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using System;
using System.IO;
using System.Text;
using System.Reflection;
using System.Xml;
using System.Xml.Serialization;

using OpenSim.Data;
using OpenSim.Framework;
using OpenSim.Region.Framework.Interfaces;

using OpenMetaverse;

using log4net;

namespace OpenSim.Region.Framework.Scenes
{
    /// <summary>
    /// A new version of the old Channel class, simplified
    /// </summary>
    public class TerrainChannel : ITerrainChannel
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        private static string LogHeader = "[TERRAIN CHANNEL]";

        protected TerrainData m_terrainData;

        public int Width { get { return m_terrainData.SizeX; } }  // X dimension
        // Unfortunately, for historical reasons, in this module 'Width' is X and 'Height' is Y
        public int Height { get { return m_terrainData.SizeY; } } // Y dimension
        public int Altitude { get { return m_terrainData.SizeZ; } } // Y dimension

        // Default, not-often-used builder
        public TerrainChannel()
        {
            m_terrainData = new HeightmapTerrainData((int)Constants.RegionSize, (int)Constants.RegionSize, (int)Constants.RegionHeight);
            FlatLand();
            // PinHeadIsland();
        }

        // Create terrain of given size
        public TerrainChannel(int pX, int pY)
        {
            m_terrainData = new HeightmapTerrainData(pX, pY, (int)Constants.RegionHeight);
        }

        // Create terrain of specified size and initialize with specified terrain.
        // TODO: join this with the terrain initializers.
        public TerrainChannel(String type, int pX, int pY, int pZ)
        {
            m_terrainData = new HeightmapTerrainData(pX, pY, pZ);
            if (type.Equals("flat"))
                FlatLand();
            else
                PinHeadIsland();
        }

        // Create channel passed a heightmap and expected dimensions of the region.
        // The heightmap might not fit the passed size so accomodations must be made.
        public TerrainChannel(double[,] pM, int pSizeX, int pSizeY, int pAltitude)
        {
            int hmSizeX = pM.GetLength(0);
            int hmSizeY = pM.GetLength(1);

            m_terrainData = new HeightmapTerrainData(pSizeX, pSizeY, pAltitude);

            for (int xx = 0; xx < pSizeX; xx++)
                for (int yy = 0; yy < pSizeY; yy++)
                    if (xx > hmSizeX || yy > hmSizeY)
                        m_terrainData[xx, yy] = TerrainData.DefaultTerrainHeight;
                    else
                        m_terrainData[xx, yy] = (float)pM[xx, yy];
        }

        public TerrainChannel(TerrainData pTerrData)
        {
            m_terrainData = pTerrData;
        }

        #region ITerrainChannel Members

        // ITerrainChannel.MakeCopy()
        public ITerrainChannel MakeCopy()
        {
            return this.Copy();
        }

        // ITerrainChannel.GetTerrainData()
        public TerrainData GetTerrainData()
        {
            return m_terrainData;
        }

        // ITerrainChannel.GetFloatsSerialized()
        // This one dimensional version is ordered so height = map[y*sizeX+x];
        // DEPRECATED: don't use this function as it does not retain the dimensions of the terrain
        //     and the caller will probably do the wrong thing if the terrain is not the legacy 256x256.
        public float[] GetFloatsSerialised()
        {
            int points = Width * Height;
            float[] heights = new float[points];

            int idx = 0;
            for (int jj = 0; jj < Height; jj++)
                for (int ii = 0; ii < Width; ii++)
                {
                    heights[idx++] = m_terrainData[ii, jj];
                }

            return heights;
        }

        // ITerrainChannel.GetDoubles()
        public double[,] GetDoubles()
        {
            double[,] heights = new double[Width, Height];

            int idx = 0; // index into serialized array
            for (int ii = 0; ii < Width; ii++)
            {
                for (int jj = 0; jj < Height; jj++)
                {
                    heights[ii, jj] = (double)m_terrainData[ii, jj];
                    idx++;
                }
            }

            return heights;
        }

        // ITerrainChannel.this[x,y]
        public double this[int x, int y]
        {
            get {
                if (x < 0 || x >= Width || y < 0 || y >= Height)
                    return 0;
                return (double)m_terrainData[x, y];
            }
            set
            {
                if (Double.IsNaN(value) || Double.IsInfinity(value))
                    return;

                m_terrainData[x, y] = (float)value;
            }
        }

        // ITerrainChannel.GetHieghtAtXYZ(x, y, z)
        public float GetHeightAtXYZ(float x, float y, float z)
        {
            if (x < 0 || x >= Width || y < 0 || y >= Height)
                return 0;
            return m_terrainData[(int)x, (int)y];
        }

        // ITerrainChannel.Tainted()
        public bool Tainted(int x, int y)
        {
            return m_terrainData.IsTaintedAt(x, y);
        }

        // ITerrainChannel.SaveToXmlString()
        public string SaveToXmlString()
        {
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.Encoding = Util.UTF8;
            using (StringWriter sw = new StringWriter())
            {
                using (XmlWriter writer = XmlWriter.Create(sw, settings))
                {
                    WriteXml(writer);
                }
                string output = sw.ToString();
                return output;
            }
        }

        // ITerrainChannel.LoadFromXmlString()
        public void LoadFromXmlString(string data)
        {
            StringReader sr = new StringReader(data);
            XmlTextReader reader = new XmlTextReader(sr);
            reader.Read();

            ReadXml(reader);
            reader.Close();
            sr.Close();
        }

        // ITerrainChannel.Merge
        public void Merge(ITerrainChannel newTerrain, Vector3 displacement, float radianRotation, Vector2 rotationDisplacement)
        {
            for (int xx = 0; xx < newTerrain.Width; xx++)
            {
                for (int yy = 0; yy < newTerrain.Height; yy++)
                {
                    int dispX = (int)displacement.X;
                    int dispY = (int)displacement.Y;
                    float newHeight = (float)newTerrain[xx, yy] + displacement.Z;
                    if (radianRotation == 0)
                    {
                        // If no rotation, place the new height in the specified location
                        dispX += xx;
                        dispY += yy;
                        if (dispX >= 0 && dispX < m_terrainData.SizeX && dispY >= 0 && dispY < m_terrainData.SizeY)
                        {
                            m_terrainData[dispX, dispY] = newHeight;
                        }
                    }
                    else
                    {
                        // If rotating, we have to smooth the result because the conversion
                        //    to ints will mean heightmap entries will not get changed
                        // First compute the rotation location for the new height.
                        dispX += (int)(rotationDisplacement.X
                            + ((float)xx - rotationDisplacement.X) * Math.Cos(radianRotation)
                            - ((float)yy - rotationDisplacement.Y) * Math.Sin(radianRotation) );

                        dispY += (int)(rotationDisplacement.Y
                            + ((float)xx - rotationDisplacement.X) * Math.Sin(radianRotation)
                            + ((float)yy - rotationDisplacement.Y) * Math.Cos(radianRotation) );

                        if (dispX >= 0 && dispX < m_terrainData.SizeX && dispY >= 0 && dispY < m_terrainData.SizeY)
                        {
                            float oldHeight = m_terrainData[dispX, dispY];
                            // Smooth the heights around this location if the old height is far from this one
                            for (int sxx = dispX - 2; sxx < dispX + 2; sxx++)
                            {
                                for (int syy = dispY - 2; syy < dispY + 2; syy++)
                                {
                                    if (sxx >= 0 && sxx < m_terrainData.SizeX && syy >= 0 && syy < m_terrainData.SizeY)
                                    {
                                        if (sxx == dispX && syy == dispY)
                                        {
                                            // Set height for the exact rotated point
                                            m_terrainData[dispX, dispY] = newHeight;
                                        }
                                        else
                                        {
                                            if (Math.Abs(m_terrainData[sxx, syy] - newHeight) > 1f)
                                            {
                                                // If the adjacent height is far off, force it to this height
                                                m_terrainData[sxx, syy] = newHeight;
                                            }
                                        }
                                    }
                                }
                            }
                        }

                        if (dispX >= 0 && dispX < m_terrainData.SizeX && dispY >= 0 && dispY < m_terrainData.SizeY)
                        {
                            m_terrainData[dispX, dispY] = (float)newTerrain[xx, yy];
                        }
                    }
                }
            }
        }

        #endregion

        public TerrainChannel Copy()
        {
            TerrainChannel copy = new TerrainChannel();
            copy.m_terrainData = m_terrainData.Clone();
            return copy;
        }

        private void WriteXml(XmlWriter writer)
        {
            if (Width == Constants.RegionSize && Height == Constants.RegionSize)
            {
                // Downward compatibility for legacy region terrain maps.
                // If region is exactly legacy size, return the old format XML.
                writer.WriteStartElement(String.Empty, "TerrainMap", String.Empty);
                ToXml(writer);
                writer.WriteEndElement();
            }
            else
            {
                // New format XML that includes width and length.
                writer.WriteStartElement(String.Empty, "TerrainMap2", String.Empty);
                ToXml2(writer);
                writer.WriteEndElement();
            }
        }

        private void ReadXml(XmlReader reader)
        {
            // Check the first element. If legacy element, use the legacy reader.
            if (reader.IsStartElement("TerrainMap"))
            {
                reader.ReadStartElement("TerrainMap");
                FromXml(reader);
            }
            else
            {
                reader.ReadStartElement("TerrainMap2");
                FromXml2(reader);
            }
        }

        // Write legacy terrain map. Presumed to be 256x256 of data encoded as floats in a byte array.
        private void ToXml(XmlWriter xmlWriter)
        {
            float[] mapData = GetFloatsSerialised();
            byte[] buffer = new byte[mapData.Length * 4];
            for (int i = 0; i < mapData.Length; i++)
            {
                byte[] value = BitConverter.GetBytes(mapData[i]);
                Array.Copy(value, 0, buffer, (i * 4), 4);
            }
            XmlSerializer serializer = new XmlSerializer(typeof(byte[]));
            serializer.Serialize(xmlWriter, buffer);
        }

        // Read legacy terrain map. Presumed to be 256x256 of data encoded as floats in a byte array.
        private void FromXml(XmlReader xmlReader)
        {
            XmlSerializer serializer = new XmlSerializer(typeof(byte[]));
            byte[] dataArray = (byte[])serializer.Deserialize(xmlReader);
            int index = 0;

            m_terrainData = new HeightmapTerrainData(Height, Width, (int)Constants.RegionHeight);
            
            for (int y = 0; y < Height; y++)
            {
                for (int x = 0; x < Width; x++)
                {
                    float value;
                    value = BitConverter.ToSingle(dataArray, index);
                    index += 4;
                    this[x, y] = (double)value;
                }
            }
        }

        private class TerrainChannelXMLPackage
        {
            public int Version;
            public int SizeX;
            public int SizeY;
            public int SizeZ;
            public float CompressionFactor;
            public short[] Map;
            public TerrainChannelXMLPackage(int pX, int pY, int pZ, float pCompressionFactor, short[] pMap)
            {
                Version = 1;
                SizeX = pX;
                SizeY = pY;
                SizeZ = pZ;
                CompressionFactor = pCompressionFactor;
                Map = pMap;
            }
        }

        // New terrain serialization format that includes the width and length.
        private void ToXml2(XmlWriter xmlWriter)
        {
            TerrainChannelXMLPackage package = new TerrainChannelXMLPackage(Width, Height, Altitude, m_terrainData.CompressionFactor,
                                            m_terrainData.GetCompressedMap());
            XmlSerializer serializer = new XmlSerializer(typeof(TerrainChannelXMLPackage));
            serializer.Serialize(xmlWriter, package);
        }

        // New terrain serialization format that includes the width and length.
        private void FromXml2(XmlReader xmlReader)
        {
            XmlSerializer serializer = new XmlSerializer(typeof(TerrainChannelXMLPackage));
            TerrainChannelXMLPackage package = (TerrainChannelXMLPackage)serializer.Deserialize(xmlReader);
            m_terrainData = new HeightmapTerrainData(package.Map, package.CompressionFactor, package.SizeX, package.SizeY, package.SizeZ);
        }

        // Fill the heightmap with the center bump terrain
        private void PinHeadIsland()
        {
            for (int x = 0; x < Width; x++)
            {
                for (int y = 0; y < Height; y++)
                {
                    m_terrainData[x, y] = (float)TerrainUtil.PerlinNoise2D(x, y, 2, 0.125) * 10;
                    float spherFacA = (float)(TerrainUtil.SphericalFactor(x, y, m_terrainData.SizeX / 2.0, m_terrainData.SizeY / 2.0, 50) * 0.01d);
                    float spherFacB = (float)(TerrainUtil.SphericalFactor(x, y, m_terrainData.SizeX / 2.0, m_terrainData.SizeY / 2.0, 100) * 0.001d);
                    if (m_terrainData[x, y]< spherFacA)
                        m_terrainData[x, y]= spherFacA;
                    if (m_terrainData[x, y]< spherFacB)
                        m_terrainData[x, y] = spherFacB;
                }
            }
        }

        private void FlatLand()
        {
            m_terrainData.ClearLand();
        }
    }
}