Distribution/Features/Supplier/SupplierController.cs

@@ -36,7 +36,18 @@ public class SupplierController(SupplierService service) : ControllerBase
     [HttpDelete("{id:guid}")]
     public async Task<IActionResult> Delete(Guid id, CancellationToken ct)
     {
-        var deleted = await service.DeleteAsync(id, ct);
-        return deleted ? NoContent() : NotFound();
+        try
+        {
+            var deleted = await service.DeleteAsync(id, ct);
+            return deleted ? NoContent() : NotFound();
+        }
+        catch (InvalidOperationException ex) { return Conflict(new { error = ex.Message }); }
+    }
+
+    [HttpPost("{id:guid}/evaluate")]
+    public async Task<IActionResult> Evaluate(Guid id, CancellationToken ct)
+    {
+        var result = await service.EvaluateAsync(id, ct);
+        return result is null ? NotFound() : Ok(result);
     }
 }

Distribution/Features/Supplier/SupplierService.cs

@@ -1,8 +1,14 @@
+using Distribution.Features.Grn;
+using Distribution.Features.Po;
 using Distribution.Infra.UoW;
 
 namespace Distribution.Features.Supplier;
 
-public class SupplierService(ISupplierRepository repo, IUnitOfWork uow)
+public class SupplierService(
+    ISupplierRepository repo,
+    IPoRepository purchaseOrderRepo,
+    IGrnRepository goodsReceiptRepo,
+    IUnitOfWork uow)
 {
     private static SupplierResponse Map(Models.Supplier s) =>
         new(s.Id, s.Name, s.ContactInfo, s.PerformanceScore, s.IsActive, s.CreatedAt);
@@ -52,10 +58,83 @@ public class SupplierService(ISupplierRepository repo, IUnitOfWork uow)
         var supplier = await repo.GetByIdAsync(id);
         if (supplier is null || !supplier.IsActive) return false;
 
+        if (await purchaseOrderRepo.HasActiveForSupplierAsync(id))
+            throw new InvalidOperationException(
+                "Cannot delete a supplier that is referenced by an active purchase order.");
+
         await uow.BeginAsync(ct);
         try { repo.Remove(supplier); await uow.CommitAsync(ct); }
         catch { await uow.RollbackAsync(ct); throw; }
 
         return true;
     }
+
+    /// <summary>
+    /// The only writer of Supplier.PerformanceScore. Computes a simple 0-100 score from this
+    /// supplier's own purchase-order history:
+    ///   - lineFulfillmentRatio: received (non-cancelled, fully-received) Po lines / all non-active
+    ///     Po lines seen (received + cancelled) - how reliably the supplier fulfils what it commits to.
+    ///   - acceptanceRatio: AcceptedQuantity / (AcceptedQuantity + RejectedQuantity) across every
+    ///     GoodsReceipt against this supplier's Pos - how much of what arrives is usable.
+    /// score = round(average(lineFulfillmentRatio, acceptanceRatio) * 100, 2).
+    /// Defaults to 50 (neutral) when there is no history yet, rather than hardcoding a fixed score.
+    /// </summary>
+    public async Task<SupplierResponse?> EvaluateAsync(Guid id, CancellationToken ct = default)
+    {
+        var supplier = await repo.GetByIdAsync(id);
+        if (supplier is null || !supplier.IsActive) return null;
+
+        var purchaseOrders = await purchaseOrderRepo.GetBySupplierAsync(id);
+
+        var receivedLines = 0;
+        var cancelledLines = 0;
+        foreach (var po in purchaseOrders)
+        {
+            foreach (var item in po.Items.Where(i => i.IsActive))
+            {
+                if (item.IsCancelled) cancelledLines++;
+                else if (item.ReceivedQuantity >= item.Quantity) receivedLines++;
+            }
+        }
+
+        var totalAccepted = 0;
+        var totalRejected = 0;
+        foreach (var po in purchaseOrders)
+        {
+            foreach (var receipt in await goodsReceiptRepo.GetByPurchaseOrderIdAsync(po.Id))
+            {
+                foreach (var item in receipt.Items.Where(i => i.IsActive))
+                {
+                    totalAccepted += item.AcceptedQuantity;
+                    totalRejected += item.RejectedQuantity;
+                }
+            }
+        }
+
+        var lineFulfillmentRatio = receivedLines + cancelledLines > 0
+            ? (decimal)receivedLines / (receivedLines + cancelledLines)
+            : (decimal?)null;
+
+        var acceptanceRatio = totalAccepted + totalRejected > 0
+            ? (decimal)totalAccepted / (totalAccepted + totalRejected)
+            : (decimal?)null;
+
+        decimal score;
+        if (lineFulfillmentRatio.HasValue && acceptanceRatio.HasValue)
+            score = Math.Round((lineFulfillmentRatio.Value + acceptanceRatio.Value) / 2m * 100m, 2);
+        else if (lineFulfillmentRatio.HasValue)
+            score = Math.Round(lineFulfillmentRatio.Value * 100m, 2);
+        else if (acceptanceRatio.HasValue)
+            score = Math.Round(acceptanceRatio.Value * 100m, 2);
+        else
+            score = 50m;
+
+        supplier.PerformanceScore = score;
+
+        await uow.BeginAsync(ct);
+        try { repo.Update(supplier); await uow.CommitAsync(ct); }
+        catch { await uow.RollbackAsync(ct); throw; }
+
+        return Map(supplier);
+    }
 }