/**
 * <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: BinarySignature.java,v 1.4 2006/10/11 07:57:58 wprinz Exp $
 */
package at.knowcenter.wag.egov.egiz.pdf;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateEncodingException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

import at.gv.egiz.pdfas.exceptions.ErrorCode;
import at.gv.egiz.pdfas.exceptions.pdf.KZSettingNotFoundException;
import at.gv.egiz.pdfas.framework.input.PdfDataSource;
import at.gv.egiz.pdfas.framework.output.DataSink;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;
import at.knowcenter.wag.egov.egiz.exceptions.PlaceholderException;
import at.knowcenter.wag.egov.egiz.exceptions.PresentableException;
import at.knowcenter.wag.egov.egiz.exceptions.SettingNotFoundException;
import at.knowcenter.wag.egov.egiz.sig.SignatureFieldDefinition;
import at.knowcenter.wag.egov.egiz.sig.SignatureTypes;
import at.knowcenter.wag.egov.egiz.tools.CodingHelper;
import at.knowcenter.wag.exactparser.ByteArrayUtils;

import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.PRStream;
import com.lowagie.text.pdf.PdfArray;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfDictionary;
import com.lowagie.text.pdf.PdfIndirectObject;
import com.lowagie.text.pdf.PdfIndirectReference;
import com.lowagie.text.pdf.PdfName;
import com.lowagie.text.pdf.PdfNumber;
import com.lowagie.text.pdf.PdfObject;
import com.lowagie.text.pdf.PdfPTable;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfStamper;
import com.lowagie.text.pdf.PdfStamperImp;
import com.lowagie.text.pdf.PdfString;
import com.lowagie.text.pdf.PdfTemplate;

/**
 * Contains various extension functions to digitally sign documents.
 * 
 * <p>
 * These functions are used to replace parts of the original Egiz plain text
 * signature mechanism.
 * </p>
 * 
 * @author wprinz
 */
public abstract class BinarySignature
{
  /**
   * The tolerance area of the line break algorithm.
   * 
   * @see Placeholder#replacePlaceholderWithTolerance(byte[], List, byte[], int)
   */
  public static final int LINE_BREAK_TOLERANCE = 10;

  /**
   * The number of bytes left out for the certificate placeholder.
   */
  public static final int CERTIFICATE_PLACEHOLDER_LENGTH = 10000;

  /**
   * The placeholder character used to fill out Strings in the layout process.
   */
  public static final byte LAYOUT_PLACEHOLDER = 'w';

  /**
   * This placeholder is used to fill out holes between the byte ranges before
   * the document is signed.
   */
  public static final byte SIGN_PLACEHOLDER = 0;

  /**
   * The nil brev used to define an unrecognized value.
   */
  public static final byte[] BREV_NIL = { 'n', 'i', 'l' };

  /**
   * The date brev.
   */
  public static final byte[] BREV_DAT = { 'd', 'a', 't' };

  /**
   * The issure brev.
   */
  public static final byte[] BREV_ISS = { 'i', 's', 's' };

  /**
   * The serial number brev.
   */
  public static final byte[] BREV_SNR = { 's', 'n', 'r' };

  /**
   * The value brev.
   */
  public static final byte[] BREV_VAL = { 'v', 'a', 'l' };

  /**
   * The SIG_ID brev.
   */
  public static final byte[] BREV_SID = { 's', 'i', 'd' };

  /**
   * No explicit encoding.
   */
  public static final byte[] ENCODING_NIL = { 'n', 'i', 'l' };

  /**
   * PDF WinAnsiEncoding.
   */
  public static final byte[] ENCODING_WIN = { 'w', 'i', 'n' };

  /**
   * URL encoding.
   */
  public static final byte[] ENCODING_URL = { 'u', 'r', 'l' };

  /**
   * The PDFName of the Egiz Dictionary.
   * 
   * <p>
   * Used to locate and identify the Egiz Dictionary in the document.
   * </p>
   */
  public static final PdfName EGIZ_DICT_NAME = new PdfName("EGIZSigDict");

  /**
   * The PDFName of the Original Document Size (ODS) field in an Egiz
   * Dictionary.
   * 
   * <p>
   * The ODS must be a positive integral number.
   * </p>
   */
  public static final PdfName EGIZ_ODS_NAME = new PdfName("ODS");

  /**
   * The PDFName of the Kennzeichnung attribute.
   */
  public static final PdfName EGIZ_KZ_NAME = new PdfName("ID");

  /**
   * The PDFName of the /replaces field in an Egiz Dictionary.
   */
  public static final PdfName EGIZ_REPLACES_NAME = new PdfName("replaces");

  /**
   * The PDFName of the /encodings field in an Egiz Dictionary.
   */
  public static final PdfName EGIZ_ENCODINGS_NAME = new PdfName("encodings");

  /**
   * The PDFName of the byte ranges array.
   */
  public static final PdfName EGIZ_BYTERANGES_NAME = new PdfName("ByteRange");

  /**
   * The PdfName of the certificate array.
   */
  public static final PdfName EGIZ_CERTIFICATE_NAME = new PdfName("Cert");

  /**
   * The PDFName of the Signature XObject field in an Egiz Dictionary.
   * 
   * <p>
   * This must be an indirect reference to the XObject containing the Signature
   * table.
   * </p>
   */
  public static final PdfName EGIZ_XOBJ_NAME = new PdfName("SigXObject");

  /**
   * The number placeholder that is used to give numbers a fixed length.
   */
  protected static final PdfNumber NUMBER_PLACEHOLDER = new PdfNumber(99999999);

  /**
   * Extracts the signature text only.
   * 
   * <p>
   * The signature text is the text of the Signature XObject.
   * </p>
   * 
   * @param egiz_dict
   *          The Egiz Dictionary.
   * 
   * @return Returns the signature text.
   */
  public static String extractSignatureTextOnly(PdfDictionary egiz_dict) throws IOException
  {
    PdfIndirectReference xobj_ir = (PdfIndirectReference) egiz_dict.get(EGIZ_XOBJ_NAME);
    PRStream temp_stream = (PRStream) PdfReader.getPdfObject(xobj_ir);

    byte[] stream_bytes = PdfReader.getStreamBytes(temp_stream);

    return Utils.extractPureTextFromContentStream(stream_bytes);
  }

  /**
   * Retrieves the size of the original document from the Egiz Dictionary.
   * 
   * @param egiz_dict
   *          The Egiz Dictionary.
   * @return Returns the size (in bytes) of the original document.
   */
  public static int getOriginalDocumentSizeFromEgizDict(PdfDictionary egiz_dict)
  {
    PdfObject ods_obj = egiz_dict.get(EGIZ_ODS_NAME);
    PdfNumber ods_number = (PdfNumber) PdfReader.getPdfObject(ods_obj);

    return ods_number.intValue();
  }

  /**
   * Retrieves the previous Egiz dictionary from the given one, if a previous
   * dictionary exists.
   * 
   * @param egiz_dict
   *          The Egiz Dictionary.
   * @return Returns the previous Egiz Dictionary, or null if there is none.
   */
  public static PdfDictionary getPreviousFromEgizDict(PdfDictionary egiz_dict)
  {
    PdfObject prev_obj = egiz_dict.get(PdfName.PREV);
    PdfDictionary previous_dict = (PdfDictionary) PdfReader.getPdfObject(prev_obj);
    return previous_dict;
  }

  /**
   * Retrieves the Egiz Dictionary from the document if present.
   * 
   * @param reader
   *          The reader to retrieve the dictionary from.
   * @return Returns the Egiz Dictionary, if present, or returns null, if no
   *         egiz dictionary was found.
   */
  public static PdfDictionary getEgizDictFromReader(PdfReader reader)
  {
    PdfIndirectReference dict_ir = getEgizDictIndRefFromReader(reader);
    if (dict_ir == null)
    {
      return null;
    }

    PdfDictionary egiz_dict = (PdfDictionary) PdfReader.getPdfObject(dict_ir);

    return egiz_dict;
  }

  /**
   * Retrieves the Egiz Dictionary's indirect reference from the reader.
   * 
   * @param reader
   *          The reader.
   * @return Returns the indirect reference of the Egiz Dictionary, or null, if
   *         none exists.
   */
  public static PdfIndirectReference getEgizDictIndRefFromReader(PdfReader reader)
  {
    PdfDictionary catalog = reader.getCatalog();
    PdfIndirectReference dict_ir = (PdfIndirectReference) catalog.get(EGIZ_DICT_NAME);
    return dict_ir;
  }

  /**
   * Retrieves the chain of Egiz Dictionaries from the reader.
   * 
   * <p>
   * The first element in the List will be the top most (oldest) Egiz
   * Dictionary. The last element in the List will be the bottom most (latest)
   * Egiz Dictionary. If the list is empty, no dictionary could be found at all,
   * which means that the document is not digitally signed.
   * </p>
   * 
   * @param reader
   *          The reader.
   * @return Returns the List of PdfDictionaries from the document.
   */
  public static List getEgizDictChainFromReader(PdfReader reader)
  {
    List dicts = new ArrayList();

    PdfDictionary current_dict = getEgizDictFromReader(reader);
    if (current_dict != null)
    {
      dicts.add(0, current_dict);

      while ((current_dict = getPreviousFromEgizDict(current_dict)) != null)
      {
        dicts.add(0, current_dict);
      }
    }

    return dicts;
  }

  /**
   * Builds a digest of the given data.
   * 
   * @param data
   *          The data to be digested.
   * @param length
   *          The length of the data portion that should be used for digesting.
   *          This allows to build the digest only over parts of the data.
   * @return Returns the created digest.
   * @throws PDFDocumentException
   *           Forwarded exception.
   */
  public static byte[] buildDigest(final byte[] data, final int length) throws PDFDocumentException
  {
    MessageDigest sha_512 = null;
    try
    {
      sha_512 = MessageDigest.getInstance("SHA-512");
    }
    catch (NoSuchAlgorithmException e)
    {
      e.printStackTrace();
      throw new PDFDocumentException(202, "Digest algorithm not supported - NoSuchAlgorithmException", e);
    }

    sha_512.reset();
    sha_512.update(data, 0, length);
    byte[] digest = sha_512.digest();

    return digest;
  }

  /**
   * Retrieves the signable text from the given document.
   * 
   * @param data
   *          The data.
   * @param ods
   *          The original document size.
   * @return Returns the signable text.
   */
  public static String retrieveSignableTextFromData(final byte[] data, final int ods)
  {
    // byte[] digest = buildDigest(data, ods);
    String raw_text = CodingHelper.encodeBase64(data);// digest); // data);

    return raw_text;
  }

  /**
   * Fills the holes in the byte ranges with the SIGN_PLACEHOLDER.
   * 
   * @param data
   *          The given byte ranged data.
   * @param byte_ranges
   *          The byte ranges.
   * @return Returns the filled text.
   */
  public static byte[] prepareDataToSign(final byte[] data, final List byte_ranges)
  {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    Iterator it = byte_ranges.iterator();
    int last_end = 0;
    while (it.hasNext())
    {
      StringInfo si = (StringInfo) it.next();

      for (int i = last_end; i < si.string_start; i++)
      {
        baos.write(SIGN_PLACEHOLDER);
      }

      baos.write(data, si.string_start, si.string_length);

      last_end = si.string_start + si.string_length;
    }
    byte[] data_to_sign = baos.toByteArray();

    return data_to_sign;
  }

  // TODO old code - remove
  //  /**
  //   * Extracts the binary 'text' of a document.
  //   * 
  //   * <p>
  //   * If the document contains an Egiz Dictionary, which means that it is already
  //   * signed, the binary text is the Base64 coded string of the original document
  //   * followed by the Ascii representation of the signature block.
  //   * </p>
  //   * <p>
  //   * If the document does not contain an Egiz Dictionary, which means that it is
  //   * unsigned, only the binary Base64 coded original document is returned as
  //   * binary text.
  //   * </p>
  //   * <p>
  //   * This function is intented for being used instead of the "text extraction"
  //   * mechanism used in the plain text Egiz project.
  //   * </p>
  //   * 
  //   * @param doc
  //   *          The file.
  //   * @return Returns the binary text of the document.
  //   * @throws PDFDocumentException
  //   *           Forwarded exception.
  //   */
  //  public static String extractTextBinary(File doc) throws PDFDocumentException
  //  {
  //    try
  //    {
  //      FileInputStream fis = new FileInputStream(doc);
  //      return extractTextBinary(fis);
  //    }
  //    catch (FileNotFoundException e)
  //    {
  //      throw new PDFDocumentException(202, e);
  //    }
  //  }
  //
  //  /**
  //   * Extracts the text binary.
  //   * 
  //   * @param is
  //   * @return Returns the binary text.
  //   * @throws PDFDocumentException
  //   */
  //  public static String extractTextBinary(InputStream is) throws PDFDocumentException
  //  {
  //    try
  //    {
  //      // for some stupid reason this produces a read error if the is comes from
  //      // a
  //      // multipart servlet form..???
  //      ByteArrayOutputStream baos = new ByteArrayOutputStream();
  //      int i = -1;
  //      int acc = 0;
  //      byte[] b = new byte[1000];
  //      while ((i = is.read(b)) > 0)
  //      {
  //        acc += i;
  //        System.out.print(" " + i);
  //        baos.write(b, 0, i);
  //      }
  //      System.out.println("acc = " + acc);
  //      byte[] pdf = baos.toByteArray();
  //
  //      return extractTextBinary(pdf);
  //    }
  //    catch (IOException e)
  //    {
  //      throw new PDFDocumentException(202, e);
  //    }
  //  }
  //
  //  /**
  //   * Extracts the signable text from a binary pdf document.
  //   * 
  //   * <p>
  //   * The signable text is the text that will be signed or verified afterwards.
  //   * </p>
  //   * 
  //   * @param pdf
  //   *          The pdf document.
  //   * @return Returns the extracted text String.
  //   * @throws PDFDocumentException
  //   *           Forwarded exception.
  //   */
  //  public static String extractTextBinary(final byte[] pdf) throws PDFDocumentException
  //  {
  //    try
  //    {
  //      PdfReader reader = new PdfReader(new ByteArrayInputStream(pdf));
  //      PdfDictionary egiz_dict = getEgizDictFromReader(reader);
  //      if (egiz_dict == null)
  //      {
  //        System.out.println("NO Egiz Dict found - whole doc = original doc");
  //
  //        int ods = pdf.length;
  //        return retrieveSignableTextFromData(pdf, ods);
  //      }
  //
  //      String sig_text = extractSignatureTextOnly(egiz_dict);
  //
  //      int ods = getOriginalDocumentSizeFromEgizDict(egiz_dict);
  //
  //      String raw_text = retrieveSignableTextFromData(pdf, ods);
  //      raw_text += "\n";
  //      raw_text += sig_text;
  //
  //      return raw_text;
  //    }
  //    catch (IOException e)
  //    {
  //      throw new PDFDocumentException(202, e);
  //    }
  //  }

  // TODO obsolete code - remove
  //  /**
  //   * Retrieves the List of SignatureHolders containing the information of all
  //   * digital signatures of the given document.
  //   * 
  //   * <p>
  //   * If the List of SignatureHolders is empty, the document is not signed
  //   * anyways.
  //   * </p>
  //   * 
  //   * @param pdf
  //   *          The complete pdf document.
  //   * @return Returns the List of SignatureHolders.
  //   * @throws PDFDocumentException
  //   * @throws SignatureTypesException
  //   * @throws SignatureException
  //   */
  //  public static List extractSignatureHoldersBinary(final byte[] pdf) throws PDFDocumentException, SignatureTypesException, SignatureException
  //  {
  //    try
  //    {
  //      PdfReader reader = new PdfReader(new ByteArrayInputStream(pdf));
  //      List chain = getEgizDictChainFromReader(reader);
  //
  //      List signatures = new ArrayList();
  //      Iterator it = chain.iterator();
  //      while (it.hasNext())
  //      {
  //        PdfDictionary dict = (PdfDictionary) it.next();
  //
  //        int ods = getOriginalDocumentSizeFromEgizDict(dict);
  //        String signature_text = extractSignatureTextOnly(dict);
  //
  //        SignatureTypes sig_types = SignatureTypes.getInstance();
  //        List types = sig_types.getSignatureTypeDefinitions();
  //        SignatureBlock sig_block = new SignatureBlock(types);
  //        boolean could_separate = sig_block.separateBlockFromRawText(signature_text, false);
  //
  //        if (could_separate)
  //        {
  //          SignatureObject sig_object = sig_block.getSignatureObject();
  //
  //          SignatureHolder holder = new BinarySignatureHolder(pdf, ods, sig_object);
  //          signatures.add(holder);
  //        }
  //      }
  //
  //      return signatures;
  //    }
  //    catch (IOException e)
  //    {
  //      throw new PDFDocumentException(201, e);
  //    }
  //  }

  // /**
  // * Signs a document with the given signature table using the Incremental
  // * Update method.
  // *
  // * <p>
  // * The table containing the signature text will be appended. As specified by
  // * the parameters, the signature will be appended to the last page, or a
  // plain
  // * new page will be created for the signature to hold.
  // * </p>
  // * <p>
  // * The table will be completely wrapped by an XObject, which will also be
  // * indirectly referenced by the Egiz Dictionary. This will ease the
  // * verification process.
  // * </p>
  // * <p>
  // * An Egiz Dictionary will be added to the new document that contains
  // * information about the signature. Basically the size of the original
  // * document and the reference of the signature table.
  // * </p>
  // *
  // * @param original_document
  // * The file name of the original document.
  // * @param new_document
  // * The file name of the new document to be created.
  // * @param pdf_table
  // * The PdfPTable that contains the signature block.
  // * @param pos_x
  // * The x position where the table should be inserted.
  // * @param pos_y
  // * The y position where the table should be inserted (on the last
  // * page). If this is negative, a new page will be appended to the
  // * document. Then the table will be inserted on that new page using
  // * the absolute value of pos_y. Note that pos_y specifies the top
  // * line of the table.
  // * @throws PresentableException
  // * Forwarded exception.
  // *
  // * @see #writeIncrementalUpdate(byte[], PdfPTable, float, float, boolean)
  // */
  // public static void writeIncrementalUpdate(String original_document,
  // String new_document, PdfPTable pdf_table, float pos_x, float pos_y,
  // int egiz_dict_num_replaces) throws PresentableException
  // {
  // try
  // {
  // File original_document_file = new File(original_document);
  // FileInputStream fis = new FileInputStream(original_document_file);
  // byte[] pdf = new byte[(int) original_document_file.length()];
  // fis.read(pdf);
  // fis.close();
  //
  // byte[] signed_pdf = writeIncrementalUpdate(pdf, pdf_table, pos_x, pos_y,
  // egiz_dict_num_replaces);
  //
  // File new_document_file = new File(new_document);
  // FileOutputStream fos = new FileOutputStream(new_document_file);
  // fos.write(signed_pdf);
  // fos.close();
  // }
  // catch (IOException e)
  // {
  // throw new PresentableException(e);
  // }
  // }

  /**
   * Signs a document with the given signature table using the Incremental
   * Update method.
   * 
   * <p>
   * The table containing the signature text will be appended. As specified by
   * the parameters, the signature will be appended to the last page, or a plain
   * new page will be created for the signature to hold.
   * </p>
   * <p>
   * The table will be completely wrapped by an XObject, which will also be
   * indirectly referenced by the Egiz Dictionary. This will ease the
   * verification process.
   * </p>
   * <p>
   * An Egiz Dictionary will be added to the new document that contains
   * information about the signature. Basically the size of the original
   * document and the reference of the signature table.
   * </p>
   * 
   * @param original_document
   *          The original document.
   * @param pdf_table
   *          The PdfPTable that contains the signature block.
   * @param pi
   *          The PositioningInstruction telling the algorithm where to place
   *          the signature block.
   * @return Returns the new document.
   * @throws PresentableException
   *           Forwarded exception.
   */
  public static IncrementalUpdateInformation writeIncrementalUpdate(PdfDataSource original_document, DataSink written_pdf, PdfPTable pdf_table, PositioningInstruction pi,
      List variable_field_definitions, List all_field_definitions) throws PresentableException
  {
    try
    {
      IncrementalUpdateInformation iui = new IncrementalUpdateInformation();
      iui.original_document = original_document;
      iui.start_index = original_document.getLength();

      Document.compress = false;

      // System.out.println("wprinz: STAMPING PDF");

      InputStream is = original_document.createInputStream();
      PdfReader reader = new PdfReader(is);
      is.close();

      OutputStream baos = written_pdf.createOutputStream("application/pdf");
      // ByteArrayOutputStream baos = new ByteArrayOutputStream();
      
      // IMPORTANT: append the new content to the original document using
      // incremental updated
      // The stamper allows this by setting append = true
      PdfStamper stamper = new PdfStamper(reader, baos, '\0', true);

      if (pi.isMakeNewPage())
      {
        int pdf_page_num = reader.getNumberOfPages();

        Rectangle psize = reader.getPageSizeWithRotation(pdf_page_num);
        Rectangle rect = new Rectangle(psize);
        stamper.insertPage(pdf_page_num + 1, rect);
      }

      if (pi.getPage() < 1 || pi.getPage() > stamper.getReader().getNumberOfPages())
      {
        throw new PDFDocumentException(224, "The provided page (=" + pi.getPage() + ") is out of range.");
      }
      PdfContentByte content = stamper.getOverContent(pi.getPage());
      // content = StampContent einer PageStamp.

      // System.out.println("table_width = " + pdf_table.getTotalWidth() + ",
      // table_height = " + pdf_table.getTotalHeight());

      PdfTemplate table_template = content.createTemplate(pdf_table.getTotalWidth(), pdf_table.getTotalHeight());

      pdf_table.writeSelectedRows(0, -1, 0, pdf_table.getTotalHeight(), table_template);

      // table_template.moveTo(0, 0);
      // table_template.lineTo(pdf_table.getTotalWidth(),
      // pdf_table.getTotalHeight());
      // table_template.stroke();
      // table_template.moveTo(0, 0);
      // table_template.lineTo(100, 100);
      // table_template.stroke();

      // pdf_table.writeSelectedRows(0, -1, SIGNATURE_BORDER / 2,
      // table_position, content);

      content.addTemplate(table_template, pi.getX(), pi.getY() - pdf_table.getTotalHeight());

      // For debugging print a 100x100 grid
      // {
      // Rectangle psize = reader.getPageSizeWithRotation(pos.page);
      // float page_width = psize.width();
      // float page_height = psize.height();
      // for (float x = 0; x < page_width; x += 100)
      // {
      // content.moveTo(x, 0);
      // content.lineTo(x, page_height);
      // content.stroke();
      // }
      // for (float y = 0; y < page_height; y += 100)
      // {
      // content.moveTo(0, y);
      // content.lineTo(page_width, y);
      // content.stroke();
      // }
      // }

      // content.setLineWidth(10.0f);
      // content.moveTo(0, 0);
      // content.lineTo(100, 100);
      // content.stroke();

      // PdfIndirectReference page_ref =
      // stamper.getWriter().getPageReference(signature_page);
      // System.out.println("page_ref = " + page_ref.toString());

      // PdfObject page_obj = PdfReader.getPdfObject(page_ref);
      // System.out.println("page_obj = " + page_obj);

      // PdfDictionary page_dict = (PdfDictionary) page_obj;
      // PdfObject resources_obj = page_dict.get(PdfName.RESOURCES);
      // System.out.println("resources_obj = " + resources_obj);
      // PdfDictionary resources = (PdfDictionary)
      // PdfReader.getPdfObject(resources_obj);
      // for (Iterator it = resources.getKeys().iterator(); it.hasNext();)
      // {
      // PdfName key = (PdfName) it.next();
      // PdfObject value = resources.get(key);
      // System.out.println(" " + key + " = " + value);
      // }

      // add the EGIZ dict:
      if (variable_field_definitions != null)
      {
        createEgizDict(stamper, table_template, iui, variable_field_definitions, all_field_definitions);
      }

      stamper.close();
      // System.out.println("wprinz: STAMPING FINISHED");

      // just to make sure the stream is really closed
      baos.close();
      // iui.signed_pdf = baos.toByteArray();

      return iui;
    }
    catch (IOException e)
    {
      e.printStackTrace();
      throw new PresentableException(ErrorCode.CANNOT_WRITE_PDF, e);
    }
    catch (DocumentException e)
    {
      e.printStackTrace();
      throw new PresentableException(ErrorCode.CANNOT_WRITE_PDF, e);
    }
  }

  /**
   * Creates the EGIZ Dictionary and adds it to the document.
   * 
   * @param stamper
   *          The PdfStamper.
   * @param table_template
   *          The Template of the Signature block.
   * @param iui
   *          The IncrementalUpdateInformation.
   * @param variable_field_definitions
   *          The field definitions.
   * @throws IOException
   * @throws SettingNotFoundException
   */
  protected static void createEgizDict(PdfStamper stamper, PdfTemplate table_template, IncrementalUpdateInformation iui, List variable_field_definitions, List all_field_definitions)
      throws IOException, SettingNotFoundException
  {
    // iui.temp_ir = table_template.getIndirectReference();
    iui.temp_ir_number = table_template.getIndirectReference().getNumber();
    iui.temp_ir_generation = table_template.getIndirectReference().getGeneration();

    byte[] content_stream = table_template.toPdf(null);
    iui.content_stream_length = content_stream.length;

    iui.replaces = determineReplacesInContentStream(content_stream, 0, content_stream.length, variable_field_definitions);
    iui.kz_list = determineKZ(content_stream, 0, content_stream.length, all_field_definitions);

    // PdfIndirectReference previous_egiz_dict_ind_ref =
    // getEgizDictIndRefFromReader(reader);

    PdfDictionary egiz_dict = new PdfDictionary(EGIZ_DICT_NAME);
    egiz_dict.put(EGIZ_XOBJ_NAME, table_template.getIndirectReference());
    egiz_dict.put(EGIZ_ODS_NAME, NUMBER_PLACEHOLDER);

    PdfArray kz_array = new PdfArray();
    for (int i = 0; i < iui.kz_list.size(); i++)
    {
      kz_array.add(NUMBER_PLACEHOLDER); // start
      kz_array.add(NUMBER_PLACEHOLDER); // length
    }
    egiz_dict.put(EGIZ_KZ_NAME, kz_array);

    int num_replaces = calcNumReps(iui.replaces);
    int num_holes = num_replaces + 1 + 1;
    // +1 = the /encodings hole
    // +1 = the /Cert
    int num_byte_ranges = num_holes + 1;

    PdfArray byte_ranges_array = new PdfArray();
    for (int i = 0; i < num_byte_ranges; i++)
    {
      byte_ranges_array.add(NUMBER_PLACEHOLDER); // start
      byte_ranges_array.add(NUMBER_PLACEHOLDER); // length
    }
    egiz_dict.put(EGIZ_BYTERANGES_NAME, byte_ranges_array);

    PdfArray encodings_array = new PdfArray();
    encodings_array.add(new PdfName(new String(ENCODING_NIL))); // the
    // /encodings
    encodings_array.add(new PdfName(new String(ENCODING_NIL))); // the /Cert

    // array itself
    PdfArray replaces_array = new PdfArray();
    replaces_array.add(new PdfName(new String(BREV_NIL, "US-ASCII"))); // the
    // /encodings
    replaces_array.add(new PdfName(new String(BREV_NIL, "US-ASCII"))); // the
    // /Cert

    Iterator it = iui.replaces.iterator();
    while (it.hasNext())
    {
      ReplaceInfo ri = (ReplaceInfo) it.next();
      for (int i = 0; i < ri.replaces.size(); i++)
      {
        byte[] brev = typeToBrev(ri.sfd.field_name);
        String brev_string = new String(brev, "US-ASCII");
        PdfName brev_name = new PdfName(brev_string);
        replaces_array.add(brev_name);

        encodings_array.add(new PdfName(new String(ENCODING_WIN, "US-ASCII")));
      }
    }
    egiz_dict.put(EGIZ_REPLACES_NAME, replaces_array);

    egiz_dict.put(EGIZ_ENCODINGS_NAME, encodings_array);

    PdfArray cert_array = new PdfArray();
    byte[] cert_bytes = new byte[CERTIFICATE_PLACEHOLDER_LENGTH];
    for (int i = 0; i < cert_bytes.length; i++)
    {
      cert_bytes[i] = 0;
    }
    PdfString cert_placeholder = new PdfString(cert_bytes);
    cert_array.add(cert_placeholder);
    egiz_dict.put(EGIZ_CERTIFICATE_NAME, cert_array);

    // if (previous_egiz_dict_ind_ref != null)
    // {
    // egiz_dict.put(PdfName.PREV, previous_egiz_dict_ind_ref);
    // }
    // no EGIZ chain

    PdfIndirectObject dict_ref = stamper.getWriter().addToBody(egiz_dict);
    // iui.egiz_dict_ir = dict_ref.getIndirectReference();
    iui.egiz_dict_ir_number = dict_ref.getIndirectReference().getNumber();
    iui.egiz_dict_ir_generation = dict_ref.getIndirectReference().getGeneration();

    PdfIndirectReference root_ref = (PdfIndirectReference) stamper.getReader().getTrailer().get(PdfName.ROOT);
    PdfDictionary root = (PdfDictionary) PdfReader.getPdfObject(root_ref);
    // root.put(EGIZ_DICT_NAME, dict_ref.getIndirectReference());
    ((PdfStamperImp) stamper.getWriter()).markUsed(root);

    // PdfDictionary extra_cata = stamper.getWriter().getExtraCatalog();
    // extra_cata.put(dict_type, dict_ref.getIndirectReference());

    ((PdfStamperImp) stamper.getWriter()).setEgizDictTrailerInfo(EGIZ_DICT_NAME, dict_ref.getIndirectReference());
  }

  /**
   * Converts a field name (type) to the corresponding BREV.
   * 
   * @param type
   *          The field name (type).
   * @return Returns the corresponding BREV, or BREV_NIL if the type is not
   *         recognized.
   */
  protected static byte[] typeToBrev(String type)
  {
    if (type.equals(SignatureTypes.SIG_DATE))
    {
      return BREV_DAT;
    }
    if (type.equals(SignatureTypes.SIG_ISSUER))
    {
      return BREV_ISS;
    }
    if (type.equals(SignatureTypes.SIG_VALUE))
    {
      return BREV_VAL;
    }
    if (type.equals(SignatureTypes.SIG_NUMBER))
    {
      return BREV_SNR;
    }
    if (type.equals(SignatureTypes.SIG_ID))
    {
      return BREV_SID;
    }

    return BREV_NIL;
  }

  /**
   * Updates the information in the egiz dictionary to reflect the real offsets
   * of the byte ranges.
   * 
   * <p>
   * This replaces the "dummy numbers" in the egiz dictionary with the correct
   * values.
   * </p>
   * 
   * @param iui
   *          The IncrementalUpdateInformation.
   * @throws PDFDocumentException
   */
  public static void markByteRanges(IncrementalUpdateInformation iui) throws PDFDocumentException
  {
    try
    {
      iui.byte_ranges = new ArrayList();

      int num_digits = Integer.toString(NUMBER_PLACEHOLDER.intValue()).length();
      byte[] signed_pdf = iui.signed_pdf;

      String str = iui.egiz_dict_ir_number + " " + iui.egiz_dict_ir_generation + " obj";
      byte[] obj_bytes = str.getBytes("US-ASCII");
      int obj_index = ByteArrayUtils.lastIndexOf(signed_pdf, obj_bytes);
      int obj_start = obj_index + obj_bytes.length;

      String ods_str = "/ODS ";
      byte[] ods_bytes = ods_str.getBytes("US-ASCII");
      int ods_index = ByteArrayUtils.indexOf(signed_pdf, obj_start, ods_bytes);
      int ods_start = ods_index + ods_bytes.length;

      String kz_str = "/ID[";
      byte[] kz_bytes = kz_str.getBytes("US-ASCII");
      int kz_index = ByteArrayUtils.indexOf(signed_pdf, obj_start, kz_bytes);
      int kz_start = kz_index + kz_bytes.length;

      String br_str = "/ByteRange[";
      byte[] br_bytes = br_str.getBytes("US-ASCII");
      int br_index = ByteArrayUtils.indexOf(signed_pdf, obj_start, br_bytes);
      int array_start = br_index + br_bytes.length;

      String enc_str = "/encodings[";
      byte[] enc_bytes = enc_str.getBytes("US-ASCII");
      int enc_index = ByteArrayUtils.indexOf(signed_pdf, obj_start, enc_bytes);
      int enc_start = enc_index + enc_bytes.length;

      String cert_str = "/Cert[(";
      byte[] cert_bytes = cert_str.getBytes("US-ASCII");
      int cert_index = ByteArrayUtils.indexOf(signed_pdf, obj_start, cert_bytes);
      int cert_start = cert_index + cert_bytes.length;

      replaceNumber(signed_pdf, ods_start, signed_pdf.length, num_digits);

      // update the Kennzeichnung byte ranges
      int cur_pos = kz_start;
      for (int i = 0; i < iui.kz_list.size(); i++)
      {
        StringInfo si = (StringInfo) iui.kz_list.get(i);

        replaceNumber(signed_pdf, cur_pos, si.string_start, num_digits);
        cur_pos += num_digits;
        cur_pos += 1;
        replaceNumber(signed_pdf, cur_pos, si.string_length, num_digits);
        cur_pos += num_digits;
        cur_pos += 1;
      }

      int num_replaces = calcNumReps(iui.replaces);
      int num_holes = num_replaces + 1 + 1; // +1 = the /encodings hole
      // int num_byte_ranges = num_holes + 1;

      cur_pos = array_start;
      int cur_br_start = 0;

      // write the /encodings byte range
      {
        int enc_length = (1 + 3) * num_holes;

        StringInfo byte_range = new StringInfo();
        byte_range.string_start = cur_br_start;
        byte_range.string_length = enc_start;
        iui.byte_ranges.add(byte_range);

        replaceNumber(signed_pdf, cur_pos, byte_range.string_start, num_digits);
        cur_pos += num_digits;
        cur_pos += 1;
        replaceNumber(signed_pdf, cur_pos, byte_range.string_length, num_digits);
        cur_pos += num_digits;
        cur_pos += 1;

        cur_br_start = enc_start + enc_length;

        iui.enc_start = enc_start;
        iui.enc_length = enc_length;
      }

      // write the /Cert byte range
      {
        int cert_length = CERTIFICATE_PLACEHOLDER_LENGTH;

        StringInfo byte_range = new StringInfo();
        byte_range.string_start = cur_br_start;
        byte_range.string_length = cert_start - cur_br_start;
        iui.byte_ranges.add(byte_range);

        replaceNumber(signed_pdf, cur_pos, byte_range.string_start, num_digits);
        cur_pos += num_digits;
        cur_pos += 1;
        replaceNumber(signed_pdf, cur_pos, byte_range.string_length, num_digits);
        cur_pos += num_digits;
        cur_pos += 1;

        cur_br_start = cert_start + cert_length;

        iui.cert_start = cert_start;
        iui.cert_length = cert_length;
      }

      Iterator rit = iui.replaces.iterator();
      while (rit.hasNext())
      {
        ReplaceInfo ri = (ReplaceInfo) rit.next();

        // byte [] value_bytes = ri.value.getBytes("ISO-8859-1");
        // int write_pos = 0;

        Iterator sit = ri.replaces.iterator();
        while (sit.hasNext())
        {
          StringInfo si = (StringInfo) sit.next();

          StringInfo byte_range = new StringInfo();
          byte_range.string_start = cur_br_start;
          byte_range.string_length = si.string_start - cur_br_start;
          iui.byte_ranges.add(byte_range);

          replaceNumber(signed_pdf, cur_pos, byte_range.string_start, num_digits);
          cur_pos += num_digits;
          cur_pos += 1;
          replaceNumber(signed_pdf, cur_pos, byte_range.string_length, num_digits);
          cur_pos += num_digits;
          cur_pos += 1;

          cur_br_start = si.string_start + si.string_length;
        }

      }

      StringInfo byte_range = new StringInfo();
      byte_range.string_start = cur_br_start;
      byte_range.string_length = signed_pdf.length - cur_br_start;
      iui.byte_ranges.add(byte_range);

      replaceNumber(signed_pdf, cur_pos, byte_range.string_start, num_digits);
      cur_pos += num_digits;
      cur_pos += 1;
      replaceNumber(signed_pdf, cur_pos, byte_range.string_length, num_digits);
      cur_pos += num_digits;
      cur_pos += 1;

    }
    catch (IOException e)
    {
      throw new PDFDocumentException(201, e);
    }

  }

  /**
   * Replaces the certificate placeholder with the certificate from the signed
   * Signature Object.
   * 
   * @param iui
   *          The IncrementalUpdateInformation.
   * @throws PDFDocumentException
   */
  public static void replaceCertificate(IncrementalUpdateInformation iui) throws PDFDocumentException
  {
    X509Certificate certificate = iui.signed_signature_object.getX509Certificate();
    try
    {
      byte[] der = certificate.getEncoded();
      byte[] encoded = CodingHelper.encodeBase64(der).getBytes("US-ASCII");
      byte[] escaped = Placeholder.escapePDFString(encoded);
      if (escaped.length > iui.cert_length)
      {
        throw new PlaceholderException("certificate", escaped.length - iui.cert_length);
      }
      System.arraycopy(escaped, 0, iui.signed_pdf, iui.cert_start, escaped.length);
    }
    catch (CertificateEncodingException e)
    {
      throw new PDFDocumentException(300, e);
    }
    catch (UnsupportedEncodingException e)
    {
      throw new PDFDocumentException(300, e);
    }

    // X509Cert cert = iui.signed_signature_object.getX509Cert();
    // // X509Certificate certificate = cert.getX509Certificate();
    // try
    // {
    // byte[] encoded = cert.getCertString().getBytes("US-ASCII"); //
    // certificate.getEncoded();
    // byte[] escaped = Placeholder.escapePDFString(encoded);
    // if (escaped.length > iui.cert_length)
    // {
    // throw new PlaceholderException("certificate", escaped.length -
    // iui.cert_length);
    // }
    // System.arraycopy(escaped, 0, iui.signed_pdf, iui.cert_start,
    // escaped.length);
    // }
    // // catch (CertificateEncodingException e)
    // // {
    // // throw new PDFDocumentException(300, e);
    // // }
    // catch (UnsupportedEncodingException e)
    // {
    // throw new PDFDocumentException(300, e);
    // }
  }

  /**
   * Replaces the placeholders with values from the signed SignatureObject.
   * 
   * @param iui
   *          The IncrementalUpdateInformation.
   * @throws PDFDocumentException
   */
  public static void replacePlaceholders(IncrementalUpdateInformation iui) throws PDFDocumentException
  {
    final byte[] signed_pdf = iui.signed_pdf;

    // int num_replaces = calcNumReps(iui.replaces);
    // int num_holes = num_replaces + 1 + 1; // +1 = the /encodings hole; +1 =
    // the
    // /Cert

    int encoding_entry_index = 0;
    {// /encodings itself
      int enc_offset = iui.enc_start + encoding_entry_index * 4;
      signed_pdf[enc_offset] = '/';
      System.arraycopy(ENCODING_NIL, 0, signed_pdf, enc_offset + 1, ENCODING_NIL.length);
      encoding_entry_index++;
    }
    {// /Cert itself
      int enc_offset = iui.enc_start + encoding_entry_index * 4;
      signed_pdf[enc_offset] = '/';
      System.arraycopy(ENCODING_NIL, 0, signed_pdf, enc_offset + 1, ENCODING_NIL.length);
      encoding_entry_index++;
    }

    for (int i = 0; i < iui.replaces.size(); i++)
    {
      ReplaceInfo ri = (ReplaceInfo) iui.replaces.get(i);

      try
      {
        String value = ri.value;

        if (value == null)
        {
          value = "";
        }

        byte[] encoding = ENCODING_WIN;
        byte[] replace_bytes = Placeholder.applyWinAnsiEncoding(value);

        String restored_value = Placeholder.unapplyWinAnsiEncoding(replace_bytes);
        if (!value.equals(restored_value))
        {
          // debug:
          System.out.println("WinAnsiEncoding doesn't fit - using URL instead!");
          // /debug!

          replace_bytes = Placeholder.applyURLEncoding(value);

          encoding = ENCODING_URL;
        }

        for (int string_index = 0; string_index < ri.replaces.size(); string_index++)
        {
          int enc_offset = iui.enc_start + encoding_entry_index * 4;
          signed_pdf[enc_offset] = '/';
          System.arraycopy(encoding, 0, signed_pdf, enc_offset + 1, encoding.length);
          encoding_entry_index++;
        }

        Placeholder.replacePlaceholderWithTolerance(signed_pdf, ri.replaces, replace_bytes, LINE_BREAK_TOLERANCE);
      }
      catch (PlaceholderException e)
      {
        throw new PlaceholderException(ri.sfd.field_name, e.getMissing());
      }

    }
  }

  /**
   * Calculates the number of actual String replaces from a given ReplaceInfo
   * list.
   * <p>
   * This is used to determine the number of actual replaces that has to be
   * carried out. Accordingly to this number, entries in the dictionary are
   * created.
   * </p>
   * 
   * @param replaces
   *          The ReplaceInfo list.
   * @return Returns the number of string replaces.
   */
  protected static int calcNumReps(List replaces)
  {
    int number = 0;
    Iterator it = replaces.iterator();
    while (it.hasNext())
    {
      ReplaceInfo ri = (ReplaceInfo) it.next();
      number += ri.replaces.size();
    }
    return number;
  }

  /**
   * Determines the List of ReplaceInfo objects of replaces in the content
   * stream regarding the given field definitions.
   * 
   * <p>
   * This method collects all variable String fields in a content stream and
   * orders them according to their start offset.
   * </p>
   * 
   * @param pdf
   *          The PDF.
   * @param begin
   *          The start of the content stream.
   * @param end
   *          The end of the content stream.
   * @param field_definitions
   *          The field definitions that are counceled to find out which and
   *          where varaible strings are.
   * @return Returns the list of ReplaceInfo objects specifying the variable
   *         areas.
   */
  protected static List determineReplacesInContentStream(final byte[] pdf, int begin, int end, List field_definitions)
  {
    List replaces = new ArrayList();
    try
    {

      List strings = Placeholder.parseStrings(pdf, begin, end);

      for (int index = 0; index < field_definitions.size(); index++)
      {
        SignatureFieldDefinition sfd = (SignatureFieldDefinition) field_definitions.get(index);

        if (sfd.placeholder_length > 0)
        {
          ReplaceInfo ri = new ReplaceInfo();
          ri.sfd = sfd;
          ri.replaces = new ArrayList();

          byte[] caption = sfd.caption.getBytes("ISO-8859-1");

          int caption_index = findIndex(strings, caption);
          int start_index = skipStrings(strings, caption_index, caption);
          int next_index = findFirstNotPlaceholder(strings, start_index);

          for (int i = start_index; i < next_index; i++)
          {
            StringInfo si = (StringInfo) strings.get(i);
            ri.replaces.add(si);
          }

          replaces.add(ri);
        }
      }
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }

    // sort replaces
    Collections.sort(replaces, new Comparator() {
      public int compare(Object arg0, Object arg1)
      {
        ReplaceInfo ri0 = (ReplaceInfo) arg0;
        ReplaceInfo ri1 = (ReplaceInfo) arg1;
        int start0 = ((StringInfo) ri0.replaces.get(0)).string_start;
        int start1 = ((StringInfo) ri1.replaces.get(0)).string_start;
        return start0 - start1;
      }
    });

    return replaces;
  }

  /**
   * Determines the Kennzeichnug in the content stream.
   * 
   * @param pdf
   *          The PDF.
   * @param begin
   *          The start of the content stream.
   * @param end
   *          The end of the content stream.
   * @param field_definitions
   *          The field definitions.
   * @return Returns the List of StringInfo objects representing the KZ field.
   * @throws SettingNotFoundException
   *           F.e.
   */
  protected static List determineKZ(final byte[] pdf, int begin, int end, List field_definitions) throws SettingNotFoundException
  {
    try
    {
      List strings = Placeholder.parseStrings(pdf, begin, end);

      for (int index = 0; index < field_definitions.size(); index++)
      {
        SignatureFieldDefinition sfd = (SignatureFieldDefinition) field_definitions.get(index);

        if (sfd.field_name.equals(SignatureTypes.SIG_KZ))
        {
          List kz_list = new ArrayList();

          byte[] caption = sfd.caption.getBytes("ISO-8859-1");

          int caption_index = findIndex(strings, caption);
          int start_index = skipStrings(strings, caption_index, caption);

          int end_index = -1;
          for (end_index = start_index; end_index < strings.size(); end_index++)
          {
            StringInfo si = (StringInfo) strings.get(end_index);

            if (startsWithCaption(si, field_definitions))
            {
              break;
            }

            kz_list.add(si);
          }

          return kz_list;
        }
      }
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }
    throw new KZSettingNotFoundException("Field " + SignatureTypes.SIG_KZ + " not found.");
  }

  /**
   * Finds the index of the StringInfo within the StringInfo list that has the
   * given content (caption).
   * 
   * @param strings
   *          The list of StringInfos.
   * @param caption
   *          The text to be matched to the strings.
   * @return Returns the index of the found string, or -1 if no string matched.
   */
  protected static int findIndex(List strings, byte[] caption)
  {
    for (int i = 0; i < strings.size(); i++)
    {
      if (isCaption(strings, i, caption))
      {
        return i;
      }
    }
    return -1;
  }

  protected static boolean isCaption(List strings, int index, byte[] caption)
  {
    try
    {

      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      for (int i = index; i < strings.size(); i++)
      {
        StringInfo si = (StringInfo) strings.get(i);
        baos.write(si.copyStringBytes());
      }
      byte[] str_data = baos.toByteArray();
      byte[] unescaped = Placeholder.unescapePDFString(str_data);
      if (ByteArrayUtils.compareByteArrays(unescaped, 0, caption))
      {
        return true;
      }
      else
      {
        return false;
      }
    }
    catch (IOException e)
    {
      e.printStackTrace();
      return false;
    }

  }

  protected static int skipStrings(List strings, int index, byte[] caption)
  {
    int length = 0;
    for (int i = index; i < strings.size(); i++)
    {
      StringInfo si = (StringInfo) strings.get(i);
      length += si.string_length;

      if (length >= caption.length)
      {
        return i + 1;
      }
    }
    return -1;
  }

  /**
   * Tells, if the given StringInfo contains only placeholder characters.
   * 
   * @param si
   *          The StringInfo.
   * @param placeholder
   *          The placeholder character.
   * @return Returns true, if the string contains only the given placeholder
   *         characters, false otherwise.
   */
  protected static boolean isPlaceholder(StringInfo si, byte placeholder)
  {
    byte[] string_bytes = si.copyStringBytes();
    for (int i = 0; i < string_bytes.length; i++)
    {
      if (string_bytes[i] != placeholder)
      {
        return false;
      }
    }
    return true;
  }

  protected static boolean startsWithCaption(StringInfo si, List field_definitions)
  {
    try
    {
      for (int i = 0; i < field_definitions.size(); i++)
      {
        SignatureFieldDefinition sfd = (SignatureFieldDefinition) field_definitions.get(i);

        String caption = sfd.caption;
        String str = si.getString("ISO-8859-1");

        if (caption.startsWith(str))
        {
          return true;
        }
      }
      return false;
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
      return false;
    }
  }

  /**
   * Finds the first string after and at the given index not being a placeholder
   * string.
   * 
   * @param strings
   *          The list of StringInfos.
   * @param start
   *          The index where to start the search.
   * @return Returns the index of the first not placeholder string, or
   *         strings.size() if no more non placeholder strings could be found.
   */
  protected static int findFirstNotPlaceholder(List strings, int start)
  {
    for (int i = start; i < strings.size(); i++)
    {
      StringInfo si = (StringInfo) strings.get(i);
      if (!isPlaceholder(si, LAYOUT_PLACEHOLDER))
      {
        return i;
      }
    }
    return strings.size();
  }

  /**
   * Restores the given String to its placeholder.
   * 
   * @param pdf
   *          The PDF.
   * @param si
   *          The string.
   * @param placeholder
   *          The placeholder the string should be filled with.
   */
  public static void restorePlaceholder(final byte[] pdf, StringInfo si, final byte placeholder)
  {
    byte[] ph = new byte[si.string_length];
    for (int i = 0; i < ph.length; i++)
    {
      ph[i] = placeholder;
    }
    System.arraycopy(ph, 0, pdf, si.string_start, ph.length);
  }

  /**
   * Reconstructs the replaces from the PDF and forms suitable value strings.
   * 
   * @param pdf
   *          The PDF.
   * @param brevs
   *          The brevs.
   * @param sis
   *          The StringInfo objects of the strings.
   * @return Returns the List of ReplaceInfo objects containing the restored
   *         values.
   * @throws PDFDocumentException
   */
  public static List reconstructReplaces(final byte[] pdf, byte[][] brevs, StringInfo[] sis, byte[][] encodings) throws PDFDocumentException
  {
    try
    {
      List replaces = new ArrayList();

      ReplaceInfo cur_ri = null;

      for (int cur = 0; cur < brevs.length; cur++)
      {
        if (ByteArrayUtils.compareByteArrays(brevs[cur], 0, BREV_NIL))
        {
          continue;
        }

        if (cur_ri == null || !ByteArrayUtils.compareByteArrays(cur_ri.brev, 0, brevs[cur]))
        {
          cur_ri = new ReplaceInfo();

          cur_ri.replaces = new ArrayList();

          cur_ri.brev = brevs[cur];
          cur_ri.enc = encodings[cur];

          replaces.add(cur_ri);
        }

        cur_ri.replaces.add(sis[cur]);
      }

      // restore value Strings
      Iterator rit = replaces.iterator();
      while (rit.hasNext())
      {
        ReplaceInfo ri = (ReplaceInfo) rit.next();
        ri.value = Placeholder.reconstructStringFromPartition(pdf, ri.replaces, ri.enc);

        // System.out.println(new String(ri.brev, "US-ASCII") + ": " +
        // ri.value);
      }

      return replaces;
    }
    catch (IOException e)
    {
      throw new PDFDocumentException(310, e);
    }

  }

  /**
   * Reads an unsigned integer number.
   * 
   * @param pdf
   *          The PDF.
   * @param start_index
   *          The start index of the number.
   * @param num_digits
   *          The number of digits.
   * @return Returns the read number.
   */
  public static int readNumber(final byte[] pdf, final int start_index, final int num_digits)
  {
    try
    {
      byte[] n_bytes = new byte[num_digits];
      System.arraycopy(pdf, start_index, n_bytes, 0, num_digits);
      String n_string = new String(n_bytes, "US-ASCII");

      int n = Integer.parseInt(n_string);
      return n;
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
      return -1;
    }
  }

  /**
   * Replaces a number by the new value.
   * 
   * @param pdf
   *          The PDF.
   * @param start_index
   *          The start index of the number.
   * @param number
   *          The new number.
   * @param num_digits
   *          The number of digits.
   */
  public static void replaceNumber(final byte[] pdf, final int start_index, final int number, final int num_digits)
  {
    try
    {
      if (number < 0)
      {
        throw new IllegalArgumentException("The given number " + number + " must not be negative.");
      }
      String number_string = Integer.toString(number);
      if (number_string.length() > num_digits)
      {
        throw new IllegalArgumentException("The given number " + number + " has more than " + num_digits + " digits.");
      }

      int leading_zeros = num_digits - number_string.length();
      String zeros_string = "";
      for (int i = 0; i < leading_zeros; i++)
      {
        zeros_string += "0";
      }

      String total_string = zeros_string + number_string;
      byte[] total_bytes = total_string.getBytes("US-ASCII");
      System.arraycopy(total_bytes, 0, pdf, start_index, num_digits);
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }
  }

  // TODO old code - remove
  //  /**
  //   * For debugging purposes.
  //   * 
  //   * @param args
  //   * @throws IOException
  //   */
  //  public static void main(String[] args) throws IOException
  //  {
  //    File signed_doc = new File("C:/wprinz/temp.pdf");
  //
  //    PdfReader reader = new PdfReader(new FileInputStream(signed_doc));
  //    PdfDictionary egiz_dict = getEgizDictFromReader(reader);
  //    if (egiz_dict == null)
  //    {
  //      System.out.println("NO Egiz Dict");
  //      return;
  //    }
  //
  //    String sig_text = extractSignatureTextOnly(egiz_dict);
  //    System.out.println("Sig Text:");
  //    System.out.println(sig_text);
  //
  //    int ods = getOriginalDocumentSizeFromEgizDict(egiz_dict);
  //    System.out.println("Original Document Size = " + ods);
  //  }

}