govee-csharp-connector/GoveeCSharpConnector/Services/GoveeUdpService.cs

using GoveeCSharpConnector.Interfaces;
using GoveeCSharpConnector.Objects;
using System.Net;
using System.Net.Sockets;
using System.Reactive.Linq;
using System.Reactive.Subjects;
using System.Reactive.Threading.Tasks;
using System.Text;
using System.Text.Json;
namespace GoveeCSharpConnector.Services;

public class GoveeUdpService : IGoveeUdpService {

    private bool _UDPListenerActive = true;
    private readonly UdpClient _UDPClient = new();
    private const int _GoveeMulticastPortSend = 4001;
    private const int _GoveeMulticastPortListen = 4002;
    private const string _GoveeMulticastAddress = "239.255.255.250";

    private readonly Subject<string> _MessageSubject = new();
    private readonly SemaphoreSlim _SemaphoreSlim = new(1, 1);
    private readonly Subject<GoveeUdpDevice> _ScanResultSubject = new();
    private readonly Subject<GoveeUdpState> _StateResultSubject = new();

    public bool IsListening() =>
        _UDPListenerActive;

    public GoveeUdpService() =>
        SetupUdpClientListenerAsync();

    public IObservable<string> Messages =>
        _MessageSubject;

    public Task<IList<GoveeUdpDevice>> GetDevicesAsync(TimeSpan? timeout = null) {
        if (!_UDPListenerActive) {
            throw new Exception("Udp Listener not started!");
        }
        // Block this Method until current call reaches end of Method
        _SemaphoreSlim.Wait();
        try {
            // Build Message
            GoveeUdpMessage message = new() {
                Msg = new Msg {
                    Cmd = "scan",
                    Data = new { account_topic = "reserve" }
                }
            };
            // Subscribe to ScanResultSubject
            Task<IList<GoveeUdpDevice>> devicesTask = _ScanResultSubject
                .TakeUntil(Observable.Timer(timeout ?? TimeSpan.FromMilliseconds(250)))
                .ToList()
                .ToTask();
            // Send Message
            SendUdpMessage(JsonSerializer.Serialize(message), _GoveeMulticastAddress, _GoveeMulticastPortSend);
            // Return List
            return devicesTask;
        } catch (Exception e) {
            Console.WriteLine(e);
            throw;
        } finally {
            // Release Method Block
            _ = _SemaphoreSlim.Release();
        }
    }

    public Task<GoveeUdpState> GetStateAsync(string deviceAddress, int uniCastPort = 4003, TimeSpan? timeout = null) {
        if (!_UDPListenerActive) {
            throw new Exception("Udp Listener not started!");
        }
        // Build Message
        GoveeUdpMessage message = new() {
            Msg = new Msg {
                Cmd = "devStatus",
                Data = new { }
            }
        };
        // Subscribe to ScanResultSubject
        Task<GoveeUdpState> devicesTask = _StateResultSubject
            .TakeUntil(Observable.Timer(timeout ?? TimeSpan.FromMilliseconds(250)))
            .ToTask();
        // Send Message
        SendUdpMessage(JsonSerializer.Serialize(message), deviceAddress, uniCastPort);
        // Return state
        return devicesTask;
    }

    public void ToggleDevice(string deviceAddress, bool on, int uniCastPort = 4003) {
        // Build Message
        GoveeUdpMessage message = new() {
            Msg = new Msg {
                Cmd = "turn",
                Data = new { value = on ? 1 : 0 }
            }
        };
        // Send Message
        SendUdpMessage(JsonSerializer.Serialize(message), deviceAddress, uniCastPort);
    }

    public void SetBrightness(string deviceAddress, int brightness, int uniCastPort = 4003) {
        // Build Message
        GoveeUdpMessage message = new() {
            Msg = new Msg {
                Cmd = "brightness",
                Data = new { value = brightness }
            }
        };
        // Send Message
        SendUdpMessage(JsonSerializer.Serialize(message), deviceAddress, uniCastPort);
    }

    public void SetColor(string deviceAddress, RgbColor color, int uniCastPort = 4003) {
        // Build Message
        GoveeUdpMessage message = new() {
            Msg = new Msg {
                Cmd = "colorwc",
                Data = new {
                    color = new {
                        r = color.R,
                        g = color.G,
                        b = color.B
                    },
                    colorTempInKelvin = 0
                }
            }
        };
        // Send Message
        SendUdpMessage(JsonSerializer.Serialize(message), deviceAddress, uniCastPort);
    }

    public void SetColorTemp(string deviceAddress, int colorTempInKelvin, int uniCastPort = 4003) {
        // Build Message
        GoveeUdpMessage message = new() {
            Msg = new Msg {
                Cmd = "colorwc",
                Data = new {
                    color = new {
                        r = 0,
                        g = 0,
                        b = 0
                    },
                    colorTempInKelvin
                }
            }
        };
        // Send Message
        SendUdpMessage(JsonSerializer.Serialize(message), deviceAddress, uniCastPort);
    }

    public Task StartUdpListenerAsync() {
        _UDPListenerActive = true;
        return StartListenerAsync();
    }

    public void StopUdpListener() {
        _UDPListenerActive = false;
        _UDPClient.DropMulticastGroup(IPAddress.Parse(_GoveeMulticastAddress));
        _UDPClient.Close();
    }

    private static void SendUdpMessage(string message, string receiverAddress, int receiverPort) {
        UdpClient client = new();
        try {
            byte[] data = Encoding.UTF8.GetBytes(message);
            Task<int> task = client.SendAsync(data, data.Length, receiverAddress, receiverPort);
            task.Wait();
        } catch (Exception) {
            throw;
        } finally {
            client.Close();
        }
    }

    private Task SetupUdpClientListenerAsync() {
        _UDPClient.ExclusiveAddressUse = false;
        IPEndPoint localEndPoint = new(IPAddress.Any, _GoveeMulticastPortListen);
        _UDPClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
        _UDPClient.Client.Bind(localEndPoint);
        return StartListenerAsync();
    }

    private Task StartListenerAsync() {
        _UDPClient.JoinMulticastGroup(IPAddress.Parse(_GoveeMulticastAddress));
        return StartListenerTask();
    }

    private Task StartListenerTask() {
        while (_UDPListenerActive) {
            IPEndPoint remoteEndPoint = new(IPAddress.Any, 0);
            byte[] data = _UDPClient.Receive(ref remoteEndPoint);

            string message = Encoding.UTF8.GetString(data);

            UdPMessageReceived(message);
            _MessageSubject.OnNext(message);
        }
        return Task.CompletedTask;
    }

    private void UdPMessageReceived(string message) {
        GoveeUdpMessage response = JsonSerializer.Deserialize<GoveeUdpMessage>(message);
        switch (response.Msg.Cmd) {
            case "scan":
                GoveeUdpDevice device = JsonSerializer.Deserialize<GoveeUdpDevice>(response.Msg.Data.ToString());
                _ScanResultSubject.OnNext(device);
                break;
            case "devStatus":
                GoveeUdpState state = JsonSerializer.Deserialize<GoveeUdpState>(response.Msg.Data.ToString());
                _StateResultSubject.OnNext(state);
                break;
        }
    }

}