/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2009 Sun Microsystems, Inc.
 * Portions Copyright 2013-2015 ForgeRock AS.
 */
package org.opends.server.types;

import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.forgerock.opendj.ldap.ByteSequenceReader;

import org.forgerock.i18n.LocalizableMessage;
import org.opends.server.api.CompressedSchema;
import org.opends.server.core.DirectoryServer;

import static org.opends.messages.CoreMessages.*;

/**
 * This class defines a data structure that contains configuration
 * information about how an entry should be encoded.
 */
@org.opends.server.types.PublicAPI(
     stability=org.opends.server.types.StabilityLevel.VOLATILE,
     mayInstantiate=true,
     mayExtend=false,
     mayInvoke=true)
public final class EntryEncodeConfig
{
  /**
   * The encode mask value that can be used to indicate that the
   * encoded entry should not contain a DN.
   */
  private static final byte ENCODE_FLAG_EXCLUDE_DN = 0x01;



  /**
   * The encode mask value that can be used that the encoded
   * representation should compress the set of object classes.
   */
  private static final byte ENCODE_FLAG_COMPRESS_OCS = 0x02;



  /**
   * The encode mask value that can be used that the encoded
   * representation should compress the set of attribute descriptions
   * to conserve space and improve performance.
   */
  private static final byte ENCODE_FLAG_COMPRESS_ADS = 0x04;



  /**
   * A reference to an entry encode configuration with all the default
   * settings.
   */
  public static final EntryEncodeConfig
       DEFAULT_CONFIG = new EntryEncodeConfig();



  /** Indicates whether to compress the attribute descriptions. */
  private final boolean compressAttrDescriptions;

  /** Indicates whether to compress the object class sets. */
  private final boolean compressObjectClassSets;

  /** Indicates whether to exclude the DN. */
  private final boolean excludeDN;

  /** The encoded representation of this encode configuration. */
  private final byte encodedRepresentation;

  /** The compressed schema handler for this encode configuration. */
  private final CompressedSchema compressedSchema;



  /**
   * Creates a new encoded entry configuration with the default
   * settings.
   */
  public EntryEncodeConfig()
  {
    excludeDN                = false;
    compressAttrDescriptions = false;
    compressObjectClassSets  = false;

    compressedSchema = DirectoryServer.getDefaultCompressedSchema();

    encodedRepresentation = 0x00;
  }



  /**
   * Creates a new encoded entry configuration with the specified
   * settings.
   *
   * @param  excludeDN                 Indicates whether to exclude
   *                                   the DN from the encoded entry.
   * @param  compressAttrDescriptions  Indicates whether to compress
   *                                   attribute descriptions.
   * @param  compressObjectClassSets   Indicates whether to compress
   *                                   object class sets.
   */
  public EntryEncodeConfig(boolean excludeDN,
                           boolean compressAttrDescriptions,
                           boolean compressObjectClassSets)
  {
    this.excludeDN                = excludeDN;
    this.compressAttrDescriptions = compressAttrDescriptions;
    this.compressObjectClassSets  = compressObjectClassSets;

    compressedSchema = DirectoryServer.getDefaultCompressedSchema();

    byte flagByte = 0x00;
    if (excludeDN)
    {
      flagByte |= ENCODE_FLAG_EXCLUDE_DN;
    }

    if (compressAttrDescriptions)
    {
      flagByte |= ENCODE_FLAG_COMPRESS_ADS;
    }

    if (compressObjectClassSets)
    {
      flagByte |= ENCODE_FLAG_COMPRESS_OCS;
    }

    encodedRepresentation = flagByte;
  }



  /**
   * Creates a new encoded entry configuration with the specified
   * settings.
   *
   * @param  excludeDN                 Indicates whether to exclude
   *                                   the DN from the encoded entry.
   * @param  compressAttrDescriptions  Indicates whether to compress
   *                                   attribute descriptions.
   * @param  compressObjectClassSets   Indicates whether to compress
   *                                   object class sets.
   * @param  compressedSchema          The compressed schema manager
   *                                   for this encode config.
   */
  public EntryEncodeConfig(boolean excludeDN,
                           boolean compressAttrDescriptions,
                           boolean compressObjectClassSets,
                           CompressedSchema compressedSchema)
  {
    this.excludeDN                = excludeDN;
    this.compressAttrDescriptions = compressAttrDescriptions;
    this.compressObjectClassSets  = compressObjectClassSets;
    this.compressedSchema         = compressedSchema;

    byte flagByte = 0x00;
    if (excludeDN)
    {
      flagByte |= ENCODE_FLAG_EXCLUDE_DN;
    }

    if (compressAttrDescriptions)
    {
      flagByte |= ENCODE_FLAG_COMPRESS_ADS;
    }

    if (compressObjectClassSets)
    {
      flagByte |= ENCODE_FLAG_COMPRESS_OCS;
    }

    encodedRepresentation = flagByte;
  }



  /**
   * Indicates whether the encoded entry should exclude the DN.
   *
   * @return  {@code true} if the encoded entry should exclude the DN,
   *          or {@code false} if not.
   */
  public boolean excludeDN()
  {
    return excludeDN;
  }



  /**
   * Indicates whether the encoded entry should use compressed
   * attribute descriptions.
   *
   * @return  {@code true} if the encoded entry should use compressed
   *          attribute descriptions, or {@code false} if not.
   */
  public boolean compressAttributeDescriptions()
  {
    return compressAttrDescriptions;
  }



  /**
   * Indicates whether the encoded entry should use compressed object
   * class sets.
   *
   * @return  {@code true} if the encoded entry should use compressed
   *          object class sets, or {@code false} if not.
   */
  public boolean compressObjectClassSets()
  {
    return compressObjectClassSets;
  }



  /**
   * Retrieves the compressed schema manager that may be used to
   * generate compact schema encodings with this entry encode
   * configuration.
   *
   * @return  The compressed schema manager that may be used to
   *          generate compact schema encodings with this entry encode
   *          configuration.
   */
  public CompressedSchema getCompressedSchema()
  {
    return compressedSchema;
  }



  /**
   * Encodes this entry encode configuration into a byte array
   * suitable for inclusion in the encoded entry.
   *
   * @param buffer The buffer to encode this configuration to.
   */
  public void encode(ByteStringBuilder buffer)
  {
    buffer.appendBERLength(1);
    buffer.appendByte(encodedRepresentation);
  }


  /**
   * Decodes the entry encode configuration from current position and
   * length of the given byte array.
   *
   * @param  buffer            The byte array containing the encoded
   *                           entry.
   * @param  length            The number of bytes contained in the
   *                           encode configuration.
   * @param  compressedSchema  The compressed schema manager to use
   *                           when decoding.
   *
   * @return  The decoded configuration.
   *
   * @throws  DirectoryException  If the configuration cannot be
   *                              properly decoded.
   */
  public static EntryEncodeConfig
                     decode(ByteSequenceReader buffer, int length,
                            CompressedSchema compressedSchema)
         throws DirectoryException
  {
    if (length != 1)
    {
      LocalizableMessage message = ERR_ENTRYENCODECFG_INVALID_LENGTH.get();
      throw new DirectoryException(
                     DirectoryServer.getServerErrorResultCode(),
                     message);
    }

    byte b = buffer.readByte();
    boolean excludeDN = is(b, ENCODE_FLAG_EXCLUDE_DN);
    boolean compressAttrDescriptions = is(b, ENCODE_FLAG_COMPRESS_ADS);
    boolean compressObjectClassSets = is(b, ENCODE_FLAG_COMPRESS_OCS);
    return new EntryEncodeConfig(excludeDN, compressAttrDescriptions,
                                 compressObjectClassSets,
                                 compressedSchema);
  }

  private static boolean is(byte b, byte flag)
  {
    return (b & flag) == flag;
  }

  /**
   * Retrieves a string representation of this entry encode
   * configuration.
   *
   * @return  A string representation of this entry encode
   *          configuration.
   */
  public String toString()
  {
    StringBuilder buffer = new StringBuilder();
    toString(buffer);
    return buffer.toString();
  }



  /**
   * Appends a string representation of this entry encode
   * configuration to the provided buffer.
   *
   * @param  buffer  The buffer to which the information should be
   *                 appended.
   */
  public void toString(StringBuilder buffer)
  {
    buffer.append("EntryEncodeConfig(excludeDN=");
    buffer.append(excludeDN);
    buffer.append(", compressAttrDescriptions=");
    buffer.append(compressAttrDescriptions);
    buffer.append(", compressObjectClassSets=");
    buffer.append(compressObjectClassSets);
    buffer.append(")");
  }
}