feat(CUB-39): create background job for filament usage sync

backend/API/Jobs/FilamentUsageSyncJob.cs

@@ -0,0 +1,79 @@
+using Extrudex.Domain.Interfaces;
+using Extrudex.Infrastructure.Configuration;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+
+namespace Extrudex.API.Jobs;
+
+/// <summary>
+/// Background job that periodically syncs filament usage data from
+/// Moonraker printers. Runs as a hosted service and polls all active
+/// Moonraker printers on a configurable interval to persist usage
+/// data to the Extrudex database.
+/// 
+/// Configuration is bound from the "FilamentUsageSync" section in
+/// appsettings.json. Set Enabled=false to disable without removing
+/// the service registration.
+/// </summary>
+public class FilamentUsageSyncJob : BackgroundService
+{
+    private readonly IFilamentUsageSyncService _syncService;
+    private readonly FilamentUsageSyncOptions _options;
+    private readonly ILogger<FilamentUsageSyncJob> _logger;
+
+    /// <summary>
+    /// Creates a new FilamentUsageSyncJob.
+    /// </summary>
+    /// <param name="syncService">The service that performs the actual sync logic.</param>
+    /// <param name="options">Configuration options for polling interval and timeouts.</param>
+    /// <param name="logger">Logger for diagnostic output.</param>
+    public FilamentUsageSyncJob(
+        IFilamentUsageSyncService syncService,
+        IOptions<FilamentUsageSyncOptions> options,
+        ILogger<FilamentUsageSyncJob> logger)
+    {
+        _syncService = syncService;
+        _options = options.Value;
+        _logger = logger;
+    }
+
+    /// <inheritdoc />
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        if (!_options.Enabled)
+        {
+            _logger.LogInformation("Filament usage sync job is disabled via configuration — exiting");
+            return;
+        }
+
+        _logger.LogInformation(
+            "Filament usage sync job starting — polling every {Interval}",
+            _options.PollingInterval);
+
+        // Delay briefly on startup to allow the web host to fully initialize
+        await Task.Delay(TimeSpan.FromSeconds(10), stoppingToken);
+
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                var syncedCount = await _syncService.SyncAllAsync(stoppingToken);
+
+                _logger.LogInformation(
+                    "Filament usage sync completed — {SyncedCount} printer(s) synced. Next sync in {Interval}",
+                    syncedCount, _options.PollingInterval);
+            }
+            catch (Exception ex) when (ex is not OperationCanceledException)
+            {
+                _logger.LogError(ex,
+                    "Error during filament usage sync cycle — will retry in {Interval}",
+                    _options.PollingInterval);
+            }
+
+            await Task.Delay(_options.PollingInterval, stoppingToken);
+        }
+
+        _logger.LogInformation("Filament usage sync job shutting down");
+    }
+}