using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;

namespace ScreenConnect;

public abstract class DisposableComCallableWrapper : CriticalFinalizerDisposableObject
{
	private delegate int NativeProc(IntPtr unknownPointer);

	private delegate void ManagedProc(IntPtr unknownPointer, int referenceCountFromNativeProc);

	private static Dictionary<IntPtr, (NativeProc, NativeProc)> RedirectorMap = new Dictionary<IntPtr, (NativeProc, NativeProc)>();

	public DisposableComCallableWrapper()
	{
		foreach (IntPtr item in (from _ in GetType().GetInterfaces()
			where Marshal.IsTypeVisibleFromCom(_)
			select Marshal.GetComInterfaceForObject(this, _)).Append(Marshal.GetIUnknownForObject(this)))
		{
			TryHook(item, 2, Release)(item);
		}
	}

	private unsafe static NativeProc TryHook(IntPtr interfacePtr, int vtableIndex, ManagedProc managedProc)
	{
		lock (RedirectorMap)
		{
			IntPtr* ptr = (IntPtr*)((nint)(*(IntPtr*)(void*)interfacePtr) + (nint)vtableIndex * (nint)sizeof(IntPtr));
			if (RedirectorMap.TryGetValue((IntPtr)ptr, out var value))
			{
				return value.Item1;
			}
			NativeProc baseProc = (NativeProc)Marshal.GetDelegateForFunctionPointer(*ptr, typeof(NativeProc));
			NativeProc nativeProc = delegate(IntPtr unknownPointer)
			{
				int num = baseProc(unknownPointer);
				managedProc(unknownPointer, num);
				return num;
			};
			RedirectorMap.Add((IntPtr)ptr, (baseProc, nativeProc));
			*ptr = Marshal.GetFunctionPointerForDelegate((Delegate)nativeProc);
			return baseProc;
		}
	}

	private static void Release(IntPtr unknownPointer, int referenceCountFromNativeProc)
	{
		if (referenceCountFromNativeProc == 0)
		{
			((IDisposable)Marshal.GetObjectForIUnknown(unknownPointer)).DisposeQuietly();
		}
	}
}