/*
* 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.Generic;
using System.Threading;
using libsecondlife;
using libsecondlife.Packets;
using Nini.Config;
using OpenSim.Framework;
using OpenSim.Region.Environment.Interfaces;
using OpenSim.Region.Environment.Scenes;

namespace OpenSim.Region.Environment.Modules
{
    public class AssetDownloadModule : IRegionModule
    {
        private Scene m_scene;
        private Dictionary<LLUUID, Scene> RegisteredScenes = new Dictionary<LLUUID, Scene>();
        ///
        /// Assets requests (for each user) which are waiting for asset server data.  This includes texture requests
        /// </summary>
        private Dictionary<LLUUID, Dictionary<LLUUID,AssetRequest>> RequestedAssets;

        /// <summary>
        /// Asset requests with data which are ready to be sent back to requesters.  This includes textures.
        /// </summary>
        private List<AssetRequest> AssetRequests;

        public AssetDownloadModule()
        {
            RequestedAssets = new Dictionary<LLUUID, Dictionary<LLUUID, AssetRequest>>();
            AssetRequests = new List<AssetRequest>();
        }

        public void Initialise(Scene scene, IConfigSource config)
        {
            if (!RegisteredScenes.ContainsKey(scene.RegionInfo.RegionID))
            {
                RegisteredScenes.Add(scene.RegionInfo.RegionID, scene);
              //  scene.EventManager.OnNewClient += NewClient;
            }

            if (m_scene == null)
            {
                m_scene = scene;
               // m_thread = new Thread(new ThreadStart(RunAssetQueue));
              //  m_thread.Name = "AssetDownloadQueueThread";
               // m_thread.IsBackground = true;
               // m_thread.Start();
               // OpenSim.Framework.ThreadTracker.Add(m_thread);
            }
        }

        public void PostInitialise()
        {
        }

        public void Close()
        {
        }

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

        public bool IsSharedModule
        {
            get { return true; }
        }

        public void NewClient(IClientAPI client)
        {
           // client.OnRequestAsset += AddAssetRequest;
        }

        /// <summary>
        /// Make an asset request the result of which will be packeted up and sent directly back to the client.
        /// </summary>
        /// <param name="userInfo"></param>
        /// <param name="transferRequest"></param>
        public void AddAssetRequest(IClientAPI userInfo, TransferRequestPacket transferRequest)
        {
            LLUUID requestID = null;
            byte source = 2;
            if (transferRequest.TransferInfo.SourceType == 2)
            {
                //direct asset request
                requestID = new LLUUID(transferRequest.TransferInfo.Params, 0);
            }
            else if (transferRequest.TransferInfo.SourceType == 3)
            {
                //inventory asset request
                requestID = new LLUUID(transferRequest.TransferInfo.Params, 80);
                source = 3;
                //Console.WriteLine("asset request " + requestID);
            }

            //not found asset
            // so request from asset server
            Dictionary<LLUUID, AssetRequest> userRequests = null;
            if (RequestedAssets.TryGetValue(userInfo.AgentId, out userRequests))
            {
                if (!userRequests.ContainsKey(requestID))
                {
                    AssetRequest request = new AssetRequest();
                    request.RequestUser = userInfo;
                    request.RequestAssetID = requestID;
                    request.TransferRequestID = transferRequest.TransferInfo.TransferID;
                    request.AssetRequestSource = source;
                    request.Params = transferRequest.TransferInfo.Params;
                    userRequests[requestID] = request;
                    m_scene.AssetCache.GetAsset(requestID, AssetCallback, false);
                }
            }
            else
            {
                userRequests = new Dictionary<LLUUID, AssetRequest>();
                AssetRequest request = new AssetRequest();
                request.RequestUser = userInfo;
                request.RequestAssetID = requestID;
                request.TransferRequestID = transferRequest.TransferInfo.TransferID;
                request.AssetRequestSource = source;
                request.Params = transferRequest.TransferInfo.Params;
                userRequests.Add(requestID, request);
                RequestedAssets[userInfo.AgentId] = userRequests;
                m_scene.AssetCache.GetAsset(requestID, AssetCallback, false);
            }
        }

        public void AssetCallback(LLUUID assetID, AssetBase asset)
        {
            if (asset != null)
            {
                foreach (Dictionary<LLUUID, AssetRequest> userRequests in RequestedAssets.Values)
                {
                    if (userRequests.ContainsKey(assetID))
                    {
                        AssetRequest req = userRequests[assetID];
                        if (req != null)
                        {
                            req.AssetInf = asset;
                            req.NumPackets = CalculateNumPackets(asset.Data);

                            userRequests.Remove(assetID);
                            AssetRequests.Add(req);
                        }
                    }
                }
            }
        }

        private void RunAssetQueue()
        {
            while (true)
            {
                try
                {
                    ProcessAssetQueue();
                    Thread.Sleep(500);
                }
                catch (Exception)
                {
                  //  m_log.Error("[ASSET CACHE]: " + e.ToString());
                }
            }
        }

        /// <summary>
        /// Process the asset queue which sends packets directly back to the client.
        /// </summary>
        private void ProcessAssetQueue()
        {
            //should move the asset downloading to a module, like has been done with texture downloading
            if (AssetRequests.Count == 0)
            {
                //no requests waiting
                return;
            }
            // if less than 5, do all of them
            int num = Math.Min(5, AssetRequests.Count);

            AssetRequest req;
            for (int i = 0; i < num; i++)
            {
                req = (AssetRequest)AssetRequests[i];
                //Console.WriteLine("sending asset " + req.RequestAssetID);
                TransferInfoPacket Transfer = new TransferInfoPacket();
                Transfer.TransferInfo.ChannelType = 2;
                Transfer.TransferInfo.Status = 0;
                Transfer.TransferInfo.TargetType = 0;
                if (req.AssetRequestSource == 2)
                {
                    Transfer.TransferInfo.Params = new byte[20];
                    Array.Copy(req.RequestAssetID.GetBytes(), 0, Transfer.TransferInfo.Params, 0, 16);
                    int assType = (int)req.AssetInf.Type;
                    Array.Copy(Helpers.IntToBytes(assType), 0, Transfer.TransferInfo.Params, 16, 4);
                }
                else if (req.AssetRequestSource == 3)
                {
                    Transfer.TransferInfo.Params = req.Params;
                    // Transfer.TransferInfo.Params = new byte[100];
                    //Array.Copy(req.RequestUser.AgentId.GetBytes(), 0, Transfer.TransferInfo.Params, 0, 16);
                    //Array.Copy(req.RequestUser.SessionId.GetBytes(), 0, Transfer.TransferInfo.Params, 16, 16);
                }
                Transfer.TransferInfo.Size = (int)req.AssetInf.Data.Length;
                Transfer.TransferInfo.TransferID = req.TransferRequestID;
                req.RequestUser.OutPacket(Transfer, ThrottleOutPacketType.Asset);

                if (req.NumPackets == 1)
                {
                    TransferPacketPacket TransferPacket = new TransferPacketPacket();
                    TransferPacket.TransferData.Packet = 0;
                    TransferPacket.TransferData.ChannelType = 2;
                    TransferPacket.TransferData.TransferID = req.TransferRequestID;
                    TransferPacket.TransferData.Data = req.AssetInf.Data;
                    TransferPacket.TransferData.Status = 1;
                    req.RequestUser.OutPacket(TransferPacket, ThrottleOutPacketType.Asset);
                }
                else
                {
                    int processedLength = 0;
                    // libsecondlife hardcodes 1500 as the maximum data chunk size
                    int maxChunkSize = 1250;
                    int packetNumber = 0;

                    while (processedLength < req.AssetInf.Data.Length)
                    {
                        TransferPacketPacket TransferPacket = new TransferPacketPacket();
                        TransferPacket.TransferData.Packet = packetNumber;
                        TransferPacket.TransferData.ChannelType = 2;
                        TransferPacket.TransferData.TransferID = req.TransferRequestID;

                        int chunkSize = Math.Min(req.AssetInf.Data.Length - processedLength, maxChunkSize);
                        byte[] chunk = new byte[chunkSize];
                        Array.Copy(req.AssetInf.Data, processedLength, chunk, 0, chunk.Length);

                        TransferPacket.TransferData.Data = chunk;

                        // 0 indicates more packets to come, 1 indicates last packet
                        if (req.AssetInf.Data.Length - processedLength > maxChunkSize)
                        {
                            TransferPacket.TransferData.Status = 0;
                        }
                        else
                        {
                            TransferPacket.TransferData.Status = 1;
                        }

                        req.RequestUser.OutPacket(TransferPacket, ThrottleOutPacketType.Asset);

                        processedLength += chunkSize;
                        packetNumber++;
                    }
                }
            }

            //remove requests that have been completed
            for (int i = 0; i < num; i++)
            {
                AssetRequests.RemoveAt(0);
            }
        }

        /// <summary>
        /// Calculate the number of packets required to send the asset to the client.
        /// </summary>
        /// <param name="data"></param>
        /// <returns></returns>
        private int CalculateNumPackets(byte[] data)
        {
            const uint m_maxPacketSize = 600;
            int numPackets = 1;

            if (data.LongLength > m_maxPacketSize)
            {
                // over max number of bytes so split up file
                long restData = data.LongLength - m_maxPacketSize;
                int restPackets = (int)((restData + m_maxPacketSize - 1) / m_maxPacketSize);
                numPackets += restPackets;
            }

            return numPackets;
        }

        public class AssetRequest
        {
            public IClientAPI RequestUser;
            public LLUUID RequestAssetID;
            public AssetBase AssetInf;
            public AssetBase ImageInfo;
            public LLUUID TransferRequestID;
            public long DataPointer = 0;
            public int NumPackets = 0;
            public int PacketCounter = 0;
            public bool IsTextureRequest;
            public byte AssetRequestSource = 2;
            public byte[] Params = null;
            //public bool AssetInCache;
            //public int TimeRequested; 
            public int DiscardLevel = -1;

            public AssetRequest()
            {
            }
        }
    }
}