using System;
using System.Runtime.InteropServices;

namespace Steamworks;

public abstract class CallResult
{
	internal abstract Type GetCallbackType();

	internal abstract void OnRunCallResult(IntPtr pvParam, bool bFailed, ulong hSteamAPICall);

	internal abstract void SetUnregistered();
}
public sealed class CallResult<T> : CallResult, IDisposable
{
	public delegate void APIDispatchDelegate(T param, bool bIOFailure);

	private SteamAPICall_t m_hAPICall = SteamAPICall_t.Invalid;

	private bool m_bDisposed;

	public SteamAPICall_t Handle => m_hAPICall;

	private event APIDispatchDelegate m_Func;

	public static CallResult<T> Create(APIDispatchDelegate func = null)
	{
		return new CallResult<T>(func);
	}

	public CallResult(APIDispatchDelegate func = null)
	{
		this.m_Func = func;
	}

	~CallResult()
	{
		Dispose();
	}

	public void Dispose()
	{
		if (!m_bDisposed)
		{
			GC.SuppressFinalize(this);
			Cancel();
			m_bDisposed = true;
		}
	}

	public void Set(SteamAPICall_t hAPICall, APIDispatchDelegate func = null)
	{
		if (func != null)
		{
			this.m_Func = func;
		}
		if (this.m_Func == null)
		{
			throw new Exception("CallResult function was null, you must either set it in the CallResult Constructor or via Set()");
		}
		if (m_hAPICall != SteamAPICall_t.Invalid)
		{
			CallbackDispatcher.Unregister(m_hAPICall, this);
		}
		m_hAPICall = hAPICall;
		if (hAPICall != SteamAPICall_t.Invalid)
		{
			CallbackDispatcher.Register(hAPICall, this);
		}
	}

	public bool IsActive()
	{
		return m_hAPICall != SteamAPICall_t.Invalid;
	}

	public void Cancel()
	{
		if (IsActive())
		{
			CallbackDispatcher.Unregister(m_hAPICall, this);
		}
	}

	internal override Type GetCallbackType()
	{
		return typeof(T);
	}

	internal override void OnRunCallResult(IntPtr pvParam, bool bFailed, ulong hSteamAPICall_)
	{
		if ((SteamAPICall_t)hSteamAPICall_ == m_hAPICall)
		{
			try
			{
				this.m_Func((T)Marshal.PtrToStructure(pvParam, typeof(T)), bFailed);
			}
			catch (Exception e)
			{
				CallbackDispatcher.ExceptionHandler(e);
			}
		}
	}

	internal override void SetUnregistered()
	{
		m_hAPICall = SteamAPICall_t.Invalid;
	}
}