namespace UniversalNetFrame451;

public class EventQueue<T> : IDisposable
{
    public EventQueue(Action<T> queueHandler, int timeoutMillionSecond = Timeout.Infinite, Action<T> timeoutHandler = null)
    {
        if (timeoutMillionSecond < -1)
            throw new ArgumentException($"Invalid timeout time {timeoutMillionSecond}");

        this._queueHandler = queueHandler;
        this._timeoutHandler = timeoutHandler;
        this._timeoutMillionSeconds = timeoutMillionSecond;
        Task.Factory.StartNew(WorkingTask, TaskCreationOptions.LongRunning);
    }

    private ConcurrentQueue<T> _queue = [];
    private readonly Action<T> _queueHandler;

    private CancellationToken _cancellation = new(false);
    private readonly AutoResetEvent _queueEvent = new(false);
    private readonly ManualResetEvent _pauseController = new(true);

    private Timer _timeoutTimer;
    private bool disposedValue;
    private readonly int _timeoutMillionSeconds;
    private readonly Action<T> _timeoutHandler;

    public T LastItem { get; private set; }
    public int Count { get => this._queue.Count; }

    public void Pause() => this._pauseController.Reset();
    public void Resume() => this._pauseController.Set();

    public bool Enqueue(T input)
    {
        if (this._queue is null)
            return false;

        this.LastItem = input;
        this._queue.Enqueue(input);
        this._queueEvent.Set();

        return true;
    }

    private void WorkingTask()
    {
        for (T content; !this._cancellation.IsCancellationRequested; this._pauseController.WaitOne(-1))
        {
            if (!this._queue.TryDequeue(out content))
            {
                this._queueEvent.Reset();
                this._queueEvent.WaitOne(-1);
                continue;
            }

            if (!this._timeoutMillionSeconds.Equals(Timeout.Infinite))
                this._timeoutTimer = new(TimeoutCallBack, content, this._timeoutMillionSeconds, int.MaxValue);

            this._queueHandler?.Invoke(content);
            this._timeoutTimer?.Dispose();
        }

        this._queue = null;
    }

    private void TimeoutCallBack(object state)
    {
        this._timeoutTimer?.Dispose();
        if (state is not T content)
            return;
        this._timeoutHandler?.Invoke(content);
    }

    #region Dispose
    protected virtual void Dispose(bool disposing)
    {
        if (!disposedValue)
        {
            if (disposing)
            {
                // TODO: dispose managed state (managed objects)
                this._cancellation = new(true);
            }

            // TODO: free unmanaged resources (unmanaged objects) and override finalizer
            // TODO: set large fields to null
            disposedValue = true;
        }
    }

    // // TODO: override finalizer only if 'Dispose(bool disposing)' has code to free unmanaged resources
    ~EventQueue()
    {
        // Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
        Dispose(disposing: false);
    }

    public void Dispose()
    {
        // Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
        Dispose(disposing: true);
        GC.SuppressFinalize(this);
    }
    #endregion
}