/*
    *  Licensed to the Apache Software Foundation (ASF) under one
    *  or more contributor license agreements.  See the NOTICE file
    *  distributed with this work for additional information
    *  regarding copyright ownership.  The ASF licenses this file
    *  to you under the Apache 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.apache.org/licenses/LICENSE-2.0
   *  
   *  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.apache.directory.shared.kerberos.messages;
  
  
  import java.nio.BufferOverflowException;
  import java.nio.ByteBuffer;
  
  import org.apache.directory.api.asn1.EncoderException;
  import org.apache.directory.api.asn1.ber.tlv.BerValue;
  import org.apache.directory.api.asn1.ber.tlv.TLV;
  import org.apache.directory.api.asn1.ber.tlv.UniversalTag;
  import org.apache.directory.api.util.Strings;
  import org.apache.directory.server.i18n.I18n;
  import org.apache.directory.shared.kerberos.KerberosConstants;
  import org.apache.directory.shared.kerberos.KerberosMessageType;
  import org.apache.directory.shared.kerberos.KerberosTime;
  import org.apache.directory.shared.kerberos.components.EncryptionKey;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * Encrypted part of the application response.
   *  It will store the object described by the ASN.1 grammar :
   * <pre>
   * EncAPRepPart    ::= [APPLICATION 27] SEQUENCE {
   *         ctime           [0] KerberosTime,
   *         cusec           [1] Microseconds,
   *         subkey          [2] &lt;EncryptionKey&gt; OPTIONAL,
   *         seq-number      [3] UInt32 OPTIONAL
   * }
   * </pre>
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class EncApRepPart extends KerberosMessage
  {
      /** The logger */
      private static final Logger LOG = LoggerFactory.getLogger( EncApRepPart.class );
  
      /** Speedup for logs */
      private static final boolean IS_DEBUG = LOG.isDebugEnabled();
  
      /** The client time */
      private KerberosTime ctime;
  
      /** the microsecond part of the client's timestamp */
      private int cusec;
  
      /** Encryption key */
      private EncryptionKey subkey; //optional
  
      /** Sequence number */
      private Integer seqNumber; //optional
  
      // Storage for computed lengths
      private int ctimeLength;
      private int cusecLength;
      private int subKeyLength;
      private int seqNumberLength;
      private int encApRepPartSeqLength;
      private int encApRepPartLength;
  
  
      /**
       * Creates a new instance of EncApRepPart.
       */
      public EncApRepPart()
      {
          super( KerberosMessageType.ENC_AP_REP_PART );
      }
  
  
      /**
       * Returns the client {@link KerberosTime}.
       *
       * @return The client {@link KerberosTime}.
       */
      public KerberosTime getCTime()
      {
          return ctime;
      }
 
 
     /**
      * @param ctime the ctime to set
      */
     public void setCTime( KerberosTime ctime )
     {
         this.ctime = ctime;
     }
 
 
     /**
      * @return the cusec
      */
     public int getCusec()
     {
         return cusec;
     }
 
 
     /**
      * @param cusec the cusec to set
      */
     public void setCusec( int cusec )
     {
         this.cusec = cusec;
     }
 
 
     /**
      * @return the subkey
      */
     public EncryptionKey getSubkey()
     {
         return subkey;
     }
 
 
     /**
      * @param subkey the subkey to set
      */
     public void setSubkey( EncryptionKey subkey )
     {
         this.subkey = subkey;
     }
 
 
     /**
      * @return the seqNumber
      */
     public Integer getSeqNumber()
     {
         return seqNumber;
     }
 
 
     /**
      * @param seqNumber the seqNumber to set
      */
     public void setSeqNumber( Integer seqNumber )
     {
         this.seqNumber = seqNumber;
     }
 
 
     /**
      * Compute the Authenticator length
      * <pre>
      * Authenticator :
      * 
      * 0x7B L1 EncApRepPart [APPLICATION 27]
      *  |
      *  +--&gt; 0x30 L2 SEQ
      *        |
      *        +--&gt; 0xA0 11 ctime tag
      *        |     |
      *        |     +--&gt; 0x18 0x0F ttt ctime (KerberosTime)
      *        |
      *        +--&gt; 0xA1 L3 cusec tag
      *        |     |
      *        |     +--&gt; 0x02 L3-1 cusec (INTEGER)
      *        |
      *        +--&gt; 0xA2 L4 subkey (EncryptionKey)
      *        |
      *        +--&gt; 0xA3 L5 seq-number tag
      *              |
      *              +--&gt; 0x02 L5-1 NN seq-number (INTEGER)
      * </pre>
      */
     @Override
     public int computeLength()
     {
         // Compute the ctime length.
         ctimeLength = 1 + 1 + 0x0F;
         encApRepPartSeqLength = 1 + TLV.getNbBytes( ctimeLength ) + ctimeLength;
 
         // Compute the cusec length
         cusecLength = 1 + 1 + BerValue.getNbBytes( cusec );
         encApRepPartSeqLength += 1 + TLV.getNbBytes( cusecLength ) + cusecLength;
 
         // Compute the subkey length, if any
         if ( subkey != null )
         {
             subKeyLength = subkey.computeLength();
             encApRepPartSeqLength += 1 + TLV.getNbBytes( subKeyLength ) + subKeyLength;
         }
 
         // Compute the sequence size, if any
         if ( seqNumber != null )
         {
             seqNumberLength = 1 + 1 + BerValue.getNbBytes( seqNumber );
             encApRepPartSeqLength += 1 + TLV.getNbBytes( seqNumberLength ) + seqNumberLength;
         }
 
         encApRepPartLength = 1 + TLV.getNbBytes( encApRepPartSeqLength ) + encApRepPartSeqLength;
 
         return 1 + TLV.getNbBytes( encApRepPartLength ) + encApRepPartLength;
     }
 
 
     /**
      * Encode the EncApRepPart message to a PDU. 
      * <pre>
      * EncApRepPart :
      * 
      * 0x7B LL
      *   0x30 LL
      *     0xA0 0x11 
      *       0x18 0x0F ttt ctime 
      *     0xA1 LL 
      *       0x02 LL NN cusec
      *    [0xA2 LL
      *       0x30 LL abcd] subkey
      *    [0xA3 LL
      *       0x02 LL NN] seq-number
      * </pre>
      * @return The constructed PDU.
      */
     @Override
     public ByteBuffer encode( ByteBuffer buffer ) throws EncoderException
     {
         if ( buffer == null )
         {
             buffer = ByteBuffer.allocate( computeLength() );
         }
 
         try
         {
             // The EncApRepPart APPLICATION Tag
             buffer.put( ( byte ) KerberosConstants.ENC_AP_REP_PART_TAG );
             buffer.put( TLV.getBytes( encApRepPartLength ) );
 
             // The EncApRepPart SEQ Tag
             buffer.put( ( byte ) UniversalTag.SEQUENCE.getValue() );
             buffer.put( TLV.getBytes( encApRepPartSeqLength ) );
 
             // The ctime ------------------------------------------------------
             // The tag
             buffer.put( ( byte ) KerberosConstants.ENC_AP_REP_PART_CTIME_TAG );
             buffer.put( ( byte ) 0x11 );
 
             // The value
             buffer.put( ( byte ) UniversalTag.GENERALIZED_TIME.getValue() );
             buffer.put( ( byte ) 0x0F );
             buffer.put( ctime.getBytes() );
 
             // The cusec ------------------------------------------------------
             // The tag
             buffer.put( ( byte ) KerberosConstants.ENC_AP_REP_PART_CUSEC_TAG );
             buffer.put( TLV.getBytes( cusecLength ) );
 
             // The value
             BerValue.encode( buffer, cusec );
 
             // The subkey if any ----------------------------------------------
             if ( subkey != null )
             {
                 // The tag
                 buffer.put( ( byte ) KerberosConstants.ENC_AP_REP_PART_SUB_KEY_TAG );
                 buffer.put( TLV.getBytes( subKeyLength ) );
 
                 // The value
                 subkey.encode( buffer );
             }
 
             // The seq-number, if any -----------------------------------------
             if ( seqNumber != null )
             {
                 // The tag
                 buffer.put( ( byte ) KerberosConstants.ENC_AP_REP_PART_SEQ_NUMBER_TAG );
                 buffer.put( TLV.getBytes( seqNumberLength ) );
 
                 // The value
                 BerValue.encode( buffer, seqNumber );
             }
 
         }
         catch ( BufferOverflowException boe )
         {
             LOG.error( I18n.err( I18n.ERR_139, 1 + TLV.getNbBytes( encApRepPartLength )
                 + encApRepPartLength, buffer.capacity() ) );
             throw new EncoderException( I18n.err( I18n.ERR_138 ), boe );
         }
 
         if ( IS_DEBUG )
         {
             LOG.debug( "EncApRepPart encoding : {}", Strings.dumpBytes( buffer.array() ) );
             LOG.debug( "EncApRepPart initial value : {}", this );
         }
 
         return buffer;
     }
 
 
     /**
      * @see Object#toString()
      */
     public String toString()
     {
         StringBuilder sb = new StringBuilder();
 
         sb.append( "EncApRepPart : \n" );
 
         sb.append( "    ctime : " ).append( ctime ).append( '\n' );
         sb.append( "    cusec : " ).append( cusec ).append( '\n' );
 
         if ( subkey != null )
         {
             sb.append( "    subkey : " ).append( subkey ).append( '\n' );
         }
 
         if ( seqNumber != null )
         {
             sb.append( "    seq-number : " ).append( seqNumber ).append( '\n' );
         }
 
         return sb.toString();
     }
 }