// https://stackoverflow.com/questions/19415646/should-i-avoid-async-void-event-handlers
private async void _OnClientConnectionStateChangedCallback(bool clientConnectionState)
{
// lock current execution context
await _semaphore.WaitAsync();
// due to the peculiarities of the work of the old and new client
// where the old one, in case of an unauthorized state, generates two events of changing the state of the connection at once
// the first is positive, and the second, negative
// while a negative one is generated after receiving the first request (which is a request to obtain data about an authorized user)
// the new client, in an unauthorized state, generates only one event, negative
// so the code is structured to be compatible with these two situations
// to solve this problem, the concept of an internal state was introduced (there are three of them at once)
// no decisions about the state of the connection will be made until the incoming state is different from the previous one
if (_internalConnectionState == null || _internalConnectionState.Value != clientConnectionState)
{
var isAuthorized = false;
// so, if we have connected to the host, this does not mean that the connection is active (for example, the user has not yet logged into the ZClient)
// therefore, before we say in the affirmative that the connection has been established, we will try to get an authorized user
if (clientConnectionState)
{
var userRequest = ZRequestFactory.CreateUserInfoRequest();
var response = await ZRouter.GetResponseAsync(userRequest);
if (response.StatusCode == ZResponseStatusCode.Ok)
{
_currentUserInfo = _ParseUserInfo(response.ResponsePackets);
_pingTimer.Start();
isAuthorized = true;
}
else
{
_logger.Warning($"Request failed {userRequest}");
}
// set current connection state
_internalConnectionState = isAuthorized;
}
else
{
// reset internal connection state
_internalConnectionState = null;
_currentUserInfo = null;
_pingTimer.Stop();
}
// ReSharper disable once InvertIf
if (_raiseOnConnectionChangedEvent)
{
_RaiseOnConnectionChangedEvent(IsConnected, _currentUserInfo);
_raiseOnConnectionChangedEvent = true;
}
}
_semaphore.Release();
}
public ZUserDto Parse(ZPacket packet)
{
var user = new ZUserDto();
using (var memory = new MemoryStream(packet.Payload, false))
using (var binaryReader = new BinaryReader(memory, Encoding.ASCII))
{
user.UserId = binaryReader.ReadZUInt32();
user.UserName = binaryReader.ReadZString();
}
return(user);
}
private void _RaiseOnConnectionChangedEvent(bool connectionState, ZUserDto authorizedUserDto) => ConnectionChanged?.Invoke((IZConnection)this, new ZConnectionChangedEventArgs(connectionState, authorizedUserDto));
/// <inheritdoc />
/// <summary>
/// Creates an instance of <see cref="T:Zlo4NET.Api.Models.Shared.ZConnectionChangedEventArgs" />
/// </summary>
public ZConnectionChangedEventArgs(bool isConnected, ZUserDto authorizedUserDto)
{
IsConnected = isConnected;
AuthorizedUser = authorizedUserDto;
}
/// <summary>
/// Creates an instance of <see cref="ZAuthorizedEventArgs"/>
/// </summary>
public ZAuthorizedEventArgs(ZUserDto user)
{
AuthorizedUser = user;
}
