feat(gateway): initial commit

PluralKit.Bot/Services/RedisGatewayService.cs

@@ -0,0 +1,63 @@
+using System.Text.Json;
+
+using Serilog;
+
+using StackExchange.Redis;
+
+using Myriad.Gateway;
+using Myriad.Serialization;
+
+namespace PluralKit.Bot;
+
+public class RedisGatewayService
+{
+    private readonly BotConfig _config;
+    private readonly JsonSerializerOptions _jsonSerializerOptions;
+    private ConnectionMultiplexer _redis;
+    private ILogger _logger;
+
+    public RedisGatewayService(BotConfig config, ILogger logger)
+    {
+        _jsonSerializerOptions = new JsonSerializerOptions().ConfigureForMyriad();
+        _config = config;
+        _logger = logger.ForContext<RedisGatewayService>();
+    }
+
+    public event Func<IGatewayEvent, Task>? OnEventReceived;
+
+    public async Task Start()
+    {
+        _redis = await ConnectionMultiplexer.ConnectAsync(_config.RedisGatewayUrl);
+        var channel = await _redis.GetSubscriber().SubscribeAsync("evt");
+        channel.OnMessage(Handle);
+    }
+
+    public async Task Handle(ChannelMessage message)
+    {
+        var packet = JsonSerializer.Deserialize<GatewayPacket>(message.Message, _jsonSerializerOptions);
+        if (packet.Opcode != GatewayOpcode.Dispatch) return;
+        var evt = DeserializeEvent(packet.EventType, (JsonElement)packet.Payload);
+        if (evt == null) return;
+        await OnEventReceived(evt);
+    }
+
+    private IGatewayEvent? DeserializeEvent(string eventType, JsonElement payload)
+    {
+        if (!IGatewayEvent.EventTypes.TryGetValue(eventType, out var clrType))
+        {
+            _logger.Debug("Received unknown event type {EventType}", eventType);
+            return null;
+        }
+
+        try
+        {
+            _logger.Verbose("Deserializing {EventType} to {ClrType}", eventType, clrType);
+            return JsonSerializer.Deserialize(payload.GetRawText(), clrType, _jsonSerializerOptions) as IGatewayEvent;
+        }
+        catch (JsonException e)
+        {
+            _logger.Error(e, "Error deserializing event {EventType} to {ClrType}", eventType, clrType);
+            return null;
+        }
+    }
+}