/*
 * 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:
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 * CDDL HEADER END
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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.SyncPipePluginConfig;
import com.unboundid.directory.sdk.sync.internal.SynchronizationServerExtension;
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.ResultCode;
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 the Sync Pipe.  These
 * extensions may be used to
 * <ul>
 *   <li>Filter out certain changes from being synchronized.</li>
 *   <li>Add and remove attributes that should be synchronized with the
 *       destination independent of whether they changed at the source or
 *       not.</li>
 *   <li>Manipulate the changes that are synchronized to ignore certain
 *       modified attributes or change the representation of modified
 *       attributes.</li>
 *   <li>Skip certain steps in Sync Pipe processing, e.g. attribute
 *       and DN mapping.</li>
 * </ul>
 * Most plugins will need to override the {@code postMapping} method but not
 * the {@code preMapping} method.  These extensions do not have access to the
 * Sync Source or Sync Destination.
 * <BR>
 * <H2>Configuring Sync Pipe Plugins</H2>
 * In order to configure a sync pipe plugin created using this API, use a
 * command like:
 * <PRE>
 *      dsconfig create-sync-pipe-plugin \
 *           --plugin-name "<I>{plugin-name}</I>" \
 *           --type third-party \
 *           --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 sync pipe plugin
 * instance, "<I>{class-name}</I>" is the fully-qualified name of the Java class
 * that extends {@code com.unboundid.directory.sdk.sync.api.SyncPipePlugin},
 * and "<I>{name=value}</I>" represents name-value pairs for any arguments to
 * provide to the sync pipe plugin.  If multiple arguments should be provided to
 * the sync pipe plugin, then the
 * "<CODE>--set extension-argument:<I>{name=value}</I></CODE>" option should be
 * provided multiple times.
 *
 * @see  com.unboundid.directory.sdk.sync.scripting.ScriptedSyncPipePlugin
 */
@Extensible()
@SynchronizationServerExtension(appliesToLocalContent=false,
     appliesToSynchronizedContent=true)
@ThreadSafety(level= ThreadSafetyLevel.INTERFACE_THREADSAFE)
public abstract class SyncPipePlugin
       implements UnboundIDExtension, Reconfigurable<SyncPipePluginConfig>,
        ExampleUsageProvider
{
  /**
   * Creates a new instance of this sync pipe plugin.  All sync pipe plugin
   * implementations must include a default constructor, but any
   * initialization should generally be done in the
   * {@code initializeSyncPipePlugin} method.
   */
  public SyncPipePlugin()
  {
    // No implementation is required.
  }



  /**
   * {@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 sync pipe 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 sync pipe plugin.
   *
   * @throws  LDAPException  If a problem occurs while initializing this sync
   *                         pipe plugin.
   */
  public void initializeSyncPipePlugin(final SyncServerContext serverContext,
                                       final SyncPipePluginConfig config,
                                       final ArgumentParser parser)
         throws LDAPException
  {
    // No initialization will be performed by default.
  }



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



  /**
   * {@inheritDoc}
   */
  public ResultCode applyConfiguration(final SyncPipePluginConfig 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 sync pipe plugin
   * is taken out of service.  This can happen when it is deleted from the
   * configuration and at server shutdown.
   */
  public void finalizeSyncPipePlugin()
  {
    // No implementation is required.
  }



  /**
   * This method is called immediately before the attributes and DN in
   * the source entry are mapped into the equivalent destination entry.
   * This equivalent destination entry is then compared to the actual
   * destination entry to determine which of the modified attributes need
   * to be updated.
   * <p>
   * This method is typically used to either filter out certain changes
   * (by returning {@link PreStepResult#ABORT_OPERATION}) or to manipulate the
   * source entry before it is converted into an equivalent destination entry.
   * Attributes that will not otherwise be affected by attribute mapping
   * can be set in {@code equivalentDestinationEntry}.  Although, due to the
   * possibility of being overwritten in the mapping phase, manipulation of
   * {@code equivalentDestinationEntry} is typically reserved for the
   * {@link #postMapping} method.
   * <p>
   * The set of source attributes that should be synchronized at the destination
   * can be manipulated by calling
   * {@link SyncOperation#addModifiedSourceAttribute} and
   * {@link SyncOperation#removeModifiedSourceAttribute} on
   * {@code operation}.
   * <p>
   * Additional steps must be taken if this plugin adds destination attributes
   * in {@code equivalentDestinationEntry} that need to be modified at the
   * destination.  For operations with an operation type of
   * {@link com.unboundid.directory.sdk.sync.types.SyncOperationType#CREATE},
   * any updates made to
   * {@code equivalentDestinationEntry} will be included in the
   * entry created at the destination.  However, for operations with an
   * operation type of
   * {@link com.unboundid.directory.sdk.sync.types.SyncOperationType#MODIFY},
   * destination attributes
   * added by this plugin that need to be modified must be updated
   * explicitly by calling
   * {@link SyncOperation#addModifiedDestinationAttribute}.
   * <p>
   * With the exception of aborting changes or skipping the mapping step
   * completely, most plugins will not need to override this method since
   * the {@link #postMapping} method has access to the fully mapped destination
   * entry.
   *
   * @param  sourceEntry                 The entry that was fetched from the
   *                                     source.
   * @param  equivalentDestinationEntry  The destination entry that is
   *                                     equivalent to the source.  This entry
   *                                     will be empty except for any
   *                                     modifications that have been performed
   *                                     by other sync pipe plugins.
   * @param  operation                   The operation that is being
   *                                     synchronized.
   *
   * @return  The result of the plugin processing.  Note:
   *          {@code PreStepResult#3SKIP_CURRENT_STEP} should only be returned
   *          if this plugin takes responsibility for fully constructing the
   *          equivalent destination entry.
   */
  public PreStepResult preMapping(final Entry sourceEntry,
                                  final Entry equivalentDestinationEntry,
                                  final SyncOperation operation)
  {
    return PreStepResult.CONTINUE;
  }



  /**
   * This method is called immediately after the attributes and DN in
   * the source entry are mapped into the equivalent destination entry.
   * Once this mapping is complete, this equivalent destination entry is then
   * compared to the actual destination entry to determine which of the modified
   * attributes need to be updated.
   * <p>
   * This method is typically used to manipulate the equivalent destination
   * entry before these necessary changes are calculated.  It can also be used
   * to filter out certain changes (by returning
   * {@link PostStepResult#ABORT_OPERATION}), but this is typically done in
   * the {@link #preMapping} method.
   * <p>
   * The set of source attributes that should be synchronized at the destination
   * can be manipulated by calling
   * {@link SyncOperation#addModifiedSourceAttribute} and
   * {@link SyncOperation#removeModifiedSourceAttribute} on
   * {@code operation}.
   * <p>
   * Additional steps must be taken if this plugin adds destination attributes
   * in {@code equivalentDestinationEntry} that need to be modified at the
   * destination.  For operations with an operation type of
   * {@link com.unboundid.directory.sdk.sync.types.SyncOperationType#CREATE},
   * any updates made to
   * {@code equivalentDestinationEntry} will be included in the
   * entry created at the destination.  However, for operations with an
   * operation type of
   * {@link com.unboundid.directory.sdk.sync.types.SyncOperationType#MODIFY},
   * destination attributes
   * added by this plugin that need to be modified must be updated
   * explicitly by calling
   * {@link SyncOperation#addModifiedDestinationAttribute}.
   * <p>
   * With the exception of aborting changes or skipping the mapping step
   * completely, most plugins will override this method instead of
   * {@link #preMapping} because this method has access to the fully mapped
   * destination entry.
   *
   * @param  sourceEntry                 The entry that was fetched from the
   *                                     source.
   * @param  equivalentDestinationEntry  The destination entry that is
   *                                     equivalent to the source.  This entry
   *                                     will include all attributes mapped
   *                                     from the source entry.
   * @param  operation                   The operation that is being
   *                                     synchronized.
   *
   * @return  The result of the plugin processing.
   */
  public PostStepResult postMapping(final Entry sourceEntry,
                                    final Entry equivalentDestinationEntry,
                                    final SyncOperation operation)
  {
    return PostStepResult.CONTINUE;
  }



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



  /**
   * Appends a string representation of this sync pipe 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();
  }
}