/*
    *  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.api.ldap.codec.controls.search.pagedSearch;
  
  
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  
  import org.apache.directory.api.asn1.Asn1Object;
  import org.apache.directory.api.asn1.DecoderException;
  import org.apache.directory.api.asn1.EncoderException;
  import org.apache.directory.api.asn1.ber.Asn1Decoder;
  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.i18n.I18n;
  import org.apache.directory.api.ldap.codec.api.ControlDecorator;
  import org.apache.directory.api.ldap.codec.api.LdapApiService;
  import org.apache.directory.api.ldap.model.message.controls.PagedResults;
  import org.apache.directory.api.ldap.model.message.controls.PagedResultsImpl;
  import org.apache.directory.api.util.Strings;
  
  
  /**
   * A codec decorator for the {@link PagedResultsImpl}.
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class PagedResultsDecorator extends ControlDecorator<PagedResults> implements PagedResults
  {
      /** The entry change global length */
      private int pscSeqLength;
  
      /** An instance of this decoder */
      private static final Asn1Decoder decoder = new Asn1Decoder();
  
  
      /**
       * Creates a new instance of PagedResultsDecorator with a newly created decorated
       * PagedResults Control.
       */
      public PagedResultsDecorator( LdapApiService codec )
      {
          this( codec, new PagedResultsImpl() );
      }
  
  
      /**
       * Creates a new instance of PagedResultsDecorator using the supplied PagedResults
       * Control to be decorated.
       *
       * @param  pagedResults The PagedResults Control to be decorated.
       */
      public PagedResultsDecorator( LdapApiService codec, PagedResults pagedResults )
      {
          super( codec, pagedResults );
      }
  
  
      /**
       * Compute the PagedSearchControl length, which is the sum
       * of the control length and the value length.
       * 
       * <pre>
       * PagedSearchControl value length :
       * 
       * 0x30 L1 
       *   | 
       *   +--> 0x02 0x0(1-4) [0..2^63-1] (size) 
       *   +--> 0x04 L2 (cookie)
       * </pre> 
       */
      public int computeLength()
      {
          int sizeLength = 1 + 1 + BerValue.getNbBytes( getSize() );
  
          int cookieLength;
  
          if ( getCookie() != null )
          {
              cookieLength = 1 + TLV.getNbBytes( getCookie().length ) + getCookie().length;
          }
         else
         {
             cookieLength = 1 + 1;
         }
 
         pscSeqLength = sizeLength + cookieLength;
         valueLength = 1 + TLV.getNbBytes( pscSeqLength ) + pscSeqLength;
 
         return valueLength;
     }
 
 
     /**
      * Encodes the paged search control.
      * 
      * @param buffer The encoded sink
      * @return A ByteBuffer that contains the encoded PDU
      * @throws EncoderException If anything goes wrong.
      */
     public ByteBuffer encode( ByteBuffer buffer ) throws EncoderException
     {
         if ( buffer == null )
         {
             throw new EncoderException( I18n.err( I18n.ERR_04023 ) );
         }
 
         // Now encode the PagedSearch specific part
         buffer.put( UniversalTag.SEQUENCE.getValue() );
         buffer.put( TLV.getBytes( pscSeqLength ) );
 
         BerValue.encode( buffer, getSize() );
         BerValue.encode( buffer, getCookie() );
 
         return buffer;
     }
 
 
     /**
      * {@inheritDoc}
      */
     public byte[] getValue()
     {
         if ( value == null )
         {
             try
             {
                 computeLength();
                 ByteBuffer buffer = ByteBuffer.allocate( valueLength );
 
                 // Now encode the PagedSearch specific part
                 buffer.put( UniversalTag.SEQUENCE.getValue() );
                 buffer.put( TLV.getBytes( pscSeqLength ) );
 
                 BerValue.encode( buffer, getSize() );
                 BerValue.encode( buffer, getCookie() );
 
                 value = buffer.array();
             }
             catch ( Exception e )
             {
                 return null;
             }
         }
 
         return value;
     }
 
 
     /**
      * @return The requested or returned number of entries
      */
     public int getSize()
     {
         return getDecorated().getSize();
     }
 
 
     /**
      * Set the number of entry requested or returned
      *
      * @param size The number of entries 
      */
     public void setSize( int size )
     {
         getDecorated().setSize( size );
     }
 
 
     /**
      * @return The stored cookie
      */
     public byte[] getCookie()
     {
         return getDecorated().getCookie();
     }
 
 
     /**
      * Set the cookie
      *
      * @param cookie The cookie to store in this control
      */
     public void setCookie( byte[] cookie )
     {
         // Copy the bytes
         if ( !Strings.isEmpty( cookie ) )
         {
             byte[] copy = new byte[cookie.length];
             System.arraycopy( cookie, 0, copy, 0, cookie.length );
             getDecorated().setCookie( copy );
         }
         else
         {
             getDecorated().setCookie( null );
         }
     }
 
 
     /**
      * @return The integer value for the current cookie
      */
     public int getCookieValue()
     {
         int value = 0;
 
         switch ( getCookie().length )
         {
             case 1:
                 value = getCookie()[0] & 0x00FF;
                 break;
 
             case 2:
                 value = ( ( getCookie()[0] & 0x00FF ) << 8 ) + ( getCookie()[1] & 0x00FF );
                 break;
 
             case 3:
                 value = ( ( getCookie()[0] & 0x00FF ) << 16 ) + ( ( getCookie()[1] & 0x00FF ) << 8 )
                     + ( getCookie()[2] & 0x00FF );
                 break;
 
             case 4:
                 value = ( ( getCookie()[0] & 0x00FF ) << 24 ) + ( ( getCookie()[1] & 0x00FF ) << 16 )
                     + ( ( getCookie()[2] & 0x00FF ) << 8 ) + ( getCookie()[3] & 0x00FF );
                 break;
 
         }
 
         return value;
     }
 
 
     /**
      * @see Object#hashCode()
      */
     @Override
     public int hashCode()
     {
         int hash = super.hashCode();
 
         hash = hash * 17 + pscSeqLength;
 
         return hash;
     }
 
 
     /**
      * @see Object#equals(Object)
      */
     @Override
     public boolean equals( Object o )
     {
         if ( !super.equals( o ) )
         {
             return false;
         }
 
         PagedResults otherControl = ( PagedResults ) o;
 
         return ( getSize() == otherControl.getSize() ) && Arrays.equals( getCookie(), otherControl.getCookie() );
     }
 
 
     /**
      * Return a String representing this PagedSearchControl.
      */
     public String toString()
     {
         StringBuffer sb = new StringBuffer();
 
         sb.append( "    Paged Search Control\n" );
         sb.append( "        oid : " ).append( getOid() ).append( '\n' );
         sb.append( "        critical : " ).append( isCritical() ).append( '\n' );
         sb.append( "        size   : '" ).append( getSize() ).append( "'\n" );
         sb.append( "        cookie   : '" ).append( Strings.dumpBytes( getCookie() ) ).append( "'\n" );
 
         return sb.toString();
     }
 
 
     /**
      * {@inheritDoc}
      */
     public Asn1Object decode( byte[] controlBytes ) throws DecoderException
     {
         ByteBuffer bb = ByteBuffer.wrap( controlBytes );
         PagedResultsContainer container = new PagedResultsContainer( getCodecService(), this );
         decoder.decode( bb, container );
         return this;
     }
 }