feat(backend): extract audio duration during transcoding and persist to track

backend/Musify.Infrastructure/MassTransit/Activities/Audio/TranscodeAudioActivity.cs

@@ -38,16 +38,22 @@ namespace Musify.Infrastructure.MassTransit.Activities.Audio
 
             try
             {
+                TimeSpan duration;
                 await using (var fileStream = File.OpenRead(sourceFilePath))
                 {
-                    await audioTranscoder.TranscodeToAudioFileAsync(
+                    duration = await audioTranscoder.TranscodeToAudioFileAsync(
                         fileStream,
                         workingDirectory,
                         executeContext.CancellationToken);
                 }
 
                 File.Delete(sourceFilePath);
-                return executeContext.Completed();
+
+                var log = new TranscodeAudioLog(workingDirectory);
+                return executeContext.CompletedWithVariables(log, new Dictionary<string, object>
+                {
+                    [RoutingSlipVariableNames.Audio.DurationSeconds] = (int)Math.Round(duration.TotalSeconds)
+                } );
             }
             catch (Exception exception)
             {

backend/Musify.Infrastructure/MassTransit/Activities/Audio/UpdateTrackAudioActivity.cs

@@ -47,11 +47,16 @@ namespace Musify.Infrastructure.MassTransit.Activities.Audio
 
             try
             {
+                var durationSeconds = executeContext.GetVariable<int>(executeContext.Arguments.DurationSecondsVariable)
+                    ?? throw new InvalidOperationException($"Missing routing slip variable {executeContext.Arguments.DurationSecondsVariable}");
+
                 var log = new UpdateTrackAudioLog(
                     track.Id,
-                    track.AudioFolderName);
+                    track.AudioFolderName,
+                    track.Duration);
 
                 track.AudioFolderName = Path.GetFileName(audioFolderKey);
+                track.Duration = durationSeconds;
                 track.AudioTranscodeProcessingStatus = ProcessingStatus.Completed;
                 await database.SaveChangesAsync(executeContext.CancellationToken);
 
@@ -92,6 +97,7 @@ namespace Musify.Infrastructure.MassTransit.Activities.Audio
                     throw new InvalidOperationException($"Track with id {compensateContext.Log.TrackId} not found");
 
                 track.AudioFolderName = compensateContext.Log.PreviousAudioFolderName;
+                track.Duration = compensateContext.Log.PreviousDuration;
                 track.AudioTranscodeProcessingStatus = ProcessingStatus.Failed;
                 await database.SaveChangesAsync(compensateContext.CancellationToken);
 

backend/Musify.Infrastructure/MassTransit/Arguments/UpdateTrackAudioArguments.cs

@@ -2,5 +2,6 @@
 {
     public record UpdateTrackAudioArguments(
         Guid TrackId,
-        string AudioFolderKey);
+        string AudioFolderKey,
+        string DurationSecondsVariable);
 }

backend/Musify.Infrastructure/MassTransit/Logs/UpdateTrackAudioLog.cs

@@ -2,5 +2,6 @@
 {
     public record UpdateTrackAudioLog(
         Guid TrackId,
-        string? PreviousAudioFolderName);
+        string? PreviousAudioFolderName,
+        int PreviousDuration);
 }

backend/Musify.Infrastructure/MassTransit/RoutingSlip/Builders/AudioWorkflowRoutingSlipBuilder.cs

@@ -58,7 +58,8 @@ namespace Musify.Infrastructure.MassTransit.RoutingSlip.Builders
                 EndpointHelper.BuildExecuteActivityUri(UpdateTrackAudioActivity.ExecuteEndpointName),
                 new UpdateTrackAudioArguments(
                     message.TrackId,
-                    message.DestinationFolderKey));
+                    message.DestinationFolderKey,
+                    RoutingSlipVariableNames.Audio.DurationSeconds));
 
             routingSlipBuilder.AddVariable(RoutingSlipVariableNames.Workflow.SubjectId, message.TrackId);
             routingSlipBuilder.AddVariable(RoutingSlipVariableNames.Workflow.ProcessKind, RoutingSlipVariableNames.ProcessKinds.TrackAudio);

backend/Musify.Infrastructure/MassTransit/RoutingSlip/RoutingSlipVariableNames.cs

@@ -21,6 +21,7 @@ namespace Musify.Infrastructure.MassTransit
         {
             internal const string SourceFilePath = "Audio.SourceFilePath";
             internal const string TranscodedDirectory = "Audio.TranscodedDirectory";
+            internal const string DurationSeconds = "Audio.DurationSeconds";
         }
 
         internal static class Picture