Merge branch 'dev' into agent/dex/CUB-39-filament-usage-sync

backend/Domain/Interfaces/ICostPerPrintService.cs

@@ -0,0 +1,76 @@
+namespace Extrudex.Domain.Interfaces;
+
+/// <summary>
+/// Service interface for calculating the cost of goods sold (COGS) per print job.
+/// Uses the spool's purchase price and the print job's derived grams consumed
+/// to produce a cost breakdown. Handles missing cost data gracefully by returning
+/// warnings rather than throwing exceptions.
+/// </summary>
+public interface ICostPerPrintService
+{
+    /// <summary>
+    /// Calculates the cost per print for a specific print job.
+    /// </summary>
+    /// <param name="printJobId">The unique identifier of the print job.</param>
+    /// <param name="cancellationToken">Optional cancellation token.</param>
+    /// <returns>
+    /// A <see cref="CostPerPrintResult"/> containing the cost breakdown,
+    /// or warnings if cost data is missing or incomplete.
+    /// </returns>
+    Task<CostPerPrintResult> CalculateAsync(Guid printJobId, CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Calculates cost breakdowns for all print jobs associated with a specific spool.
+    /// Useful for spool-level COGS reporting.
+    /// </summary>
+    /// <param name="spoolId">The unique identifier of the spool.</param>
+    /// <param name="cancellationToken">Optional cancellation token.</param>
+    /// <returns>
+    /// A list of <see cref="CostPerPrintResult"/> for each print job on the spool.
+    /// Jobs with missing cost data will include warnings.
+    /// </returns>
+    Task<IReadOnlyList<CostPerPrintResult>> CalculateBySpoolAsync(Guid spoolId, CancellationToken cancellationToken = default);
+}
+
+/// <summary>
+/// Result of a cost-per-print calculation. Contains the cost breakdown
+/// and any warnings about missing or incomplete cost data.
+/// </summary>
+public class CostPerPrintResult
+{
+    /// <summary>The print job identifier this result belongs to.</summary>
+    public Guid PrintJobId { get; set; }
+
+    /// <summary>Human-readable name of the print job.</summary>
+    public string PrintName { get; set; } = string.Empty;
+
+    /// <summary>The spool identifier that provided filament.</summary>
+    public Guid SpoolId { get; set; }
+
+    /// <summary>Serial number of the spool.</summary>
+    public string SpoolSerial { get; set; } = string.Empty;
+
+    /// <summary>Total millimeters of filament extruded.</summary>
+    public decimal MmExtruded { get; set; }
+
+    /// <summary>Derived grams consumed for this print.</summary>
+    public decimal GramsDerived { get; set; }
+
+    /// <summary>The spool's purchase price. Null if not recorded.</summary>
+    public decimal? PurchasePrice { get; set; }
+
+    /// <summary>The spool's total weight in grams when full.</summary>
+    public decimal? WeightTotalGrams { get; set; }
+
+    /// <summary>Cost per gram of filament. Null if purchase price or total weight is missing.</summary>
+    public decimal? CostPerGram { get; set; }
+
+    /// <summary>Calculated cost of this print job. Null if cost data is incomplete.</summary>
+    public decimal? CostPerPrint { get; set; }
+
+    /// <summary>
+    /// Warnings about missing or incomplete data that prevented a full calculation.
+    /// Empty when all data is available and the calculation succeeded.
+    /// </summary>
+    public List<string> Warnings { get; set; } = new();
+}