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Author: Ashish Khanal

Consumer/Domain/HeartRateExtensions.cs

@@ -10,7 +10,7 @@ public static class HeartRateExtensions
 
     public static HeartRateZone GetHeartRateZone(this HeartRate heartRate, int maxHeartRate)
     {
-        var percentage = heartRate.Value / maxHeartRate;
+        var percentage = (double)heartRate.Value / maxHeartRate; // Integer division, if heartRate.Value is less than maxHeartRate, it'll result in 0. So just cast either of those to have a floating point division.
         var zone = HeartRateZone.None;
 
         if (percentage >= Zone5Threshold) zone = HeartRateZone.Zone5;

Consumer/Program.cs

@@ -54,7 +54,10 @@
 
 builder.Services.AddHostedService<HeartRateZoneWorker>();
 
+// A host is an object that encapsulates an app's resources and lifetime functionality, such as DI, Logging, Configuration, App shutdown, IHostedService implementations etc.
+// The host and console app are not the same thing - the host is just a part that runs inside your console application.
 using IHost host = builder.Build();
+
 // https://learn.microsoft.com/en-us/dotnet/core/extensions/logging?tabs=command-line#create-logs-in-main
 var logger = host.Services.GetRequiredService<ILogger<Program>>();
 logger.LogInformation("Host created. Now running it.");

Consumer/Workers/HeartRateZoneWorker.cs

@@ -19,8 +19,14 @@ protected override async Task ExecuteAsync(CancellationToken stoppingToken)
         producer.InitTransactions(_defaultTimeout);
         consumer.Subscribe(BiometricsImportedTopicName);
 
+        // Methods that take a CancellationToken as an argument periodically check the token to see if they should cancel their operation and return.
         while (!stoppingToken.IsCancellationRequested)
         {
+            // If there are no more messages to process, the Consume method will not return null or exit immediately;
+            // instead, it will continue to wait for new messages (blocking behavior).
+            // While the Consume method does block the current thread it's running on (waiting for new messages),
+            // it does not block other threads in your application or make the entire application slow.
+            // Other background services or tasks will continue to run normally in separate threads.
             var result = consumer.Consume(stoppingToken);
             logger.LogInformation("Message Received: {0}", result.Message.Value);
             await HandleMessage(result.Message.Value, stoppingToken);
@@ -39,6 +45,7 @@ private async Task HandleMessage(Biometrics metrics, CancellationToken stoppingT
                 consumer.Position(topicPartition))); // consumer.Position gets the current position (offset) for the specified topic / partition.
 
         producer.BeginTransaction();
+        // Send the current offsets (the position in the topic/partition it has consumed up to) to the transaction.
         producer.SendOffsetsToTransaction(offsets, consumer.ConsumerGroupMetadata, _defaultTimeout);
 
         try