From 9f4edf39dda5277a2fc2b360810fe9e63d677632 Mon Sep 17 00:00:00 2001
From: Roland Bewick <roland.bewick@gmail.com>
Date: Tue, 20 Aug 2024 12:57:23 +0700
Subject: [PATCH] fix: check for duplicate payment

---
 transactions/payments_test.go        | 23 +++++++++++++++++++++++
 transactions/transactions_service.go | 10 ++++++++++
 2 files changed, 33 insertions(+)

diff --git a/transactions/payments_test.go b/transactions/payments_test.go
index 25f2b71e..563b803a 100644
--- a/transactions/payments_test.go
+++ b/transactions/payments_test.go
@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/getAlby/hub/constants"
+	"github.com/getAlby/hub/db"
 	"github.com/getAlby/hub/lnclient"
 	"github.com/getAlby/hub/tests"
 	"github.com/stretchr/testify/assert"
@@ -28,6 +29,28 @@ func TestSendPaymentSync_NoApp(t *testing.T) {
 	assert.Equal(t, "123preimage", *transaction.Preimage)
 }
 
+func TestSendPaymentSync_Duplicate(t *testing.T) {
+	ctx := context.TODO()
+
+	defer tests.RemoveTestService()
+	svc, err := tests.CreateTestService()
+	assert.NoError(t, err)
+
+	svc.DB.Create(&db.Transaction{
+		State:       constants.TRANSACTION_STATE_SETTLED,
+		Type:        constants.TRANSACTION_TYPE_OUTGOING,
+		PaymentHash: tests.MockLNClientTransaction.PaymentHash,
+		AmountMsat:  123000,
+	})
+
+	transactionsService := NewTransactionsService(svc.DB, svc.EventPublisher)
+	transaction, err := transactionsService.SendPaymentSync(ctx, tests.MockLNClientTransaction.Invoice, svc.LNClient, nil, nil)
+
+	assert.Error(t, err)
+	assert.Equal(t, "this invoice has already been paid", err.Error())
+	assert.Nil(t, transaction)
+}
+
 func TestSendPaymentSync_FailedRemovesFeeReserve(t *testing.T) {
 	ctx := context.TODO()
 
diff --git a/transactions/transactions_service.go b/transactions/transactions_service.go
index 4adf05cc..0d193ba4 100644
--- a/transactions/transactions_service.go
+++ b/transactions/transactions_service.go
@@ -174,6 +174,16 @@ func (svc *transactionsService) SendPaymentSync(ctx context.Context, payReq stri
 	var dbTransaction db.Transaction
 
 	err = svc.db.Transaction(func(tx *gorm.DB) error {
+		var existingSettledTransaction db.Transaction
+		if tx.Limit(1).Find(&existingSettledTransaction, &db.Transaction{
+			Type:        constants.TRANSACTION_TYPE_OUTGOING,
+			PaymentHash: paymentRequest.PaymentHash,
+			State:       constants.TRANSACTION_STATE_SETTLED,
+		}).RowsAffected > 0 {
+			logger.Logger.WithField("payment_hash", dbTransaction.PaymentHash).Info("this invoice has already been paid")
+			return errors.New("this invoice has already been paid")
+		}
+
 		err := svc.validateCanPay(tx, appId, uint64(paymentRequest.MSatoshi))
 		if err != nil {
 			return err