using Microsoft.AspNet.SignalR.Client;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks.Dataflow;

namespace Communicator
{
    public class UISignalRClient : ICommunicator
    {
        private string _connectionUrl;
        private string _hubName;
        private HubConnection? _hubConnection;
        private IHubProxy? _hubProxy;

        private readonly BufferBlock<KeyValuePair<string, object>> _changedDataItems;
        private readonly CancellationTokenSource _cancellationTokenSource;

        private ICommunicatorProvider? _provider;

        private bool disposedValue;

        public UISignalRClient()
        {
            _connectionUrl = "http://localhost:9999/NewUI";
            _hubName = "UIHub";

            _changedDataItems = new();
            _cancellationTokenSource = new();

            Task processReceivedDataTask = new(ProcessReceivedData);
            processReceivedDataTask.Start();
        }

        public bool Initialize(ICommunicatorProvider provider)
        {
            ArgumentNullException.ThrowIfNull(provider, nameof(provider));
            _provider = provider;

            if (_hubConnection is not null)
            {
                return true;
            }

            try
            {
                _hubConnection = new HubConnection(_connectionUrl);
                _hubConnection.StateChanged += OnStateChanged;

                _hubProxy = _hubConnection.CreateHubProxy(_hubName);
                _hubProxy.On<Dictionary<string, object>>(nameof(ReceiveAllDataItems), ReceiveAllDataItems);
                _hubProxy.On<Dictionary<string, object>>(nameof(ReceiveChangedDataItems), ReceiveChangedDataItems);
                _hubConnection.Start().Wait();

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }



        private void ReceiveAllDataItems(Dictionary<string, object> dataItems)
        {
            if (dataItems.Count <= 0)
            {
                return;
            }
            _provider?.NotifyAllDataReceived(dataItems);
        }

        private void ReceiveChangedDataItems(Dictionary<string, object> dataItems)
        {
            if (dataItems.Count <= 0)
            {
                return;
            }

            foreach (var item in dataItems)
            {
                _changedDataItems.Post(item);
            }
        }

        private async void ProcessReceivedData()
        {
            while (await _changedDataItems.OutputAvailableAsync() && !_cancellationTokenSource.IsCancellationRequested)
            {
                var item = await _changedDataItems.ReceiveAsync();
                _provider?.NotifyDataChanged(item.Key, item.Value);
            }
        }

        private void OnStateChanged(StateChange obj)
        {
            //TODO:
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!disposedValue)
            {
                if (disposing)
                {
                    // TODO: dispose managed state (managed objects)
                    if (_hubConnection is not null)
                    {
                        _hubConnection.StateChanged -= OnStateChanged;
                        _hubConnection.Dispose();

                        _changedDataItems.Complete();
                        _cancellationTokenSource.Cancel();
                        _cancellationTokenSource.Dispose();
                    }
                }

                // 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
        // ~SignalRClient()
        // {
        //     // 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);
        }
    }
}