Swarm/DysonNetwork.Ring/Connection/WebSocketService.cs

using System.Collections.Concurrent;
using System.Net.WebSockets;
using DysonNetwork.Shared.Data;
using DysonNetwork.Shared.Proto;
using DysonNetwork.Shared.Stream;
using NATS.Client.Core;
using WebSocketPacket = DysonNetwork.Shared.Data.WebSocketPacket;

namespace DysonNetwork.Ring.Connection;

public class WebSocketService
{
    private readonly INatsConnection _nats;
    private readonly ILogger<WebSocketService> _logger;
    private readonly IDictionary<string, IWebSocketPacketHandler> _handlerMap;

    public WebSocketService(
        IEnumerable<IWebSocketPacketHandler> handlers,
        ILogger<WebSocketService> logger,
        INatsConnection nats
    )
    {
        _logger = logger;
        _handlerMap = handlers.ToDictionary(h => h.PacketType);
        _nats = nats;
    }

    private static readonly ConcurrentDictionary<
        (Guid AccountId, string DeviceId),
        (WebSocket Socket, CancellationTokenSource Cts)
    > ActiveConnections = new();

    private static readonly ConcurrentDictionary<string, string> ActiveSubscriptions = new(); // deviceId -> chatRoomId

    public bool TryAdd(
        (Guid AccountId, string DeviceId) key,
        WebSocket socket,
        CancellationTokenSource cts
    )
    {
        if (ActiveConnections.TryGetValue(key, out _))
            Disconnect(key,
                "Just connected somewhere else with the same identifier."); // Disconnect the previous one using the same identifier
        return ActiveConnections.TryAdd(key, (socket, cts));
    }

    public void Disconnect((Guid AccountId, string DeviceId) key, string? reason = null)
    {
        if (!ActiveConnections.TryGetValue(key, out var data)) return;
        try
        {
            data.Socket.CloseAsync(
                WebSocketCloseStatus.NormalClosure,
                reason ?? "Server just decided to disconnect.",
                CancellationToken.None
            );
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Error while closing WebSocket for {AccountId}:{DeviceId}", key.AccountId,
                key.DeviceId);
        }

        data.Cts.Cancel();
        ActiveConnections.TryRemove(key, out _);
    }

    public static bool GetDeviceIsConnected(string deviceId)
    {
        return ActiveConnections.Any(c => c.Key.DeviceId == deviceId);
    }

    public static bool GetAccountIsConnected(Guid accountId)
    {
        return ActiveConnections.Any(c => c.Key.AccountId == accountId);
    }

    public static void SendPacketToAccount(Guid accountId, WebSocketPacket packet)
    {
        var connections = ActiveConnections.Where(c => c.Key.AccountId == accountId);
        var packetBytes = packet.ToBytes();
        var segment = new ArraySegment<byte>(packetBytes);

        foreach (var connection in connections)
        {
            connection.Value.Socket.SendAsync(
                segment,
                WebSocketMessageType.Binary,
                true,
                CancellationToken.None
            );
        }
    }

    public void SendPacketToDevice(string deviceId, WebSocketPacket packet)
    {
        var connections = ActiveConnections.Where(c => c.Key.DeviceId == deviceId);
        var packetBytes = packet.ToBytes();
        var segment = new ArraySegment<byte>(packetBytes);

        foreach (var connection in connections)
        {
            connection.Value.Socket.SendAsync(
                segment,
                WebSocketMessageType.Binary,
                true,
                CancellationToken.None
            );
        }
    }

    public async Task HandlePacket(
        Account currentUser,
        string deviceId,
        WebSocketPacket packet,
        WebSocket socket
    )
    {
        if (packet.Type == WebSocketPacketType.Ping)
        {
            await socket.SendAsync(
                new ArraySegment<byte>(new WebSocketPacket
                {
                    Type = WebSocketPacketType.Pong
                }.ToBytes()),
                WebSocketMessageType.Binary,
                true,
                CancellationToken.None
            );
            return;
        }

        if (_handlerMap.TryGetValue(packet.Type, out var handler))
        {
            await handler.HandleAsync(currentUser, deviceId, packet, socket, this);
            return;
        }

        if (packet.Endpoint is not null)
        {
            try
            {
                var endpoint = packet.Endpoint.Replace("DysonNetwork.", "").ToLower();
                await _nats.PublishAsync(WebSocketPacketEvent.SubjectPrefix + endpoint, new WebSocketPacketEvent
                {
                    AccountId = Guid.Parse(currentUser.Id),
                    DeviceId = deviceId,
                    PacketBytes = packet.ToBytes()
                });
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error forwarding packet to endpoint: {Endpoint}", packet.Endpoint);
            }
        }

        await socket.SendAsync(
            new ArraySegment<byte>(new WebSocketPacket
            {
                Type = WebSocketPacketType.Error,
                ErrorMessage = $"Unprocessable packet: {packet.Type}"
            }.ToBytes()),
            WebSocketMessageType.Binary,
            true,
            CancellationToken.None
        );
    }
}