Initial Commit

Sources/TemperatureSensorClient/Interface.swift

@@ -0,0 +1,14 @@
+import Foundation
+import CoreUnitTypes
+import Models
+import NIO
+
+public struct TemperatureSensorClient {
+  public var state: (TemperatureSensor, PsychrometricEnvironment.Units?) -> EventLoopFuture<Temperature>
+  
+  public init(
+    state: @escaping (TemperatureSensor, PsychrometricEnvironment.Units?) -> EventLoopFuture<Temperature>
+  ) {
+    self.state = state
+  }
+}

Sources/TemperatureSensorClient/Live.swift

@@ -0,0 +1,51 @@
+import CoreUnitTypes
+import Foundation
+import MQTTNIO
+
+extension TemperatureSensorClient {
+  
+  public static func live(client: MQTTClient) -> TemperatureSensorClient {
+    .init(
+      state: { sensor, units in
+        client.logger.debug("Adding listener for temperature sensor...")
+        let subscription = MQTTSubscribeInfoV5.init(topicFilter: sensor.topic, qos: .atLeastOnce)
+        return client.v5.subscribe(to: [subscription])
+          .flatMap { _ in
+            let promise = client.eventLoopGroup.next().makePromise(of: Temperature.self)
+            client.addPublishListener(named: "temperature-sensor", { result in
+              switch result.temperature() {
+              case let .success(celsius):
+                let userUnits = units ?? PsychrometricEnvironment.shared.units
+                let temperatureUnits = Temperature.Units.defaultFor(units: userUnits)
+                promise.succeed(.init(celsius[temperatureUnits], units: temperatureUnits))
+              case let .failure(error):
+                promise.fail(error)
+              }
+            })
+            
+            return promise.futureResult
+          }
+      }
+    )
+  }
+}
+
+public enum TemperatureError: Error {
+  case invalidTemperature
+}
+
+// MARK: - Helpers
+extension Result where Success == MQTTPublishInfo, Failure == Error {
+  
+  fileprivate func temperature() -> Result<Temperature, Error> {
+    flatMap { info in
+      var buffer = info.payload
+      guard let string = buffer.readString(length: buffer.readableBytes),
+            let temperatureValue = Double(string)
+      else {
+        return .failure(TemperatureError.invalidTemperature)
+      }
+      return .success(.celsius(temperatureValue))
+    }
+  }
+}