/*
 * 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
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * 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
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  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 2009-2010 Sun Microsystems, Inc.
 *      Portions Copyright 2010 ForgeRock AS
 */
package org.opends.server.replication.server;

import static org.opends.messages.ReplicationMessages.*;
import static org.opends.server.loggers.ErrorLogger.logError;
import static org.opends.server.loggers.debug.DebugLogger.debugEnabled;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.zip.DataFormatException;

import org.opends.messages.Category;
import org.opends.messages.Message;
import org.opends.messages.Severity;
import org.opends.server.replication.common.ChangeNumber;
import org.opends.server.replication.common.MultiDomainServerState;
import org.opends.server.replication.common.ServerState;
import org.opends.server.replication.common.ServerStatus;
import org.opends.server.replication.protocol.*;
import org.opends.server.types.Attribute;
import org.opends.server.types.Attributes;
import org.opends.server.types.DebugLogLevel;
import org.opends.server.types.DirectoryException;
import org.opends.server.types.ResultCode;
import org.opends.server.util.ServerConstants;

/**
 * This class defines a server handler, which handles all interaction with a
 * peer replication server.
 */
public class ECLServerHandler extends ServerHandler
{

  // This is a string identifying the operation, provided by the client part
  // of the ECL, used to help interpretation of messages logged.
  String operationId;

  // Iterator on the draftCN database.
  private DraftCNDbIterator draftCNDbIter = null;

  boolean draftCompat = false;
  /**
   * Specifies the last draft changer number (seqnum) requested.
   */
  public int lastDraftCN = 0;
  /**
   * Specifies whether the draft change number (seqnum) db has been read until
   * its end.
   */
  public boolean isEndOfDraftCNReached = false;
  /**
   * Specifies whether the current search has been requested to be persistent
   * or not.
   */
  public short isPersistent;
  /**
   * Specifies the current search phase : INIT or PERSISTENT.
   */
  public int searchPhase = INIT_PHASE;
  /**
   * Specifies the cookie contained in the request, specifying where
   * to start serving the ECL.
   */
  public String startCookie;
  /**
   * Specifies the value of the cookie before the change currently processed
   * is returned. It is updated with the change number of the change
   * currently processed (thus becoming the "current" cookie just
   * before the change is returned.
   */
  public MultiDomainServerState previousCookie =
    new MultiDomainServerState();
  /**
   * Specifies the excluded DNs (like cn=admin, ...).
   */
  public ArrayList<String> excludedServiceIDs = new ArrayList<String>();
  //HashSet<String> excludedServiceIDs = new HashSet<String>();

  /**
   * Eligible changeNumber - only changes older or equal to eligibleCN
   * are published in the ECL.
   */
  public ChangeNumber eligibleCN = null;

  /**
   * Provides a string representation of this object.
   * @return the string representation.
   */
  public String dumpState()
  {
    return new String(
        this.getClass().getCanonicalName() +
        "[" +
        "[draftCompat=" + draftCompat +
        "] [persistent=" + isPersistent +
        "] [lastDraftCN=" + lastDraftCN +
        "] [isEndOfDraftCNReached=" + isEndOfDraftCNReached +
        "] [searchPhase=" + searchPhase +
        "] [startCookie=" + startCookie +
        "] [previousCookie=" + previousCookie +
    "]]");
  }

  /**
   * Class that manages the 'by domain' state variables for the search being
   * currently processed on the ECL.
   * For example :
   * if search on 'cn=changelog' is being processed when 2 replicated domains
   * dc=us and dc=europe are configured, then there will be 2 DomainContext
   * used, one for ds=us, and one for dc=europe.
   */
  private class DomainContext
  {
    ReplicationServerDomain rsd;

    boolean active;              // active when there are still changes
    // supposed eligible for the ECL.

    MessageHandler mh;           // the message handler from which are read
    // the changes for this domain
    private UpdateMsg nextMsg;
    private UpdateMsg nextNonEligibleMsg;
    ServerState startState;
    ServerState currentState;
    ServerState stopState;
    long domainLatestTrimDate;

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString()
    {
      StringBuilder buffer = new StringBuilder();
      toString(buffer);
      return buffer.toString();
    }
    /**
     * Provide a string representation of this object for debug purpose..
     */
    public void toString(StringBuilder buffer)
    {
      buffer.append(
          "[ [active=" + active +
          "] [rsd=" + rsd +
          "] [nextMsg=" + nextMsg + "(" +
          (nextMsg != null?
              new Date(nextMsg.getChangeNumber().getTime()).toString():"")
              + ")" +
              "] [nextNonEligibleMsg="      + nextNonEligibleMsg +
              "] [startState=" + startState +
              "] [stopState= " + stopState +
              "] [currentState= " + currentState + "]]");
    }

    /**
     * Get the next message elligible regarding
     * the crossDomain elligible CN. Put it in the context table.
     * @param opid The operation id.
     */
    private void getNextEligibleMessageForDomain(String opid)
    {
      if (debugEnabled())
        TRACER.debugInfo(" In ECLServerHandler, for " + mh.getServiceId() +
          " getNextEligibleMessageForDomain(" + opid+ ") "
          + "ctxt=" + toString());

      assert(nextMsg == null);
      try
      {
        // Before get a new message from the domain, evaluate in priority
        // a message that has not been published to the ECL because it was
        // not eligible
        if (nextNonEligibleMsg != null)
        {
          boolean hasBecomeEligible =
            (nextNonEligibleMsg.getChangeNumber().getTime()
                <= eligibleCN.getTime());

          if (debugEnabled())
            TRACER.debugInfo(" In ECLServerHandler, for " + mh.getServiceId() +
                " getNextEligibleMessageForDomain(" + opid+ ") "
              + " stored nonEligibleMsg " + nextNonEligibleMsg
              + " has now become eligible regarding "
              + " the eligibleCN ("+ eligibleCN
              + " ):" + hasBecomeEligible);

          if (hasBecomeEligible)
          {
            // it is now elligible
            nextMsg = nextNonEligibleMsg;
            nextNonEligibleMsg = null;
          }
          else
          {
            // the oldest is still not elligible - let's wait next
          }
        }
        else
        {
          // Here comes a new message !!!
          // non blocking
          UpdateMsg newMsg;
          do {
            newMsg = mh.getnextMessage(false);
            // when the replication changelog is trimmed, the last (latest) chg
            // is left in the db (whatever its age), and we don't want this chg
            // to be returned in the external changelog.
            // So let's check if the chg time is older than the trim date
          } while ((newMsg!=null) &&
              (newMsg.getChangeNumber().getTime() < domainLatestTrimDate));

          if (debugEnabled())
            TRACER.debugInfo(" In ECLServerHandler, for " + mh.getServiceId() +
                " getNextEligibleMessageForDomain(" + opid+ ") "
                + " got new message : "
                +  " serviceId=[" + mh.getServiceId()
                + "] [newMsg=" + newMsg + "]" + dumpState());

          // in non blocking mode, return null when no more msg
          if (newMsg != null)
          {
            boolean isEligible = (newMsg.getChangeNumber().getTime()
                <= eligibleCN.getTime());

          if (debugEnabled())
              TRACER.debugInfo(" In ECLServerHandler, for " + mh.getServiceId()
                + " getNextEligibleMessageForDomain(" + opid+ ") "
                + "newMsg isEligible=" + isEligible + " since "
                + "newMsg=[" + newMsg.getChangeNumber()
                + " " + new Date(newMsg.getChangeNumber().getTime()).toString()
                + "] eligibleCN=[" + eligibleCN
                + " " + new Date(eligibleCN.getTime()).toString()+"]"
                + dumpState());

            if (isEligible)
            {
              nextMsg = newMsg;
            }
            else
            {
              nextNonEligibleMsg = newMsg;
            }
          }
        }
      }
      catch(Exception e)
      {
        TRACER.debugCaught(DebugLogLevel.ERROR, e);
      }
    }
  }

  // The global list of contexts by domain for the search currently processed.
  DomainContext[] domainCtxts = new DomainContext[0];

  private String clDomCtxtsToString(String msg)
  {
    StringBuilder buffer = new StringBuilder();
    buffer.append(msg+"\n");
    for (int i=0;i<domainCtxts.length;i++)
    {
      domainCtxts[i].toString(buffer);
      buffer.append("\n");
    }
    return buffer.toString();
  }

  static int UNDEFINED_PHASE = 0;
  static int INIT_PHASE = 1;
  static int PERSISTENT_PHASE = 2;

  /**
   * Starts this handler based on a start message received from remote server.
   * @param inECLStartMsg The start msg provided by the remote server.
   * @return Whether the remote server requires encryption or not.
   * @throws DirectoryException When a problem occurs.
   */
  public boolean processStartFromRemote(ServerStartECLMsg inECLStartMsg)
  throws DirectoryException
  {
    try
    {
      protocolVersion = ProtocolVersion.minWithCurrent(
          inECLStartMsg.getVersion());
      generationId = inECLStartMsg.getGenerationId();
      serverURL = inECLStartMsg.getServerURL();
      setInitialServerState(inECLStartMsg.getServerState());
      setSendWindowSize(inECLStartMsg.getWindowSize());
      if (protocolVersion > ProtocolVersion.REPLICATION_PROTOCOL_V1)
      {
        // We support connection from a V1 RS
        // Only V2 protocol has the group id in repl server start message
        this.groupId = inECLStartMsg.getGroupId();
      }
    }
    catch(Exception e)
    {
      Message message = Message.raw(e.getLocalizedMessage());
      throw new DirectoryException(ResultCode.OTHER, message);
    }
    return inECLStartMsg.getSSLEncryption();
  }

  /**
   * Send the ReplServerStartDSMsg to the remote ECL server.
   * @param requestedProtocolVersion The provided protocol version.
   * @return The StartMsg sent.
   * @throws IOException When an exception occurs.
   */
  private StartMsg sendStartToRemote(short requestedProtocolVersion)
  throws IOException
  {
    // Before V4 protocol, we sent a ReplServerStartMsg
    if (protocolVersion < ProtocolVersion.REPLICATION_PROTOCOL_V4)
    {

      // Peer DS uses protocol < V4 : send it a ReplServerStartMsg
      ReplServerStartMsg outReplServerStartMsg
      = new ReplServerStartMsg(
          replicationServerId,
          replicationServerURL,
          getServiceId(),
          maxRcvWindow,
          replicationServerDomain.getDbServerState(),
          protocolVersion,
          localGenerationId,
          sslEncryption,
          getLocalGroupId(),
          replicationServerDomain.
          getReplicationServer().getDegradedStatusThreshold());

      session.publish(outReplServerStartMsg, requestedProtocolVersion);

      return outReplServerStartMsg;
    }
    else
    {
      // Peer DS uses protocol V4 : send it a ReplServerStartDSMsg
      ReplServerStartDSMsg outReplServerStartDSMsg
      = new ReplServerStartDSMsg(
          replicationServerId,
          replicationServerURL,
          getServiceId(),
          maxRcvWindow,
          new ServerState(),
          protocolVersion,
          localGenerationId,
          sslEncryption,
          getLocalGroupId(),
          0,
          replicationServer.getWeight(),
          0);


      session.publish(outReplServerStartDSMsg);
      return outReplServerStartDSMsg;
    }
  }

  /**
   * Creates a new handler object to a remote replication server.
   * @param session The session with the remote RS.
   * @param queueSize The queue size to manage updates to that RS.
   * @param replicationServerURL The hosting local RS URL.
   * @param replicationServerId The hosting local RS serverId.
   * @param replicationServer The hosting local RS object.
   * @param rcvWindowSize The receiving window size.
   */
  public ECLServerHandler(
      ProtocolSession session,
      int queueSize,
      String replicationServerURL,
      int replicationServerId,
      ReplicationServer replicationServer,
      int rcvWindowSize)
  {
    super(session, queueSize, replicationServerURL, replicationServerId,
        replicationServer, rcvWindowSize);
    try
    {
      setServiceIdAndDomain(ServerConstants.DN_EXTERNAL_CHANGELOG_ROOT, true);
    }
    catch(DirectoryException de)
    {
      // no chance to have a bad domain set here
    }


  }

  /**
   * Creates a new handler object to a remote replication server.
   * @param replicationServerURL The hosting local RS URL.
   * @param replicationServerId The hosting local RS serverId.
   * @param replicationServer The hosting local RS object.
   * @param startECLSessionMsg the start parameters.
   * @throws DirectoryException when an errors occurs.
   */
  public ECLServerHandler(
      String replicationServerURL,
      int replicationServerId,
      ReplicationServer replicationServer,
      StartECLSessionMsg startECLSessionMsg)
  throws DirectoryException
  {
    // queueSize is hard coded to 1 else super class hangs for some reason
    super(null, 1, replicationServerURL, replicationServerId,
        replicationServer, 0);
    try
    {
      setServiceIdAndDomain(ServerConstants.DN_EXTERNAL_CHANGELOG_ROOT, true);
    }
    catch(DirectoryException de)
    {
      // no chance to have a bad domain set here
    }
    this.initialize(startECLSessionMsg);
  }

  /**
   * Starts the handler from a remote start message received from
   * the remote server.
   * @param inECLStartMsg The provided ReplServerStart message received.
   */
  public void startFromRemoteServer(ServerStartECLMsg inECLStartMsg)
  {
    try
    {
      // Process start from remote
      boolean sessionInitiatorSSLEncryption =
        processStartFromRemote(inECLStartMsg);

      // lock with timeout
      if (this.replicationServerDomain != null)
        lockDomain(true);

      this.localGenerationId = -1;

      // send start to remote
      StartMsg outStartMsg =
        sendStartToRemote(protocolVersion);

      // log
      logStartHandshakeRCVandSND(inECLStartMsg, outStartMsg);

      // until here session is encrypted then it depends on the negociation
      // The session initiator decides whether to use SSL.
      if (!sessionInitiatorSSLEncryption)
        session.stopEncryption();

      // wait and process StartSessionMsg from remote RS
      StartECLSessionMsg inStartECLSessionMsg =
        waitAndProcessStartSessionECLFromRemoteServer();
      if (inStartECLSessionMsg == null)
        {
          // client wants to properly close the connection (client sent a
          // StopMsg)
          logStopReceived();
          abortStart(null);
          return;
        }

      logStartECLSessionHandshake(inStartECLSessionMsg);

      // initialization
      initialize(inStartECLSessionMsg);
    }
    catch(DirectoryException de)
    {
      abortStart(de.getMessageObject());
    }
    catch(Exception e)
    {
      abortStart(Message.raw(e.getLocalizedMessage()));
    }
    finally
    {
      if ((replicationServerDomain != null) &&
          replicationServerDomain.hasLock())
      {
        replicationServerDomain.release();
      }
    }
  }

  /**
   * Wait receiving the StartSessionMsg from the remote DS and process it.
   * @return the startSessionMsg received
   * @throws DirectoryException
   * @throws IOException
   * @throws ClassNotFoundException
   * @throws DataFormatException
   * @throws NotSupportedOldVersionPDUException
   */
  private StartECLSessionMsg waitAndProcessStartSessionECLFromRemoteServer()
  throws DirectoryException, IOException, ClassNotFoundException,
  DataFormatException,
  NotSupportedOldVersionPDUException
  {
    ReplicationMsg msg = null;
    msg = session.receive();

    if (msg instanceof StopMsg)
    {
      // client wants to stop handshake (was just for handshake phase one for RS
      // choice). Return null to make the session be terminated.
      return null;
    } else if (!(msg instanceof StartECLSessionMsg))
    {
      Message message = Message.raw(
          "Protocol error: StartECLSessionMsg required." + msg + " received.");
      abortStart(message);
    }

    // Process StartSessionMsg sent by remote DS
    StartECLSessionMsg startECLSessionMsg = (StartECLSessionMsg) msg;

    return startECLSessionMsg;
  }

  /**
   * Initialize the handler from a provided cookie value.
   * @param crossDomainStartState The provided cookie value.
   * @throws DirectoryException When an error is raised.
   */
  public void initializeCLSearchFromGenState(String crossDomainStartState)
  throws DirectoryException
  {
    initializeCLDomCtxts(crossDomainStartState, false);
  }

  /**
   * Initialize the handler from a provided draft first change number.
   * @param startDraftCN The provided draft first change number.
   * @throws DirectoryException When an error is raised.
   */
  public void initializeCLSearchFromDraftCN(int startDraftCN)
  throws DirectoryException
  {
    String crossDomainStartState;
    try
    {
      draftCompat = true;

      DraftCNDbHandler draftCNDb = replicationServer.getDraftCNDbHandler();

      // Any (optimizable) condition on draft CN in the request filter ?
      if (startDraftCN <= 1)
      {
        // Request filter DOES NOT contain any firstDraftCN
        // So we'll generate from the beginning of what we have stored here.

        // Get starting state from first DraftCN from DraftCNdb
        if (draftCNDb.count() == 0)
        {
        // DraftCNdb IS EMPTY hence start from what we have in the changelog db.
          isEndOfDraftCNReached = true;
          crossDomainStartState = null;
        }
        else
        {
          // DraftCNdb IS NOT EMPTY hence start from
          // the generalizedServerState related to the start of the draftDb
          crossDomainStartState = draftCNDb.getValue(draftCNDb.getFirstKey());

          // And get an iterator to traverse the draftCNDb
          draftCNDbIter =
              draftCNDb.generateIterator(draftCNDb.getFirstKey());
        }
      }
      else
      {
        // Request filter DOES contain a startDraftCN

        // Read the draftCNDb to see whether it contains startDraftCN
        crossDomainStartState = draftCNDb.getValue(startDraftCN);

        if (crossDomainStartState != null)
        {
          // startDraftCN (from the request filter) is present in the draftCnDb
          // Get an iterator to traverse the draftCNDb
          draftCNDbIter =
            draftCNDb.generateIterator(startDraftCN);
        }
        else
        {
          // startDraftCN provided in the request IS NOT in the DraftCNDb

          // Is the provided startDraftCN <= the potential last DraftCN

          // Get the draftLimits (from the eligibleCN got at the beginning of
          // the operation) in order to have the potential last DraftCN.
          int[] limits = replicationServer.getECLDraftCNLimits(
              eligibleCN, excludedServiceIDs);

          if (startDraftCN<=limits[1])
          {
          // startDraftCN is between first and potential last and has never been
            // returned yet
            if (draftCNDb.count() == 0)
            {
              // db is empty
              isEndOfDraftCNReached = true;
              crossDomainStartState = null;
            }
            else
            {
             crossDomainStartState = draftCNDb.getValue(draftCNDb.getLastKey());
              draftCNDbIter =
                  draftCNDb.generateIterator(draftCNDb.getLastKey());
            }
            // TODO:ECL ... ok we'll start from the end of the draftCNDb BUT ...
            // this may be very long. Work on perf improvement here.
          }
          else
          {
            // startDraftCN is > the potential last DraftCN
            throw new DirectoryException(ResultCode.SUCCESS, Message.raw(""));
          }
        }
      }
      this.draftCompat = true;

      initializeCLDomCtxts(crossDomainStartState, true);
    }
    catch(DirectoryException de)
    {
      TRACER.debugCaught(DebugLogLevel.ERROR, de);
      if (draftCNDbIter != null)
        draftCNDbIter.releaseCursor();
      throw(de);
    }
    catch(Exception e)
    {
      TRACER.debugCaught(DebugLogLevel.ERROR, e);
      if (draftCNDbIter != null)
        draftCNDbIter.releaseCursor();
      throw new DirectoryException(
          ResultCode.OPERATIONS_ERROR,
          Message.raw(Category.SYNC,
              Severity.FATAL_ERROR,e.getLocalizedMessage()));
    }
  }

  /**
   * Initialize the context for each domain.
   * @param  providedCookie the provided generalized state
   * @param  allowUnknownDomains Provides all changes for domains not included
   *           in the provided cookie.
   * @throws DirectoryException When an error occurs.
   */
  public void initializeCLDomCtxts(String providedCookie,
      boolean allowUnknownDomains)
  throws DirectoryException
  {
    // This map is initialized from the providedCookie.
    // Below, it will be traversed and each domain configured with ECL will be
    // checked and removed from the map.
    // At the end, normally the map should be empty.
    // Depending on allowUnknownDomains provided flag, a non empty map will
    // be considered as an error when allowUnknownDomains is false.
    HashMap<String,ServerState> startStatesFromProvidedCookie =
      new HashMap<String,ServerState>();

    ReplicationServer rs = this.replicationServer;

    // Parse the provided cookie and overwrite startState from it.
    if ((providedCookie != null) && (providedCookie.length()!=0))
      startStatesFromProvidedCookie =
        MultiDomainServerState.splitGenStateToServerStates(providedCookie);

    try
    {
      Iterator<ReplicationServerDomain> rsdi = rs.getDomainIterator();

      // Creates the table that will contain the real-time info for each
      // and every domain.
      HashSet<DomainContext> tmpSet = new HashSet<DomainContext>();
      String missingDomains = "";
      int i =0;
      if (rsdi != null)
      {
        while (rsdi.hasNext())
        {
          // process a domain
          ReplicationServerDomain rsd = rsdi.next();

          // skip the 'unreal' changelog domain
          if (rsd == this.replicationServerDomain)
            continue;

          // skip the excluded domains
          if (excludedServiceIDs.contains(rsd.getBaseDn()))
          {
            // this is an excluded domain
            if (allowUnknownDomains)
              startStatesFromProvidedCookie.remove(rsd.getBaseDn());
            continue;
          }

          // skip unused domains
          if (rsd.getDbServerState().isEmpty())
            continue;

          // Creates the new domain context
          DomainContext newDomainCtxt = new DomainContext();
          newDomainCtxt.active = true;
          newDomainCtxt.rsd = rsd;
          newDomainCtxt.domainLatestTrimDate = rsd.getLatestDomainTrimDate();

          // Assign the start state for the domain
          if (isPersistent ==
            StartECLSessionMsg.PERSISTENT_CHANGES_ONLY)
          {
            newDomainCtxt.startState = rsd.getEligibleState(eligibleCN, true);
            startStatesFromProvidedCookie.remove(rsd.getBaseDn());
          }
          else
          {
            // let's take the start state for this domain from the provided
            // cookie
            newDomainCtxt.startState =
              startStatesFromProvidedCookie.remove(rsd.getBaseDn());

            if ((providedCookie==null)||(providedCookie.length()==0)
                ||allowUnknownDomains)
            {
              // when there is no cookie provided in the request,
              // let's start traversing this domain from the beginning of
              // what we have in the replication changelog
              if (newDomainCtxt.startState == null)
                newDomainCtxt.startState = new ServerState();
            }
            else
            {
              // when there is a cookie provided in the request,
              if (newDomainCtxt.startState == null)
              {
                missingDomains += (rsd.getBaseDn() + ":;");
                continue;
              }
              else if (!newDomainCtxt.startState.isEmpty())
              {
                // when the provided startState is older than the replication
                // changelogdb start state, it means that the replication
                // changelog db has been trimed and the cookie is not valid
                // anymore.
                boolean cookieTooOld = false;
                for (int serverId : rsd.getStartState())
                {
                  ChangeNumber dbOldestChange =
                    rsd.getStartState().getMaxChangeNumber(serverId);
                  ChangeNumber providedChange =
                    newDomainCtxt.startState.getMaxChangeNumber(serverId);
                  if ((providedChange != null)
                      && (providedChange.older(dbOldestChange)))
                  {
                    cookieTooOld=true;
                  }
                }

                if (cookieTooOld)
                {
                  // the provided start
                  throw new DirectoryException(ResultCode.UNWILLING_TO_PERFORM,
                      ERR_RESYNC_REQUIRED_TOO_OLD_DOMAIN_IN_PROVIDED_COOKIE.get(
                          newDomainCtxt.rsd.getBaseDn()));
                }
              }
            }

            // Set the stop state for the domain from the eligibleCN
            newDomainCtxt.stopState = rsd.getEligibleState(eligibleCN, true);
          }
          newDomainCtxt.currentState = new ServerState();

          // Creates an unconnected SH for the domain
          MessageHandler mh = new MessageHandler(maxQueueSize,
              replicationServerURL, replicationServerId, replicationServer);
          // set initial state
          mh.setInitialServerState(newDomainCtxt.startState);
          // set serviceID and domain
          mh.setServiceIdAndDomain(rsd.getBaseDn(), false);
          // register the unconnected into the domain
          rsd.registerHandler(mh);
          newDomainCtxt.mh = mh;

          previousCookie.update(
              newDomainCtxt.rsd.getBaseDn(),
              newDomainCtxt.startState);

          // store the new context
          tmpSet.add(newDomainCtxt);
          i++;
        }
      }

      if (missingDomains.length()>0)
      {
        // If there are domain missing in the provided cookie,
        // the request is rejected and a full resync is required.
        throw new DirectoryException(ResultCode.UNWILLING_TO_PERFORM,
          ERR_RESYNC_REQUIRED_MISSING_DOMAIN_IN_PROVIDED_COOKIE.get(
              missingDomains,
              "<" + (providedCookie + missingDomains)+ ">"));
      }

      domainCtxts = tmpSet.toArray(new DomainContext[0]);

      // When it is valid to have the provided cookie containing unknown domains
      // (allowUnknownDomains is true), 2 cases must be considered :
      // - if the cookie contains a domain that is replicated but where
      //   ECL is disabled, then this case is considered above
      // - if the cookie contains a domain that is even not replicated
      //   then this case need to be considered here in another loop.
      if (!startStatesFromProvidedCookie.isEmpty())
      {
        if (allowUnknownDomains)
          for (String providedDomain : startStatesFromProvidedCookie.keySet())
            if (rs.getReplicationServerDomain(providedDomain, false) == null)
              // the domain provided in the cookie is not replicated
              startStatesFromProvidedCookie.remove(providedDomain);
      }

      // Now do the final checking
      if (!startStatesFromProvidedCookie.isEmpty())
      {
        // After reading all the known domains from the provided cookie, there
        // is one (or several) domain that are not currently configured.
        // This domain has probably been removed or replication disabled on it.
        // The request is rejected and full resync is required.
        String unknownDomains = startStatesFromProvidedCookie.toString();
        String possibleCookie = "";
        for (int j=0; j<domainCtxts.length; j++)
        {
          possibleCookie += (domainCtxts[j].rsd.getBaseDn() + ":"
                           + domainCtxts[j].startState + ";");
        }
        throw new DirectoryException(ResultCode.UNWILLING_TO_PERFORM,
            ERR_RESYNC_REQUIRED_UNKNOWN_DOMAIN_IN_PROVIDED_COOKIE.get(
                unknownDomains +
                ". Possible cookie: <" + possibleCookie+ ">"));
      }

      // the next record from the DraftCNdb should be the one
      startCookie = providedCookie;

      // Initializes each and every domain with the next(first) eligible message
      // from the domain.
      for (int j=0; j<domainCtxts.length; j++)
      {
        domainCtxts[j].getNextEligibleMessageForDomain(operationId);

        if (domainCtxts[j].nextMsg == null)
          domainCtxts[j].active = false;
      }
    }
    catch(DirectoryException de)
    {
      throw de;
    }
    catch(Exception e)
    {
      TRACER.debugCaught(DebugLogLevel.ERROR, e);
      // FIXME:ECL do not publish internal exception plumb to the client
      throw new DirectoryException(
          ResultCode.OPERATIONS_ERROR,
          Message.raw(Category.SYNC, Severity.INFORMATION,"Exception raised: " +
              e),
              e);
    }
    if (debugEnabled())
      TRACER.debugInfo(
        " initializeCLDomCtxts ends with " + " " + dumpState());
  }

  /**
   * Registers this handler into its related domain and notifies the domain.
   */
  private void registerIntoDomain()
  {
    if (replicationServerDomain!=null)
      replicationServerDomain.registerHandler(this);
  }

  /**
   * Shutdown this handler.
   */
  public void shutdown()
  {
    if (debugEnabled())
      TRACER.debugInfo(this + " shutdown()" + draftCNDbIter);
    if (this.draftCNDbIter != null)
    {
      draftCNDbIter.releaseCursor();
      draftCNDbIter = null;
    }
    for (int i=0;i<domainCtxts.length;i++)
    {
      if (!domainCtxts[i].rsd.unRegisterHandler(domainCtxts[i].mh))
      {
        logError(Message.raw(Category.SYNC, Severity.NOTICE,
            this +" shutdown() - error when unregistering handler "
            + domainCtxts[i].mh));
      }
      domainCtxts[i].rsd.stopServer(domainCtxts[i].mh);
    }
    super.shutdown();
    domainCtxts = null;
  }

  /**
   * Request to shutdown the associated writer.
   */
  protected void shutdownWriter()
  {
    shutdownWriter = true;
    if (writer!=null)
    {
      ECLServerWriter eclWriter = (ECLServerWriter)this.writer;
      eclWriter.shutdownWriter();
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public String getMonitorInstanceName()
  {
    String str = serverURL + " " + String.valueOf(serverId);

    return "Connected External Changelog Server " + str +
    ServerConstants.DN_EXTERNAL_CHANGELOG_ROOT;
  }

  /**
   * Retrieves a set of attributes containing monitor data that should be
   * returned to the client if the corresponding monitor entry is requested.
   *
   * @return  A set of attributes containing monitor data that should be
   *          returned to the client if the corresponding monitor entry is
   *          requested.
   */
  @Override
  public ArrayList<Attribute> getMonitorData()
  {
    // Get the generic ones
    ArrayList<Attribute> attributes = super.getMonitorData();

    // Add the specific RS ones
    attributes.add(Attributes.create("External-Changelog-Server",
        serverURL));

    // TODO:ECL No monitoring exist for ECL.
    return attributes;
  }
  /**
   * {@inheritDoc}
   */
  @Override
  public String toString()
  {
    String localString;
    localString = "External changelog Server ";
    if (this.serverId != 0)
      localString += serverId + " " + serverURL + " " + getServiceId()
       + " " + this.getOperationId();
    else
      localString += this.getClass().getCanonicalName()+ " " + operationId;
    return localString;
  }
  /**
   * Gets the status of the connected DS.
   * @return The status of the connected DS.
   */
  public ServerStatus getStatus()
  {
    // There is no other status possible for the ECL Server Handler to
    // be normally connected.
    return ServerStatus.NORMAL_STATUS;
  }
  /**
   * {@inheritDoc}
   */
  @Override
  public boolean isDataServer()
  {
    return true;
  }

  /**
   * Initialize the handler.
   * @param startECLSessionMsg The provided starting state.
   * @throws DirectoryException when a problem occurs.
   */
  public void initialize(StartECLSessionMsg startECLSessionMsg)
  throws DirectoryException
  {

    this.operationId = startECLSessionMsg.getOperationId();

    isPersistent  = startECLSessionMsg.isPersistent();
    lastDraftCN   = startECLSessionMsg.getLastDraftChangeNumber();
    searchPhase   = INIT_PHASE;
    try
    {
      previousCookie = new MultiDomainServerState(
        startECLSessionMsg.getCrossDomainServerState());
    }
    catch(Exception e)
    {
      TRACER.debugCaught(DebugLogLevel.ERROR, e);
      throw new DirectoryException(
          ResultCode.UNWILLING_TO_PERFORM,
          ERR_INVALID_COOKIE_SYNTAX.get());
    }
    excludedServiceIDs = startECLSessionMsg.getExcludedServiceIDs();
    replicationServer.disableEligibility(excludedServiceIDs);
    eligibleCN = replicationServer.getEligibleCN();

    if (startECLSessionMsg.getECLRequestType()==
      StartECLSessionMsg.REQUEST_TYPE_FROM_COOKIE)
    {
      initializeCLSearchFromGenState(
          startECLSessionMsg.getCrossDomainServerState());
    }
    else if (startECLSessionMsg.getECLRequestType()==
      StartECLSessionMsg.REQUEST_TYPE_FROM_DRAFT_CHANGE_NUMBER)
    {
      initializeCLSearchFromDraftCN(
          startECLSessionMsg.getFirstDraftChangeNumber());
    }

    if (session != null)
    {
      try
      {
        // Disable timeout for next communications
        session.setSoTimeout(0);
      }
      catch(Exception e) {}

      // sendWindow MUST be created before starting the writer
      sendWindow = new Semaphore(sendWindowSize);

      // create reader
      reader = new ServerReader(session, this);
      reader.start();

      if (writer == null)
      {
        // create writer
        writer = new ECLServerWriter(session,this,replicationServerDomain);
        writer.start();
      }

      // Resume the writer
      ((ECLServerWriter)writer).resumeWriter();

      // TODO:ECL Potential race condition if writer not yet resumed here
    }

    if (isPersistent == StartECLSessionMsg.PERSISTENT_CHANGES_ONLY)
    {
      closeInitPhase();
    }

    /* TODO: From replication changenumber
    //--
    if (startCLMsg.getStartMode()==2)
    {
      if (CLSearchFromProvidedExactCN(startCLMsg.getChangeNumber()))
        return;
    }

    //--
    if (startCLMsg.getStartMode()==4)
    {
      // to get the CL first and last
      initializeCLDomCtxts(null); // from start
      ChangeNumber crossDomainEligibleCN = computeCrossDomainEligibleCN();

      try
      {
        // to get the CL first and last
        // last rely on the crossDomainEligibleCN thhus must have been
        // computed before
        int[] limits = computeCLLimits(crossDomainEligibleCN);
        // Send the response
        CLLimitsMsg msg = new CLLimitsMsg(limits[0], limits[1]);
        session.publish(msg);
      }
      catch(Exception e)
      {
        TRACER.debugCaught(DebugLogLevel.ERROR, e);
        try
        {
          session.publish(
            new ErrorMsg(
             replicationServerDomain.getReplicationServer().getServerId(),
             serverId,
             Message.raw(Category.SYNC, Severity.INFORMATION,
                 "Exception raised: " + e.getMessage())));
        }
        catch(IOException ioe)
        {
          // FIXME: close conn ?
        }
      }
      return;
    }
     */

    // Store into domain
    registerIntoDomain();

    if (debugEnabled())
      TRACER.debugInfo(
          this.getClass().getCanonicalName()+ " " + operationId +
          " initialized: " +
          " " + dumpState() + " " +
          " " + clDomCtxtsToString(""));

  }

  /**
   * Select the next update that must be sent to the server managed by this
   * ServerHandler.
   *
   * @return the next update that must be sent to the server managed by this
   *         ServerHandler.
   * @exception DirectoryException when an error occurs.
   */
  public ECLUpdateMsg takeECLUpdate()
  throws DirectoryException
  {
    boolean interrupted = true;
    ECLUpdateMsg msg = getNextECLUpdate();

    // TODO:ECL We should refactor so that a SH always have a session
    if (session == null)
      return msg;

    boolean acquired = false;
    do
    {
      try
      {
        acquired = sendWindow.tryAcquire((long) 500, TimeUnit.MILLISECONDS);
        interrupted = false;
      } catch (InterruptedException e)
      {
        // loop until not interrupted
      }
    } while (((interrupted) || (!acquired)) && (!shutdownWriter));
    if (msg != null)
    {
      incrementOutCount();
    }
    return msg;
  }

  /**
   * Get the next message - non blocking - null when none.
   * This method is currently not used but we don't want to keep the mother
   * class method since it make no sense for ECLServerHandler.
   * @param synchronous - not used
   * @return the next message
   */
  protected UpdateMsg getnextMessage(boolean synchronous)
  {
    UpdateMsg msg = null;
    try
    {
      ECLUpdateMsg eclMsg = getNextECLUpdate();
      if (eclMsg!=null)
        msg = eclMsg.getUpdateMsg();
    }
    catch(DirectoryException de)
    {
      TRACER.debugCaught(DebugLogLevel.ERROR, de);
    }
    return msg;
  }

  /**
   * Returns the next update message for the External Changelog (ECL).
   * @return the ECL update message, null when there aren't anymore.
   * @throws DirectoryException when an error occurs.
   */
  public ECLUpdateMsg getNextECLUpdate()
  throws DirectoryException
  {
    ECLUpdateMsg oldestChange = null;

    if (debugEnabled())
      TRACER.debugInfo("In cn=changelog" + this +
          " getNextECLUpdate starts: " + dumpState());

    try
    {

      //  getMessage:
      //    get the oldest msg:
      //    after:
      //     if stopState of domain is covered then domain is out candidate
      //       until no domain candidate mean generalized stopState
      //       has been reached
      //     else
      //       get one msg from that domain
      //       no (null) msg returned: should not happen since we go to a state
      //       that is computed/expected

      // Persistent:
      // ----------
      //  step 1&2: same as non persistent
      //
      //  step 3: reinit all domain are candidate
      //    take the oldest
      //    if one domain has no msg, still is candidate

      int iDom = 0;
      boolean continueLooping = true;
      while ((continueLooping) && (searchPhase == INIT_PHASE))
      {
        // Step 1 & 2
        if (searchPhase == INIT_PHASE)
        {
          // Normally we whould not loop .. except ...
          continueLooping = false;

          iDom = getOldestChangeFromDomainCtxts();

          // iDom == -1 means that there is no oldest change to process
          if (iDom == -1)
          {
            closeInitPhase();

            // signals end of phase 1 to the caller
            return null;
          }

          // Build the ECLUpdateMsg to be returned
          oldestChange = new ECLUpdateMsg(
              (LDAPUpdateMsg)domainCtxts[iDom].nextMsg,
              null, // cookie will be set later
              domainCtxts[iDom].rsd.getBaseDn(),
              0); //  draftChangeNumber may be set later
          domainCtxts[iDom].nextMsg = null;

          if (draftCompat)
          {
            // either retrieve a draftCN from the draftCNDb
            // or assign a new draftCN and store in the db

            DraftCNDbHandler draftCNDb=replicationServer.getDraftCNDbHandler();

            // We also need to check if the draftCNdb is consistent with
            // the changelogdb.
            // if not, 2 potential reasons
            // a/ : changelog has been purged (trim)let's traverse the draftCNDb
            // b/ : changelog is late .. let's traverse the changelogDb
            // The following loop allows to loop until being on the same cn
            // in the 2 dbs

            // replogcn : the oldest change from the changelog db
            ChangeNumber cnFromChangelogDb =
              oldestChange.getUpdateMsg().getChangeNumber();
            String dnFromChangelogDb = domainCtxts[iDom].rsd.getBaseDn();

            while (true)
            {
              if (!isEndOfDraftCNReached)
              {
                // we did not reach yet the end of the DraftCNdb

                // the next change from the DraftCN db
                ChangeNumber cnFromDraftCNDb = draftCNDbIter.getChangeNumber();
                String dnFromDraftCNDb = draftCNDbIter.getServiceID();

                // are replogcn and DraftCNcn should be the same change ?
                int areCNEqual = cnFromChangelogDb.compareTo(cnFromDraftCNDb);
                int areDNEqual = dnFromChangelogDb.compareTo(dnFromDraftCNDb);

                if (debugEnabled())
                  TRACER.debugInfo("getNextECLUpdate generating draftCN "
                    + " comparing the 2 db DNs :"
                    + dnFromChangelogDb + "?=" + cnFromChangelogDb
                    + " timestamps:" + new Date(cnFromChangelogDb.getTime())
                    + " ?older" +   new Date(cnFromDraftCNDb.getTime()));

                if ((areDNEqual==0) && (areCNEqual==0))
                {
                  // same domain and same CN => same change

                  // assign the DraftCN found to the change from the changelogdb
                  if (debugEnabled())
                    TRACER.debugInfo("getNextECLUpdate generating draftCN "
                      + " assigning draftCN=" + draftCNDbIter.getDraftCN()
                      + " to change=" + oldestChange);

                  oldestChange.setDraftChangeNumber(
                      draftCNDbIter.getDraftCN());

                  break;
                }
                else
                {
                  // replogcn and DraftCNcn are NOT on the same change
                  if (cnFromDraftCNDb.older(cnFromChangelogDb))
                  {
                    // the change from the DraftCNDb is older
                    // that means that the change has been purged from the
                    // changelogDb (and DraftCNdb not yet been trimed)

                    try
                    {
                      // let's traverse the DraftCNdb searching for the change
                      // found in the changelogDb.
                      if (debugEnabled())
                      TRACER.debugInfo("getNextECLUpdate generating draftCN "
                          + " will skip " + cnFromDraftCNDb
                          + " and read next change from the DraftCNDb.");

                      isEndOfDraftCNReached = (draftCNDbIter.next()==false);

                      if (debugEnabled())
                      TRACER.debugInfo("getNextECLUpdate generating draftCN "
                          + " has skiped to "
                          + " sn=" + draftCNDbIter.getDraftCN()
                          + " cn=" + draftCNDbIter.getChangeNumber()
                          + " End of draftCNDb ?"+isEndOfDraftCNReached);

                      if (isEndOfDraftCNReached)
                      {
                        // we are at the end of the DraftCNdb in the append mode

                        // generate a new draftCN and assign to this change
                        oldestChange.setDraftChangeNumber(
                            replicationServer.getNewDraftCN());

                        // store in DraftCNdb the pair
                        // (draftCN_of_the_cur_change, state_before_this_change)
                        draftCNDb.add(
                            oldestChange.getDraftChangeNumber(),
                            previousCookie.toString(),
                            oldestChange.getServiceId(),
                            oldestChange.getUpdateMsg().getChangeNumber());

                        break;
                      }
                      else
                      {
                        // let's go to test this new change fro the DraftCNdb
                        continue;
                      }
                    }
                    catch(Exception e)
                    {
                    }
                  }
                  else
                  {
                    // the change from the changelogDb is older
                    // it should have been stored lately
                    // let's continue to traverse the changelogdb
                    if (debugEnabled())
                    TRACER.debugInfo("getNextECLUpdate: will skip "
                        + cnFromChangelogDb
                        + " and read next from the regular changelog.");
                    continueLooping = true;
                    break; // TO BE CHECKED
                  }
                }
              }
              else
              {
                // we are at the end of the DraftCNdb in the append mode
                // store in DraftCNdb the pair
                // (DraftCN of the current change, state before this change)
                oldestChange.setDraftChangeNumber(
                    replicationServer.getNewDraftCN());

                draftCNDb.add(
                    oldestChange.getDraftChangeNumber(),
                    this.previousCookie.toString(),
                    domainCtxts[iDom].rsd.getBaseDn(),
                    oldestChange.getUpdateMsg().getChangeNumber());

                break;
              }
            } // while DraftCN
          } // if draftCompat

          // here we have the right oldest change
          // and in the draft case, we have its draft changenumber

          // Set and test the domain of the oldestChange see if we reached
          // the end of the phase for this domain
          domainCtxts[iDom].currentState.update(
              oldestChange.getUpdateMsg().getChangeNumber());

          if (domainCtxts[iDom].currentState.cover(domainCtxts[iDom].stopState))
          {
            domainCtxts[iDom].active = false;
          }
          if (draftCompat && (lastDraftCN>0) &&
              (oldestChange.getDraftChangeNumber()>lastDraftCN))
          {
            domainCtxts[iDom].active = false;
          }
          if (domainCtxts[iDom].active)
          {
            // populates the table with the next eligible msg from idomain
            // in non blocking mode, return null when no more eligible msg
            domainCtxts[iDom].getNextEligibleMessageForDomain(operationId);
          }
        } // phase == INIT_PHASE
      } // while (...)

      if (searchPhase == PERSISTENT_PHASE)
      {
        if (debugEnabled())
          clDomCtxtsToString("In getNextECLUpdate (persistent): " +
          "looking for the generalized oldest change");

        for (int ido=0; ido<domainCtxts.length; ido++)
        {
          // get next msg
          domainCtxts[ido].getNextEligibleMessageForDomain(operationId);
        }

        // take the oldest one
        iDom = getOldestChangeFromDomainCtxts();

        if (iDom != -1)
        {
          String suffix = this.domainCtxts[iDom].rsd.getBaseDn();

          oldestChange = new ECLUpdateMsg(
              (LDAPUpdateMsg)domainCtxts[iDom].nextMsg,
              null, // set later
              suffix, 0);
          domainCtxts[iDom].nextMsg = null; // clean

          domainCtxts[iDom].currentState.update(
              oldestChange.getUpdateMsg().getChangeNumber());

          if (draftCompat)
          {
            // should generate DraftCN
            DraftCNDbHandler draftCNDb =replicationServer.getDraftCNDbHandler();

            oldestChange.setDraftChangeNumber(
                replicationServer.getNewDraftCN());

            // store in DraftCNdb the pair
            // (DraftCN of the current change, state before this change)
            draftCNDb.add(
                oldestChange.getDraftChangeNumber(),
                this.previousCookie.toString(),
                domainCtxts[iDom].rsd.getBaseDn(),
                oldestChange.getUpdateMsg().getChangeNumber());
          }
        }
      }
    }
    catch(Exception e)
    {
      TRACER.debugCaught(DebugLogLevel.ERROR, e);
      throw new DirectoryException(
          ResultCode.OPERATIONS_ERROR,
          Message.raw(Category.SYNC, Severity.INFORMATION,"Exception raised: "),
          e);
    }

    if (oldestChange != null)
    {
      if (debugEnabled())
        TRACER.debugInfo("getNextECLUpdate updates previousCookie:"
          + oldestChange.getUpdateMsg().getChangeNumber());

      // Update the current state
      previousCookie.update(
          oldestChange.getServiceId(),
          oldestChange.getUpdateMsg().getChangeNumber());

      // Set the current value of global state in the returned message
      oldestChange.setCookie(previousCookie);

      if (debugEnabled())
        TRACER.debugInfo("getNextECLUpdate returns result oldest change =" +
                oldestChange);

    }
    return oldestChange;
  }

  /**
   * Terminates the first (non persistent) phase of the search on the ECL.
   */
  private void closeInitPhase()
  {
    // starvation of changelog messages
    // all domain have been unactived means are covered
    if (debugEnabled())
      TRACER.debugInfo("In cn=changelog" + "," + this + " closeInitPhase(): "
          + dumpState());

    // go to persistent phase if one
    for (int i=0; i<domainCtxts.length; i++)
      domainCtxts[i].active = true;

    if (this.isPersistent != StartECLSessionMsg.NON_PERSISTENT)
    {
      // INIT_PHASE is done AND search is persistent => goto PERSISTENT_PHASE
      searchPhase = PERSISTENT_PHASE;

      if (writer ==null)
      {
        writer = new ECLServerWriter(session,this,replicationServerDomain);
        writer.start();  // start suspended
      }

    }
    else
    {
      // INIT_PHASE is done AND search is not persistent => reinit
      searchPhase = UNDEFINED_PHASE;
    }

    if (draftCNDbIter!=null)
    {
      // End of INIT_PHASE => always release the iterator
      draftCNDbIter.releaseCursor();
      draftCNDbIter = null;
    }
  }

  /**
   * Get the index in the domainCtxt table of the domain with the oldest change.
   * @return the index of the domain with the oldest change, -1 when none.
   */
  private int getOldestChangeFromDomainCtxts()
  {
    int oldest = -1;
    for (int i=0; i<domainCtxts.length; i++)
    {
      if ((domainCtxts[i].active))
      {
        // on the first loop, oldest==-1
        // .msg is null when the previous (non blocking) nextMessage did
        // not have any eligible msg to return
        if (domainCtxts[i].nextMsg != null)
        {
          if ((oldest==-1) ||
              (domainCtxts[i].nextMsg.compareTo(domainCtxts[oldest].nextMsg)<0))
          {
            oldest = i;
          }
        }
      }
    }

    if (debugEnabled())
      TRACER.debugInfo("In cn=changelog"
          + "," + this + " getOldestChangeFromDomainCtxts() returns " +
          ((oldest!=-1)?domainCtxts[oldest].nextMsg:"-1"));

    return oldest;
  }

  /**
   * Returns the client operation id.
   * @return The client operation id.
   */
  public String getOperationId()
  {
    return operationId;
  }

  /**
   * Getter for the persistent property of the current search.
   * @return Whether the current search is persistent or not.
   */
  public short isPersistent() {
    return this.isPersistent;
  }

  /**
   * Getter for the current search phase (INIT or PERSISTENT).
   * @return Whether the current search is persistent or not.
   */
  public int getSearchPhase() {
    return this.searchPhase;
  }

  /**
   * Refresh the eligibleCN by requesting the replication server.
   */
  public void refreshEligibleCN()
  {
    eligibleCN = replicationServer.getEligibleCN();
  }

}