/**
 * 
 */
package at.gv.egiz.pdfas.framework.vfilter;

/**
 * The parameters of the VerificationFilter algorithm.
 * 
 * @author wprinz
 */
public interface VerificationFilterParameters
{

  /**
   * Tells the VerificationFilter to extract binary signatures only.
   * 
   * <p>
   * Not scanning for textual signatures allows the algorithm to skip text
   * extraction and signature extraction, which are both time and memory
   * intensive processes.
   * </p>
   * 
   * @return Returns true if the VerificationFilter should extract binary
   *         signatures only.
   */
  public boolean extractBinarySignaturesOnly();

  /**
   * Tells the VerificationFilter to assume that there are only singatures (and
   * their Incremental Update blocks) younger than the original document.
   * 
   * <p>
   * This is equivalent to saying that the document was not updated using an
   * Incremental update block other than a signature after being singed. The
   * incremental update blocks after the original document contain only
   * signatures (either text or binary).
   * </p>
   * <p>
   * This is equivalent to saying that there exists no Incremental Update block
   * that would render a text signature before it invalid.
   * </p>
   * <p>
   * Under this assumption, the process of finding all text signatures
   * simplifies to one text extraction of the whole document and one signature
   * extraction. This is of course a massive performance gain.
   * </p>
   * <p>
   * Actually the algorithm performs a text extraction of the whole document not
   * including trailing binary signature Incremental Update blocks. This means
   * that if a the last n Incremental Update blocks of a document are binary,
   * there is no use extract text from them.
   * </p>
   * <p>
   * Note that if there are Incremental Update blocks with text after a
   * signature thus this assumption does not hold the signatures older than this
   * block will break.
   * </p>
   * 
   * @return Returns true if the Verification filter should assume that there
   *         are only signature blocks after the original document.
   */
  public boolean assumeOnlySignatureUpdateBlocks();

  /**
   * Tells the VerificationFilter so scan for old signatures in the rest text.
   * 
   * <p>
   * The rest text is the text of the oldest text signature or the original
   * document text if there is no text signature.
   * </p>
   * 
   * @return Returns true if the VerificationFilter should scan for old text
   *         signatures in the rest text.
   */
  public boolean scanForOldSignatures();
}