/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at legal-notices/CDDLv1_0.txt.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2006-2008 Sun Microsystems, Inc.
 *      Portions Copyright 2014-2015 ForgeRock AS
 */
package org.opends.server.plugins;

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

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.opendj.config.server.ConfigChangeResult;
import org.forgerock.opendj.config.server.ConfigException;
import org.forgerock.opendj.ldap.schema.AttributeUsage;
import org.opends.server.admin.server.ConfigurationChangeListener;
import org.opends.server.admin.std.meta.PluginCfgDefn;
import org.opends.server.admin.std.server.EntryUUIDPluginCfg;
import org.opends.server.admin.std.server.PluginCfg;
import org.opends.server.api.plugin.DirectoryServerPlugin;
import org.opends.server.api.plugin.PluginResult;
import org.opends.server.api.plugin.PluginType;
import org.opends.server.core.DirectoryServer;
import org.opends.server.types.*;
import org.opends.server.types.operation.PreOperationAddOperation;

/**
 * This class implements a Directory Server plugin that will add the entryUUID
 * attribute to an entry whenever it is added or imported as per RFC 4530.  For
 * entries added over LDAP, the entryUUID will be based on a semi-random UUID
 * (which is still guaranteed to be unique).  For entries imported from LDIF,
 * the UUID will be constructed from the entry DN using a repeatable algorithm.
 * This will ensure that LDIF files imported in parallel across multiple systems
 * will have identical entryUUID values.
 */
public final class EntryUUIDPlugin
       extends DirectoryServerPlugin<EntryUUIDPluginCfg>
       implements ConfigurationChangeListener<EntryUUIDPluginCfg>
{
  /**
   * The name of the entryUUID attribute type.
   */
  private static final String ENTRYUUID = "entryuuid";



  /** The attribute type for the "entryUUID" attribute. */
  private final AttributeType entryUUIDType;

  /** The current configuration for this plugin. */
  private EntryUUIDPluginCfg currentConfig;



  /**
   * Creates a new instance of this Directory Server plugin.  Every plugin must
   * implement a default constructor (it is the only one that will be used to
   * create plugins defined in the configuration), and every plugin constructor
   * must call <CODE>super()</CODE> as its first element.
   */
  public EntryUUIDPlugin()
  {
    super();


    // Get the entryUUID attribute type.  This needs to be done in the
    // constructor in order to make the associated variables "final".
    AttributeType at = DirectoryServer.getAttributeTypeOrNull(ENTRYUUID);
    if (at == null)
    {
      String definition =
           "( 1.3.6.1.1.16.4 NAME 'entryUUID' DESC 'UUID of the entry' " +
           "EQUALITY uuidMatch ORDERING uuidOrderingMatch " +
           "SYNTAX 1.3.6.1.1.16.1 SINGLE-VALUE NO-USER-MODIFICATION " +
           "USAGE directoryOperation X-ORIGIN 'RFC 4530' )";

      at = new AttributeType(definition, ENTRYUUID,
                             Collections.singleton(ENTRYUUID), ENTRYUUID, null,
                             null, DirectoryConfig.getDefaultAttributeSyntax(),
                             AttributeUsage.DIRECTORY_OPERATION, false, true,
                             false, true);
    }

    entryUUIDType = at;
  }



  /** {@inheritDoc} */
  @Override
  public final void initializePlugin(Set<PluginType> pluginTypes,
                                     EntryUUIDPluginCfg configuration)
         throws ConfigException
  {
    currentConfig = configuration;
    configuration.addEntryUUIDChangeListener(this);

    // Make sure that the plugin has been enabled for the appropriate types.
    for (PluginType t : pluginTypes)
    {
      switch (t)
      {
        case LDIF_IMPORT:
        case PRE_OPERATION_ADD:
          // These are acceptable.
          break;

        default:
          throw new ConfigException(ERR_PLUGIN_ENTRYUUID_INVALID_PLUGIN_TYPE.get(t));
      }
    }
  }



  /** {@inheritDoc} */
  @Override
  public final void finalizePlugin()
  {
    currentConfig.removeEntryUUIDChangeListener(this);
  }



  /** {@inheritDoc} */
  @Override
  public final PluginResult.ImportLDIF
               doLDIFImport(LDIFImportConfig importConfig, Entry entry)
  {
    // See if the entry being imported already contains an entryUUID attribute.
    // If so, then leave it alone.
    List<Attribute> uuidList = entry.getAttribute(entryUUIDType);
    if (uuidList != null)
    {
      return PluginResult.ImportLDIF.continueEntryProcessing();
    }


    // Construct a new UUID.  In order to make sure that UUIDs are consistent
    // when the same LDIF is generated on multiple servers, we'll base the UUID
    // on the byte representation of the normalized DN.
    byte[] dnBytes = entry.getName().toNormalizedByteString().toByteArray();
    UUID uuid = UUID.nameUUIDFromBytes(dnBytes);

    uuidList = Attributes.createAsList(entryUUIDType, uuid.toString());
    entry.putAttribute(entryUUIDType, uuidList);

    // We shouldn't ever need to return a non-success result.
    return PluginResult.ImportLDIF.continueEntryProcessing();
  }



  /** {@inheritDoc} */
  @Override
  public final PluginResult.PreOperation
               doPreOperation(PreOperationAddOperation addOperation)
  {
    // See if the entry being added already contains an entryUUID attribute.
    // It shouldn't, since it's NO-USER-MODIFICATION, but if it does then leave
    // it alone.
    Map<AttributeType,List<Attribute>> operationalAttributes =
         addOperation.getOperationalAttributes();
    List<Attribute> uuidList = operationalAttributes.get(entryUUIDType);
    if (uuidList != null)
    {
      return PluginResult.PreOperation.continueOperationProcessing();
    }


    // Construct a new random UUID.
    UUID uuid = UUID.randomUUID();
    uuidList = Attributes.createAsList(entryUUIDType, uuid.toString());

    // Add the attribute to the entry and return.
    addOperation.setAttribute(entryUUIDType, uuidList);
    return PluginResult.PreOperation.continueOperationProcessing();
  }



  /** {@inheritDoc} */
  @Override
  public boolean isConfigurationAcceptable(PluginCfg configuration,
                                           List<LocalizableMessage> unacceptableReasons)
  {
    EntryUUIDPluginCfg cfg = (EntryUUIDPluginCfg) configuration;
    return isConfigurationChangeAcceptable(cfg, unacceptableReasons);
  }



  /** {@inheritDoc} */
  @Override
  public boolean isConfigurationChangeAcceptable(
                      EntryUUIDPluginCfg configuration,
                      List<LocalizableMessage> unacceptableReasons)
  {
    boolean configAcceptable = true;

    // Ensure that the set of plugin types contains only LDIF import and
    // pre-operation add.
    for (PluginCfgDefn.PluginType pluginType : configuration.getPluginType())
    {
      switch (pluginType)
      {
        case LDIFIMPORT:
        case PREOPERATIONADD:
          // These are acceptable.
          break;


        default:
          unacceptableReasons.add(ERR_PLUGIN_ENTRYUUID_INVALID_PLUGIN_TYPE.get(pluginType));
          configAcceptable = false;
      }
    }

    return configAcceptable;
  }



  /** {@inheritDoc} */
  @Override
  public ConfigChangeResult applyConfigurationChange(
                                 EntryUUIDPluginCfg configuration)
  {
    currentConfig = configuration;
    return new ConfigChangeResult();
  }
}