using System;
using System.IO;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;

namespace MQTTnet.Implementations
{
    public class WebSocketStream : Stream
    {
        private readonly ClientWebSocket _webSocket;

        public WebSocketStream(ClientWebSocket webSocket)
        {
            _webSocket = webSocket;
        }

        public override void Flush()
        {
        }

        public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
        {
            var currentOffset = offset;
            var targetOffset = offset + count;
            while ( _webSocket.State == WebSocketState.Open && currentOffset < targetOffset )
            {
                var response = await _webSocket.ReceiveAsync(new ArraySegment<byte>(buffer, currentOffset, count), cancellationToken).ConfigureAwait(false);
                currentOffset += response.Count;

                if ( response.MessageType == WebSocketMessageType.Close )
                {
                    await _webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, string.Empty, cancellationToken).ConfigureAwait(false);
                }
            }

            return currentOffset - offset;
        }

        public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
        {
            return _webSocket.SendAsync(new ArraySegment<byte>( buffer, offset, count ), WebSocketMessageType.Binary, true, cancellationToken);
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            return ReadAsync(buffer, offset, count).GetAwaiter().GetResult();
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            WriteAsync( buffer, offset, count ).GetAwaiter().GetResult();
        }

        public override bool CanRead => true;
        public override bool CanSeek => false;
        public override bool CanWrite => true;

        public override long Length
        {
            get { throw new NotSupportedException(); }
        }

        public override long Position
        {
            get { throw new NotSupportedException(); }
            set { throw new NotSupportedException(); }
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotSupportedException();
        }

        public override void SetLength(long value)
        {
            throw new NotSupportedException();
        }
    }
}