/**
    * Copyright 2005-2012 The Kuali Foundation
    *
    * Licensed under the Educational Community License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.opensource.org/licenses/ecl2.php
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.kuali.rice.core.api.util;
  
  import org.apache.commons.codec.binary.Base64;
  import org.kuali.rice.core.api.exception.RiceRuntimeException;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.ObjectOutput;
  import java.io.ObjectOutputStream;
  import java.io.UnsupportedEncodingException;
  import java.security.GeneralSecurityException;
  import java.security.MessageDigest;
  
  /**
   * A utility class for generating checksum values from Serializable objects.
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public final class ChecksumUtils {
  
      /**
  	 * Creates a checksum for the given object which must be serializable.
  	 *
  	 * @param object the serializable object for which to calculate the checksum
       * 
  	 * @return A checksum value for the object.
  	 */
  	public static String calculateChecksum(Object object) {
  		ByteArrayOutputStream bos = new ByteArrayOutputStream();
          ObjectOutput out = null;
          try {
              out = new ObjectOutputStream(bos);
              out.writeObject(object);
          } catch (IOException e) {
              throw new RiceRuntimeException(e);
          } finally {
              try {
                  out.close();
              } catch (IOException e) {}
          }
          try {
              MessageDigest md = MessageDigest.getInstance("SHA-1");
              return new String( Base64.encodeBase64(md.digest(bos.toByteArray())), "UTF-8");
          } catch( GeneralSecurityException ex ) {
          	throw new RiceRuntimeException(ex);
          } catch( UnsupportedEncodingException ex ) {
          	throw new RiceRuntimeException(ex);
          }
  	}
  
      @SuppressWarnings("unused")
      private ChecksumUtils() {
          throw new UnsupportedOperationException("Should never be executed.");
      }
  
  }