/*
 * 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
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 *
 *      Copyright 2010-2021 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.Configurable;
import com.unboundid.directory.sdk.common.internal.ExampleUsageProvider;
import com.unboundid.directory.sdk.common.internal.UnboundIDExtension;
import com.unboundid.directory.sdk.sync.config.SyncDestinationConfig;
import com.unboundid.directory.sdk.sync.internal.SynchronizationServerExtension;
import com.unboundid.directory.sdk.sync.types.EndpointException;
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.Modification;
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
 * wish to push changes processed by the Data Sync Server to an
 * arbitrary destination. This type of sync destination is generic and can
 * support a wide range of endpoints. In addition, this type of sync destination
 * supports one-way notifications, where the source and destination entries are
 * never compared but instead changes are pushed straight through.
 *
 * <H2>Configuring Sync Destinations</H2>
 * In order to configure a sync destination created using this API, use
 * a command like:
 * <PRE>
 *      dsconfig create-sync-destination \
 *           --sync-destination-name "<I>{name}</I>" \
 *           --type third-party \
 *           --set "extension-class:<I>{class-name}</I>" \
 *           --set "extension-argument:<I>{name=value}</I>"
 * </PRE>
 * where "<I>{name}</I>" is the name to use for the sync destination
 * instance, "<I>{class-name}</I>" is the fully-qualified name of the Java class
 * that extends
 * {@code com.unboundid.directory.sdk.sync.api.SyncDestination},
 * and "<I>{name=value}</I>" represents name-value pairs for any arguments to
 * provide to the sync destination. If multiple arguments should be
 * provided to extension, then the
 * "<CODE>--set extension-argument:<I>{name=value}</I></CODE>" option should be
 * provided multiple times.
 *
 * @see
 *    com.unboundid.directory.sdk.sync.scripting.ScriptedSyncDestination
 */
@Extensible()
@SynchronizationServerExtension(appliesToLocalContent=false,
                                appliesToSynchronizedContent=true)
@ThreadSafety(level= ThreadSafetyLevel.INTERFACE_THREADSAFE)
public abstract class SyncDestination
       implements UnboundIDExtension,
                  Configurable,
                  ExampleUsageProvider
{
  /**
   * Creates a new instance of this notification destination.  All
   * implementations must include a default constructor, but any
   * initialization should generally be done in the
   * {@link #initializeSyncDestination} method.
   */
  public SyncDestination()
  {
    // No implementation is required.
  }



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



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



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



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



  /**
   * Initializes this sync destination. This hook is called when a Sync Pipe
   * first starts up, or when the <i>resync</i> process first starts up. Any
   * initialization should be performed here. This method should generally store
   * the {@link SyncServerContext} in a class
   * member so that it can be used elsewhere in the implementation.
   * <p>
   * The default implementation is empty.
   *
   * @param  serverContext  A handle to the server context for the server in
   *                        which this extension is running. Extensions should
   *                        typically store this in a class member.
   * @param  config         The general configuration for this object.
   * @param  parser         The argument parser which has been initialized from
   *                        the configuration for this sync destination.
   * @throws  EndpointException
   *                        if a problem occurs while initializing this
   *                        sync destination.
   */
  public void initializeSyncDestination(
                                     final SyncServerContext serverContext,
                                     final SyncDestinationConfig config,
                                     final ArgumentParser parser)
                                       throws EndpointException
  {
    // No initialization will be performed by default.
  }



  /**
   * This hook is called when a Sync Pipe shuts down, or when the <i>resync</i>
   * process shuts down. Any clean-up of this sync destination should be
   * performed here.
   * <p>
   * The default implementation is empty.
   */
  public void finalizeSyncDestination()
  {
    // No implementation is performed by default.
  }



  /**
   * Return the URL or path identifying the destination endpoint
   * to which this extension is transmitting data. This is used for logging
   * purposes only, so it could just be a server name or hostname and port, etc.
   *
   * @return the path to the destination endpoint
   */
  public abstract String getCurrentEndpointURL();



  /**
   * Return a full destination entry (in LDAP form) from the destination
   * endpoint, corresponding to the source {@link Entry} that is passed in.
   * This method should perform any queries necessary to gather the latest
   * values for all the attributes to be synchronized and return them in an
   * Entry.
   * <p>
   * This method only needs to be implemented if the 'synchronization-mode' on
   * the Sync Pipe is set to 'standard'. If it is set to 'notification', this
   * method will never be called, and the pipe will pass changes straight
   * through to one of {@link #createEntry}, {@link #modifyEntry}, or
   * {@link #deleteEntry}.
   * <p>
   * Note that the if the source entry was renamed (see
   * {@link SyncOperation#isModifyDN}), the
   * <code>destEntryMappedFromSrc</code> will have the new DN; the old DN can
   * be obtained by calling
   * {@link SyncOperation#getDestinationEntryBeforeChange()} and getting the DN
   * from there. This method should return the entry in its existing form
   * (i.e. with the old DN, before it is changed).
   * <p>
   * This method <b>must be thread safe</b>, as it will be called repeatedly and
   * concurrently by each of the Sync Pipe worker threads as they process
   * entries.
   * @param destEntryMappedFromSrc
   *          the LDAP entry which corresponds to the destination "entry" to
   *          fetch
   * @param  operation
   *          the sync operation for this change
   * @return a list containing the full LDAP entries that matched this search
   *          (there may be more than one), or an empty list if no such entry
   *          exists
   * @throws EndpointException
   *           if there is an error fetching the entry
   */
  public List<Entry> fetchEntry(final Entry destEntryMappedFromSrc,
                                final SyncOperation operation)
                                  throws EndpointException
  {
    throw new UnsupportedOperationException(
            "The fetchEntry() method must be implemented in the '" +
            getExtensionName() + "' extension if the Sync Pipe is " +
            "running in standard mode (see 'synchronization-mode' " +
            "in the Sync Pipe configuration).");
  }



  /**
   * Creates a full destination "entry", corresponding to the LDAP
   * {@link Entry} that is passed in. This method is responsible for
   * transforming the contents of the entry into the desired format and
   * transmitting it to the target destination. It should perform any inserts or
   * updates necessary to make sure the entry is fully created on the
   * destination endpoint.
   * <p>
   * This method <b>must be thread safe</b>, as it will be called repeatedly and
   * concurrently by the Sync Pipe worker threads as they process CREATE
   * operations.
   * @param entryToCreate
   *          the LDAP entry which corresponds to the destination
   *          "entry" to create
   * @param  operation
   *          the sync operation for this change
   * @throws EndpointException
   *           if there is an error creating the entry
   */
  public abstract void createEntry(final Entry entryToCreate,
                                   final SyncOperation operation)
                                      throws EndpointException;



  /**
   * Modify an "entry" on the destination, corresponding to the LDAP
   * {@link Entry} that is passed in. This method is responsible for
   * transforming the contents of the entry into the desired format and
   * transmitting it to the target destination. It may perform multiple updates
   * (including inserting or deleting other attributes) in order to fully
   * synchronize the entire entry on the destination endpoint.
   * <p>
   * Note that the if the source entry was renamed (see
   * {@link SyncOperation#isModifyDN}), the
   * <code>fetchedDestEntry</code> will have the old DN; the new DN can
   * be obtained by calling
   * {@link SyncOperation#getDestinationEntryAfterChange()} and getting the DN
   * from there.
   * <p>
   * This method <b>must be thread safe</b>, as it will be called repeatedly and
   * concurrently by the Sync Pipe worker threads as they process MODIFY
   * operations.
   * @param entryToModify
   *          the LDAP entry which corresponds to the destination
   *          "entry" to modify. If the synchronization mode is 'standard',
   *          this will be the entry that was returned by {@link #fetchEntry};
   *          otherwise if the synchronization mode is 'notification', this
   *          will be the destination entry mapped from the source entry, before
   *          changes are applied.
   * @param modsToApply
   *          a list of Modification objects which should be applied; these will
   *          have any configured attribute mappings already applied
   * @param  operation
   *          the sync operation for this change
   * @throws EndpointException
   *           if there is an error modifying the entry
   */
  public abstract void modifyEntry(final Entry entryToModify,
                                   final List<Modification> modsToApply,
                                   final SyncOperation operation)
                                          throws EndpointException;



  /**
   * Delete a full "entry" from the destination, corresponding to the LDAP
   * {@link Entry} that is passed in. This method may perform multiple deletes
   * or updates if necessary to fully delete the entry from the destination
   * endpoint.
   * <p>
   * This method <b>must be thread safe</b>, as it will be called repeatedly and
   * concurrently by the Sync Pipe worker threads as they process DELETE
   * operations.
   * @param entryToDelete
   *          the LDAP entry which corresponds to the destination
   *          "entry" to delete. If the synchronization mode is 'standard',
   *          this will be the entry that was returned by {@link #fetchEntry};
   *          otherwise if the synchronization mode is 'notification', this
   *          will be the mapped destination entry.
   * @param  operation
   *          the sync operation for this change
   * @throws EndpointException
   *           if there is an error deleting the entry
   */
  public abstract void deleteEntry(final Entry entryToDelete,
                                   final SyncOperation operation)
                                        throws EndpointException;
}