using Qrakhen.Qamp.Core.Values.Objects;
using System.Runtime.InteropServices;
using Qrakhen.Qamp.Core.Collections;

namespace Qrakhen.Qamp.Core.Values;

[StructLayout(LayoutKind.Sequential, Size = sizeof(ulong))]
public readonly struct Ptr
{
    private static readonly PushStack<Obj> _register = new();

    [Serialized] public readonly Address Address;

    //private readonly IntPtr _pointer;
    //public IntPtr Pointer => _pointer;

    public Obj? Value {
        get {
            if (_register.TryGet(Address, out Obj obj))
                return obj;
            return null;
            //if (_pointer == IntPtr.Zero)
            //    throw new ObjectDisposedException(nameof(Ptr));
            //return (Obj)GCHandle.FromIntPtr(_pointer).Target!;
        }
    }

    private Ptr(Address address)
    {
        //_pointer = GCHandle.ToIntPtr(GCHandle.Alloc(obj, GCHandleType.Normal));
        Address = address;
    }

    public static Ptr Create(Obj obj)
    {
        return new Ptr(_register.Add(obj));
    }

    public T? As<T>(bool throwWhenNull = true) where T : Obj
    {
        T? value = Value as T;
        if (value == null && throwWhenNull)
            throw new RuntimeException($"Could not convert Object {Value} to target type {typeof(T)}.", Value);
        return value;
    }

    public override string ToString() => $"0x{Value}";

    public static byte[] SerializeFunctions()
    {
        List<byte> result = new();
        for (int i = 0; i < _register.Count; i++) {
            Obj obj = _register.Get(i);
            if (obj == null || obj.__gcMarked)
                continue;
            byte[] bytes;
            if (obj is Function function) {
                bytes = function.Serialize();
            } else if (obj is Context context) {
                bytes = context.Function.Serialize();
            } else {
                continue;
            }

            result.AddRange(i.GetBytes());
            result.AddRange(bytes.Length.GetBytes());
            result.AddRange(bytes);
            result.Add(0);
        }
        return result.ToArray();
    }
}