// /**
//  * File: ObjectReader.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using System.Text;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Linq;
using ln.logging;
using System.Collections;
namespace ln.types.serialize
{
    public class ObjectReader : IDisposable
    {
        public Stream Stream { get; }

        public object[] ReferencedObjects
        {
            get => referencedObjects.ToArray();
            set => referencedObjects = new List<object>(value);
        }

        List<object> referencedObjects = new List<object>();

        public ObjectReader(Stream stream)
        {
            Stream = stream;
        }
        public ObjectReader(String fileName)
        {
            Stream = new FileStream(fileName,FileMode.Open);
        }

        public virtual object QueryReferencedObject(object re)
        {
            return referencedObjects[(int)re];
        }

        private object QueryObjectReplacement(object replacement)
        {
            if (replacement is ListReplacement)
            {
                ListReplacement listReplacement = (ListReplacement)replacement;

                object list = Activator.CreateInstance(typeof(List<>).MakeGenericType(new Type[] { listReplacement.elementType }), new object[] { listReplacement.elements });
                return list;

            } else if (replacement is DictionaryReplacement)
            {
                DictionaryReplacement dictionaryReplacement = (DictionaryReplacement)replacement;
                IDictionary dictionary = (IDictionary)Activator.CreateInstance(typeof(Dictionary<,>).MakeGenericType(new Type[] { dictionaryReplacement.keyType, dictionaryReplacement.valueType }));

                for (int n=0;n<dictionaryReplacement.keys.Length;n++)
                {
                    dictionary.Add(dictionaryReplacement.keys[n], dictionaryReplacement.values[n]);
                }
                return dictionary;
            }

            return QueryReferencedObject(replacement);
        }


        public T Read<T>()
        {
            return (T)Read();
        }

        public object Read()
        {
            byte[] b;
            int pos = (int)Stream.Position;
            char ch = (char)Stream.ReadByte();

            Logging.Log(LogLevel.DEBUG, "Read: {0} @ 0x{1:x8}", ch, pos);

            switch (ch)
            {
                case 'N':
                    return null;
                case 'O':
                    return ReadObject();
                case 'o':
                    return QueryObjectReplacement(Read());
                case 's':
                    return ReadString();
                case '8':
                    return (byte)Stream.ReadByte();
                case '2':
                    b = new byte[2];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToInt16(b, 0);
                case '4':
                    b = new byte[4];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToInt32(b, 0);
                case 'L':
                    b = new byte[8];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToInt64(b, 0);
                case '3':
                    b = new byte[2];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToUInt16(b, 0);
                case '5':
                    b = new byte[4];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToUInt32(b, 0);
                case 'l':
                    b = new byte[8];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToUInt64(b, 0);
                case 'f':
                    b = new byte[4];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToSingle(b, 0);
                case 'd':
                    b = new byte[8];
                    Stream.Read(b, 0, b.Length);
                    return BitConverter.ToDouble(b, 0);
                case 'B':
                    return true;
                case 'b':
                    return false;
                case 'S':
                    return ReadStruct();
                case 'A':
                    return ReadArray();
                case 'T':
                    return ReadType();
                default:
                    throw new NotImplementedException(String.Format("Identifier {0} (0x{1:x8})",ch,(int)ch));
            }
        }

        private Type ReadType()
        {
            Logging.Log(LogLevel.DEBUG, "readType()");
            string assemblyName = Read() as string;
            String typeName = Read() as string;
            object nn = Read();
            int nGenericArgs = (int)nn;
            Type[] genericArgs = new Type[nGenericArgs];

            for (int n=0;n<nGenericArgs;n++)
            {
                genericArgs[n] = (Type)Read();
            }

            Type type = Assembly.Load(assemblyName).GetType(typeName);
            if (nGenericArgs > 0)
            {
                type = type.MakeGenericType(genericArgs);
            }
            return type;
        }

        public Array ReadArray()
        {
            List<object> items = new List<object>();

            Type eType = Read<Type>();
            int length = (int)Read();

            Array array = Array.CreateInstance(eType, length);

            for (int n = 0; n < length; n++)
                array.SetValue(Read(), n);

            return array;
        }

        public object ReadObject()
        {
            Type type = Read<Type>();
            object o = Activator.CreateInstance(type,true);

            referencedObjects.Add(o);

            ReadFields(o);

            return o;
        }

        public void ReadThis(object o)
        {
            Stream.ReadByte();
            Read<Type>();
            ReadFields(o);
        }

        private void ReadFields(object o)
        {
            Type type = o.GetType();
            int nFields = Read<int>();

            for (int n = 0; n < nFields; n++)
            {
                string fieldName = Read<string>();
                object value = Read();

                FieldInfo fieldInfo = type.GetField(fieldName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
                fieldInfo.SetValue(o, value);
            }
        }

        public object ReadStruct()
        {
            Type type = Read<Type>();
            object o = Activator.CreateInstance(type);

            ReadFields(o);

            return o;
        }
        private string ReadString()
        {
            int length = (int)Read();

            Logging.Log(LogLevel.DEBUG, "ReadString({0})", length);

            byte[] buffer = new byte[length];
            Stream.Read(buffer, 0, length);
            return Encoding.UTF8.GetString(buffer);
        }

        public void Dispose()
        {
            Stream.Close();
            Stream.Dispose();
        }
    }
}