/*
 * 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
 * docs/licenses/cddl.txt
 * or http://www.opensource.org/licenses/cddl1.php.
 * 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
 * docs/licenses/cddl.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]
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 *
 *      Copyright 2010-2020 Ping Identity Corporation
 */
package com.unboundid.directory.sdk.sync.api;



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

import com.unboundid.directory.sdk.common.internal.ExampleUsageProvider;
import com.unboundid.directory.sdk.common.internal.Reconfigurable;
import com.unboundid.directory.sdk.common.internal.UnboundIDExtension;
import com.unboundid.directory.sdk.sync.config.LDAPSyncDestinationPluginConfig;
import com.unboundid.directory.sdk.sync.internal.SynchronizationServerExtension;
import com.unboundid.directory.sdk.sync.scripting.
            ScriptedLDAPSyncDestinationPlugin;
import com.unboundid.directory.sdk.sync.types.PostStepResult;
import com.unboundid.directory.sdk.sync.types.PreStepResult;
import com.unboundid.directory.sdk.sync.types.SyncOperation;
import com.unboundid.directory.sdk.sync.types.SyncServerContext;
import com.unboundid.ldap.sdk.Entry;
import com.unboundid.ldap.sdk.LDAPException;
import com.unboundid.ldap.sdk.LDAPInterface;
import com.unboundid.ldap.sdk.Modification;
import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.ldap.sdk.SearchRequest;
import com.unboundid.ldap.sdk.UpdatableLDAPRequest;
import com.unboundid.util.Extensible;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
import com.unboundid.util.args.ArgumentException;
import com.unboundid.util.args.ArgumentParser;



/**
 * This class defines an API that must be implemented by extensions that
 * perform processing on synchronization operations within an LDAP Sync
 * Destination.  These extensions may be used to
 * <ul>
 *   <li>Filter out certain changes from being synchronized.</li>
 *   <li>Change how an entry is fetched.</li>
 *   <li>Change how an entry is modified or created.</li>
 * </ul>
 * <BR>
 * A note on exception handling: in general subclasses should not
 * catch LDAPExceptions that are thrown when using the provided
 * LDAPInterface unless there are specific exceptions that are
 * expected.  The Data Sync Server will handle
 * LDAPExceptions in an appropriate way based on the specific
 * cause of the exception.  For example, some errors will result
 * in the SyncOperation being retried, and others will trigger
 * fail over to a different server.
 * <BR>
 * <H2>Configuring LDAP Sync Destination Plugins</H2>
 * In order to configure an LDAP sync destination plugin created using this API,
 * use a command like:
 * <PRE>
 *      dsconfig create-sync-destination-plugin \
 *           --plugin-name "<I>{plugin-name}</I>" \
 *           --type third-party-ldap \
 *           --set "extension-class:<I>{class-name}</I>" \
 *           --set "extension-argument:<I>{name=value}</I>"
 * </PRE>
 * where "<I>{plugin-name}</I>" is the name to use for the LDAP sync destination
 * plugin instance, "<I>{class-name}</I>" is the fully-qualified name of the
 * Java class that extends
 * {@code com.unboundid.directory.sdk.sync.api.LDAPSyncDestinationPlugin}, and
 * "<I>{name=value}</I>" represents name-value pairs for any arguments to
 * provide to the LDAP sync destination plugin.  If multiple arguments should be
 * provided to the LDAP sync destination plugin, then the
 * "<CODE>--set extension-argument:<I>{name=value}</I></CODE>" option should be
 * provided multiple times.
 *
 * @see  ScriptedLDAPSyncDestinationPlugin
 */
@Extensible()
@SynchronizationServerExtension(appliesToLocalContent=false,
     appliesToSynchronizedContent=true)
@ThreadSafety(level= ThreadSafetyLevel.INTERFACE_THREADSAFE)
public abstract class LDAPSyncDestinationPlugin
       implements UnboundIDExtension,
                  Reconfigurable<LDAPSyncDestinationPluginConfig>,
                  ExampleUsageProvider
{
  /**
   * Creates a new instance of this LDAP sync destination plugin.  All sync
   * destination implementations must include a default constructor, but any
   * initialization should generally be done in the
   * {@code initializeLDAPSyncDestinationPlugin} method.
   */
  public LDAPSyncDestinationPlugin()
  {
    // No implementation is required.  However, we need to reference the
    // scripted LDAP sync destination plugin so that checkstyle is satisfied
    // with the import.
    final ScriptedLDAPSyncDestinationPlugin scriptedPlugin = null;
  }



  /**
   * {@inheritDoc}
   */
  public abstract String getExtensionName();



  /**
   * {@inheritDoc}
   */
  public abstract String[] getExtensionDescription();



  /**
   * {@inheritDoc}
   */
  public void defineConfigArguments(final ArgumentParser parser)
         throws ArgumentException
  {
    // No arguments will be allowed by default.
  }



  /**
   * Initializes this LDAP sync destination plugin.  This method will be called
   * before any other methods in the class.
   *
   * @param  serverContext  A handle to the server context for the
   *                        Data Sync Server in which this extension is
   *                        running.  Extensions should typically store this
   *                        in a class member.
   * @param  config         The general configuration for this proxy
   *                        transformation.
   * @param  parser         The argument parser which has been initialized from
   *                        the configuration for this LDAP sync destination
   *                        plugin.
   *
   * @throws  LDAPException  If a problem occurs while initializing this ldap
   *                         sync destination plugin.
   */
  public void initializeLDAPSyncDestinationPlugin(
                   final SyncServerContext serverContext,
                   final LDAPSyncDestinationPluginConfig config,
                   final ArgumentParser parser)
         throws LDAPException
  {
    // No initialization will be performed by default.
  }



  /**
   * {@inheritDoc}
   */
  public boolean isConfigurationAcceptable(
                      final LDAPSyncDestinationPluginConfig config,
                      final ArgumentParser parser,
                      final List<String> unacceptableReasons)
  {
    // No extended validation will be performed by default.
    return true;
  }



  /**
   * {@inheritDoc}
   */
  public ResultCode applyConfiguration(
                         final LDAPSyncDestinationPluginConfig config,
                         final ArgumentParser parser,
                         final List<String> adminActionsRequired,
                         final List<String> messages)
  {
    // By default, no configuration changes will be applied.
    return ResultCode.SUCCESS;
  }



  /**
   * Performs any cleanup which may be necessary when this LDAP sync destination
   * plugin is taken out of service.  This can happen when it is deleted from
   * the configuration and at server shutdown.
   */
  public void finalizeLDAPSyncDestinationPlugin()
  {
    // No implementation is required.
  }



  /**
   * This method is called before a destination entry is fetched.  A
   * connection to the destination server is provided along with the
   * {@code SearchRequest} that will be sent to the server.  This method is
   * overridden by plugins that need to have access to the search request
   * before it is sent to the destination server.  This includes updating the
   * search request as well as performing the search instead of the core server,
   * including doing additional searches.  For plugins that need to manipulate
   * the entries that the core LDAP Sync Destination code retrieves from the
   * destination, implementing the {@link #postFetch} method is more natural.
   * <p>
   * This method might be called multiple times for a single synchronization
   * operation, specifically when there are multiple search criteria or
   * multiple base DNs defined for the Sync Destination.
   *
   * @param  destinationConnection  A connection to the destination server.
   * @param  searchRequest          The search request that the LDAP Sync
   *                                Destination will use to fetch the entry.
   * @param  fetchedEntries         A list of entries that have been fetched.
   *                                When the search criteria matches multiple
   *                                entries, they should all be returned.  A
   *                                plugin that wishes to implement the fetch
   *                                should put the fetched entries here and
   *                                return
   *                                {@code PreStepResult#SKIP_CURRENT_STEP}.
   * @param  operation              The synchronization operation for this
   *                                change.
   *
   * @return  The result of the plugin processing. Be very careful when
   *          returning {@code PreStepResult#RETRY_OPERATION_UNLIMITED} as this
   *          can stall all in flight operations until this operation completes.
   *          This return value should only be used in situations where a
   *          remote service (e.g., the LDAP server) is unavailable. In this
   *          case, it's preferable to just throw the underlying LDAPException,
   *          which the Data Sync Server will handle correctly based on
   *          the type of the operation. Note:
   *          {@code PreStepResult#SKIP_CURRENT_STEP} should only be returned
   *          if this plugin takes responsibility for fully fetching the entry
   *          according to the search request and for populating the
   *          fetched entry list.
   *
   * @throws  LDAPException  In general subclasses should not catch
   *                         LDAPExceptions that are thrown when
   *                         using the LDAPInterface unless there
   *                         are specific exceptions that are
   *                         expected.  The Data Sync Server
   *                         will handle LDAPExceptions in an
   *                         appropriate way based on the specific
   *                         cause of the exception.  For example,
   *                         some errors will result in the
   *                         SyncOperation being retried, and others
   *                         will trigger fail over to a different
   *                         server.  Plugins should only throw
   *                         LDAPException for errors related to
   *                         communication with the LDAP server.
   *                         Use the return code to indicate other
   *                         types of errors, which might require
   *                         retry.
   */
  public PreStepResult preFetch(final LDAPInterface destinationConnection,
                                final SearchRequest searchRequest,
                                final List<Entry> fetchedEntries,
                                final SyncOperation operation)
       throws LDAPException
  {
    return PreStepResult.CONTINUE;
  }



  /**
   * This method is called after an attempt to fetch a destination entry.  An
   * connection to the destination server is provided along with the
   * {@code SearchRequest} that was sent to the server.  This method is
   * overridden by plugins that need to manipulate the search results that
   * are returned to the Sync Pipe.  This can include filtering out certain
   * entries, remove information from the entries, or adding additional
   * information, possibly by doing a followup LDAP search.
   * <p>
   * This method might be called multiple times for a single synchronization
   * operation, specifically when there are multiple search criteria or
   * multiple base DNs defined for the Sync Destination.
   * <p>
   * This method will not be called if the search fails, for instance, if
   * the base DN of the search does not exist.
   *
   * @param  destinationConnection  A connection to the destination server.
   * @param  searchRequest          The search request that the LDAP Sync
   *                                Destination used to fetch the entry.
   * @param  fetchedEntries         A list of entries that have been fetched.
   *                                When the search criteria matches multiple
   *                                entries, they will all be returned.  Entries
   *                                in this list can be edited directly, and the
   *                                list can be edited as well.
   * @param  operation              The synchronization operation for this
   *                                change.
   *
   * @return  The result of the plugin processing. Be very careful when
   *          returning {@code PostStepResult#RETRY_OPERATION_UNLIMITED} as this
   *          can stall all in flight operations until this operation completes.
   *          This return value should only be used in situations where a
   *          remote service (e.g., the LDAP server) is unavailable. In this
   *          case, it's preferable to just throw the underlying LDAPException,
   *          which the Data Sync Server will handle correctly based on
   *          the type of the operation.
   *
   * @throws  LDAPException  In general subclasses should not catch
   *                         LDAPExceptions that are thrown when
   *                         using the LDAPInterface unless there
   *                         are specific exceptions that are
   *                         expected.  The Data Sync Server
   *                         will handle LDAPExceptions in an
   *                         appropriate way based on the specific
   *                         cause of the exception.  For example,
   *                         some errors will result in the
   *                         SyncOperation being retried, and others
   *                         will trigger fail over to a different
   *                         server.  Plugins should only throw
   *                         LDAPException for errors related to
   *                         communication with the LDAP server.
   *                         Use the return code to indicate other
   *                         types of errors, which might require
   *                         retry.
   */
  public PostStepResult postFetch(final LDAPInterface destinationConnection,
                                  final SearchRequest searchRequest,
                                  final List<Entry> fetchedEntries,
                                  final SyncOperation operation)
       throws LDAPException
  {
    return PostStepResult.CONTINUE;
  }



  /**
   * This method is called before a destination entry is created.  A
   * connection to the destination server is provided along with the
   * {@code Entry} that will be sent to the server.  This method is
   * overridden by plugins that need to alter the entry before it is created
   * at the server.
   *
   * @param  destinationConnection  A connection to the destination server.
   * @param  entryToCreate          The entry that will be created at the
   *                                destination.  A plugin that wishes to
   *                                create the entry should be sure to return
   *                                {@code PreStepResult#SKIP_CURRENT_STEP}.
   * @param  operation              The synchronization operation for this
   *                                change.
   *
   * @return  The result of the plugin processing. Be very careful when
   *          returning {@code PreStepResult#RETRY_OPERATION_UNLIMITED} as this
   *          can stall all in flight operations until this operation completes.
   *          This return value should only be used in situations where a
   *          remote service (e.g., the LDAP server) is unavailable. In this
   *          case, it's preferable to just throw the underlying LDAPException,
   *          which the Data Sync Server will handle correctly based on
   *          the type of the operation.
   *
   * @throws  LDAPException  In general subclasses should not catch
   *                         LDAPExceptions that are thrown when
   *                         using the LDAPInterface unless there
   *                         are specific exceptions that are
   *                         expected.  The Data Sync Server
   *                         will handle LDAPExceptions in an
   *                         appropriate way based on the specific
   *                         cause of the exception.  For example,
   *                         some errors will result in the
   *                         SyncOperation being retried, and others
   *                         will trigger fail over to a different
   *                         server.  Plugins should only throw
   *                         LDAPException for errors related to
   *                         communication with the LDAP server.
   *                         Use the return code to indicate other
   *                         types of errors, which might require
   *                         retry.
   */
  public PreStepResult preCreate(final LDAPInterface destinationConnection,
                                 final Entry entryToCreate,
                                 final SyncOperation operation)
       throws LDAPException
  {
    return PreStepResult.CONTINUE;
  }



  /**
   * This method is called before a destination entry is modified.  A
   * connection to the destination server is provided along with the
   * {@code Entry} that will be sent to the server.  This method is
   * overridden by plugins that need to perform some processing on an entry
   * before it is modified.
   *
   * @param  destinationConnection  A connection to the destination server.
   * @param  entryToModify          The entry that will be modified at the
   *                                destination.  A plugin that wishes to
   *                                modify the entry should be sure to return
   *                                {@code PreStepResult#SKIP_CURRENT_STEP}.
   * @param  modsToApply            A modifiable list of the modifications to
   *                                apply at the server.
   * @param  operation              The synchronization operation for this
   *                                change.
   *
   * @return  The result of the plugin processing. Be very careful when
   *          returning {@code PreStepResult#RETRY_OPERATION_UNLIMITED} as this
   *          can stall all in flight operations until this operation completes.
   *          This return value should only be used in situations where a
   *          remote service (e.g., the LDAP server) is unavailable. In this
   *          case, it's preferable to just throw the underlying LDAPException,
   *          which the Data Sync Server will handle correctly based on
   *          the type of the operation.
   *
   * @throws  LDAPException  In general subclasses should not catch
   *                         LDAPExceptions that are thrown when
   *                         using the LDAPInterface unless there
   *                         are specific exceptions that are
   *                         expected.  The Data Sync Server
   *                         will handle LDAPExceptions in an
   *                         appropriate way based on the specific
   *                         cause of the exception.  For example,
   *                         some errors will result in the
   *                         SyncOperation being retried, and others
   *                         will trigger fail over to a different
   *                         server.  Plugins should only throw
   *                         LDAPException for errors related to
   *                         communication with the LDAP server.
   *                         Use the return code to indicate other
   *                         types of errors, which might require
   *                         retry.
   */
  public PreStepResult preModify(final LDAPInterface destinationConnection,
                                 final Entry entryToModify,
                                 final List<Modification> modsToApply,
                                 final SyncOperation operation)
       throws LDAPException
  {
    return PreStepResult.CONTINUE;
  }



  /**
   * This method is called before a destination entry is deleted.  A
   * connection to the destination server is provided along with the
   * {@code Entry} that will be sent to the server.  This method is
   * overridden by plugins that need to perform some processing on an entry
   * before it is deleted.  A plugin could choose to mark an entry as disabled
   * instead of deleting it for instance, or move the entry to a different
   * part of the directory hierarchy.
   *
   * @param  destinationConnection  A connection to the destination server.
   * @param  entryToDelete          The entry that will be deleted at the
   *                                destination.  A plugin that wishes to
   *                                delete the entry should be sure to return
   *                                {@code PreStepResult#SKIP_CURRENT_STEP}.
   * @param  operation              The synchronization operation for this
   *                                change.
   *
   * @return  The result of the plugin processing. Be very careful when
   *          returning {@code PreStepResult#RETRY_OPERATION_UNLIMITED} as this
   *          can stall all in flight operations until this operation completes.
   *          This return value should only be used in situations where a
   *          remote service (e.g., the LDAP server) is unavailable. In this
   *          case, it's preferable to just throw the underlying LDAPException,
   *          which the Data Sync Server will handle correctly based on
   *          the type of the operation.
   *
   * @throws  LDAPException  In general subclasses should not catch
   *                         LDAPExceptions that are thrown when
   *                         using the LDAPInterface unless there
   *                         are specific exceptions that are
   *                         expected.  The Data Sync Server
   *                         will handle LDAPExceptions in an
   *                         appropriate way based on the specific
   *                         cause of the exception.  For example,
   *                         some errors will result in the
   *                         SyncOperation being retried, and others
   *                         will trigger fail over to a different
   *                         server.  Plugins should only throw
   *                         LDAPException for errors related to
   *                         communication with the LDAP server.
   *                         Use the return code to indicate other
   *                         types of errors, which might require
   *                         retry.
   */
  public PreStepResult preDelete(final LDAPInterface destinationConnection,
                                 final Entry entryToDelete,
                                 final SyncOperation operation)
       throws LDAPException
  {
    return PreStepResult.CONTINUE;
  }



  /**
   * This method is called prior to executing any add, modify, delete, or
   * search from the destination but after the respective pre method (e.g
   * preFetch or preModify). A connection to the destination server is provided
   * along with the {@code UpdatableLDAPRequest} that will be sent to the
   * server. this method is overridden by plugins that need to modify the
   * LDAP request prior to execution. For example, attaching a {@code Control}
   * to the request. Callers of this method can use {@code instanceof}
   * to determine which type of LDAP request is being made.
   *
   * @param destinationConnection A connection to the destination server.
   * @param request               The LDAP request that will be sent to
   *                              the destination server.
   * @param operation             The synchronization operation for this
   *                              change.
   *
   * @return  The result of the plugin processing. Be very careful when
   *          returning {@code PreStepResult#RETRY_OPERATION_UNLIMITED} as this
   *          can stall all in flight operations until this operation completes.
   *          This return value should only be used in situations where a
   *          remote service (e.g., the LDAP server) is unavailable. In this
   *          case, it's preferable to just throw the underlying LDAPException,
   *          which the Data Sync Server will handle correctly based on
   *          the type of the operation.
   *
   * @throws  LDAPException  In general subclasses should not catch
   *                         LDAPExceptions that are thrown when
   *                         using the LDAPInterface unless there
   *                         are specific exceptions that are
   *                         expected.  The Data Sync Server
   *                         will handle LDAPExceptions in an
   *                         appropriate way based on the specific
   *                         cause of the exception.  For example,
   *                         some errors will result in the
   *                         SyncOperation being retried, and others
   *                         will trigger fail over to a different
   *                         server.  Plugins should only throw
   *                         LDAPException for errors related to
   *                         communication with the LDAP server.
   *                         Use the return code to indicate other
   *                         types of errors, which might require
   *                         retry.
   */
  public PreStepResult transformRequest(
          final LDAPInterface destinationConnection,
          final UpdatableLDAPRequest request,
          final SyncOperation operation)
    throws LDAPException
  {
    return PreStepResult.CONTINUE;
  }



  /**
   * Retrieves a string representation of this LDAP sync destination plugin.
   *
   * @return  A string representation of this LDAP sync destination plugin.
   */
  @Override()
  public final String toString()
  {
    final StringBuilder buffer = new StringBuilder();
    toString(buffer);
    return buffer.toString();
  }



  /**
   * Appends a string representation of this LDAP sync destination plugin to the
   * provided buffer.
   *
   * @param  buffer  The buffer to which the string representation should be
   *                 appended.
   */
  public abstract void toString(final StringBuilder buffer);



  /**
   * {@inheritDoc}
   */
  public Map<List<String>,String> getExamplesArgumentSets()
  {
    return Collections.emptyMap();
  }
}