/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

using System;
using System.Collections.Generic;
using System.Net;
using System.Reflection;
using System.Threading;
using OpenMetaverse;
using OpenMetaverse.StructuredData;
using log4net;
using OpenSim.Framework;
using OpenSim.Framework.Client;
using OpenSim.Framework.Communications;
using OpenSim.Framework.Communications.Cache;
using OpenSim.Framework.Capabilities;
using OpenSim.Region.Framework.Interfaces;
using OpenSim.Services.Interfaces;
using OSD = OpenMetaverse.StructuredData.OSD;
using GridRegion = OpenSim.Services.Interfaces.GridRegion;

namespace OpenSim.Region.Framework.Scenes
{
    public delegate void KiPrimitiveDelegate(uint localID);

    public delegate void RemoveKnownRegionsFromAvatarList(UUID avatarID, List<ulong> regionlst);

    /// <summary>
    /// Class that Region communications runs through
    /// </summary>
    public class SceneCommunicationService //one instance per region
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        protected CommunicationsManager m_commsProvider;
        protected IInterregionCommsOut m_interregionCommsOut;
        protected RegionInfo m_regionInfo;
        protected Scene m_scene;

        protected RegionCommsListener regionCommsHost;

        protected List<UUID> m_agentsInTransit;

        /// <summary>
        /// An agent is crossing into this region
        /// </summary>
        public event AgentCrossing OnAvatarCrossingIntoRegion;

        /// <summary>
        /// A user will arrive shortly, set up appropriate credentials so it can connect
        /// </summary>
        public event ExpectUserDelegate OnExpectUser;

        /// <summary>
        /// A Prim will arrive shortly
        /// </summary>
        public event CloseAgentConnection OnCloseAgentConnection;

        /// <summary>
        /// A new prim has arrived
        /// </summary>
        public event PrimCrossing OnPrimCrossingIntoRegion;

        ///// <summary>
        ///// A New Region is up and available
        ///// </summary>
        //public event RegionUp OnRegionUp;

        /// <summary>
        /// We have a child agent for this avatar and we're getting a status update about it
        /// </summary>
        public event ChildAgentUpdate OnChildAgentUpdate;
        //public event RemoveKnownRegionsFromAvatarList OnRemoveKnownRegionFromAvatar;

        /// <summary>
        /// Time to log one of our users off.   Grid Service sends this mostly
        /// </summary>
        public event LogOffUser OnLogOffUser;

        /// <summary>
        /// A region wants land data from us!
        /// </summary>
        public event GetLandData OnGetLandData;

        private AgentCrossing handlerAvatarCrossingIntoRegion = null; // OnAvatarCrossingIntoRegion;
        private ExpectUserDelegate handlerExpectUser = null; // OnExpectUser;
        private CloseAgentConnection handlerCloseAgentConnection = null; // OnCloseAgentConnection;
        private PrimCrossing handlerPrimCrossingIntoRegion = null; // OnPrimCrossingIntoRegion;
        //private RegionUp handlerRegionUp = null; // OnRegionUp;
        private ChildAgentUpdate handlerChildAgentUpdate = null; // OnChildAgentUpdate;
        //private RemoveKnownRegionsFromAvatarList handlerRemoveKnownRegionFromAvatar = null; // OnRemoveKnownRegionFromAvatar;
        private LogOffUser handlerLogOffUser = null;
        private GetLandData handlerGetLandData = null; // OnGetLandData

        public KiPrimitiveDelegate KiPrimitive;

        public SceneCommunicationService(CommunicationsManager commsMan)
        {
            m_commsProvider = commsMan;
            m_agentsInTransit = new List<UUID>();
        }

        public void SetScene(Scene s)
        {
            m_scene = s;
            m_regionInfo = s.RegionInfo;
            m_interregionCommsOut = m_scene.RequestModuleInterface<IInterregionCommsOut>();
        }

        /// <summary>
        /// Register a region with the grid
        /// </summary>
        /// <param name="regionInfos"></param>
        /// <exception cref="System.Exception">Thrown if region registration fails.</exception>
        public void RegisterRegion(IInterregionCommsOut comms_out, RegionInfo regionInfos)
        {
        }

        /// <summary>
        /// This region is shutting down, de-register all events!
        /// De-Register region from Grid!
        /// </summary>
        public void Close()
        {
        }

        #region CommsManager Event handlers

        /// <summary>
        /// A New User will arrive shortly, Informs the scene that there's a new user on the way
        /// </summary>
        /// <param name="agent">Data we need to ensure that the agent can connect</param>
        ///
        protected void NewUserConnection(AgentCircuitData agent)
        {
            handlerExpectUser = OnExpectUser;
            if (handlerExpectUser != null)
            {
                //m_log.Info("[INTER]: " + debugRegionName + ": SceneCommunicationService: OnExpectUser Fired for User:" + agent.firstname + " " + agent.lastname);
                handlerExpectUser(agent);
            }
        }

        /// <summary>
        /// The Grid has requested us to log-off the user
        /// </summary>
        /// <param name="AgentID">Unique ID of agent to log-off</param>
        /// <param name="RegionSecret">The secret string that the region establishes with the grid when registering</param>
        /// <param name="message">The message to send to the user that tells them why they were logged off</param>
        protected void GridLogOffUser(UUID AgentID, UUID RegionSecret, string message)
        {
            handlerLogOffUser = OnLogOffUser;
            if (handlerLogOffUser != null)
            {
                handlerLogOffUser(AgentID, RegionSecret, message);
            }
        }

        /// <summary>
        /// Inform the scene that we've got an update about a child agent that we have
        /// </summary>
        /// <param name="cAgentData"></param>
        /// <returns></returns>
        protected bool ChildAgentUpdate(ChildAgentDataUpdate cAgentData)
        {
            handlerChildAgentUpdate = OnChildAgentUpdate;
            if (handlerChildAgentUpdate != null)
                handlerChildAgentUpdate(cAgentData);

            return true;
        }


        protected void AgentCrossing(UUID agentID, Vector3 position, bool isFlying)
        {
            handlerAvatarCrossingIntoRegion = OnAvatarCrossingIntoRegion;
            if (handlerAvatarCrossingIntoRegion != null)
            {
                handlerAvatarCrossingIntoRegion(agentID, position, isFlying);
            }
        }

        protected void PrimCrossing(UUID primID, Vector3 position, bool isPhysical)
        {
            handlerPrimCrossingIntoRegion = OnPrimCrossingIntoRegion;
            if (handlerPrimCrossingIntoRegion != null)
            {
                handlerPrimCrossingIntoRegion(primID, position, isPhysical);
            }
        }

        protected bool CloseConnection(UUID agentID)
        {
            m_log.Debug("[INTERREGION]: Incoming Agent Close Request for agent: " + agentID);

            handlerCloseAgentConnection = OnCloseAgentConnection;
            if (handlerCloseAgentConnection != null)
            {
                return handlerCloseAgentConnection(agentID);
            }
            
            return false;
        }

        protected LandData FetchLandData(uint x, uint y)
        {
            handlerGetLandData = OnGetLandData;
            if (handlerGetLandData != null)
            {
                return handlerGetLandData(x, y);
            }
            return null;
        }

        #endregion

        #region Inform Client of Neighbours

        private delegate void InformClientOfNeighbourDelegate(
            ScenePresence avatar, AgentCircuitData a, GridRegion reg, IPEndPoint endPoint, bool newAgent);

        private void InformClientOfNeighbourCompleted(IAsyncResult iar)
        {
            InformClientOfNeighbourDelegate icon = (InformClientOfNeighbourDelegate) iar.AsyncState;
            icon.EndInvoke(iar);
        }

        /// <summary>
        /// Async component for informing client of which neighbours exist
        /// </summary>
        /// <remarks>
        /// This needs to run asynchronously, as a network timeout may block the thread for a long while
        /// </remarks>
        /// <param name="remoteClient"></param>
        /// <param name="a"></param>
        /// <param name="regionHandle"></param>
        /// <param name="endPoint"></param>
        private void InformClientOfNeighbourAsync(ScenePresence avatar, AgentCircuitData a, GridRegion reg,
                                                  IPEndPoint endPoint, bool newAgent)
        {
            // Let's wait just a little to give time to originating regions to catch up with closing child agents
            // after a cross here
            Thread.Sleep(500);

            uint x, y;
            Utils.LongToUInts(reg.RegionHandle, out x, out y);
            x = x / Constants.RegionSize;
            y = y / Constants.RegionSize;
            m_log.Info("[INTERGRID]: Starting to inform client about neighbour " + x + ", " + y + "(" + endPoint.ToString() + ")");

            string capsPath = "http://" + reg.ExternalHostName + ":" + reg.HttpPort
                  + "/CAPS/" + a.CapsPath + "0000/";

            string reason = String.Empty;

           
            bool regionAccepted = m_interregionCommsOut.SendCreateChildAgent(reg.RegionHandle, a, 0, out reason);

            if (regionAccepted && newAgent)
            {
                IEventQueue eq = avatar.Scene.RequestModuleInterface<IEventQueue>();
                if (eq != null)
                {
                    #region IP Translation for NAT
                    IClientIPEndpoint ipepClient;
                    if (avatar.ClientView.TryGet(out ipepClient))
                    {
                        endPoint.Address = NetworkUtil.GetIPFor(ipepClient.EndPoint, endPoint.Address);
                    }
                    #endregion

                    eq.EnableSimulator(reg.RegionHandle, endPoint, avatar.UUID);
                    eq.EstablishAgentCommunication(avatar.UUID, endPoint, capsPath);
                    m_log.DebugFormat("[CAPS]: Sending new CAPS seed url {0} to client {1} in region {2}",
                                      capsPath, avatar.UUID, avatar.Scene.RegionInfo.RegionName);
                }
                else
                {
                    avatar.ControllingClient.InformClientOfNeighbour(reg.RegionHandle, endPoint);
                    // TODO: make Event Queue disablable!
                }

                m_log.Info("[INTERGRID]: Completed inform client about neighbour " + endPoint.ToString());
                
            }
            
        }

        public List<GridRegion> RequestNeighbours(Scene pScene, uint pRegionLocX, uint pRegionLocY)
        {
            Border[] northBorders = pScene.NorthBorders.ToArray();
            Border[] southBorders = pScene.SouthBorders.ToArray();
            Border[] eastBorders = pScene.EastBorders.ToArray();
            Border[] westBorders = pScene.WestBorders.ToArray();

            // Legacy one region.  Provided for simplicity while testing the all inclusive method in the else statement.
            if (northBorders.Length <= 1 && southBorders.Length <= 1 && eastBorders.Length <= 1 && westBorders.Length <= 1)
            {
                return m_scene.GridService.GetNeighbours(m_regionInfo.ScopeID, m_regionInfo.RegionID);
            }
            else
            {
                Vector2 extent = Vector2.Zero;
                for (int i = 0; i < eastBorders.Length; i++)
                {
                    extent.X = (eastBorders[i].BorderLine.Z > extent.X) ? eastBorders[i].BorderLine.Z : extent.X;
                }
                for (int i = 0; i < northBorders.Length; i++)
                {
                    extent.Y = (northBorders[i].BorderLine.Z > extent.Y) ? northBorders[i].BorderLine.Z : extent.Y;
                }

                // Loss of fraction on purpose
                extent.X = ((int)extent.X / (int)Constants.RegionSize) + 1;
                extent.Y = ((int)extent.Y / (int)Constants.RegionSize) + 1;

                int startX = (int)(pRegionLocX - 1) * (int)Constants.RegionSize;
                int startY = (int)(pRegionLocY - 1) * (int)Constants.RegionSize;

                int endX = ((int)pRegionLocX + (int)extent.X) * (int)Constants.RegionSize;
                int endY = ((int)pRegionLocY + (int)extent.Y) * (int)Constants.RegionSize;

                List<GridRegion> neighbours = m_scene.GridService.GetRegionRange(m_regionInfo.ScopeID, startX, endX, startY, endY);
                neighbours.RemoveAll(delegate(GridRegion r) { return r.RegionID == m_regionInfo.RegionID; });

                return neighbours;
            }
        }

        /// <summary>
        /// This informs all neighboring regions about agent "avatar".
        /// Calls an asynchronous method to do so..  so it doesn't lag the sim.
        /// </summary>
        public void EnableNeighbourChildAgents(ScenePresence avatar, List<RegionInfo> lstneighbours)
        {
            List<GridRegion> neighbours = new List<GridRegion>();

            if (m_regionInfo != null)
            {
                neighbours = RequestNeighbours(avatar.Scene,m_regionInfo.RegionLocX, m_regionInfo.RegionLocY);
            }
            else
            {
                m_log.Debug("[ENABLENEIGHBOURCHILDAGENTS]: m_regionInfo was null in EnableNeighbourChildAgents, is this a NPC?");
            }

            /// We need to find the difference between the new regions where there are no child agents
            /// and the regions where there are already child agents. We only send notification to the former.
            List<ulong> neighbourHandles = NeighbourHandles(neighbours); // on this region
            neighbourHandles.Add(avatar.Scene.RegionInfo.RegionHandle);  // add this region too
            List<ulong> previousRegionNeighbourHandles ;

            if (avatar.Scene.CapsModule != null)
            {
                previousRegionNeighbourHandles =
                    new List<ulong>(avatar.Scene.CapsModule.GetChildrenSeeds(avatar.UUID).Keys);
            }
            else
            {
                previousRegionNeighbourHandles = new List<ulong>();
            }

            List<ulong> newRegions = NewNeighbours(neighbourHandles, previousRegionNeighbourHandles);
            List<ulong> oldRegions = OldNeighbours(neighbourHandles, previousRegionNeighbourHandles);
           
            //Dump("Current Neighbors", neighbourHandles);
            //Dump("Previous Neighbours", previousRegionNeighbourHandles);
            //Dump("New Neighbours", newRegions);
            //Dump("Old Neighbours", oldRegions);

            /// Update the scene presence's known regions here on this region
            avatar.DropOldNeighbours(oldRegions);

            /// Collect as many seeds as possible
            Dictionary<ulong, string> seeds;
            if (avatar.Scene.CapsModule != null)
                seeds
                    = new Dictionary<ulong, string>(avatar.Scene.CapsModule.GetChildrenSeeds(avatar.UUID));
            else
                seeds = new Dictionary<ulong, string>();
            
            //m_log.Debug(" !!! No. of seeds: " + seeds.Count);
            if (!seeds.ContainsKey(avatar.Scene.RegionInfo.RegionHandle))
                seeds.Add(avatar.Scene.RegionInfo.RegionHandle, avatar.ControllingClient.RequestClientInfo().CapsPath);

            /// Create the necessary child agents
            List<AgentCircuitData> cagents = new List<AgentCircuitData>();
            foreach (GridRegion neighbour in neighbours)
                {
                if (neighbour.RegionHandle != avatar.Scene.RegionInfo.RegionHandle)
                {

                    AgentCircuitData agent = avatar.ControllingClient.RequestClientInfo();
                    agent.BaseFolder = UUID.Zero;
                    agent.InventoryFolder = UUID.Zero;
                    agent.startpos = new Vector3(128, 128, 70);
                    agent.child = true;

                    if (newRegions.Contains(neighbour.RegionHandle))
                    {
                        agent.CapsPath = CapsUtil.GetRandomCapsObjectPath();
                        avatar.AddNeighbourRegion(neighbour.RegionHandle, agent.CapsPath);
                        seeds.Add(neighbour.RegionHandle, agent.CapsPath);
                    }
                    else
                        agent.CapsPath = avatar.Scene.CapsModule.GetChildSeed(avatar.UUID, neighbour.RegionHandle);

                    cagents.Add(agent);
                }
            }

            /// Update all child agent with everyone's seeds
            foreach (AgentCircuitData a in cagents)
            {
                a.ChildrenCapSeeds = new Dictionary<ulong, string>(seeds);
            }

            if (avatar.Scene.CapsModule != null)
            {
                // These two are the same thing!
                avatar.Scene.CapsModule.SetChildrenSeed(avatar.UUID, seeds);
            }
            avatar.KnownRegions = seeds;
            //avatar.Scene.DumpChildrenSeeds(avatar.UUID);
            //avatar.DumpKnownRegions();

            bool newAgent = false;
            int count = 0;
            foreach (GridRegion neighbour in neighbours)
            {
                // Don't do it if there's already an agent in that region
                if (newRegions.Contains(neighbour.RegionHandle))
                    newAgent = true;
                else
                    newAgent = false;

                if (neighbour.RegionHandle != avatar.Scene.RegionInfo.RegionHandle)
                {
                    InformClientOfNeighbourDelegate d = InformClientOfNeighbourAsync;
                    try
                    {
                        d.BeginInvoke(avatar, cagents[count], neighbour, neighbour.ExternalEndPoint, newAgent,
                                      InformClientOfNeighbourCompleted,
                                      d);
                    }
                    
                    catch (ArgumentOutOfRangeException)
                    {
                        m_log.ErrorFormat(
                           "[REGIONINFO]: Neighbour Regions response included the current region in the neighbor list.  The following region will not display to the client: {0} for region {1} ({2}, {3}).",
                           neighbour.ExternalHostName,
                           neighbour.RegionHandle,
                           neighbour.RegionLocX,
                           neighbour.RegionLocY);
                    }
                    catch (Exception e)
                    {
                        m_log.ErrorFormat(
                            "[REGIONINFO]: Could not resolve external hostname {0} for region {1} ({2}, {3}).  {4}",
                            neighbour.ExternalHostName,
                            neighbour.RegionHandle,
                            neighbour.RegionLocX,
                            neighbour.RegionLocY,
                            e);

                        // FIXME: Okay, even though we've failed, we're still going to throw the exception on,
                        // since I don't know what will happen if we just let the client continue

                        // XXX: Well, decided to swallow the exception instead for now.  Let us see how that goes.
                        // throw e;

                    }
                }
                count++;
            }
        }

        /// <summary>
        /// This informs a single neighboring region about agent "avatar".
        /// Calls an asynchronous method to do so..  so it doesn't lag the sim.
        /// </summary>
        public void InformNeighborChildAgent(ScenePresence avatar, GridRegion region)
        {
            AgentCircuitData agent = avatar.ControllingClient.RequestClientInfo();
            agent.BaseFolder = UUID.Zero;
            agent.InventoryFolder = UUID.Zero;
            agent.startpos = new Vector3(128, 128, 70);
            agent.child = true;

            InformClientOfNeighbourDelegate d = InformClientOfNeighbourAsync;
            d.BeginInvoke(avatar, agent, region, region.ExternalEndPoint, true,
                          InformClientOfNeighbourCompleted,
                          d);
        }

        #endregion

        public delegate void InformNeighbourThatRegionUpDelegate(INeighbourService nService, RegionInfo region, ulong regionhandle);

        private void InformNeighborsThatRegionisUpCompleted(IAsyncResult iar)
        {
            InformNeighbourThatRegionUpDelegate icon = (InformNeighbourThatRegionUpDelegate) iar.AsyncState;
            icon.EndInvoke(iar);
        }

        /// <summary>
        /// Asynchronous call to information neighbouring regions that this region is up
        /// </summary>
        /// <param name="region"></param>
        /// <param name="regionhandle"></param>
        private void InformNeighboursThatRegionIsUpAsync(INeighbourService neighbourService, RegionInfo region, ulong regionhandle)
        {
            uint x = 0, y = 0;
            Utils.LongToUInts(regionhandle, out x, out y);

            GridRegion neighbour = null;
            if (neighbourService != null)
                neighbour = neighbourService.HelloNeighbour(regionhandle, region);
            else
                m_log.DebugFormat("[SCS]: No neighbour service provided for informing neigbhours of this region");

            if (neighbour != null)
            {
                m_log.DebugFormat("[INTERGRID]: Successfully informed neighbour {0}-{1} that I'm here", x / Constants.RegionSize, y / Constants.RegionSize);
                m_scene.EventManager.TriggerOnRegionUp(neighbour);
            }
            else
            {
                m_log.WarnFormat("[INTERGRID]: Failed to inform neighbour {0}-{1} that I'm here.", x / Constants.RegionSize, y / Constants.RegionSize);
            }
        }


        public void InformNeighborsThatRegionisUp(INeighbourService neighbourService, RegionInfo region)
        {
            //m_log.Info("[INTER]: " + debugRegionName + ": SceneCommunicationService: Sending InterRegion Notification that region is up " + region.RegionName);

            for (int x = (int)region.RegionLocX - 1; x <= region.RegionLocX + 1; x++)
            {
                for (int y = (int)region.RegionLocY - 1; y <= region.RegionLocY + 1; y++)
                {
                    if (!((x == region.RegionLocX) && (y == region.RegionLocY))) // skip this region
                    {
                        ulong handle = Utils.UIntsToLong((uint)x * Constants.RegionSize, (uint)y * Constants.RegionSize);
                        InformNeighbourThatRegionUpDelegate d = InformNeighboursThatRegionIsUpAsync;

                        d.BeginInvoke(neighbourService, region, handle,
                                      InformNeighborsThatRegionisUpCompleted,
                                      d);
                    }
                }
            }
        }


        public delegate void SendChildAgentDataUpdateDelegate(AgentPosition cAgentData, ulong regionHandle);

        /// <summary>
        /// This informs all neighboring regions about the settings of it's child agent.
        /// Calls an asynchronous method to do so..  so it doesn't lag the sim.
        ///
        /// This contains information, such as, Draw Distance, Camera location, Current Position, Current throttle settings, etc.
        ///
        /// </summary>
        private void SendChildAgentDataUpdateAsync(AgentPosition cAgentData, ulong regionHandle)
        {
            //m_log.Info("[INTERGRID]: Informing neighbors about my agent in " + m_regionInfo.RegionName);
            try
            {
                //m_commsProvider.InterRegion.ChildAgentUpdate(regionHandle, cAgentData);
                m_interregionCommsOut.SendChildAgentUpdate(regionHandle, cAgentData);
            }
            catch
            {
                // Ignore; we did our best
            }

            //if (regionAccepted)
            //{
            //    //m_log.Info("[INTERGRID]: Completed sending a neighbor an update about my agent");
            //}
            //else
            //{
            //    //m_log.Info("[INTERGRID]: Failed sending a neighbor an update about my agent");
            //}
                
        }

        private void SendChildAgentDataUpdateCompleted(IAsyncResult iar)
        {
            SendChildAgentDataUpdateDelegate icon = (SendChildAgentDataUpdateDelegate) iar.AsyncState;
            icon.EndInvoke(iar);
        }

        public void SendChildAgentDataUpdate(AgentPosition cAgentData, ScenePresence presence)
        {
            // This assumes that we know what our neighbors are.
            try
            {
                foreach (ulong regionHandle in presence.KnownChildRegionHandles)
                {
                    if (regionHandle != m_regionInfo.RegionHandle)
                    {
                        SendChildAgentDataUpdateDelegate d = SendChildAgentDataUpdateAsync;
                        d.BeginInvoke(cAgentData, regionHandle,
                                      SendChildAgentDataUpdateCompleted,
                                      d);
                    }
                }
            }
            catch (InvalidOperationException)
            {
                // We're ignoring a collection was modified error because this data gets old and outdated fast.
            }

        }

        public delegate void SendCloseChildAgentDelegate(UUID agentID, ulong regionHandle);

        /// <summary>
        /// This Closes child agents on neighboring regions
        /// Calls an asynchronous method to do so..  so it doesn't lag the sim.
        /// </summary>
        protected void SendCloseChildAgentAsync(UUID agentID, ulong regionHandle)
        {

            m_log.Debug("[INTERGRID]: Sending close agent to " + regionHandle);
            // let's do our best, but there's not much we can do if the neighbour doesn't accept.

            //m_commsProvider.InterRegion.TellRegionToCloseChildConnection(regionHandle, agentID);
            m_interregionCommsOut.SendCloseAgent(regionHandle, agentID);
        }

        private void SendCloseChildAgentCompleted(IAsyncResult iar)
        {
            SendCloseChildAgentDelegate icon = (SendCloseChildAgentDelegate)iar.AsyncState;
            icon.EndInvoke(iar);
        }

        public void SendCloseChildAgentConnections(UUID agentID, List<ulong> regionslst)
        {
            foreach (ulong handle in regionslst)
            {
                SendCloseChildAgentDelegate d = SendCloseChildAgentAsync;
                d.BeginInvoke(agentID, handle,
                              SendCloseChildAgentCompleted,
                              d);
            }
        }


        /// <summary>
        /// Try to teleport an agent to a new region.
        /// </summary>
        /// <param name="remoteClient"></param>
        /// <param name="RegionHandle"></param>
        /// <param name="position"></param>
        /// <param name="lookAt"></param>
        /// <param name="flags"></param>
        public virtual void RequestTeleportToLocation(ScenePresence avatar, ulong regionHandle, Vector3 position,
                                                      Vector3 lookAt, uint teleportFlags)
        {
            if (!avatar.Scene.Permissions.CanTeleport(avatar.UUID))
                return;

            bool destRegionUp = true;

            IEventQueue eq = avatar.Scene.RequestModuleInterface<IEventQueue>();

            // Reset animations; the viewer does that in teleports.
            avatar.Animator.ResetAnimations();

            if (regionHandle == m_regionInfo.RegionHandle)
            {
                m_log.DebugFormat(
                    "[SCENE COMMUNICATION SERVICE]: RequestTeleportToLocation {0} within {1}",
                    position, m_regionInfo.RegionName);

                // Teleport within the same region
                if (IsOutsideRegion(avatar.Scene, position) || position.Z < 0)
                {
                    Vector3 emergencyPos = new Vector3(128, 128, 128);

                    m_log.WarnFormat(
                        "[SCENE COMMUNICATION SERVICE]: RequestTeleportToLocation() was given an illegal position of {0} for avatar {1}, {2}.  Substituting {3}",
                        position, avatar.Name, avatar.UUID, emergencyPos);
                    position = emergencyPos;
                }

                // TODO: Get proper AVG Height
                float localAVHeight = 1.56f;
                float posZLimit = 22;

                // TODO: Check other Scene HeightField
                if (position.X > 0 && position.X <= (int)Constants.RegionSize && position.Y > 0 && position.Y <=(int)Constants.RegionSize)
                {
                    posZLimit = (float) avatar.Scene.Heightmap[(int) position.X, (int) position.Y];
                }

                float newPosZ = posZLimit + localAVHeight;
                if (posZLimit >= (position.Z - (localAVHeight / 2)) && !(Single.IsInfinity(newPosZ) || Single.IsNaN(newPosZ)))
                {
                    position.Z = newPosZ;
                }

                // Only send this if the event queue is null
                if (eq == null)
                    avatar.ControllingClient.SendTeleportLocationStart();
                
                avatar.ControllingClient.SendLocalTeleport(position, lookAt, teleportFlags);
                avatar.Teleport(position);
            }
            else
            {
                uint x = 0, y = 0;
                Utils.LongToUInts(regionHandle, out x, out y);
                GridRegion reg = m_scene.GridService.GetRegionByPosition(m_scene.RegionInfo.ScopeID, (int)x, (int)y);

                if (reg != null)
                {
                    m_log.DebugFormat(
                        "[SCENE COMMUNICATION SERVICE]: RequestTeleportToLocation to {0} in {1}", 
                        position, reg.RegionName);
                    
                    if (eq == null)
                        avatar.ControllingClient.SendTeleportLocationStart();

                    // Let's do DNS resolution only once in this process, please!
                    // This may be a costly operation. The reg.ExternalEndPoint field is not a passive field,
                    // it's actually doing a lot of work.
                    IPEndPoint endPoint = reg.ExternalEndPoint;
                    if (endPoint.Address == null)
                    {
                        // Couldn't resolve the name. Can't TP, because the viewer wants IP addresses.
                        destRegionUp = false;
                    }

                    if (destRegionUp)
                    {
                        uint newRegionX = (uint)(reg.RegionHandle >> 40);
                        uint newRegionY = (((uint)(reg.RegionHandle)) >> 8);
                        uint oldRegionX = (uint)(m_regionInfo.RegionHandle >> 40);
                        uint oldRegionY = (((uint)(m_regionInfo.RegionHandle)) >> 8);

                        // Fixing a bug where teleporting while sitting results in the avatar ending up removed from
                        // both regions
                        if (avatar.ParentID != (uint)0)
                            avatar.StandUp();
                        
                        if (!avatar.ValidateAttachments())
                        {
                            avatar.ControllingClient.SendTeleportFailed("Inconsistent attachment state");
                            return;
                        }

                        // the avatar.Close below will clear the child region list. We need this below for (possibly)
                        // closing the child agents, so save it here (we need a copy as it is Clear()-ed).
                        //List<ulong> childRegions = new List<ulong>(avatar.GetKnownRegionList());
                        // Compared to ScenePresence.CrossToNewRegion(), there's no obvious code to handle a teleport
                        // failure at this point (unlike a border crossing failure).  So perhaps this can never fail
                        // once we reach here...
                        //avatar.Scene.RemoveCapsHandler(avatar.UUID);

                        string capsPath = String.Empty;
                        AgentCircuitData agentCircuit = avatar.ControllingClient.RequestClientInfo();
                        agentCircuit.BaseFolder = UUID.Zero;
                        agentCircuit.InventoryFolder = UUID.Zero;
                        agentCircuit.startpos = position;
                        agentCircuit.child = true;
                        
                        if (Util.IsOutsideView(oldRegionX, newRegionX, oldRegionY, newRegionY))
                        {
                            // brand new agent, let's create a new caps seed
                            agentCircuit.CapsPath = CapsUtil.GetRandomCapsObjectPath();
                        }

                        string reason = String.Empty;

                        // Let's create an agent there if one doesn't exist yet. 
                        //if (!m_commsProvider.InterRegion.InformRegionOfChildAgent(reg.RegionHandle, agentCircuit))
                        if (!m_interregionCommsOut.SendCreateChildAgent(reg.RegionHandle, agentCircuit, teleportFlags, out reason))
                        {
                            avatar.ControllingClient.SendTeleportFailed(String.Format("Destination is not accepting teleports: {0}",
                                                                                      reason));
                            return;
                        }

                        // OK, it got this agent. Let's close some child agents
                        avatar.CloseChildAgents(newRegionX, newRegionY);

                        if (Util.IsOutsideView(oldRegionX, newRegionX, oldRegionY, newRegionY))
                        {
                            #region IP Translation for NAT
                            IClientIPEndpoint ipepClient;
                            if (avatar.ClientView.TryGet(out ipepClient))
                            {
                                capsPath
                                    = "http://"
                                      + NetworkUtil.GetHostFor(ipepClient.EndPoint, reg.ExternalHostName)
                                      + ":"
                                      + reg.HttpPort
                                      + CapsUtil.GetCapsSeedPath(agentCircuit.CapsPath);
                            }
                            else
                            {
                                capsPath
                                    = "http://"
                                      + reg.ExternalHostName
                                      + ":"
                                      + reg.HttpPort
                                      + CapsUtil.GetCapsSeedPath(agentCircuit.CapsPath);
                            }
                            #endregion

                            if (eq != null)
                            {
                                #region IP Translation for NAT
                                // Uses ipepClient above
                                if (avatar.ClientView.TryGet(out ipepClient))
                                {
                                    endPoint.Address = NetworkUtil.GetIPFor(ipepClient.EndPoint, endPoint.Address);
                                }
                                #endregion

                                eq.EnableSimulator(reg.RegionHandle, endPoint, avatar.UUID);

                                // ES makes the client send a UseCircuitCode message to the destination, 
                                // which triggers a bunch of things there.
                                // So let's wait
                                Thread.Sleep(2000);

                                eq.EstablishAgentCommunication(avatar.UUID, endPoint, capsPath);
                            }
                            else
                            {
                                avatar.ControllingClient.InformClientOfNeighbour(reg.RegionHandle, endPoint);
                            }
                        }
                        else
                        {
                            agentCircuit.CapsPath = avatar.Scene.CapsModule.GetChildSeed(avatar.UUID, reg.RegionHandle);
                            capsPath = "http://" + reg.ExternalHostName + ":" + reg.HttpPort
                                        + "/CAPS/" + agentCircuit.CapsPath + "0000/";
                        }

                        // Expect avatar crossing is a heavy-duty function at the destination.
                        // That is where MakeRoot is called, which fetches appearance and inventory.
                        // Plus triggers OnMakeRoot, which spawns a series of asynchronous updates.
                        //m_commsProvider.InterRegion.ExpectAvatarCrossing(reg.RegionHandle, avatar.ControllingClient.AgentId,
                        //                                                      position, false);

                        //{
                        //    avatar.ControllingClient.SendTeleportFailed("Problem with destination.");
                        //    // We should close that agent we just created over at destination...
                        //    List<ulong> lst = new List<ulong>();
                        //    lst.Add(reg.RegionHandle);
                        //    SendCloseChildAgentAsync(avatar.UUID, lst);
                        //    return;
                        //}

                        SetInTransit(avatar.UUID);
                        // Let's send a full update of the agent. This is a synchronous call.
                        AgentData agent = new AgentData();
                        avatar.CopyTo(agent);
                        agent.Position = position;
                        agent.CallbackURI = "http://" + m_regionInfo.ExternalHostName + ":" + m_regionInfo.HttpPort + 
                            "/agent/" + avatar.UUID.ToString() + "/" + avatar.Scene.RegionInfo.RegionHandle.ToString() + "/release/";

                        m_interregionCommsOut.SendChildAgentUpdate(reg.RegionHandle, agent);

                        m_log.DebugFormat(
                            "[CAPS]: Sending new CAPS seed url {0} to client {1}", capsPath, avatar.UUID);

                        
                        if (eq != null)
                        {
                            eq.TeleportFinishEvent(reg.RegionHandle, 13, endPoint,
                                                   0, teleportFlags, capsPath, avatar.UUID);
                        }
                        else
                        {
                            avatar.ControllingClient.SendRegionTeleport(reg.RegionHandle, 13, endPoint, 4,
                                                                        teleportFlags, capsPath);
                        }

                        // TeleportFinish makes the client send CompleteMovementIntoRegion (at the destination), which
                        // trigers a whole shebang of things there, including MakeRoot. So let's wait for confirmation
                        // that the client contacted the destination before we send the attachments and close things here.
                        if (!WaitForCallback(avatar.UUID))
                        {
                            // Client never contacted destination. Let's restore everything back
                            avatar.ControllingClient.SendTeleportFailed("Problems connecting to destination.");

                            ResetFromTransit(avatar.UUID);
                            
                            // Yikes! We should just have a ref to scene here.
                            avatar.Scene.InformClientOfNeighbours(avatar);

                            // Finally, kill the agent we just created at the destination.
                            m_interregionCommsOut.SendCloseAgent(reg.RegionHandle, avatar.UUID);

                            return;
                        }

                        // Can't go back from here
                        if (KiPrimitive != null)
                        {
                            KiPrimitive(avatar.LocalId);
                        }

                        avatar.MakeChildAgent();

                        // CrossAttachmentsIntoNewRegion is a synchronous call. We shouldn't need to wait after it
                        avatar.CrossAttachmentsIntoNewRegion(reg.RegionHandle, true);

                        // Finally, let's close this previously-known-as-root agent, when the jump is outside the view zone

                        if (Util.IsOutsideView(oldRegionX, newRegionX, oldRegionY, newRegionY))
                        {
                            Thread.Sleep(5000);
                            avatar.Close();
                            CloseConnection(avatar.UUID);
                        }
                        else
                            // now we have a child agent in this region. 
                            avatar.Reset();


                        // if (teleport success) // seems to be always success here
                        // the user may change their profile information in other region,
                        // so the userinfo in UserProfileCache is not reliable any more, delete it
                        if (avatar.Scene.NeedSceneCacheClear(avatar.UUID))
                        {
                            m_commsProvider.UserProfileCacheService.RemoveUser(avatar.UUID);
                            m_log.DebugFormat(
                                "[SCENE COMMUNICATION SERVICE]: User {0} is going to another region, profile cache removed",
                                avatar.UUID);
                        }
                    }
                    else
                    {
                        avatar.ControllingClient.SendTeleportFailed("Remote Region appears to be down");
                    }
                }
                else
                {
                    // TP to a place that doesn't exist (anymore)
                    // Inform the viewer about that
                    avatar.ControllingClient.SendTeleportFailed("The region you tried to teleport to doesn't exist anymore");
                    
                    // and set the map-tile to '(Offline)'
                    uint regX, regY;
                    Utils.LongToUInts(regionHandle, out regX, out regY);
                    
                    MapBlockData block = new MapBlockData();
                    block.X = (ushort)(regX / Constants.RegionSize);
                    block.Y = (ushort)(regY / Constants.RegionSize);
                    block.Access = 254; // == not there
                    
                    List<MapBlockData> blocks = new List<MapBlockData>();
                    blocks.Add(block);
                    avatar.ControllingClient.SendMapBlock(blocks, 0);
                }
            }
        }

        protected bool IsOutsideRegion(Scene s, Vector3 pos)
        {
            
            if (s.TestBorderCross(pos,Cardinals.N))
                return true;
            if (s.TestBorderCross(pos, Cardinals.S))
                return true;
            if (s.TestBorderCross(pos, Cardinals.E))
                return true;
            if (s.TestBorderCross(pos, Cardinals.W))
                return true;

            return false;
        }

        public bool WaitForCallback(UUID id)
        {
            int count = 200;
            while (m_agentsInTransit.Contains(id) && count-- > 0)
            {
                //m_log.Debug("  >>> Waiting... " + count);
                Thread.Sleep(100);
            }

            if (count > 0)
                return true;
            else
                return false;
        }

        public bool ReleaseAgent(UUID id)
        {
            //m_log.Debug(" >>> ReleaseAgent called <<< ");
            return ResetFromTransit(id);
        }

        public void SetInTransit(UUID id)
        {
            lock (m_agentsInTransit)
            {
                if (!m_agentsInTransit.Contains(id))
                    m_agentsInTransit.Add(id);
            }
        }

        protected bool ResetFromTransit(UUID id)
        {
            lock (m_agentsInTransit)
            {
                if (m_agentsInTransit.Contains(id))
                {
                    m_agentsInTransit.Remove(id);
                    return true;
                }
            }
            return false;
        }

        private List<ulong> NeighbourHandles(List<GridRegion> neighbours)
        {
            List<ulong> handles = new List<ulong>();
            foreach (GridRegion reg in neighbours)
            {
                handles.Add(reg.RegionHandle);
            }
            return handles;
        }

        private List<ulong> NewNeighbours(List<ulong> currentNeighbours, List<ulong> previousNeighbours)
        {
            return currentNeighbours.FindAll(delegate(ulong handle) { return !previousNeighbours.Contains(handle); });
        }

//        private List<ulong> CommonNeighbours(List<ulong> currentNeighbours, List<ulong> previousNeighbours)
//        {
//            return currentNeighbours.FindAll(delegate(ulong handle) { return previousNeighbours.Contains(handle); });
//        }

        private List<ulong> OldNeighbours(List<ulong> currentNeighbours, List<ulong> previousNeighbours)
        {
            return previousNeighbours.FindAll(delegate(ulong handle) { return !currentNeighbours.Contains(handle); });
        }

        public void CrossAgentToNewRegion(Scene scene, ScenePresence agent, bool isFlying)
        {
            Vector3 pos = agent.AbsolutePosition;
            Vector3 newpos = new Vector3(pos.X, pos.Y, pos.Z);
            uint neighbourx = m_regionInfo.RegionLocX;
            uint neighboury = m_regionInfo.RegionLocY;
            const float boundaryDistance = 1.7f;
            Vector3 northCross = new Vector3(0,boundaryDistance, 0);
            Vector3 southCross = new Vector3(0, -1 * boundaryDistance, 0);
            Vector3 eastCross = new Vector3(boundaryDistance, 0, 0);
            Vector3 westCross = new Vector3(-1 * boundaryDistance, 0, 0);

            // distance to edge that will trigger crossing
            

            // distance into new region to place avatar
            const float enterDistance = 0.5f;

            if (scene.TestBorderCross(pos + westCross, Cardinals.W))
            {
                if (scene.TestBorderCross(pos + northCross, Cardinals.N))
                {
                    Border b = scene.GetCrossedBorder(pos + northCross, Cardinals.N);
                    neighboury += (uint)(int)(b.BorderLine.Z / (int)Constants.RegionSize);
                }
                else if (scene.TestBorderCross(pos + southCross, Cardinals.S))
                {
                    Border b = scene.GetCrossedBorder(pos + southCross, Cardinals.S);
                    if (b.TriggerRegionX == 0 && b.TriggerRegionY == 0)
                    {
                        neighboury--;
                        newpos.Y = Constants.RegionSize - enterDistance;
                    }
                    else
                    {
                        neighboury = b.TriggerRegionY;
                        neighbourx = b.TriggerRegionX;
                        
                        Vector3 newposition = pos;
                        newposition.X += (scene.RegionInfo.RegionLocX - neighbourx) * Constants.RegionSize;
                        newposition.Y += (scene.RegionInfo.RegionLocY - neighboury) * Constants.RegionSize;
                        agent.ControllingClient.SendAgentAlertMessage(
                            String.Format("Moving you to region {0},{1}", neighbourx, neighboury), false);
                        InformClientToInitateTeleportToLocation(agent, neighbourx, neighboury, newposition, scene);
                        return;
                    }
                }

                Border ba = scene.GetCrossedBorder(pos + westCross, Cardinals.W);
                if (ba.TriggerRegionX == 0 && ba.TriggerRegionY == 0)
                {
                    neighbourx--;
                    newpos.X = Constants.RegionSize - enterDistance;
                }
                else
                {
                    neighboury = ba.TriggerRegionY;
                    neighbourx = ba.TriggerRegionX;


                    Vector3 newposition = pos;
                    newposition.X += (scene.RegionInfo.RegionLocX - neighbourx) * Constants.RegionSize;
                    newposition.Y += (scene.RegionInfo.RegionLocY - neighboury) * Constants.RegionSize;
                    agent.ControllingClient.SendAgentAlertMessage(
                            String.Format("Moving you to region {0},{1}", neighbourx, neighboury), false);
                    InformClientToInitateTeleportToLocation(agent, neighbourx, neighboury, newposition, scene);


                    return;
                }

            }
            else if (scene.TestBorderCross(pos + eastCross, Cardinals.E))
            {
                Border b = scene.GetCrossedBorder(pos + eastCross, Cardinals.E);
                neighbourx += (uint)(int)(b.BorderLine.Z / (int)Constants.RegionSize);
                newpos.X = enterDistance;

                if (scene.TestBorderCross(pos + southCross, Cardinals.S))
                {
                    Border ba = scene.GetCrossedBorder(pos + southCross, Cardinals.S);
                    if (ba.TriggerRegionX == 0 && ba.TriggerRegionY == 0)
                    {
                        neighboury--;
                        newpos.Y = Constants.RegionSize - enterDistance;
                    }
                    else
                    {
                        neighboury = ba.TriggerRegionY;
                        neighbourx = ba.TriggerRegionX;
                        Vector3 newposition = pos;
                        newposition.X += (scene.RegionInfo.RegionLocX - neighbourx) * Constants.RegionSize;
                        newposition.Y += (scene.RegionInfo.RegionLocY - neighboury) * Constants.RegionSize;
                        agent.ControllingClient.SendAgentAlertMessage(
                            String.Format("Moving you to region {0},{1}", neighbourx, neighboury), false);
                        InformClientToInitateTeleportToLocation(agent, neighbourx, neighboury, newposition, scene);
                        return;
                    }
                }
                else if (scene.TestBorderCross(pos + northCross, Cardinals.N))
                {
                    Border c = scene.GetCrossedBorder(pos + northCross, Cardinals.N);
                    neighboury += (uint)(int)(c.BorderLine.Z / (int)Constants.RegionSize);
                    newpos.Y = enterDistance;
                }


            }
            else if (scene.TestBorderCross(pos + southCross, Cardinals.S))
            {
                Border b = scene.GetCrossedBorder(pos + southCross, Cardinals.S);
                if (b.TriggerRegionX == 0 && b.TriggerRegionY == 0)
                {
                    neighboury--;
                    newpos.Y = Constants.RegionSize - enterDistance;
                }
                else
                {
                    neighboury = b.TriggerRegionY;
                    neighbourx = b.TriggerRegionX;
                    Vector3 newposition = pos;
                    newposition.X += (scene.RegionInfo.RegionLocX - neighbourx) * Constants.RegionSize;
                    newposition.Y += (scene.RegionInfo.RegionLocY - neighboury) * Constants.RegionSize;
                    agent.ControllingClient.SendAgentAlertMessage(
                            String.Format("Moving you to region {0},{1}", neighbourx, neighboury), false);
                    InformClientToInitateTeleportToLocation(agent, neighbourx, neighboury, newposition, scene);
                    return;
                }
            }
            else if (scene.TestBorderCross(pos + northCross, Cardinals.N))
            {

                Border b = scene.GetCrossedBorder(pos + northCross, Cardinals.N);
                neighboury += (uint)(int)(b.BorderLine.Z / (int)Constants.RegionSize);
                newpos.Y = enterDistance;
            }

            /*

            if (pos.X < boundaryDistance) //West
            {
                neighbourx--;
                newpos.X = Constants.RegionSize - enterDistance;
            }
            else if (pos.X > Constants.RegionSize - boundaryDistance) // East
            {
                neighbourx++;
                newpos.X = enterDistance;
            }

            if (pos.Y < boundaryDistance) // South
            {
                neighboury--;
                newpos.Y = Constants.RegionSize - enterDistance;
            }
            else if (pos.Y > Constants.RegionSize - boundaryDistance) // North
            {
                neighboury++;
                newpos.Y = enterDistance;
            }
            */

            CrossAgentToNewRegionDelegate d = CrossAgentToNewRegionAsync;
            d.BeginInvoke(agent, newpos, neighbourx, neighboury, isFlying, CrossAgentToNewRegionCompleted, d);
        }

        public delegate void InformClientToInitateTeleportToLocationDelegate(ScenePresence agent, uint regionX, uint regionY,
                                                                    Vector3 position,
                                                                    Scene initiatingScene);

        public void InformClientToInitateTeleportToLocation(ScenePresence agent, uint regionX, uint regionY, Vector3 position, 
            Scene initiatingScene)
        {

            // This assumes that we know what our neighbors are.
            
                InformClientToInitateTeleportToLocationDelegate d = InformClientToInitiateTeleportToLocationAsync;
                        d.BeginInvoke(agent,regionX,regionY,position,initiatingScene,
                                      InformClientToInitiateTeleportToLocationCompleted,
                                      d);
        }

        public void InformClientToInitiateTeleportToLocationAsync(ScenePresence agent, uint regionX, uint regionY, Vector3 position, 
            Scene initiatingScene)
        {
                Thread.Sleep(10000);
                IMessageTransferModule im = initiatingScene.RequestModuleInterface<IMessageTransferModule>();
                if (im != null)
                {
                    UUID gotoLocation = Util.BuildFakeParcelID(
                        Util.UIntsToLong(
                                                  (regionX *
                                                   (uint)Constants.RegionSize),
                                                  (regionY *
                                                   (uint)Constants.RegionSize)),
                        (uint)(int)position.X,
                        (uint)(int)position.Y,
                        (uint)(int)position.Z);
                    GridInstantMessage m = new GridInstantMessage(initiatingScene, UUID.Zero,
                    "Region", agent.UUID,
                    (byte)InstantMessageDialog.GodLikeRequestTeleport, false,
                    "", gotoLocation, false, new Vector3(127, 0, 0),
                    new Byte[0]);
                    im.SendInstantMessage(m, delegate(bool success)
                    {
                        m_log.DebugFormat("[CLIENT]: Client Initiating Teleport sending IM success = {0}", success);
                    });

                }
        }

        private void InformClientToInitiateTeleportToLocationCompleted(IAsyncResult iar)
        {
            InformClientToInitateTeleportToLocationDelegate icon =
                (InformClientToInitateTeleportToLocationDelegate) iar.AsyncState;
            icon.EndInvoke(iar);
        }

        public delegate ScenePresence CrossAgentToNewRegionDelegate(ScenePresence agent, Vector3 pos, uint neighbourx, uint neighboury, bool isFlying);

        /// <summary>
        /// This Closes child agents on neighboring regions
        /// Calls an asynchronous method to do so..  so it doesn't lag the sim.
        /// </summary>
        protected ScenePresence CrossAgentToNewRegionAsync(ScenePresence agent, Vector3 pos, uint neighbourx, uint neighboury, bool isFlying)
        {
            m_log.DebugFormat("[SCENE COMM]: Crossing agent {0} {1} to {2}-{3}", agent.Firstname, agent.Lastname, neighbourx, neighboury);

            ulong neighbourHandle = Utils.UIntsToLong((uint)(neighbourx * Constants.RegionSize), (uint)(neighboury * Constants.RegionSize));

            int x = (int)(neighbourx * Constants.RegionSize), y = (int)(neighboury * Constants.RegionSize);
            GridRegion neighbourRegion = m_scene.GridService.GetRegionByPosition(m_scene.RegionInfo.ScopeID, (int)x, (int)y);

            if (neighbourRegion != null && agent.ValidateAttachments())
            {
                pos = pos + (agent.Velocity);

                //CachedUserInfo userInfo = m_commsProvider.UserProfileCacheService.GetUserDetails(agent.UUID);
                //if (userInfo != null)
                //{
                //    userInfo.DropInventory();
                //}
                //else
                //{
                //    m_log.WarnFormat("[SCENE COMM]: No cached user info found for {0} {1} on leaving region {2}", 
                //            agent.Name, agent.UUID, agent.Scene.RegionInfo.RegionName);
                //}

                //bool crossingSuccessful =
                //    CrossToNeighbouringRegion(neighbourHandle, agent.ControllingClient.AgentId, pos,
                                                      //isFlying);

                SetInTransit(agent.UUID);
                AgentData cAgent = new AgentData();
                agent.CopyTo(cAgent);
                cAgent.Position = pos;
                if (isFlying)
                    cAgent.ControlFlags |= (uint)AgentManager.ControlFlags.AGENT_CONTROL_FLY;
                cAgent.CallbackURI = "http://" + m_regionInfo.ExternalHostName + ":" + m_regionInfo.HttpPort +
                    "/agent/" + agent.UUID.ToString() + "/" + agent.Scene.RegionInfo.RegionHandle.ToString() + "/release/";

                m_interregionCommsOut.SendChildAgentUpdate(neighbourHandle, cAgent);

                // Next, let's close the child agent connections that are too far away.
                agent.CloseChildAgents(neighbourx, neighboury);

                //AgentCircuitData circuitdata = m_controllingClient.RequestClientInfo();
                agent.ControllingClient.RequestClientInfo();

                //m_log.Debug("BEFORE CROSS");
                //Scene.DumpChildrenSeeds(UUID);
                //DumpKnownRegions();
                string agentcaps;
                if (!agent.KnownRegions.TryGetValue(neighbourRegion.RegionHandle, out agentcaps))
                {
                    m_log.ErrorFormat("[SCENE COMM]: No CAPS information for region handle {0}, exiting CrossToNewRegion.",
                                     neighbourRegion.RegionHandle);
                    return agent;
                }
                // TODO Should construct this behind a method
                string capsPath =
                    "http://" + neighbourRegion.ExternalHostName + ":" + neighbourRegion.HttpPort
                     + "/CAPS/" + agentcaps /*circuitdata.CapsPath*/ + "0000/";

                m_log.DebugFormat("[CAPS]: Sending new CAPS seed url {0} to client {1}", capsPath, agent.UUID);

                IEventQueue eq = agent.Scene.RequestModuleInterface<IEventQueue>();
                if (eq != null)
                {
                    eq.CrossRegion(neighbourHandle, pos, agent.Velocity, neighbourRegion.ExternalEndPoint,
                                   capsPath, agent.UUID, agent.ControllingClient.SessionId);
                }
                else
                {
                    agent.ControllingClient.CrossRegion(neighbourHandle, pos, agent.Velocity, neighbourRegion.ExternalEndPoint,
                                                capsPath);
                }

                if (!WaitForCallback(agent.UUID))
                {
                    ResetFromTransit(agent.UUID);

                    // Yikes! We should just have a ref to scene here.
                    agent.Scene.InformClientOfNeighbours(agent);

                    return agent;
                }

                agent.MakeChildAgent();
                // now we have a child agent in this region. Request all interesting data about other (root) agents
                agent.SendInitialFullUpdateToAllClients();

                agent.CrossAttachmentsIntoNewRegion(neighbourHandle, true);

                //                    m_scene.SendKillObject(m_localId);

                agent.Scene.NotifyMyCoarseLocationChange();
                // the user may change their profile information in other region,
                // so the userinfo in UserProfileCache is not reliable any more, delete it
                if (agent.Scene.NeedSceneCacheClear(agent.UUID))
                {
                    agent.Scene.CommsManager.UserProfileCacheService.RemoveUser(agent.UUID);
                    m_log.DebugFormat(
                        "[SCENE COMM]: User {0} is going to another region, profile cache removed", agent.UUID);
                }
            }

            //m_log.Debug("AFTER CROSS");
            //Scene.DumpChildrenSeeds(UUID);
            //DumpKnownRegions();
            return agent;
        }

        private void CrossAgentToNewRegionCompleted(IAsyncResult iar)
        {
            CrossAgentToNewRegionDelegate icon = (CrossAgentToNewRegionDelegate)iar.AsyncState;
            ScenePresence agent = icon.EndInvoke(iar);

            // If the cross was successful, this agent is a child agent
            if (agent.IsChildAgent)
            {
                agent.Reset();
            }
            else // Not successful
            {
                //CachedUserInfo userInfo = m_commsProvider.UserProfileCacheService.GetUserDetails(agent.UUID);
                //if (userInfo != null)
                //{
                //    userInfo.FetchInventory();
                //}
                agent.RestoreInCurrentScene();
            }
            // In any case
            agent.NotInTransit();

            //m_log.DebugFormat("[SCENE COMM]: Crossing agent {0} {1} completed.", agent.Firstname, agent.Lastname);
        }


        public void LogOffUser(UUID userid, UUID regionid, ulong regionhandle, Vector3 position, Vector3 lookat)
        {
            m_commsProvider.LogOffUser(userid, regionid, regionhandle, position, lookat);
        }

        // deprecated as of 2008-08-27
        public void LogOffUser(UUID userid, UUID regionid, ulong regionhandle, float posx, float posy, float posz)
        {
             m_commsProvider.LogOffUser(userid, regionid, regionhandle, posx, posy, posz);
        }

        public void ClearUserAgent(UUID avatarID)
        {
            m_commsProvider.UserService.ClearUserAgent(avatarID);
        }

        public void AddNewUserFriend(UUID friendlistowner, UUID friend, uint perms)
        {
            m_commsProvider.AddNewUserFriend(friendlistowner, friend, perms);
        }

        public void UpdateUserFriendPerms(UUID friendlistowner, UUID friend, uint perms)
        {
            m_commsProvider.UpdateUserFriendPerms(friendlistowner, friend, perms);
        }

        public void RemoveUserFriend(UUID friendlistowner, UUID friend)
        {
            m_commsProvider.RemoveUserFriend(friendlistowner, friend);
        }

        public List<FriendListItem> GetUserFriendList(UUID friendlistowner)
        {
            return m_commsProvider.GetUserFriendList(friendlistowner);
        }

        public List<AvatarPickerAvatar> GenerateAgentPickerRequestResponse(UUID queryID, string query)
        {
            return m_commsProvider.GenerateAgentPickerRequestResponse(queryID, query);
        }
        
        public List<GridRegion> RequestNamedRegions(string name, int maxNumber)
        {
            return m_scene.GridService.GetRegionsByName(UUID.Zero, name, maxNumber);
        }

        //private void Dump(string msg, List<ulong> handles)
        //{
        //    m_log.InfoFormat("-------------- HANDLE DUMP ({0}) ---------", msg);
        //    foreach (ulong handle in handles)
        //    {
        //        uint x, y;
        //        Utils.LongToUInts(handle, out x, out y);
        //        x = x / Constants.RegionSize;
        //        y = y / Constants.RegionSize;
        //        m_log.InfoFormat("({0}, {1})", x, y);
        //    }
        //}
    }
}
