refactor: Split out functionality in FileExtractFunction into separate methods

Author: alex-clayton-1

src/ServiceLayer.Mesh/Functions/FileExtractFunction.cs

@@ -26,65 +26,99 @@ public async Task Run([QueueTrigger("%FileExtractQueueName%")] FileExtractQueueM
 
         await using var transaction = await serviceLayerDbContext.Database.BeginTransactionAsync();
 
+        var file = await GetFileAsync(message.FileId);
+        if (file == null)
+        {
+            logger.LogWarning("Exiting function.");
+            return;
+        }
+
+        if (!IsFileSuitableForExtraction(file))
+        {
+            logger.LogWarning("Exiting function.");
+            return;
+        }
+
+        await UpdateFileStatusForExtraction(file);
+        await transaction.CommitAsync();
+
+        try
+        {
+            await ProcessFileExtraction(file, message);
+        }
+        catch (Exception ex)
+        {
+            await HandleExtractionError(file, message, ex);
+        }
+    }
+
+    private async Task<MeshFile?> GetFileAsync(string fileId)
+    {
         var file = await serviceLayerDbContext.MeshFiles
-            .FirstOrDefaultAsync(f => f.FileId == message.FileId);
+            .FirstOrDefaultAsync(f => f.FileId == fileId);
 
         if (file == null)
         {
-            logger.LogWarning("File with id: {fileId} not found in MeshFiles table. Exiting function.", message.FileId);
-            return;
+            logger.LogWarning("File with id: {fileId} not found in MeshFiles table.", fileId);
         }
 
+        return file;
+    }
+
+    private bool IsFileSuitableForExtraction(MeshFile file)
+    {
         // We only want to extract files if they are in a Discovered state,
         // or are in an Extracting state and were last touched over 12 hours ago.
         var expectedStatuses = new[] { MeshFileStatus.Discovered, MeshFileStatus.Extracting };
         if (!expectedStatuses.Contains(file.Status) ||
             (file.Status == MeshFileStatus.Extracting && file.LastUpdatedUtc > DateTime.UtcNow.AddHours(-12)))
         {
             logger.LogWarning(
-                "File with id: {fileId} found in MeshFiles table but has unexpected Status: {status}, LastUpdatedUtc: {lastUpdatedUtc}. Exiting function.",
-                message.FileId,
-                file.Status,
-                file.LastUpdatedUtc);
-            return;
+                "File with id: {fileId} found in MeshFiles table but has unexpected status: {status}.",
+                file.FileId,
+                file.Status);
+            return false;
         }
+        return true;
+    }
 
+    private async Task UpdateFileStatusForExtraction(MeshFile file)
+    {
         file.Status = MeshFileStatus.Extracting;
         file.LastUpdatedUtc = DateTime.UtcNow;
-
         await serviceLayerDbContext.SaveChangesAsync();
-        await transaction.CommitAsync();
+    }
 
-        try
+    private async Task ProcessFileExtraction(MeshFile file, FileExtractQueueMessage message)
+    {
+        var meshResponse = await meshInboxService.GetMessageByIdAsync(configuration.NbssMeshMailboxId, file.FileId);
+        if (!meshResponse.IsSuccessful)
         {
-            var meshResponse = await meshInboxService.GetMessageByIdAsync(configuration.NbssMeshMailboxId, file.FileId);
-            if (!meshResponse.IsSuccessful)
-            {
-                throw new InvalidOperationException($"Mesh extraction failed: {meshResponse.Error}");
-            }
-
-            var blobPath = await meshFileBlobStore.UploadAsync(file, meshResponse.Response.FileAttachment.Content);
-
-            var meshAcknowledgementResponse = await meshInboxService.AcknowledgeMessageByIdAsync(configuration.NbssMeshMailboxId, message.FileId);
-            if (!meshAcknowledgementResponse.IsSuccessful)
-            {
-                throw new InvalidOperationException($"Mesh acknowledgement failed: {meshAcknowledgementResponse.Error}");
-            }
-
-            file.BlobPath = blobPath;
-            file.Status = MeshFileStatus.Extracted;
-            file.LastUpdatedUtc = DateTime.UtcNow;
-            await serviceLayerDbContext.SaveChangesAsync();
-
-            await fileTransformQueueClient.EnqueueFileTransformAsync(file);
+            throw new InvalidOperationException($"Mesh extraction failed: {meshResponse.Error}");
         }
-        catch (Exception ex)
+
+        var blobPath = await meshFileBlobStore.UploadAsync(file, meshResponse.Response.FileAttachment.Content);
+
+        var meshAcknowledgementResponse = await meshInboxService.AcknowledgeMessageByIdAsync(configuration.NbssMeshMailboxId, message.FileId);
+        if (!meshAcknowledgementResponse.IsSuccessful)
         {
-            logger.LogError(ex, "An exception occurred during file extraction for fileId: {fileId}", message.FileId);
-            file.Status = MeshFileStatus.FailedExtract;
-            file.LastUpdatedUtc = DateTime.UtcNow;
-            await serviceLayerDbContext.SaveChangesAsync();
-            await fileExtractQueueClient.SendToPoisonQueueAsync(message);
+            throw new InvalidOperationException($"Mesh acknowledgement failed: {meshAcknowledgementResponse.Error}");
         }
+
+        file.BlobPath = blobPath;
+        file.Status = MeshFileStatus.Extracted;
+        file.LastUpdatedUtc = DateTime.UtcNow;
+        await serviceLayerDbContext.SaveChangesAsync();
+
+        await fileTransformQueueClient.EnqueueFileTransformAsync(file);
+    }
+
+    private async Task HandleExtractionError(MeshFile file, FileExtractQueueMessage message, Exception ex)
+    {
+        logger.LogError(ex, "An exception occurred during file extraction for fileId: {fileId}", message.FileId);
+        file.Status = MeshFileStatus.FailedExtract;
+        file.LastUpdatedUtc = DateTime.UtcNow;
+        await serviceLayerDbContext.SaveChangesAsync();
+        await fileExtractQueueClient.SendToPoisonQueueAsync(message);
     }
 }