Proof Of Concept initial

Adds initial files for a proof-of-concept project, including Dockerfile, .gitignore, project files, and MQTT-related services.

This commit sets up the basic structure and configuration for exploring and validating the core concepts of the project.

Source/ProofOfConcept/Services/MQTTClient.cs

@@ -1,20 +1,61 @@
+using Microsoft.Extensions.Options;
+using MQTTnet;
+
 namespace ProofOfConcept.Services;
 
-public class MQTTClient
+public class MQTTClient : IHostedService
 {
     private ILogger<MQTTClient> logger;
     private MQTTClientConfiguration configuration;
+    private MQTTServerConfiguration serverConfiguration;
 
-    public MQTTClient(ILogger<MQTTClient> logger, IOptionsMonitor<MQTTClientConfiguration> options)
+    private readonly IMqttClient client;
+    
+    public MQTTClient(ILogger<MQTTClient> logger, IOptions<MQTTClientConfiguration> options, IOptions<MQTTServerConfiguration> serverOptions, IMessageProcessor messageProcessor)
     {
         this.logger = logger;
-        this.configuration = options.CurrentValue;
-
-        options.OnChange(newValue =>
+        this.configuration = options.Value;
+        this.serverConfiguration = serverOptions.Value;
+        
+        client = new MqttClientFactory().CreateMqttClient();
+        
+        this.client.ApplicationMessageReceivedAsync += (e) =>
         {
-            this.configuration = newValue;
-            logger.LogInformation("Configuration of {ClassName} changed", nameof(MQTTClient));
-        });
+            logger.LogInformation("Message received: {Message}", e.ApplicationMessage.Payload);
+            messageProcessor.ProcessMessage(e.ApplicationMessage.Payload.ToString());
+            return Task.CompletedTask;
+        };
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        this.logger.LogTrace("Stating...");
+
+        MqttClientOptions options = new MqttClientOptionsBuilder()
+            .WithTcpServer("localhost", this.serverConfiguration.Port)
+            .WithClientId(this.serverConfiguration.LocalClient.ClientID)
+            .WithCredentials(this.serverConfiguration.LocalClient.Username, this.serverConfiguration.LocalClient.Password)
+            .Build();
+        await this.client.ConnectAsync(options, cancellationToken);
+        this.logger.LogTrace("Connected");
+
+        await this.client.SubscribeAsync("telemetry", cancellationToken: cancellationToken);
+        this.logger.LogTrace("Subscribed");
+        
+        this.logger.LogInformation("Started");
+    }
+
+    public async Task StopAsync(CancellationToken cancellationToken)
+    {
+        logger.LogTrace("Stopping...");
+
+        await this.client.UnsubscribeAsync("telemetry", cancellationToken: cancellationToken);
+        this.logger.LogTrace("Unsubscribed");
+        
+        await this.client.DisconnectAsync(cancellationToken: cancellationToken);
+        this.logger.LogTrace("Disconnected");
+        
+        logger.LogInformation("Stopped");
     }
 }