fix(payment): prevent duplicate wallet credit on package verify

Add idempotent verify with serializable transaction and wallet-history check
to stop concurrent callback/race from charging the wallet twice.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/CMSMicroservice.WebApi/Services/PackageService.cs

@@ -15,6 +15,7 @@ using AppModels = CMSMicroservice.Application.Common.Models;
 using Grpc.Core;
 using Google.Protobuf.WellKnownTypes;
 using System.Collections.Generic;
+using System.Data;
 using System.Linq;
 using CMSMicroservice.Protobuf.Protos;
 using Microsoft.EntityFrameworkCore;
@@ -242,66 +243,137 @@ public class PackageService : PackageContract.PackageContractBase
     
     public override async Task<CustomerVerifyPackagePurchaseResponse> CustomerVerifyPackagePurchase(CustomerVerifyPackagePurchaseRequest request, ServerCallContext context)
     {
-        // Find purchase record
+        var ct = context.CancellationToken;
+
         var purchase = await _context.UserPackagePurchases
             .Include(p => p.Package)
             .Where(p => p.Id == request.OrderId && !p.IsDeleted)
-            .FirstOrDefaultAsync(context.CancellationToken);
-        
+            .FirstOrDefaultAsync(ct);
+
         if (purchase == null)
             throw new RpcException(new Status(StatusCode.NotFound, "سفارش یافت نشد"));
-        
-        // Find the associated transaction
+
         var transaction = purchase.TransactionId.HasValue
             ? await _context.Transactions
                 .Where(t => t.Id == purchase.TransactionId.Value)
-                .FirstOrDefaultAsync(context.CancellationToken)
+                .FirstOrDefaultAsync(ct)
             : null;
-        
-        // If status from gateway callback is not OK
+
+        var paymentTx = !string.IsNullOrEmpty(request.Authority)
+            ? await _context.PaymentTransactions
+                .FirstOrDefaultAsync(pt => pt.Authority == request.Authority, ct)
+            : null;
+
+        // Idempotency: already verified — never credit wallet again
+        if (IsPackagePaymentAlreadyCompleted(transaction, paymentTx))
+        {
+            return BuildVerifyPackagePurchaseResponse(
+                purchase, transaction, paymentTx, alreadyPaid: true);
+        }
+
         if (request.Status != "OK")
         {
-            if (transaction != null)
+            if (transaction != null && transaction.PaymentStatus != Domain.Enums.PaymentStatus.Success)
             {
                 transaction.PaymentStatus = Domain.Enums.PaymentStatus.Reject;
-                await _context.SaveChangesAsync(context.CancellationToken);
+                await _context.SaveChangesAsync(ct);
             }
-            
+
             return new CustomerVerifyPackagePurchaseResponse
             {
                 Success = false,
                 Message = "پرداخت توسط کاربر لغو شد"
             };
         }
-        
-        // واکشی PaymentTransaction برای گرفتن مبلغ (تومان) جهت verify
-        var paymentTx = await _context.PaymentTransactions
-            .FirstOrDefaultAsync(pt => pt.Authority == request.Authority, context.CancellationToken);
-        
+
         var amountInToman = paymentTx?.Amount ?? purchase.Amount;
-        
-        // Verify with payment gateway (مبلغ به تومان — سرویس زرین‌پال خودش ×۱۰ می‌کنه)
         var verifyResult = await _paymentGateway.VerifyPaymentAsync(
-            request.Authority, request.Status, (decimal)amountInToman, context.CancellationToken);
-        if (paymentTx != null)
+            request.Authority, request.Status, (decimal)amountInToman, ct);
+
+        if (!verifyResult.IsSuccess)
         {
-            paymentTx.PaymentStatus = verifyResult.IsSuccess;
-            paymentTx.VerificationStatusCode = verifyResult.VerificationCode;
-            paymentTx.VerificationStatusMessage = verifyResult.Message;
-            paymentTx.CardPan = verifyResult.CardPan;
-            paymentTx.CardHash = verifyResult.CardHash;
-            paymentTx.RefId = verifyResult.TrackingCode;
+            if (paymentTx != null)
+            {
+                paymentTx.PaymentStatus = false;
+                paymentTx.VerificationStatusCode = verifyResult.VerificationCode;
+                paymentTx.VerificationStatusMessage = verifyResult.Message;
+            }
+            if (transaction != null)
+                transaction.PaymentStatus = Domain.Enums.PaymentStatus.Reject;
+
+            await _context.SaveChangesAsync(ct);
+
+            return new CustomerVerifyPackagePurchaseResponse
+            {
+                Success = false,
+                Message = verifyResult.Message ?? "خرید پکیج ناموفق بود",
+                TransactionId = transaction?.Id ?? 0
+            };
         }
-        
-        if (verifyResult.IsSuccess && transaction != null)
+
+        // Serializable transaction prevents concurrent double-credit (~1s race from duplicate callbacks)
+        await using var dbTx = await _context.Database.BeginTransactionAsync(IsolationLevel.Serializable, ct);
+        try
         {
+            // Reload inside lock scope
+            if (purchase.TransactionId.HasValue)
+            {
+                transaction = await _context.Transactions
+                    .FirstOrDefaultAsync(t => t.Id == purchase.TransactionId.Value, ct);
+            }
+            if (!string.IsNullOrEmpty(request.Authority))
+            {
+                paymentTx = await _context.PaymentTransactions
+                    .FirstOrDefaultAsync(pt => pt.Authority == request.Authority, ct);
+            }
+
+            if (IsPackagePaymentAlreadyCompleted(transaction, paymentTx))
+            {
+                await dbTx.CommitAsync(ct);
+                return BuildVerifyPackagePurchaseResponse(
+                    purchase, transaction, paymentTx, alreadyPaid: true);
+            }
+
+            if (transaction == null)
+                throw new RpcException(new Status(StatusCode.Internal, "تراکنش سفارش یافت نشد"));
+
+            // Wallet history is the idempotency key for financial side-effects
+            var alreadyCredited = await _context.UserWalletHistories
+                .AnyAsync(h => h.RefrenceId == transaction.Id && !h.IsDeleted, ct);
+
+            if (alreadyCredited)
+            {
+                transaction.PaymentStatus = Domain.Enums.PaymentStatus.Success;
+                transaction.PaymentDate ??= DateTime.UtcNow;
+                if (paymentTx != null)
+                {
+                    paymentTx.PaymentStatus = true;
+                    paymentTx.VerificationStatusCode = verifyResult.VerificationCode;
+                    paymentTx.VerificationStatusMessage = verifyResult.Message;
+                    paymentTx.RefId = verifyResult.TrackingCode;
+                }
+                await _context.SaveChangesAsync(ct);
+                await dbTx.CommitAsync(ct);
+                return BuildVerifyPackagePurchaseResponse(
+                    purchase, transaction, paymentTx, alreadyPaid: true);
+            }
+
+            if (paymentTx != null)
+            {
+                paymentTx.PaymentStatus = true;
+                paymentTx.VerificationStatusCode = verifyResult.VerificationCode;
+                paymentTx.VerificationStatusMessage = verifyResult.Message;
+                paymentTx.CardPan = verifyResult.CardPan;
+                paymentTx.CardHash = verifyResult.CardHash;
+                paymentTx.RefId = verifyResult.TrackingCode;
+            }
+
             transaction.PaymentStatus = Domain.Enums.PaymentStatus.Success;
             transaction.PaymentDate = DateTime.UtcNow;
             transaction.RefId = verifyResult.RefId;
 
-            // شارژ کیف پول کاربر
             var wallet = await _context.UserWallets
-                .FirstOrDefaultAsync(w => w.UserId == purchase.UserId, context.CancellationToken);
+                .FirstOrDefaultAsync(w => w.UserId == purchase.UserId, ct);
 
             if (wallet == null)
             {
@@ -313,7 +385,7 @@ public class PackageService : PackageContract.PackageContractBase
                     NetworkBalance = 0
                 };
                 _context.UserWallets.Add(wallet);
-                await _context.SaveChangesAsync(context.CancellationToken);
+                await _context.SaveChangesAsync(ct);
             }
 
             var discountMultiplier = purchase.Package?.DiscountMultiplier
@@ -322,8 +394,7 @@ public class PackageService : PackageContract.PackageContractBase
             wallet.Balance += purchase.Amount;
             wallet.DiscountBalance += discountAmount;
 
-            // ثبت لاگ کیف پول
-            var walletLog = new CMSMicroservice.Domain.Entities.UserWalletHistory
+            _context.UserWalletHistories.Add(new CMSMicroservice.Domain.Entities.UserWalletHistory
             {
                 WalletId = wallet.Id,
                 CurrentBalance = wallet.Balance,
@@ -335,23 +406,22 @@ public class PackageService : PackageContract.PackageContractBase
                 IsIncrease = true,
                 RefrenceId = transaction.Id,
                 PackageId = purchase.PackageId
-            };
-            _context.UserWalletHistories.Add(walletLog);
+            });
 
-            // به‌روزرسانی کاربر
             var user = await _context.Users
-                .FirstOrDefaultAsync(u => u.Id == purchase.UserId, context.CancellationToken);
+                .FirstOrDefaultAsync(u => u.Id == purchase.UserId, ct);
             if (user != null)
                 user.PackagePurchaseMethod = Domain.Enums.PackagePurchaseMethod.DirectPurchase;
+
+            await _context.SaveChangesAsync(ct);
+            await dbTx.CommitAsync(ct);
         }
-        else if (transaction != null)
+        catch
         {
-            transaction.PaymentStatus = Domain.Enums.PaymentStatus.Reject;
+            await dbTx.RollbackAsync(ct);
+            throw;
         }
-        
-        await _context.SaveChangesAsync(context.CancellationToken);
-        
-        // فعالسازی خودکار باشگاه مشتریان بعد از تأیید پرداخت موفق
+
         if (verifyResult.IsSuccess)
         {
             try
@@ -360,31 +430,54 @@ public class PackageService : PackageContract.PackageContractBase
                 {
                     UserId = purchase.UserId,
                     ForceActivation = false
-                }, context.CancellationToken);
+                }, ct);
             }
             catch (Exception ex)
             {
-                // لاگ خطا ولی پرداخت موفق بوده — کاربر می‌تونه دستی فعالسازی کنه
                 System.Console.WriteLine($"Auto club activation failed for UserId {purchase.UserId}: {ex.Message}");
             }
         }
-        
+
+        return BuildVerifyPackagePurchaseResponse(
+            purchase, transaction, paymentTx, alreadyPaid: false, verifyResult.RefId);
+    }
+
+    private static bool IsPackagePaymentAlreadyCompleted(
+        CMSMicroservice.Domain.Entities.Transaction? transaction,
+        PaymentTransaction? paymentTx)
+    {
+        return transaction?.PaymentStatus == Domain.Enums.PaymentStatus.Success
+            || paymentTx?.PaymentStatus == true;
+    }
+
+    private static CustomerVerifyPackagePurchaseResponse BuildVerifyPackagePurchaseResponse(
+        CMSMicroservice.Domain.Entities.UserPackagePurchase purchase,
+        CMSMicroservice.Domain.Entities.Transaction? transaction,
+        PaymentTransaction? paymentTx,
+        bool alreadyPaid,
+        string? referenceCode = null)
+    {
+        var refCode = referenceCode
+            ?? paymentTx?.RefId
+            ?? transaction?.RefId
+            ?? string.Empty;
+
         return new CustomerVerifyPackagePurchaseResponse
         {
-            Success = verifyResult.IsSuccess,
-            Message = verifyResult.IsSuccess ? "خرید پکیج با موفقیت تایید شد" : (verifyResult.Message ?? "خرید پکیج ناموفق بود"),
+            Success = true,
+            Message = alreadyPaid ? "پرداخت قبلاً تأیید شده بود" : "خرید پکیج با موفقیت تایید شد",
             TransactionId = transaction?.Id ?? 0,
-            ReferenceCode = verifyResult.RefId ?? string.Empty,
-            PurchaseInfo = verifyResult.IsSuccess ? new PackagePurchaseInfo
+            ReferenceCode = refCode,
+            PurchaseInfo = new PackagePurchaseInfo
             {
                 PackageId = purchase.PackageId,
                 PackageName = purchase.Package?.Title ?? string.Empty,
                 AmountPaid = purchase.Amount,
                 PurchaseDate = Timestamp.FromDateTime(DateTime.SpecifyKind(purchase.PurchasedAt, DateTimeKind.Utc))
-            } : null
+            }
         };
     }
-    
+
     private long GetCurrentUserId()
     {
         if (long.TryParse(_currentUserService.UserId, out var userId) && userId > 0)