// /**
//  * File: ObjectWriter.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.IO;
using System.Text;
using System.Reflection;
using System.Linq;
using System.Collections.Generic;
using ln.types.sync;
using System.Collections;
namespace ln.types.serialize
{
    /**
     * Types
     * 
     * N    null    
     * b "false"
     * B "true"    
     * 8    byte
     * 2    short
     * 4    int
     * L    long
     * f    float
     * d    double
     * s    string
     * 3    ushort
     * 5    uint
     * l    ulong
     * S    struct
     * A    Array
     * T    Type
     * L    List<>
     * D    Dictionary<>
     **/    

    public class ObjectWriter
    {
        public Stream Stream { get; }

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

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

        public ObjectWriter(Stream stream)
        {
            Stream = stream;
        }

        private void WriteByte(char ch)
        {
            Stream.WriteByte((byte)ch);
        }

        public virtual object QueryReference(object o)
        {
            if (referencedObjects.Contains(o))
                return referencedObjects.IndexOf(o);

            referencedObjects.Add(o);

            return o;
        }

        private object QueryObjectReplacement(object o)
        {
            Type type = o.GetType();

            if (type.IsGenericType)
            {
                Type genericTypeDefinition = type.GetGenericTypeDefinition();

                if (typeof(List<>).Equals(genericTypeDefinition))
                {
                    ListReplacement replacement = new ListReplacement();
                    replacement.elementType = type.GenericTypeArguments[0];
                    replacement.elements = new object[((IList)o).Count];
                    ((IList)o).CopyTo(replacement.elements, 0);
                    return replacement;

                } else if (typeof(Dictionary<,>).Equals(genericTypeDefinition))
                {
                    DictionaryReplacement replacement = new DictionaryReplacement();
                    replacement.keyType = type.GenericTypeArguments[0];
                    replacement.valueType = type.GenericTypeArguments[1];
                    replacement.keys = new object[((IDictionary)o).Keys.Count];
                    ((IDictionary)o).Keys.CopyTo(replacement.keys, 0);
                    replacement.values = new object[((IDictionary)o).Values.Count];
                    ((IDictionary)o).Values.CopyTo(replacement.values, 0);
                    return replacement;
                }
            }


            return QueryReference(o);
        }



        public void Write(object o)
        {
            if (o == null)
            {
                WriteByte('N');
            }
            else
            {
                Type type = o.GetType();
                if (typeof(TypeInfo).IsInstanceOfType(o))
                {
                    WriteType((Type)o);
                }
                if (type.IsValueType || typeof(string).Equals(type))
                {
                    WriteValue(o);
                }
                else if (type.IsArray)
                {
                    WriteArray(o as Array);
                }
                else
                {
                    WriteObject(o);
                }
            }
        }

        private void WriteArray(Array a)
        {
            int length = a.Length;

            WriteByte('A');
            WriteType(a.GetType().GetElementType());
            WriteValue(length);

            for (int n = 0; n < length; n++)
                Write(a.GetValue(n));
        }

        private void WriteFields(FieldInfo[] fieldInfos,object o)
        {
            WriteValue((int)fieldInfos.Length);

            foreach (FieldInfo fieldInfo in fieldInfos)
            {
                WriteValue(fieldInfo.Name);

                if (fieldInfo.GetCustomAttribute<Unsynced>() != null)
                {
                    WriteByte('N');
                }
                else if (fieldInfo.FieldType == typeof(Type))
                {
                    WriteType((Type)fieldInfo.GetValue(o));
                }
                else
                {
                    Write(fieldInfo.GetValue(o));
                }
            }
        }

        private void WriteType(Type type)
        {
            WriteByte('T');
            WriteValue(type.Assembly.GetName().Name);
            if (type.IsGenericType)
                WriteValue(type.GetGenericTypeDefinition().FullName);
            else
                WriteValue(type.FullName);

            Type[] typeArgs = type.GenericTypeArguments;
            WriteValue(typeArgs.Length);
            foreach (Type typeArg in typeArgs)
                WriteType(typeArg);
        }

        private void WriteObject(object _o)
        {
            object o = QueryObjectReplacement(_o);

            if (o == _o)
            {
                Type type = o.GetType();
                FieldInfo[] fieldInfos = type.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public).Where((x) => !x.IsNotSerialized).ToArray();

                WriteByte('O');
                WriteType(type);
                WriteFields(fieldInfos, o);
            }
            else
            {
                WriteByte('o');
                Write(o);
            }
        }

        private void WriteStruct(object o)
        {
            Type type = o.GetType();
            FieldInfo[] fieldInfos = type.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public).Where((x) => !x.DeclaringType.Equals(typeof(object))).ToArray();

            WriteByte('S');
            WriteType(type);
            WriteFields(fieldInfos, o);
        }

        private void WriteValue(object value)
        {
            Type type = value.GetType();

            if (typeof(String).Equals(type))
            {
                WriteByte('s');
                byte[] buffer = Encoding.UTF8.GetBytes(value as string);
                WriteValue(buffer.Length);
                Stream.Write(buffer, 0, buffer.Length);
            } else if (!type.IsPrimitive)
            {
                WriteStruct(value);
            }
            else if (typeof(Boolean).Equals(type))
            {
                WriteByte((bool)value ? 'B' : 'b');
            }
            else if (typeof(byte).Equals(type))
            {
                WriteByte('8');
                Stream.WriteByte((byte)value);
            }
            else if (typeof(short).Equals(type))
            {
                WriteByte('2');
                Stream.Write(BitConverter.GetBytes((short)value),0,2);
            }
            else if (typeof(int).Equals(type))
            {
                WriteByte('4');
                Stream.Write(BitConverter.GetBytes((int)value), 0, 4);
            }
            else if (typeof(long).Equals(type))
            {
                WriteByte('L');
                Stream.Write(BitConverter.GetBytes((long)value), 0, 8);
            }
            else if (typeof(float).Equals(type))
            {
                WriteByte('f');
                Stream.Write(BitConverter.GetBytes((float)value), 0, 4);
            }
            else if (typeof(double).Equals(type))
            {
                WriteByte('d');
                Stream.Write(BitConverter.GetBytes((double)value), 0, 8);
            }
            else if (typeof(ushort).Equals(type))
            {
                WriteByte('3');
                Stream.Write(BitConverter.GetBytes((ushort)value), 0, 2);
            }
            else if (typeof(uint).Equals(type))
            {
                WriteByte('5');
                Stream.Write(BitConverter.GetBytes((uint)value), 0, 4);
            }
            else if (typeof(ulong).Equals(type))
            {
                WriteByte('l');
                Stream.Write(BitConverter.GetBytes((ulong)value), 0, 8);
            }
            else
            {
                throw new NotImplementedException();
            }
        }

    }
}