using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using WinRT.Interop;
using WinRT;

unsafe
{
    DummyUnknown unknown = new();

    for (int i = 0; i < 10; i++)
    {
        var value2 = MarshalInspectable<object>.CreateMarshaler2(unknown);

        try
        {
            var abi = (IUnknownVftbl*)value2.GetAbi();
            var guid = new Guid("33D8B971-2ABF-4A2B-8071-1FFCBCBC8124");
            DummyUnknownAbi* ppv = null;

            ExceptionHelpers.ThrowExceptionForHR(Marshal.QueryInterface((IntPtr)abi, ref guid, out *(IntPtr*)&ppv));

            Console.WriteLine($"{i}: {ppv->GetNumber()}");

            ppv->Release();
        }
        finally
        {
            MarshalInspectable<object>.DisposeMarshaler(value2);
        }
    }
}

Console.WriteLine("Done!");


public unsafe class DummyUnknown : IDummyUnknown
{
    private int number = 42;

    public int GetNumber()
    {
        return number++;
    }
}

public unsafe struct DummyUnknownAbi
{
    public void** lpVtbl;

    public int QueryInterface(Guid* riid, void** ppvObject)
    {
        return ((delegate* unmanaged[Stdcall]<DummyUnknownAbi*, Guid*, void**, int>)lpVtbl[0])((DummyUnknownAbi*)Unsafe.AsPointer(ref this), riid, ppvObject);
    }

    public uint AddRef()
    {
        return ((delegate* unmanaged[Stdcall]<DummyUnknownAbi*, uint>)lpVtbl[1])((DummyUnknownAbi*)Unsafe.AsPointer(ref this));
    }

    public uint Release()
    {
        return ((delegate* unmanaged[Stdcall]<DummyUnknownAbi*, uint>)lpVtbl[2])((DummyUnknownAbi*)Unsafe.AsPointer(ref this));
    }

    public int GetNumber()
    {
        return ((delegate* unmanaged[Stdcall]<DummyUnknownAbi*, int>)lpVtbl[3])((DummyUnknownAbi*)Unsafe.AsPointer(ref this));
    }
}

[Guid("33D8B971-2ABF-4A2B-8071-1FFCBCBC8124")]
[WindowsRuntimeType]
[WindowsRuntimeHelperType(typeof(IDummyUnknown))]
public interface IDummyUnknown
{
    int GetNumber();

    [Guid("33D8B971-2ABF-4A2B-8071-1FFCBCBC8124")]
    public unsafe struct Vftbl
    {
        public static readonly IntPtr AbiToProjectionVftablePtr = InitVtbl();

        private static IntPtr InitVtbl()
        {
            Vftbl* lpVtbl = (Vftbl*)ComWrappersSupport.AllocateVtableMemory(typeof(Vftbl), sizeof(Vftbl));

            lpVtbl->IUnknownVftbl = IUnknownVftbl.AbiToProjectionVftbl;
            lpVtbl->GetNumber = &GetNumberFromAbi;

            return (IntPtr)lpVtbl;
        }

        internal IUnknownVftbl IUnknownVftbl;
        internal delegate* unmanaged[Stdcall]<IntPtr, int> GetNumber;

        [UnmanagedCallersOnly(CallConvs = new[] { typeof(CallConvStdcall) })]
        private static int GetNumberFromAbi(IntPtr thisPtr)
        {
            try
            {
                return ComWrappersSupport.FindObject<IDummyUnknown>(thisPtr).GetNumber();
            }
            catch (Exception e)
            {
                ExceptionHelpers.SetErrorInfo(e);

                return Marshal.GetHRForException(e);
            }
        }
    }
}