feat: Adds MQTTConnectionService

Sources/MQTTConnectionService/MQTTConnectionService.swift

@@ -0,0 +1,56 @@
+import EnvVars
+import Logging
+import MQTTNIO
+import NIO
+import ServiceLifecycle
+
+/// Manages the MQTT broker connection.
+public actor MQTTConnectionService: Service {
+  private let cleanSession: Bool
+  public let client: MQTTClient
+  private var shuttingDown = false
+  var logger: Logger { client.logger }
+
+  public init(
+    cleanSession: Bool = true,
+    client: MQTTClient
+  ) {
+    self.cleanSession = cleanSession
+    self.client = client
+  }
+
+  /// The entry-point of the service.
+  ///
+  /// This method connects to the MQTT broker and manages the connection.
+  /// It will attempt to gracefully shutdown the connection upon receiving
+  /// `sigterm` signals.
+  public func run() async throws {
+    await withGracefulShutdownHandler {
+      await self.connect()
+    } onGracefulShutdown: {
+      Task { await self.shutdown() }
+    }
+  }
+
+  private func shutdown() async {
+    shuttingDown = true
+    try? await client.disconnect()
+    try? await client.shutdown()
+  }
+
+  private func connect() async {
+    do {
+      try await client.connect(cleanSession: cleanSession)
+      client.addCloseListener(named: "SensorsClient") { [self] _ in
+        Task {
+          self.logger.debug("Connection closed.")
+          self.logger.debug("Reconnecting...")
+          await self.connect()
+        }
+      }
+      logger.debug("Connection successful.")
+    } catch {
+      logger.trace("Connection Failed.\n\(error)")
+    }
+  }
+}