/*
 * 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;
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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.Reflection;
using libsecondlife.Packets;
using log4net;
using OpenSim.Framework;
using OpenSim.Region.Environment.Interfaces;

namespace OpenSim.Region.Environment.Modules.Agent.TextureSender
{
    /// <summary>
    /// A TextureSender handles the process of receiving a texture requested by the client from the 
    /// AssetCache, and then sending that texture back to the client.
    /// </summary>
    public class TextureSender : ITextureSender
    {
        private static readonly ILog m_log 
            = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        /// <summary>
        /// Records the number of times texture send has been called.
        /// </summary>
        public int counter = 0;
        
        /// <summary>
        /// Holds the texture asset to send.
        /// </summary>
        private AssetBase m_asset;
        
        //public LLUUID assetID { get { return m_asset.FullID; } }
        
        /// <summary>
        /// This is actually the number of extra packets required to send the texture data!  We always assume
        /// at least one is required.
        /// </summary>
        private int NumPackets = 0;
        
        /// <summary>
        /// Holds the packet number to send next.  In this case, each packet is 1000 bytes long and starts
        /// at the 600th byte (0th indexed).
        /// </summary>
        private int PacketCounter = 0;
        
        // See ITextureSender
        public bool Cancel 
        { 
            get { return false; }
            set { m_cancel = value; }
        }
                    
        private bool m_cancel = false;
        
        // See ITextureSender
        public bool Sending 
        { 
            get { return false; }
            set { m_sending = value; }
        }
                    
        private bool m_sending = false;        
        
        public bool ImageLoaded = false;

        private IClientAPI RequestUser;

        private int RequestedDiscardLevel = -1;
        private uint StartPacketNumber = 0;

        public TextureSender(IClientAPI client, int discardLevel, uint packetNumber)
        {
            RequestUser = client;
            RequestedDiscardLevel = discardLevel;
            StartPacketNumber = packetNumber;
        }

        /// <summary>
        /// Load up the texture data to send.
        /// </summary>
        /// <param name="asset">
        /// A <see cref="AssetBase"/>
        /// </param>
        public void TextureReceived(AssetBase asset)
        {
            m_asset = asset;
            NumPackets = CalculateNumPackets(asset.Data.Length);
            PacketCounter = (int) StartPacketNumber;
            ImageLoaded = true;
        }

        // See ITextureSender
        public void UpdateRequest(int discardLevel, uint packetNumber)
        {
            RequestedDiscardLevel = discardLevel;
            StartPacketNumber = packetNumber;
            PacketCounter = (int) StartPacketNumber;
        }

        // See ITextureSender
        public bool SendTexturePacket()
        {
            //m_log.DebugFormat("[TEXTURE SENDER]: Sending packet for {0}", m_asset.FullID);
            
            SendPacket();
            counter++;
            if ((NumPackets == 0) || (RequestedDiscardLevel == -1) || (PacketCounter > NumPackets) ||
                ((RequestedDiscardLevel > 0) && (counter > 50 + (NumPackets/(RequestedDiscardLevel + 1)))))
            {
                return true;
            }
            return false;
        }

        /// <summary>
        /// Sends a texture packet to the client.
        /// </summary>
        private void SendPacket()
        {
            if (PacketCounter <= NumPackets)
            {
                if (PacketCounter == 0)
                {
                    if (NumPackets == 0)
                    {
                        ImageDataPacket im = new ImageDataPacket();
                        im.Header.Reliable = false;
                        im.ImageID.Packets = 1;
                        im.ImageID.ID = m_asset.FullID;
                        im.ImageID.Size = (uint) m_asset.Data.Length;
                        im.ImageData.Data = m_asset.Data;
                        im.ImageID.Codec = 2;
                        RequestUser.OutPacket(im, ThrottleOutPacketType.Texture);
                        PacketCounter++;
                    }
                    else
                    {
                        ImageDataPacket im = new ImageDataPacket();
                        im.Header.Reliable = false;
                        im.ImageID.Packets = (ushort) (NumPackets);
                        im.ImageID.ID = m_asset.FullID;
                        im.ImageID.Size = (uint) m_asset.Data.Length;
                        im.ImageData.Data = new byte[600];
                        Array.Copy(m_asset.Data, 0, im.ImageData.Data, 0, 600);
                        im.ImageID.Codec = 2;
                        RequestUser.OutPacket(im, ThrottleOutPacketType.Texture);
                        PacketCounter++;
                    }
                }
                else
                {
                    ImagePacketPacket im = new ImagePacketPacket();
                    im.Header.Reliable = false;
                    im.ImageID.Packet = (ushort) (PacketCounter);
                    im.ImageID.ID = m_asset.FullID;
                    int size = m_asset.Data.Length - 600 - (1000*(PacketCounter - 1));
                    if (size > 1000) size = 1000;
                    im.ImageData.Data = new byte[size];
                    try
                    {
                        Array.Copy(m_asset.Data, 600 + (1000*(PacketCounter - 1)), im.ImageData.Data, 0, size);
                    }
                    catch (ArgumentOutOfRangeException)
                    {
                        m_log.Error("[TEXTURE SENDER]: Unable to separate texture into multiple packets: Array bounds failure on asset:" +
                                    m_asset.FullID.ToString() );
                        return;
                    }
                    RequestUser.OutPacket(im, ThrottleOutPacketType.Texture);
                    PacketCounter++;
                }
            }
        }

        /// <summary>
        /// Calculate the number of packets that will be required to send the texture loaded into this sender
        /// This is actually the number of 1000 byte packets not including an initial 600 byte packet...
        /// </summary>
        /// <param name="length"></param>
        /// <returns></returns>
        private int CalculateNumPackets(int length)
        {
            int numPackets = 0;

            if (length > 600)
            {
                //over 600 bytes so split up file
                int restData = (length - 600);
                int restPackets = ((restData + 999)/1000);
                numPackets = restPackets;
            }

            return numPackets;
        }
    }
}