/**
 * <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.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import at.gv.egiz.pdfas.exceptions.framework.VerificationFilterException;
import at.gv.egiz.pdfas.impl.input.helper.DataSourceHelper;
import at.gv.egiz.pdfas.impl.vfilter.Partition;
import at.gv.egiz.pdfas.impl.vfilter.partition.BinaryPartition;
import at.gv.egiz.pdfas.impl.vfilter.partition.TextPartition;
import at.gv.egiz.pdfas.framework.input.PdfDataSource;
import at.knowcenter.wag.exactparser.parsing.results.FooterParseResult;

/**
 * Contains helpful methods used by the VerificationFilter.
 * 
 * @author wprinz
 */
public final class VerificationFilterHelper
{
  /**
   * Partitions the list of Incremental Update blocks into text and binary
   * partitions.
   * 
   * <p>
   * A partition is a sequence of Incremental Update blocks of the same type.
   * </p>
   * <p>
   * An Incremental Update block is considered to have the type "binary" if it
   * contains an egiz dictionary. A block not containing an egiz dictionary is
   * considert to have the type "text".
   * </p>
   * 
   * @param pdf
   *          The PDF.
   * @param blocks
   *          The Incremental Update blocks.
   * @return Returns the partitioning of the blocks.
   * @throws VerificationFilterException
   *           Thrown if something goes wrong.
   */
  public static List partition(PdfDataSource pdf, List blocks) throws VerificationFilterException
  {
      List partitions = new ArrayList(blocks.size());

      Iterator it = blocks.iterator();
      while (it.hasNext())
      {
        FooterParseResult fpr = (FooterParseResult) it.next();

        byte[] data = DataSourceHelper.convertDataSourceToByteArray(pdf);
        if (VerificationFilterBinaryHelper.containsEGIZDict(data, fpr))
        {
          BinaryPartition bp = null;
          if (partitions.isEmpty() || ((Partition) partitions.get(partitions.size() - 1)).isTextPartition())
          {
            bp = new BinaryPartition();
            bp.blocks = new ArrayList(blocks.size());
            partitions.add(bp);
          }
          else
          {
            bp = (BinaryPartition) partitions.get(partitions.size() - 1);
          }
          assert bp != null;

          bp.blocks.add(fpr);
        }
        else
        {
          TextPartition tp = null;
          if (partitions.isEmpty() || !((Partition) partitions.get(partitions.size() - 1)).isTextPartition())
          {
            tp = new TextPartition();
            tp.blocks = new ArrayList(blocks.size());
            partitions.add(tp);
          }
          else
          {
            tp = (TextPartition) partitions.get(partitions.size() - 1);
          }
          assert tp != null;

          tp.blocks.add(fpr);
        }
      }

      assert partitions.size() >= 1 : "There must be at least one partition";

      return partitions;
  }

  /**
   * Determines the end of the given partiton.
   * 
   * @param partition
   *          The partition.
   * @return Returns the end index of the given partition.
   */
  public static int getEndOfPartition(Partition partition)
  {
    List blocks = null;
    if (partition instanceof TextPartition)
    {
      blocks = ((TextPartition) partition).blocks;
    }
    else
    {
      blocks = ((BinaryPartition) partition).blocks;
    }

    return ((FooterParseResult) blocks.get(blocks.size() - 1)).next_index;
  }

  /**
   * Finds the last text partition in the given list of partitions.
   * 
   * @param partitions
   *          The partitions.
   * @return Returns the last TextPartition.
   */
  public static TextPartition findLastTextPartition(List partitions)
  {
    Partition lastTextPartition = (Partition) partitions.get(partitions.size() - 1);

    if (!lastTextPartition.isTextPartition())
    {
      assert partitions.size() > 1 : "The only one partition cannot be a binary partition - where is the original document?";
      Partition previousToLastPartition = (Partition) partitions.get(partitions.size() - 2);
      assert previousToLastPartition.isTextPartition() : "The previous to last partition must be a text partition or something is wrong with the partitioning algorithm.";

      lastTextPartition = previousToLastPartition;
    }

    return (TextPartition) lastTextPartition;
  }

}