
      preview = true;
    }

    // process the request
    DataSource dataSource = convertUploadToDataSource(upload_fi);

    UploadedData ud = new UploadedData();
    ud.preview = preview;
    ud.sig_app = connector;
    ud.file_name = upload_fi.getName();
    ud.dataSource = dataSource;
    // ud.file_data = document_bytes;

    return ud;
  }

  protected DataSource convertUploadToDataSource(FileItem upload_fi) throws PDFDocumentException
  {
    log.debug("file content type =" + upload_fi.getContentType()); //$NON-NLS-1$
    log.debug("file size = " + upload_fi.getSize()); //$NON-NLS-1$
    if (upload_fi.getSize() <= 0)
    {
      throw new PDFDocumentException(250, "The document is empty."); //$NON-NLS-1$
    }


    // TR: do not check MIME-type of incoming file - might vary depending on the browser used
    if ((upload_fi.getContentType() != null ) && ((upload_fi.getContentType().startsWith("application/pdf") || upload_fi.getContentType().startsWith("application/x-download") )))
    {
      try
      {
        String fileNameSuffix = TempDirHelper.extractFileNameSuffix(upload_fi.getName());
        PdfDataSource pdfDataSource = TempDirHelper.placePdfIntoTempDir(upload_fi.getInputStream(), fileNameSuffix);
        return pdfDataSource;
      }
      catch (IOException e)
      {
        throw new PDFDocumentException(201, "The document could not be placed in the temp dir.", e); //$NON-NLS-1$
      }
      // byte[] document_bytes = upload_fi.get();
    }

    try
    {
      String fileNameSuffix = TempDirHelper.extractFileNameSuffix(upload_fi.getName());
      String text = new String(upload_fi.get(), "UTF-8"); //$NON-NLS-1$
      TextDataSource textDataSource = TempDirHelper.placeTextIntoTempDir(text, fileNameSuffix);
      return textDataSource;
    }
    catch (IOException e)
    {
      throw new PDFDocumentException(201, e);
    }
  }

  protected List extractSignatureHolders(DataSource dataSource) throws PresentableException
  {
    VerificationFilterParameters parameters = SettingsHelper.readVerificationFilterParametersFromSettings();

    ExtractionStage es = new ExtractionStage();
    List signature_holders = es.extractSignatureHolders(dataSource, parameters);

    // filter out NoSignatureHolders that are possibly present due to the direct call method extractSignatureHolders() 
    List filtered_signature_holders = new ArrayList();
    Iterator it = signature_holders.iterator();
    while(it.hasNext()) {
      SignatureHolder current = (SignatureHolder) it.next();
      if(!(current instanceof NoSignatureHolder)) {
        filtered_signature_holders.add(current);
      }
    }
    
    if (filtered_signature_holders.size() == 0)
    {
      throw new PDFDocumentException(ErrorCode.DOCUMENT_NOT_SIGNED, "PDF document not signed."); //$NON-NLS-1$
    }

    return filtered_signature_holders;
  }

  // TODO obsolete method - remove
  // protected List extractSignatureHoldersFromFile(String file_name, byte[]
  // data) throws UnsupportedEncodingException, PresentableException
  // {
  // VerificationFilterParameters parameters = new
  // VerificationFilterParametersImpl(false, false, true);
  // ExtractionStage es = new ExtractionStage();
  // // VerificationFilter vf = new VerificationFilter();
  // List signature_holders = null;
  //
  // String extension = extractExtension(file_name);
  //
  // String raw_text = null;
  // if (file_name == null || (extension != null && extension.equals("txt")))
  // //$NON-NLS-1$
  // {
  // raw_text = new String(data, "UTF-8"); //$NON-NLS-1$
  //
  // signature_holders = es.extractSignatureHolders(new
  // TextDataSourceImpl(raw_text), parameters);
  // // signature_holders = vf.extractSignaturesFromPlainText(raw_text);
  // }
  // else
  // {
  // signature_holders = es.extractSignatureHolders(new
  // ByteArrayPdfDataSourceImpl(data), parameters);
  //
  // // signature_holders = vf.extractSignaturesFromPdf(data);
  // }
  //
  // if (signature_holders.size() == 0)
  // {
  // throw new PDFDocumentException(206, "PDF document not signed.");
  // //$NON-NLS-1$
  // }
  //
  // return signature_holders;
  // }

  /**
   * Extracts the extension from a file name string.
   * 
   * <p>
   * The extension of a file name is whatever text follows the last '.'.
   * </p>
   * 
   * @param file_name
   *          The file name.
   * @return Returns the extension. If the file name ends with the '.', then an
   *         empty string is returned. If the file name doesn't contain any '.'
   *         or file_name is null, null is returned.
   */
  public static String extractExtension(String file_name)
  {
    if (file_name == null)
    {
      return null;
    }

    int dot_index = file_name.lastIndexOf('.');
    if (dot_index < 0)
    {
      return null;
    }
    return file_name.substring(dot_index + 1);
  }

  protected static class UploadedData
  {
    protected boolean preview = false;

    protected String sig_app = null;

    protected String file_name = null;

    protected DataSource dataSource = null;
    // protected byte[] file_data = null;
  }
  
  /**
   * Formats the verification results for debugging. Returns  0 if no error occurs or the sum of all error-codes.
   * 
   * @param results
   *         
   * @param writer
   *          The output sink to write the formatted text to.
   * @throws SettingNotFoundException
   *           Forwarded exception.
   */
  protected static int debugVerifyResults(List results) throws SettingNotFoundException
  {
	int toreturn = 0;
    Iterator it = results.iterator();
    while (it.hasNext())
    {
      SignatureResponse result = (SignatureResponse) it.next();
      
      toreturn += Integer.valueOf(result.getSignatureCheckCode()).intValue();
    }
    return toreturn;
  }
  
  public boolean isPDF(byte[] data) {
	   final byte[] PDF_MAGIC_NUMBER = { (byte) 0x25, (byte) 0x50, (byte) 
	0x44, (byte) 0x46 }; // %PDF
	   if (data == null || data.length < PDF_MAGIC_NUMBER.length) {
	     return false;
	   }
	   byte[] documentHeader = new byte[PDF_MAGIC_NUMBER.length];
	   System.arraycopy(data, 0, documentHeader, 0, documentHeader.length);
	   return Arrays.equals(documentHeader, PDF_MAGIC_NUMBER);
	}
 
  
}