/**
 * <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: BinarySignatureHolder.java,v 1.1 2006/10/11 07:58:28 wprinz Exp $
 */
package at.knowcenter.wag.egov.egiz.pdf;

import java.io.Serializable;

import at.knowcenter.wag.egov.egiz.sig.SignatureObject;

/**
 * Data structure that holds the information of one binary signature block,
 * which is the signed/signable pdf and the corresponding SignatureObject.
 * 
 * <p>
 * The actual signed text is computed by Base64 encoding the binary data when
 * first requested.
 * </p>
 * <p>
 * The corresponding getters can be used to retrieve the signed document (e.g.
 * for displaying a preview).
 * </p>
 * 
 * @author wprinz
 */
public class BinarySignatureHolder implements Serializable, SignatureHolder
{

  /**
   * SVUID.
   */
  private static final long serialVersionUID = -7208103904479272760L;

  /**
   * The whole pdf this holder was extracted from.
   */
  private byte[] signed_pdf = null;

  /**
   * The number of bytes that give the signed document.
   */
  private int signed_pdf_length = -1;

  /**
   * The signed text of this object.
   * 
   * <p>
   * This is the value that will be signed by the Connector.
   * </p>
   */
  private String signed_text = null;

  /**
   * The signature object.
   */
  private SignatureObject signature_object = null;

  /**
   * Constructor that takes the pdf and the SignatureObject as parameters.
   * 
   * @param pdf
   *          The pdf data.
   * @param length
   *          The length (number of bytes) of the pdf data to be used for being
   *          converted into "signed text".
   * @param so
   *          The signed signature object.
   */
  public BinarySignatureHolder(final byte[] pdf, final int length, SignatureObject so)
  {
    this.signed_pdf = pdf;
    this.signed_pdf_length = length;
    this.signature_object = so;

    this.signed_text = null;
  }

  /**
   * @see at.knowcenter.wag.egov.egiz.pdf.SignatureHolder#getSignedText()
   */
  public String getSignedText()
  {
    if (this.signed_text == null)
    {
      computeSignedText();
    }
    return this.signed_text;
  }

  /**
   * @see at.knowcenter.wag.egov.egiz.pdf.SignatureHolder#getSignatureObject()
   */
  public SignatureObject getSignatureObject()
  {
    return this.signature_object;
  }

  /**
   * Computes or recomputes the signed text from the underlying binary data.
   * 
   * <p>
   * This usually encodes the binary data of given length in Base64.
   * </p>
   * 
   * <p>
   * This is usually called automatically when the signed text is first
   * requested.
   * </p>
   */
  protected void computeSignedText()
  {
    this.signed_text = BinarySignature.retrieveSignableTextFromData(this.signed_pdf, this.signed_pdf_length);
  }

  /**
   * Returns the signed_pdf.
   * @return Returns the signed_pdf.
   */
  public byte[] getSignedPdf()
  {
    return this.signed_pdf;
  }

  /**
   * Returns the signed_pdf_length.
   * @return Returns the signed_pdf_length.
   */
  public int getSignedPdfLength()
  {
    return this.signed_pdf_length;
  }

}