/**
 * <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.framework.vfilter;

import java.util.List;

import at.gv.egiz.pdfas.exceptions.framework.VerificationFilterException;
import at.gv.egiz.pdfas.framework.input.PdfDataSource;
import at.gv.egiz.pdfas.framework.input.TextDataSource;

/**
 * Extracts all signatures from a given PDF document or text.
 * 
 * @see VerificationFilterParameters
 * 
 * @author wprinz
 */
public interface VerificationFilter
{

  /**
   * Extracts the signatures from the given PDF.
   * 
   * @param pdf
   *          The PDF.
   * @param blocks
   *          The List of Incremental Update blocks. Usually this comes from a
   *          preprocessing step.
   * @param parameters
   *          The algorithm parameters.
   * @return Returns a List of SignatureHolders containing the signatures. May
   *         be empty in case no signatures have been found.
   * @throws VerificationFilterException
   *           Thrown if something goes wrong.
   */
  public List extractSignatureHolders(PdfDataSource pdf, List blocks, VerificationFilterParameters parameters) throws VerificationFilterException;

  /**
   * Extracts the text signatures from the given free-text.
   * 
   * @param text
   *          The free-text.
   * @param parameters
   *          The algorithm parameters.
   * @return Returns a List of SignatureHolders containing the signatures. May
   *         be empty in case no signatures have been found.
   * @throws VerificationFilterException
   *           Thrown if something goes wrong.
   */
  public List extractSignaturHolders(TextDataSource text, VerificationFilterParameters parameters) throws VerificationFilterException;
}