/**
 * <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.input;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.SequenceInputStream;

import at.gv.egiz.pdfas.framework.input.DataSource;
import at.gv.egiz.pdfas.framework.input.PdfDataSource;

/**
 * @author wprinz
 *
 */
public class CompoundPdfDataSourceImpl implements PdfDataSource
{
  protected DataSource originalDataSource = null;
  
  protected byte[] appendix = null;
  
  public CompoundPdfDataSourceImpl (PdfDataSource original, byte [] appendix)
  {
    this.originalDataSource = original;
    this.appendix = appendix;
  }

  /**
   * @see at.gv.egiz.pdfas.framework.input.DataSource#createInputStream()
   */
  public InputStream createInputStream()
  {
    ByteArrayInputStream bais = new ByteArrayInputStream(this.appendix);
    SequenceInputStream sis = new SequenceInputStream(this.originalDataSource.createInputStream(), bais);
    return sis;
  }

  /**
   * @see at.gv.egiz.pdfas.framework.input.DataSource#getLength()
   */
  public int getLength()
  {
    return this.originalDataSource.getLength() + this.appendix.length;
  }
  
  byte [] cache = null;

  /**
   * @see at.gv.egiz.pdfas.framework.input.DataSource#getAsByteArray()
   */
  public byte[] getAsByteArray()
  {
    if (cache != null)
    {
      return cache;
    }
    
    cache = new byte [getLength()];
    System.arraycopy(originalDataSource.getAsByteArray(), 0, cache, 0, originalDataSource.getLength());
    System.arraycopy(appendix, 0, cache, originalDataSource.getLength(), appendix.length);
    
    return cache;
  }
}