/*
 * 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 OpenSim 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;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * 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;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Reflection;
using System.Threading;
using System.Xml;
using OpenMetaverse;
using OpenMetaverse.StructuredData;
using log4net;
using Nini.Config;
using Nwc.XmlRpc;
using OpenSim.Framework;
using OpenSim.Framework.Communications.Cache;
using OpenSim.Framework.Communications.Capabilities;
using OpenSim.Framework.Servers;
using OpenSim.Region.Environment.Interfaces;
using OpenSim.Region.Interfaces;
using OpenSim.Region.Environment.Scenes;

using OSD = OpenMetaverse.StructuredData.OSD;
using OSDMap = OpenMetaverse.StructuredData.OSDMap;
using OSDArray = OpenMetaverse.StructuredData.OSDArray;
using Caps = OpenSim.Framework.Communications.Capabilities.Caps;
using BlockingLLSDQueue = OpenSim.Framework.BlockingQueue<OpenMetaverse.StructuredData.OSD>;

namespace OpenSim.Region.Environment.Modules.Framework.EventQueue
{
    public struct QueueItem
    {
        public int id;
        public OSDMap body;
    }

    public class EventQueueGetModule : IEventQueue, IRegionModule
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        private Scene m_scene = null;
        private IConfigSource m_gConfig;
        bool enabledYN = false;
        
        private Dictionary<UUID, int> m_ids = new Dictionary<UUID, int>();

        private Dictionary<UUID, BlockingLLSDQueue> queues = new Dictionary<UUID, BlockingLLSDQueue>();
        private Dictionary<UUID, UUID> m_QueueUUIDAvatarMapping = new Dictionary<UUID, UUID>();
        private Dictionary<UUID, UUID> m_AvatarQueueUUIDMapping = new Dictionary<UUID, UUID>();
            
        #region IRegionModule methods
        public void Initialise(Scene scene, IConfigSource config)
        {
            m_gConfig = config;

            IConfig startupConfig = m_gConfig.Configs["Startup"];

            ReadConfigAndPopulate(scene, startupConfig, "Startup");

            if (enabledYN)
            {
                m_scene = scene;
                scene.RegisterModuleInterface<IEventQueue>(this);
                
                // Register fallback handler
                // Why does EQG Fail on region crossings!
                
                //scene.CommsManager.HttpServer.AddLLSDHandler("/CAPS/EQG/", EventQueueFallBack);

                scene.EventManager.OnNewClient += OnNewClient;

                // TODO: Leaving these open, or closing them when we
                // become a child is incorrect. It messes up TP in a big
                // way. CAPS/EQ need to be active as long as the UDP
                // circuit is there.

                scene.EventManager.OnClientClosed += ClientClosed;
                scene.EventManager.OnMakeChildAgent += MakeChildAgent;
                scene.EventManager.OnRegisterCaps += OnRegisterCaps;
            }
            else
            {
                m_gConfig = null;
            }
        
        }

        private void ReadConfigAndPopulate(Scene scene, IConfig startupConfig, string p)
        {
            enabledYN = startupConfig.GetBoolean("EventQueue", true);
        }

        public void PostInitialise()
        {
        }

        public void Close()
        {
        }

        public string Name
        {
            get { return "EventQueueGetModule"; }
        }

        public bool IsSharedModule
        {
            get { return false; }
        }
        #endregion

        /// <summary>
        ///  Always returns a valid queue
        /// </summary>
        /// <param name="agentId"></param>
        /// <returns></returns>
        private BlockingLLSDQueue TryGetQueue(UUID agentId)
        {
            lock (queues)
            {
                if (!queues.ContainsKey(agentId))
                {
                    m_log.DebugFormat(
                        "[EVENTQUEUE]: Adding new queue for agent {0} in region {1}", 
                        agentId, m_scene.RegionInfo.RegionName);
                    
                    queues[agentId] = new BlockingLLSDQueue();
                }
                
                return queues[agentId];
            }
        }

        /// <summary>
        /// May return a null queue
        /// </summary>
        /// <param name="agentId"></param>
        /// <returns></returns>
        private BlockingLLSDQueue GetQueue(UUID agentId)
        {
            lock (queues)
            {
                if (queues.ContainsKey(agentId))
                {
                    return queues[agentId];
                }
                else
                    return null;
            }
        }

        #region IEventQueue Members

        public bool Enqueue(OSD ev, UUID avatarID)
        {
            //m_log.DebugFormat("[EVENTQUEUE]: Enqueuing event for {0} in region {1}", avatarID, m_scene.RegionInfo.RegionName);
            try
            {
                BlockingLLSDQueue queue = GetQueue(avatarID);
                if (queue != null)
                    queue.Enqueue(ev);
            } 
            catch(NullReferenceException e)
            {
                m_log.Error("[EVENTQUEUE] Caught exception: " + e);
                return false;
            }
            
            return true;
        }

        #endregion

        private void OnNewClient(IClientAPI client)
        {
            //client.OnLogout += ClientClosed;
        }

//        private void ClientClosed(IClientAPI client)
//        {
//            ClientClosed(client.AgentId);
//        }

        private void ClientClosed(UUID AgentID)
        {
            m_log.DebugFormat("[EVENTQUEUE]: Closed client {0} in region {1}", AgentID, m_scene.RegionInfo.RegionName);

            int count = 0;
            while (queues.ContainsKey(AgentID) && queues[AgentID].Count() > 0 && count++ < 5)
            {
                Thread.Sleep(1000);
            }

            lock (queues)
            {
                queues.Remove(AgentID);
            }
            List<UUID> removeitems = new List<UUID>();
            lock (m_AvatarQueueUUIDMapping)
            {
                foreach (UUID ky in m_AvatarQueueUUIDMapping.Keys)
                {
                    if (ky == AgentID)
                    {
                        removeitems.Add(ky);
                    }
                }

                foreach (UUID ky in removeitems)
                {
                    m_AvatarQueueUUIDMapping.Remove(ky);
                    m_scene.CommsManager.HttpServer.RemoveHTTPHandler("","/CAPS/EQG/" + ky.ToString() + "/");
                }

            }
            UUID searchval = UUID.Zero;

            removeitems.Clear();
            
            lock (m_QueueUUIDAvatarMapping)
            {
                foreach (UUID ky in m_QueueUUIDAvatarMapping.Keys)
                {
                    searchval = m_QueueUUIDAvatarMapping[ky];

                    if (searchval == AgentID)
                    {
                        removeitems.Add(ky);
                    }
                }

                foreach (UUID ky in removeitems)
                    m_QueueUUIDAvatarMapping.Remove(ky);

            }
        }

        private void MakeChildAgent(ScenePresence avatar)
        {
            //m_log.DebugFormat("[EVENTQUEUE]: Make Child agent {0} in region {1}.", avatar.UUID, m_scene.RegionInfo.RegionName);
            //lock (m_ids)
           // {
                //if (m_ids.ContainsKey(avatar.UUID))
                //{
                    // close the event queue.
                    //m_ids[avatar.UUID] = -1;
                //}
            //}
        }

        public void OnRegisterCaps(UUID agentID, Caps caps)
        {
            // Register an event queue for the client
            
            //m_log.DebugFormat(
            //    "[EVENTQUEUE]: OnRegisterCaps: agentID {0} caps {1} region {2}", 
            //    agentID, caps, m_scene.RegionInfo.RegionName);

            // Let's instantiate a Queue for this agent right now
            TryGetQueue(agentID);

            string capsBase = "/CAPS/EQG/";
            UUID EventQueueGetUUID = UUID.Zero;

            lock (m_AvatarQueueUUIDMapping)
            {
                // Reuse open queues.  The client does!
                if (m_AvatarQueueUUIDMapping.ContainsKey(agentID))
                {
                    m_log.DebugFormat("[EVENTQUEUE]: Found Existing UUID!");
                    EventQueueGetUUID = m_AvatarQueueUUIDMapping[agentID];
                }
                else
                {
                    EventQueueGetUUID = UUID.Random();
                    //m_log.DebugFormat("[EVENTQUEUE]: Using random UUID!");
                }
            }

            lock (m_QueueUUIDAvatarMapping)
            {
                if (!m_QueueUUIDAvatarMapping.ContainsKey(EventQueueGetUUID))
                    m_QueueUUIDAvatarMapping.Add(EventQueueGetUUID, agentID);
            }

            lock (m_AvatarQueueUUIDMapping)
            {
                if (!m_AvatarQueueUUIDMapping.ContainsKey(agentID))
                    m_AvatarQueueUUIDMapping.Add(agentID, EventQueueGetUUID);
            }

            // Register this as a caps handler
            caps.RegisterHandler("EventQueueGet",
                                 new RestHTTPHandler("POST", capsBase + EventQueueGetUUID.ToString() + "/",
                                                       delegate(Hashtable m_dhttpMethod)
                                                       {
                                                           return ProcessQueue(m_dhttpMethod, agentID, caps);
                                                       }));
            
            // This will persist this beyond the expiry of the caps handlers
            m_scene.CommsManager.HttpServer.AddHTTPHandler(
                capsBase + EventQueueGetUUID.ToString() + "/", EventQueuePath2);

            Random rnd = new Random(System.Environment.TickCount);
            lock (m_ids)
            {
                if (!m_ids.ContainsKey(agentID))
                    m_ids.Add(agentID, rnd.Next(30000000));
            }
        }

        public Hashtable ProcessQueue(Hashtable request, UUID agentID, Caps caps)
        {
            // TODO: this has to be redone to not busy-wait (and block the thread),
            // TODO: as soon as we have a non-blocking way to handle HTTP-requests.

//            if (m_log.IsDebugEnabled)
//            { 
//                String debug = "[EVENTQUEUE]: Got request for agent {0} in region {1} from thread {2}: [  ";
//                foreach (object key in request.Keys)
//                {
//                    debug += key.ToString() + "=" + request[key].ToString() + "  ";
//                }
//                m_log.DebugFormat(debug + "  ]", agentID, m_scene.RegionInfo.RegionName, System.Threading.Thread.CurrentThread.Name);
//            }

            BlockingLLSDQueue queue = TryGetQueue(agentID);
            OSD element = queue.Dequeue(15000); // 15s timeout

            Hashtable responsedata = new Hashtable();
            
            int thisID = 0;
            lock (m_ids) 
                thisID = m_ids[agentID];

            if (element == null)
            {
                //m_log.ErrorFormat("[EVENTQUEUE]: Nothing to process in " + m_scene.RegionInfo.RegionName);
                if (thisID == -1) // close-request
                {
                    m_log.ErrorFormat("[EVENTQUEUE]: 404 in " + m_scene.RegionInfo.RegionName);
                    responsedata["int_response_code"] = 404; //501; //410; //404;
                    responsedata["content_type"] = "text/plain";
                    responsedata["keepalive"] = false;
                    responsedata["str_response_string"] = "Closed EQG";
                    return responsedata;
                }
                responsedata["int_response_code"] = 502;
                responsedata["content_type"] = "text/plain";
                responsedata["keepalive"] = false;
                responsedata["str_response_string"] = "Upstream error: ";
                responsedata["error_status_text"] = "Upstream error:";
                responsedata["http_protocol_version"] = "HTTP/1.0";
                return responsedata;
            }            

            OSDArray array = new OSDArray();
            if (element == null) // didn't have an event in 15s
            {
                // Send it a fake event to keep the client polling!   It doesn't like 502s like the proxys say!
                array.Add(EventQueueHelper.KeepAliveEvent());
                m_log.DebugFormat("[EVENTQUEUE]: adding fake event for {0} in region {1}", agentID, m_scene.RegionInfo.RegionName);
            }
            else
            {
                array.Add(element);
                while (queue.Count() > 0)
                {
                    array.Add(queue.Dequeue(1));
                    thisID++;
                }
            }

            OSDMap events = new OSDMap();
            events.Add("events", array);

            events.Add("id", new OSDInteger(thisID));
            lock (m_ids)
            {
                m_ids[agentID] = thisID + 1;
            }

            responsedata["int_response_code"] = 200;
            responsedata["content_type"] = "application/xml";
            responsedata["keepalive"] = false;
            responsedata["str_response_string"] = OSDParser.SerializeLLSDXmlString(events);
            //m_log.DebugFormat("[EVENTQUEUE]: sending response for {0} in region {1}: {2}", agentID, m_scene.RegionInfo.RegionName, responsedata["str_response_string"]);

            return responsedata;
        }

        public Hashtable EventQueuePath2(Hashtable request)
        {
            string capuuid = (string)request["uri"]; //path.Replace("/CAPS/EQG/","");
            // pull off the last "/" in the path.
            Hashtable responsedata = new Hashtable();
            capuuid = capuuid.Substring(0, capuuid.Length - 1);
            capuuid = capuuid.Replace("/CAPS/EQG/", "");
            UUID AvatarID = UUID.Zero;
            UUID capUUID = UUID.Zero;
            
            // parse the path and search for the avatar with it registered
            if (UUID.TryParse(capuuid, out capUUID))
            {
                lock (m_QueueUUIDAvatarMapping)
                {
                    if (m_QueueUUIDAvatarMapping.ContainsKey(capUUID))
                    {
                        AvatarID = m_QueueUUIDAvatarMapping[capUUID];
                    }
                }
                if (AvatarID != UUID.Zero)
                {
                    // m_scene.GetCapsHandlerForUser will return null if the agent doesn't have a caps handler
                    // registered
                    return ProcessQueue(request, AvatarID, m_scene.GetCapsHandlerForUser(AvatarID));
                }
                else
                {
                    responsedata["int_response_code"] = 404;
                    responsedata["content_type"] = "text/plain";
                    responsedata["keepalive"] = false;
                    responsedata["str_response_string"] = "Not Found";
                    responsedata["error_status_text"] = "Not Found";
                    responsedata["http_protocol_version"] = "HTTP/1.0";
                    return responsedata;
                    // return 404
                }
            }
            else
            {
                responsedata["int_response_code"] = 404;
                responsedata["content_type"] = "text/plain";
                responsedata["keepalive"] = false;
                responsedata["str_response_string"] = "Not Found";
                responsedata["error_status_text"] = "Not Found";
                responsedata["http_protocol_version"] = "HTTP/1.0";
                return responsedata;
                // return 404
            }

        }

        public OSD EventQueueFallBack(string path, OSD request, string endpoint)
        {
            // This is a fallback element to keep the client from loosing EventQueueGet
            // Why does CAPS fail sometimes!?
            m_log.Warn("[EVENTQUEUE]: In the Fallback handler!   We lost the Queue in the rest handler!");
            string capuuid = path.Replace("/CAPS/EQG/","");
            capuuid = capuuid.Substring(0, capuuid.Length - 1);

//            UUID AvatarID = UUID.Zero;
            UUID capUUID = UUID.Zero;
            if (UUID.TryParse(capuuid, out capUUID))
            {
/* Don't remove this yet code cleaners!
 * Still testing this!
 * 
                lock (m_QueueUUIDAvatarMapping)
                {
                    if (m_QueueUUIDAvatarMapping.ContainsKey(capUUID))
                    {
                        AvatarID = m_QueueUUIDAvatarMapping[capUUID];
                    }
                }
                
                 
                if (AvatarID != UUID.Zero)
                {
                    // Repair the CAP!
                    //OpenSim.Framework.Communications.Capabilities.Caps caps = m_scene.GetCapsHandlerForUser(AvatarID);
                    //string capsBase = "/CAPS/EQG/";
                    //caps.RegisterHandler("EventQueueGet",
                                //new RestHTTPHandler("POST", capsBase + capUUID.ToString() + "/",
                                                      //delegate(Hashtable m_dhttpMethod)
                                                      //{
                                                      //    return ProcessQueue(m_dhttpMethod, AvatarID, caps);
                                                      //}));
                    // start new ID sequence.
                    Random rnd = new Random(System.Environment.TickCount);
                    lock (m_ids)
                    {
                        if (!m_ids.ContainsKey(AvatarID))
                            m_ids.Add(AvatarID, rnd.Next(30000000));
                    }


                    int thisID = 0;
                    lock (m_ids)
                        thisID = m_ids[AvatarID];

                    BlockingLLSDQueue queue = GetQueue(AvatarID);
                    OSDArray array = new OSDArray();
                    LLSD element = queue.Dequeue(15000); // 15s timeout
                    if (element == null)
                    {
                        
                        array.Add(EventQueueHelper.KeepAliveEvent());
                    }
                    else
                    {
                        array.Add(element);
                        while (queue.Count() > 0)
                        {
                            array.Add(queue.Dequeue(1));
                            thisID++;
                        }
                    }
                    OSDMap events = new OSDMap();
                    events.Add("events", array);

                    events.Add("id", new LLSDInteger(thisID));
                    
                    lock (m_ids)
                    {
                        m_ids[AvatarID] = thisID + 1;
                    }
                    
                    return events;
                }
                else
                {
                    return new LLSD();
                }
* 
*/
            }
            else
            {
                //return new LLSD();
            }
            
            return new OSDString("shutdown404!");
        }
    }
}