/*
 * <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: PDFSignatureCreation.java,v 1.6 2006/10/31 08:09:33 wprinz Exp $
 */
package at.knowcenter.wag.egov.egiz.pdf;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

import at.knowcenter.wag.egov.egiz.cfg.ConfigLogger;
import at.knowcenter.wag.egov.egiz.cfg.SettingsReader;
import at.knowcenter.wag.egov.egiz.exceptions.PDFDocumentException;
import at.knowcenter.wag.egov.egiz.exceptions.SettingsException;
import at.knowcenter.wag.egov.egiz.sig.SignatureObject;

/**
 * This class provides wrapper methods to get an access to abstract PDF documents (PDFSignator).
 * There exists many open source libraries and commercial libraries that can implement the abstract
 * interface. <br>
 * This class is to load the corresponding implementation of an abstract PDFSignator class. Therefor
 * it seams to be a factory. The factory settings are read from the configuration file calling the
 * SettingsReader.
 * 
 * @author wlackner
 * @see at.knowcenter.wag.egov.egiz.cfg.SettingsReader
 */
public class PDFSignatureCreation {
  /**
   * The abstract signature object
   */
  private SignatureObject sigObject_ = null;
  /**
   * The abstract pdf siganture object
   */
  private PDFSignatureObject pdfSigObject_ = null;
  /**
   * The SettingsReader instance
   */
  private SettingsReader settings_ = null;
  /**
   * The factory class prefix
   */
  private final static String CLASS_PREFIX = ".PDFSignatureObject";
  /**
   * The factory class prefix of the default library
   */
  protected final static String DEFAULT_LIBRARY = "IText";
  /**
   * The settings key defined in the settings file
   * 
   * @see SettingsReader
   */
  protected final static String SETTINGS_KEY = "pdf.signature.library";
  /**
   * The logger definition.
   */
  private static final Logger logger_ = ConfigLogger.getLogger(PDFSignatureCreation.class);

  /**
   * Load the configuration settings. Load the corresponding class implementation for the abstract
   * PDFSignature class. Init with a signature object.
   * 
   * @param sigObject the native signature object
   * @throws PDFDocumentException ErrorCode:101
   */
  public PDFSignatureCreation(SignatureObject sigObject) throws PDFDocumentException {
    try {
      loadSettings();
    } catch (PDFDocumentException e) {
      e.setErrorCode(101);
      throw e;
    }
    sigObject_ = sigObject;
  }

  /**
   * Load the factory implementation. This method trys to load the configured PDF library.
   * 
   * @throws PDFDocumentException
   */
  private PDFSignatureObject createPDFSignatureObject() throws PDFDocumentException {
    PDFSignatureObject pdf_sig_object = null;
    String class_name = this.getClass().getPackage().getName() + getClassName();
    Class pdf_sig_obj_class = null;
    try {
      pdf_sig_obj_class = Class.forName(class_name);
    } catch (ClassNotFoundException e) {
      if (logger_.isEnabledFor(Level.FATAL)) {
        logger_.fatal("Class not found:" + class_name);
      }
      throw new PDFDocumentException(203, "Can not load pdf signator library", e);
    }
    try {
      pdf_sig_object = (PDFSignatureObject) pdf_sig_obj_class.newInstance();
    } catch (InstantiationException e) {
      if (logger_.isEnabledFor(Level.FATAL)) {
        logger_.fatal("Can not instantiate:" + class_name);
      }
      throw new PDFDocumentException(203, "Can not load pdf signator library", e);
    } catch (IllegalAccessException e) {
      if (logger_.isEnabledFor(Level.FATAL)) {
        logger_.fatal("Can not access:" + class_name);
      }
      throw new PDFDocumentException(203, "Can not load pdf signator library", e);
    }
    return pdf_sig_object;
  }

  /**
   * load the class settings
   * 
   * @throws PDFDocumentException
   * @see SettingsReader
   */
  private void loadSettings() throws PDFDocumentException {
    if (settings_ == null) {
      try {
        settings_ = SettingsReader.getInstance();
      } catch (SettingsException e) {
        String log_message = "Can not load pdf signature settings. Cause:\n" + e.getMessage();
        logger_.error(log_message);
        throw new PDFDocumentException(101, log_message, e);
      }
    }
  }

  /**
   * Read the class postfix from the configuration file
   * 
   * @return the full qualified class name
   */
  private String getClassName() {
    String extract_class = settings_.getSetting(SETTINGS_KEY, DEFAULT_LIBRARY);
    return CLASS_PREFIX + extract_class;
  }

  /**
   * Creates a new pdf signature object using the configured pdf library.
   * 
   * @return a new pdf signature object
   * @throws PDFDocumentException ErrorCode:203
   */
  public PDFSignatureObject getPDFSignatureObject() throws PDFDocumentException {
    if (pdfSigObject_ == null) {
      try {
        pdfSigObject_ = createPDFSignatureObject();
      } catch (PDFDocumentException e) {
        e.setErrorCode(203);
        throw e;
      }
      pdfSigObject_.setSignatorObject(sigObject_);
    }
    return pdfSigObject_;
  }
}