/**
 * <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.web.helper;

import java.util.Date;

import org.apache.commons.lang.time.DateFormatUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import at.gv.egiz.pdfas.exceptions.ErrorCode;
import at.knowcenter.wag.egov.egiz.exceptions.SettingsException;
import at.knowcenter.wag.egov.egiz.exceptions.SignatureException;

/**
 * This class deals with invalid signing times. 
 * @author tknall
 */
public final class SigningTimeHelper {
   
   private SigningTimeHelper() {
   }
   
   private static Integer tolerance = null;
   
   /**
    * The log.
    */
   private final static Log LOG = LogFactory.getLog(SigningTimeHelper.class);
   
   private final static String FORMAT_UTC_DATE_PATTERN = "yyyy-MM-dd'T'HH:mm:ss'Z'";
   
   public static synchronized void checkSigningTimeAgainstHostTime(Date signingTime) throws SignatureException {
      if (tolerance == null) {
         try {
            String toleranceString = WebSettingsReader.getInstance().getSigningTimeTolerance();
            if (toleranceString != null) {
               tolerance = new Integer(Integer.parseInt(toleranceString));
            } else {
               LOG.warn("Configuration key signingtimetolerance missing. Disabling signing time check.");
               tolerance = new Integer(-1);
            }
         } catch (NumberFormatException e) {
            LOG.warn("Invalid configuration key signingtimetolerance. Disabling signing time check.");
            tolerance = new Integer(-1);
         } catch (SettingsException e) {
            LOG.warn("Invalid configuration key signingtimetolerance. Disabling signing time check.");
            tolerance = new Integer(-1);
         }
      }
      if (tolerance.intValue() == -1) {
         return;
      }
      
      // current time
      Date currentTime = new Date();
      
      // lower limit
      Date lowerLimit = new Date(currentTime.getTime() - tolerance.intValue()*1000);
      
      // upper limit
      Date upperLimit = new Date(currentTime.getTime() + tolerance.intValue()*1000);
      
      String signingTimeString = DateFormatUtils.formatUTC(signingTime, FORMAT_UTC_DATE_PATTERN);
      
      if (LOG.isDebugEnabled()) {
         String lower = DateFormatUtils.formatUTC(lowerLimit, FORMAT_UTC_DATE_PATTERN);
         String upper = DateFormatUtils.formatUTC(upperLimit, FORMAT_UTC_DATE_PATTERN);
         LOG.debug("Checking if signing time " + signingTimeString + " is valid according to the given time frame [ " + lower + ", " + upper + " ].");
      }
      
      if (signingTime.before(lowerLimit) || signingTime.after(upperLimit)) {
         throw new SignatureException(ErrorCode.INVALID_SIGNING_TIME, "The signing time " + signingTimeString + " is out of the given tolerance of " + tolerance.intValue() + " seconds.");
      }
      
   }
   
}