/*
    *  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.components;
  
  
  import java.nio.BufferOverflowException;
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  
  import org.apache.directory.api.asn1.AbstractAsn1Object;
  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.codec.types.TransitedEncodingType;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * The TransitedEncoding structure.
   * 
   * The ASN.1 grammar is :
   * <pre>
   * -- encoded Transited field
   * TransitedEncoding       ::= SEQUENCE {
   *         tr-type         [0] Int32 -- must be registered --,
   *         contents        [1] OCTET STRING
   * }
   * </pre>
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class TransitedEncoding extends AbstractAsn1Object
  {
      /** The logger */
      private static final Logger log = LoggerFactory.getLogger( TransitedEncoding.class );
  
      /** Speedup for logs */
      private static final boolean IS_DEBUG = log.isDebugEnabled();
  
      /** 
       * The transited type. One of :
       * NULL
       * DOMAIN_X500_COMPRESS
       */
      private TransitedEncodingType trType;
  
      /** The transited data */
      private byte[] contents;
  
      // Storage for computed lengths
      private int trTypeLength;
      private int contentsLength;
      private int transitedEncodingLength;
  
  
      /**
       * Creates a new instance of TransitedEncoding.
       */
      public TransitedEncoding()
      {
          trType = TransitedEncodingType.NULL;
          contents = Strings.EMPTY_BYTES;
      }
  
  
      /**
       * Returns the contents.
       *
       * @return The contents.
       */
      public byte[] getContents()
      {
          return contents;
      }
  
  
      /**
       * Set the contents
      * @param contents The contents
      */
     public void setContents( byte[] contents )
     {
         this.contents = contents;
     }
 
 
     /**
      * Returns the {@link TransitedEncodingType}.
      *
      * @return The {@link TransitedEncodingType}.
      */
     public TransitedEncodingType getTrType()
     {
         return trType;
     }
 
 
     /**
      * Set the transited encoding type
      * @param trType The transited encoding type
      */
     public void setTrType( TransitedEncodingType trType )
     {
         this.trType = trType;
     }
 
 
     /**
      * Compute the TransitedEncoding length
      * 
      * <pre>
      * TransitedEncoding :
      * 
      * 0x30 L1 TransitedEncoding
      *  |
      *  +--> 0xA0 L2 trType tag
      *  |     |
      *  |     +--> 0x02 L2-1 trType (int)
      *  |
      *  +--> 0xA1 L3 contents tag
      *        |
      *        +--> 0x04 L3-1 contents (OCTET STRING)
      *        
      *  where L1 = L2 + lenght(0xA0) + length(L2) +
      *             L3 + lenght(0xA1) + length(L3) 
      *  and
      *  L2 = L2-1 + length(0x02) + length( L2-1) 
      *  L3 = L3-1 + length(0x04) + length( L3-1) 
      *  </pre>
      */
     public int computeLength()
     {
         // Compute the trType. The Length will always be contained in 1 byte
         trTypeLength = 1 + 1 + BerValue.getNbBytes( trType.getValue() );
         transitedEncodingLength = 1 + TLV.getNbBytes( trTypeLength ) + trTypeLength;
 
         // Compute the contents length
         if ( contents == null )
         {
             contentsLength = 1 + 1;
         }
         else
         {
             contentsLength = 1 + TLV.getNbBytes( contents.length ) + contents.length;
         }
 
         transitedEncodingLength += 1 + TLV.getNbBytes( contentsLength ) + contentsLength;
 
         // Compute the whole sequence length
         int transitedEncodingSeqLength = 1 + BerValue.getNbBytes( transitedEncodingLength ) + transitedEncodingLength;
 
         return transitedEncodingSeqLength;
     }
 
 
     /**
      * Encode the TransitedEncoding message to a PDU. 
      * 
      * TransitedEncoding :
      * 
      * 0x30 LL
      *   0xA0 LL 
      *     0x02 0x01 trType
      *   0xA1 LL 
      *     0x04 LL contents
      * 
      * @param buffer The buffer where to put the PDU. It should have been allocated
      * before, with the right size.
      * @return The constructed PDU.
      */
     public ByteBuffer encode( ByteBuffer buffer ) throws EncoderException
     {
         if ( buffer == null )
         {
             throw new EncoderException( I18n.err( I18n.ERR_148 ) );
         }
 
         try
         {
             // The AuthorizationDataEntry SEQ Tag
             buffer.put( UniversalTag.SEQUENCE.getValue() );
             buffer.put( TLV.getBytes( transitedEncodingLength ) );
 
             // The tr-type, first the tag, then the value
             buffer.put( ( byte ) KerberosConstants.TRANSITED_ENCODING_TR_TYPE_TAG );
             buffer.put( TLV.getBytes( trTypeLength ) );
             BerValue.encode( buffer, trType.getValue() );
 
             // The contents, first the tag, then the value
             buffer.put( ( byte ) KerberosConstants.TRANSITED_ENCODING_CONTENTS_TAG );
             buffer.put( TLV.getBytes( contentsLength ) );
             BerValue.encode( buffer, contents );
         }
         catch ( BufferOverflowException boe )
         {
             log.error( I18n.err( I18n.ERR_147, 1 + TLV.getNbBytes( transitedEncodingLength )
                 + transitedEncodingLength, buffer.capacity() ) );
             throw new EncoderException( I18n.err( I18n.ERR_138 ) );
         }
 
         if ( IS_DEBUG )
         {
             log.debug( "TransitedEncoding encoding : {}", Strings.dumpBytes( buffer.array() ) );
             log.debug( "TransitedEncoding initial value : {}", toString() );
         }
 
         return buffer;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = prime * result + Arrays.hashCode( contents );
         result = prime * result + ( ( trType == null ) ? 0 : trType.hashCode() );
         return result;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean equals( Object obj )
     {
         if ( this == obj )
         {
             return true;
         }
 
         if ( obj == null )
         {
             return false;
         }
 
         TransitedEncoding other = ( TransitedEncoding ) obj;
 
         if ( !Arrays.equals( contents, other.contents ) )
         {
             return false;
         }
 
         if ( trType != other.trType )
         {
             return false;
         }
 
         return true;
     }
 
 
     /**
      * @see Object#toString()
      */
     public String toString()
     {
         StringBuilder sb = new StringBuilder();
 
         sb.append( "TransitedEncoding : {\n" );
         sb.append( "    tr-type: " ).append( trType ).append( '\n' );
 
         sb.append( "    contents: " ).append( Strings.dumpBytes( contents ) ).append( "\n}\n" );
 
         return sb.toString();
     }
 }