/**
 * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
 * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
 * joint initiative of the Federal Chancellery Austria and Graz University of
 * Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.gv.egiz.pdfas.impl.vfilter.helper;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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

import at.gv.egiz.pdfas.exceptions.ErrorCode;
import at.knowcenter.wag.egov.egiz.PdfASID;
import at.knowcenter.wag.egov.egiz.exceptions.InvalidIDException;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;
import at.knowcenter.wag.egov.egiz.pdf.BinarySignature;
import at.knowcenter.wag.egov.egiz.pdf.Placeholder;
import at.knowcenter.wag.egov.egiz.pdf.StringInfo;
import at.knowcenter.wag.exactparser.parsing.IndirectObjectReference;
import at.knowcenter.wag.exactparser.parsing.PDFUtils;
import at.knowcenter.wag.exactparser.parsing.results.ArrayParseResult;
import at.knowcenter.wag.exactparser.parsing.results.DictionaryParseResult;
import at.knowcenter.wag.exactparser.parsing.results.FooterParseResult;
import at.knowcenter.wag.exactparser.parsing.results.IndirectObjectReferenceParseResult;
import at.knowcenter.wag.exactparser.parsing.results.NumberParseResult;
import at.knowcenter.wag.exactparser.parsing.results.ObjectParseResult;

/**
 * Contains helpful methods used by the VerificationFilter to analyze the PDF for binary signatures.
 * 
 * @author wprinz
 */
public final class VerificationFilterBinaryHelper
{
  /**
   * The name of the egiz dict key.
   */
  public static final byte[] EGIZ_DICT_NAME = { 'E', 'G', 'I', 'Z', 'S', 'i', 'g', 'D', 'i', 'c', 't' };

  /**
   * The name of the ID (SIG_KZ) property in the egiz dict.
   */
  public static final byte[] EGIZ_KZ_NAME = { 'I', 'D' };

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

  /**
   * Tells, if the given incremental update block contains a binary signature.
   * 
   * <p>
   * According to definition, if a block is a binary block, it must/cannot
   * contain other signatures than this one.
   * </p>
   * 
   * @param block
   *          The incremental update block.
   * @return Returns true, if this block is a binary signature block, false
   *         otherwise.
   */
  public static boolean containsEGIZDict(final byte[] pdf, final FooterParseResult block)
  {
    int dict_index = PDFUtils.indexOfName(pdf, block.tpr.dpr.names, EGIZ_DICT_NAME);
    if (dict_index <= 0)
    {
      return false;
    }

    return true;
  }

  /**
   * Extracts the PDF AS ID of the egiz block.
   * 
   * @param pdf
   *          The pdf.
   * @param block
   *          The IU block.
   * @return Returns the extracted PDF AS ID.
   * @throws PDFDocumentException
   *           Forwarded exception.
   * @throws InvalidIDException
   *           Forwarded exception.
   */
  public static PdfASID extractKZFromEGIZBlock(final byte[] pdf, final FooterParseResult block) throws PDFDocumentException, InvalidIDException
  {
    int egiz_index = PDFUtils.indexOfName(pdf, block.tpr.dpr.names, EGIZ_DICT_NAME);
    if (egiz_index < 0)
    {
      throw new PDFDocumentException(301, "egiz_index = " + egiz_index);
    }

    IndirectObjectReferenceParseResult egiz_dict_iorpr = (IndirectObjectReferenceParseResult) block.tpr.dpr.values.get(egiz_index);
    // logger_.debug("egiz_dict_ir = " + egiz_dict_iorpr.ior.object_number
    // + " " + egiz_dict_iorpr.ior.generation_number);

    IndirectObjectReference ior = egiz_dict_iorpr.ior;

    final int egiz_dict_offset = PDFUtils.getObjectOffsetFromXRefByIndirectObjectReference(block.xpr, ior);
    // logger_.debug("egiz_dict_offset = " + egiz_dict_offset);

    ObjectParseResult obj = PDFUtils.parseObject(pdf, egiz_dict_offset);
    DictionaryParseResult egiz_dict = (DictionaryParseResult) obj.object;

    int kz_index = PDFUtils.indexOfName(pdf, egiz_dict.names, EGIZ_KZ_NAME);
    if (kz_index < 0)
    {
      throw new PDFDocumentException(301, "kz_index = " + kz_index);
    }
    ArrayParseResult kz_apr = (ArrayParseResult) egiz_dict.values.get(kz_index);

    String kz_string = restoreKZ(pdf, kz_apr);
    PdfASID kz = new PdfASID(kz_string);

    return kz;
  }

  /**
   * Restores the Kennzeichnung String from an Array.
   * 
   * @param pdf
   *          The PDF.
   * @param kz_apr
   *          The Array, as parsed from the EGIZ Dict.
   * @return Returns the restored KZ.
   * @throws PDFDocumentException
   *           Forwarded exception.
   */
  public static String restoreKZ(byte[] pdf, ArrayParseResult kz_apr) throws PDFDocumentException
  {
    try
    {
      List partition = new ArrayList();

      int linesToProcess = (kz_apr.elements.size() / 2);
      log.trace("Lines to process for KZ: " + linesToProcess);
      /*
      if (linesToProcess > 1) {
         log.debug("Multiple KZHOTFIX: forcing single line to process");
         linesToProcess = 1;
      }
      */
      for (int i = 0; i < linesToProcess; i++)
      {
        NumberParseResult start_npr = (NumberParseResult) kz_apr.elements.get(i * 2);
        NumberParseResult length_npr = (NumberParseResult) kz_apr.elements.get(i * 2 + 1);

        StringInfo si = new StringInfo();
        si.string_start = start_npr.number;
        si.string_length = length_npr.number;
        si.pdf = pdf;

        log.trace("Adding KZ: " + si.toString());
        
        partition.add(si);
      }

      String KZ = Placeholder.reconstructStringFromPartition(pdf, partition, BinarySignature.ENCODING_WIN);
      return KZ;
    }
    catch (IOException e1)
    {
      throw new PDFDocumentException(ErrorCode.DOCUMENT_CANNOT_BE_READ, e1);
    }
  }

}