feat: Implement Cancel Order functionality with command, handler, and validation

src/BackOffice.BFF.Application/UserOrderCQ/Commands/CancelOrder/CancelOrderCommandHandler.cs

@@ -0,0 +1,48 @@
+using BackOffice.BFF.Application.Common.Interfaces;
+using BackOffice.BFF.UserOrder.Protobuf.Protos.UserOrder;
+using CMSMicroservice.Protobuf.Protos.UserOrder;
+using MediatR;
+using Microsoft.Extensions.Logging;
+
+namespace BackOffice.BFF.Application.UserOrderCQ.Commands.CancelOrder;
+
+public class CancelOrderCommandHandler : IRequestHandler<CancelOrderCommand, CancelOrderResponse>
+{
+    private readonly IApplicationContractContext _context;
+    private readonly ILogger<CancelOrderCommandHandler> _logger;
+
+    public CancelOrderCommandHandler(
+        IApplicationContractContext context,
+        ILogger<CancelOrderCommandHandler> logger)
+    {
+        _context = context;
+        _logger = logger;
+    }
+
+    public async Task<CancelOrderResponse> Handle(CancelOrderCommand request, CancellationToken cancellationToken)
+    {
+        var grpcRequest = new CMSMicroservice.Protobuf.Protos.UserOrder.CancelOrderRequest
+        {
+            OrderId = request.OrderId,
+            CancelReason = request.CancelReason ?? string.Empty,
+            RefundPayment = request.RefundPayment
+        };
+
+        var response = await _context.UserOrders.CancelOrderAsync(grpcRequest, cancellationToken: cancellationToken);
+
+        _logger.LogInformation(
+            "Cancelled order {OrderId}. Status={Status} RefundProcessed={RefundProcessed}",
+            response.OrderId,
+            response.Status,
+            response.RefundProcessed);
+
+        return new CancelOrderResponse
+        {
+            OrderId = response.OrderId,
+            Status = (int)response.Status,
+            Message = response.Message,
+            RefundProcessed = response.RefundProcessed
+        };
+    }
+}
+