Working on version 2 of the MQTT client.

Sources/Client/Interface.swift

@@ -87,3 +87,41 @@ extension EventLoopFuture where Value == (Temperature, RelativeHumidity) {
     map { .init(dryBulb: $0, humidity: $1, units: units) }
   }
 }
+
+public struct Client2 {
+  
+  /// Add the publish listeners to the MQTT Broker, to be notified of published changes.
+  public var addListeners: () -> Void
+  
+  /// Connect to the MQTT Broker.
+  public var connect: () -> EventLoopFuture<Void>
+  
+  public var publishSensor: (SensorPublishRequest) -> EventLoopFuture<Void>
+  
+  /// Subscribe to appropriate topics / events.
+  public var subscribe: () -> EventLoopFuture<Void>
+  
+  /// Disconnect and close the connection to the MQTT Broker.
+  public var shutdown: () -> EventLoopFuture<Void>
+  
+  public init(
+    addListeners: @escaping () -> Void,
+    connect: @escaping () -> EventLoopFuture<Void>,
+    publishSensor: @escaping (SensorPublishRequest) -> EventLoopFuture<Void>,
+    shutdown: @escaping () -> EventLoopFuture<Void>,
+    subscribe: @escaping () -> EventLoopFuture<Void>
+  ) {
+    self.addListeners = addListeners
+    self.connect = connect
+    self.publishSensor = publishSensor
+    self.shutdown = shutdown
+    self.subscribe = subscribe
+  }
+  
+  public enum SensorPublishRequest {
+    case mixed(State.Sensors.TemperatureHumiditySensor<State.Sensors.Mixed>)
+    case postCoil(State.Sensors.TemperatureHumiditySensor<State.Sensors.PostCoil>)
+    case `return`(State.Sensors.TemperatureHumiditySensor<State.Sensors.Return>)
+    case supply(State.Sensors.TemperatureHumiditySensor<State.Sensors.Supply>)
+  }
+}