FFMpegCore/FFMpegCore/FFMpeg/Arguments/PipeArgument.cs

using System.Diagnostics;
using System.IO.Pipes;
using FFMpegCore.Pipes;

namespace FFMpegCore.Arguments
{
    public abstract class PipeArgument
    {
        private string PipeName { get; }
        public string PipePath => PipeHelpers.GetPipePath(PipeName);

        protected NamedPipeServerStream Pipe { get; private set; } = null!;
        private readonly PipeDirection _direction;

        protected PipeArgument(PipeDirection direction)
        {
            PipeName = PipeHelpers.GetUnqiuePipeName();
            _direction = direction;
        }

        public void Pre()
        {
            if (Pipe != null)
            {
                throw new InvalidOperationException("Pipe already has been opened");
            }

            Pipe = new NamedPipeServerStream(PipeName, _direction, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous);
        }

        public void Post()
        {
            Debug.WriteLine($"Disposing NamedPipeServerStream on {GetType().Name}");
            lock(Pipe)
            {

                Pipe?.Dispose();
                Pipe = null!;
            }
        }

        public async Task During(CancellationToken cancellationToken = default)
        {
            try
            {
                await ProcessDataAsync(cancellationToken).ConfigureAwait(false);
            }
            catch (OperationCanceledException)
            {
                Debug.WriteLine($"ProcessDataAsync on {GetType().Name} cancelled");
            }
            finally
            {
                Debug.WriteLine($"Disconnecting NamedPipeServerStream on {GetType().Name}");
                lock (Pipe ?? new object()) 
                    //if Pipe is null, then the lock doesnt matter,
                    //Because the next code will not execute anyways.
                    //so we can use a new object
                {
                    if (Pipe is { IsConnected: true })
                    {
                        Pipe.Disconnect();
                    }
                }
            }
        }

        protected abstract Task ProcessDataAsync(CancellationToken token);
        public abstract string Text { get; }
    }
}