using System;
using System.Collections;
using System.Collections.Generic;
using System.Xml;
using System.IO;
using libsecondlife;
using System.Security.Cryptography;
using System.Text;

namespace libsecondlife
{
    /// <summary>
    /// 
    /// </summary>
    public static class LLSD
    {
        /// <summary>
        /// 
        /// </summary>
        public class LLSDParseException : Exception
        {
            public LLSDParseException(string message) : base(message) { }
        }

        /// <summary>
        /// 
        /// </summary>
        public class LLSDSerializeException : Exception
        {
            public LLSDSerializeException(string message) : base(message) { }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="b"></param>
        /// <returns></returns>
        public static object LLSDDeserialize(byte[] b)
        {
            return LLSDDeserialize(new MemoryStream(b, false));
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="st"></param>
        /// <returns></returns>
        public static object LLSDDeserialize(Stream st)
        {
            XmlTextReader reader = new XmlTextReader(st);
            reader.Read();
            SkipWS(reader);

            if (reader.NodeType != XmlNodeType.Element || reader.LocalName != "llsd")
                throw new LLSDParseException("Expected <llsd>");

            reader.Read();
            object ret = LLSDParseOne(reader);
            SkipWS(reader);

            if (reader.NodeType != XmlNodeType.EndElement || reader.LocalName != "llsd")
                throw new LLSDParseException("Expected </llsd>");

            return ret;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        public static byte[] LLSDSerialize(object obj)
        {
            StringWriter sw = new StringWriter();
            XmlTextWriter writer = new XmlTextWriter(sw);
            writer.Formatting = Formatting.None;

            writer.WriteStartElement(String.Empty, "llsd", String.Empty);
            LLSDWriteOne(writer, obj);
            writer.WriteEndElement();

            writer.Close();

            return Encoding.UTF8.GetBytes(sw.ToString());
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="writer"></param>
        /// <param name="obj"></param>
        public static void LLSDWriteOne(XmlTextWriter writer, object obj)
        {
            if (obj == null)
            {
                writer.WriteStartElement(String.Empty, "undef", String.Empty);
                writer.WriteEndElement();
                return;
            }

            if (obj is string)
            {
                writer.WriteStartElement(String.Empty, "string", String.Empty);
                writer.WriteString((string)obj);
                writer.WriteEndElement();
            }
            else if (obj is int)
            {
                writer.WriteStartElement(String.Empty, "integer", String.Empty);
                writer.WriteString(obj.ToString());
                writer.WriteEndElement();
            }
            else if (obj is double)
            {
                writer.WriteStartElement(String.Empty, "real", String.Empty);
                writer.WriteString(obj.ToString());
                writer.WriteEndElement();
            }
            else if (obj is bool)
            {
                bool b = (bool)obj;
                writer.WriteStartElement(String.Empty, "boolean", String.Empty);
                writer.WriteString(b ? "1" : "0");
                writer.WriteEndElement();
            }
            else if (obj is ulong)
            {
                throw new Exception("ulong in LLSD is currently not implemented, fix me!");
            }
            else if (obj is LLUUID)
            {
                LLUUID u = obj as LLUUID;
                writer.WriteStartElement(String.Empty, "uuid", String.Empty);
                writer.WriteString(u.ToStringHyphenated());
                writer.WriteEndElement();
            }
            else if (obj is Hashtable)
            {
                Hashtable h = obj as Hashtable;
                writer.WriteStartElement(String.Empty, "map", String.Empty);
                foreach (string key in h.Keys)
                {
                    writer.WriteStartElement(String.Empty, "key", String.Empty);
                    writer.WriteString(key);
                    writer.WriteEndElement();
                    LLSDWriteOne(writer, h[key]);
                }
                writer.WriteEndElement();
            }
            else if (obj is ArrayList)
            {
                ArrayList a = obj as ArrayList;
                writer.WriteStartElement(String.Empty, "array", String.Empty);
                foreach (object item in a)
                {
                    LLSDWriteOne(writer, item);
                }
                writer.WriteEndElement();
            }
            else if (obj is byte[])
            {
                byte[] b = obj as byte[];
                writer.WriteStartElement(String.Empty, "binary", String.Empty);

                writer.WriteStartAttribute(String.Empty, "encoding", String.Empty);
                writer.WriteString("base64");
                writer.WriteEndAttribute();

                //// Calculate the length of the base64 output
                //long length = (long)(4.0d * b.Length / 3.0d);
                //if (length % 4 != 0) length += 4 - (length % 4);

                //// Create the char[] for base64 output and fill it
                //char[] tmp = new char[length];
                //int i = Convert.ToBase64CharArray(b, 0, b.Length, tmp, 0);

                //writer.WriteString(new String(tmp));

                writer.WriteString(Convert.ToBase64String(b));
                writer.WriteEndElement();
            }
            else
            {
                throw new LLSDSerializeException("Unknown type " + obj.GetType().Name);
            }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="reader"></param>
        /// <returns></returns>
        public static object LLSDParseOne(XmlTextReader reader)
        {
            SkipWS(reader);
            if (reader.NodeType != XmlNodeType.Element)
                throw new LLSDParseException("Expected an element");

            string dtype = reader.LocalName;
            object ret = null;

            switch (dtype)
            {
                case "undef":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return null;
                        }

                        reader.Read();
                        SkipWS(reader);
                        ret = null;
                        break;
                    }
                case "boolean":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return false;
                        }

                        reader.Read();
                        string s = reader.ReadString().Trim();

                        if (s == String.Empty || s == "false" || s == "0")
                            ret = false;
                        else if (s == "true" || s == "1")
                            ret = true;
                        else
                            throw new LLSDParseException("Bad boolean value " + s);

                        break;
                    }
                case "integer":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return 0;
                        }

                        reader.Read();
                        ret = Convert.ToInt32(reader.ReadString().Trim());
                        break;
                    }
                case "real":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return 0.0f;
                        }

                        reader.Read();
                        ret = Convert.ToDouble(reader.ReadString().Trim());
                        break;
                    }
                case "uuid":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return LLUUID.Zero;
                        }

                        reader.Read();
                        ret = new LLUUID(reader.ReadString().Trim());
                        break;
                    }
                case "string":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return String.Empty;
                        }

                        reader.Read();
                        ret = reader.ReadString();
                        break;
                    }
                case "binary":
                    {
                        if (reader.IsEmptyElement)
                        {
                            reader.Read();
                            return new byte[0];
                        }

                        if (reader.GetAttribute("encoding") != null &&
                            reader.GetAttribute("encoding") != "base64")
                        {
                            throw new LLSDParseException("Unknown encoding: " + reader.GetAttribute("encoding"));
                        }

                        reader.Read();
                        FromBase64Transform b64 = new FromBase64Transform(FromBase64TransformMode.IgnoreWhiteSpaces);
                        byte[] inp = Encoding.ASCII.GetBytes(reader.ReadString());
                        ret = b64.TransformFinalBlock(inp, 0, inp.Length);
                        break;
                    }
                case "date":
                    {
                        reader.Read();
                        throw new Exception("LLSD TODO: date");
                    }
                case "map":
                    {
                        return LLSDParseMap(reader);
                    }
                case "array":
                    {
                        return LLSDParseArray(reader);
                    }
                default:
                    throw new LLSDParseException("Unknown element <" + dtype + ">");
            }

            if (reader.NodeType != XmlNodeType.EndElement || reader.LocalName != dtype)
            {
                throw new LLSDParseException("Expected </" + dtype + ">");
            }

            reader.Read();
            return ret;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="reader"></param>
        /// <returns></returns>
        public static Hashtable LLSDParseMap(XmlTextReader reader)
        {
            Hashtable ret = new Hashtable();

            if (reader.NodeType != XmlNodeType.Element || reader.LocalName != "map")
                throw new LLSDParseException("Expected <map>");

            if (reader.IsEmptyElement)
            {
                reader.Read();
                return ret;
            }

            reader.Read();

            while (true)
            {
                SkipWS(reader);
                if (reader.NodeType == XmlNodeType.EndElement && reader.LocalName == "map")
                {
                    reader.Read();
                    break;
                }

                if (reader.NodeType != XmlNodeType.Element || reader.LocalName != "key")
                    throw new LLSDParseException("Expected <key>");

                string key = reader.ReadString();

                if (reader.NodeType != XmlNodeType.EndElement || reader.LocalName != "key")
                    throw new LLSDParseException("Expected </key>");

                reader.Read();
                object val = LLSDParseOne(reader);
                ret[key] = val;
            }

            return ret; // TODO
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="reader"></param>
        /// <returns></returns>
        public static ArrayList LLSDParseArray(XmlTextReader reader)
        {
            ArrayList ret = new ArrayList();

            if (reader.NodeType != XmlNodeType.Element || reader.LocalName != "array")
                throw new LLSDParseException("Expected <array>");

            if (reader.IsEmptyElement)
            {
                reader.Read();
                return ret;
            }

            reader.Read();

            while (true)
            {
                SkipWS(reader);

                if (reader.NodeType == XmlNodeType.EndElement && reader.LocalName == "array")
                {
                    reader.Read();
                    break;
                }

                ret.Insert(ret.Count, LLSDParseOne(reader));
            }

            return ret; // TODO
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="count"></param>
        /// <returns></returns>
        private static string GetSpaces(int count)
        {
            StringBuilder b = new StringBuilder();
            for (int i = 0; i < count; i++) b.Append(" ");
            return b.ToString();
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="obj"></param>
        /// <param name="indent"></param>
        /// <returns></returns>
        public static String LLSDDump(object obj, int indent)
        {
            if (obj == null)
            {
                return GetSpaces(indent) + "- undef\n";
            }
            else if (obj is string)
            {
                return GetSpaces(indent) + "- string \"" + (string)obj + "\"\n";
            }
            else if (obj is int)
            {
                return GetSpaces(indent) + "- integer " + obj.ToString() + "\n";
            }
            else if (obj is double)
            {
                return GetSpaces(indent) + "- float " + obj.ToString() + "\n";
            }
            else if (obj is LLUUID)
            {
                return GetSpaces(indent) + "- uuid " + ((LLUUID)obj).ToStringHyphenated() + Environment.NewLine;
            }
            else if (obj is Hashtable)
            {
                StringBuilder ret = new StringBuilder();
                ret.Append(GetSpaces(indent) + "- map" + Environment.NewLine);
                Hashtable map = (Hashtable)obj;

                foreach (string key in map.Keys)
                {
                    ret.Append(GetSpaces(indent + 2) + "- key \"" + key + "\"" + Environment.NewLine);
                    ret.Append(LLSDDump(map[key], indent + 3));
                }

                return ret.ToString();
            }
            else if (obj is ArrayList)
            {
                StringBuilder ret = new StringBuilder();
                ret.Append(GetSpaces(indent) + "- array\n");
                ArrayList list = (ArrayList)obj;

                foreach (object item in list)
                {
                    ret.Append(LLSDDump(item, indent + 2));
                }

                return ret.ToString();
            }
            else if (obj is byte[])
            {
                return GetSpaces(indent) + "- binary\n" + Helpers.FieldToHexString((byte[])obj, GetSpaces(indent)) + 
                    Environment.NewLine;
            }
            else
            {
                return GetSpaces(indent) + "- unknown type " + obj.GetType().Name + Environment.NewLine;
            }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="reader"></param>
        private static void SkipWS(XmlTextReader reader)
        {
            while (
                reader.NodeType == XmlNodeType.Comment ||
                reader.NodeType == XmlNodeType.Whitespace ||
                reader.NodeType == XmlNodeType.SignificantWhitespace ||
                reader.NodeType == XmlNodeType.XmlDeclaration)
            {
                reader.Read();
            }
        }
    }
}