From 9408714f0a8ae3d0a8c9d76b9d26cac31ffe9237 Mon Sep 17 00:00:00 2001
From: Morre <morre@mor.re>
Date: Sun, 8 Oct 2023 15:26:09 +0200
Subject: [PATCH] fix: availability date is now enforced to not be earlier than
 the month of the transaction

Resolves #768.
---
 pkg/models/account_test.go     |  1 +
 pkg/models/transaction.go      |  2 ++
 pkg/models/transaction_test.go | 22 ++++++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/pkg/models/account_test.go b/pkg/models/account_test.go
index 11735290..9b4a504c 100644
--- a/pkg/models/account_test.go
+++ b/pkg/models/account_test.go
@@ -59,6 +59,7 @@ func (suite *TestSuiteStandard) TestAccountCalculations() {
 		SourceAccountID:      externalAccount.ID,
 		DestinationAccountID: account.ID,
 		Amount:               decimal.NewFromFloat(100),
+		Date:                 time.Now(),
 		AvailableFrom:        types.MonthOf(time.Now()).AddDate(0, 1),
 		Note:                 "Future Income Transaction",
 	})
diff --git a/pkg/models/transaction.go b/pkg/models/transaction.go
index a68ca0aa..2c4fdcdc 100644
--- a/pkg/models/transaction.go
+++ b/pkg/models/transaction.go
@@ -90,6 +90,8 @@ func (t *Transaction) BeforeSave(tx *gorm.DB) (err error) {
 	// Default the AvailableForBudget date to the transaction date
 	if t.AvailableFrom.IsZero() {
 		t.AvailableFrom = types.MonthOf(t.Date)
+	} else if t.AvailableFrom.Before(types.MonthOf(t.Date)) {
+		return fmt.Errorf("availability month must not be earlier than the month of the transaction, transaction date: %s, available month %s", t.Date, t.AvailableFrom)
 	}
 
 	// Enforce ReconciledSource = false when source account is external
diff --git a/pkg/models/transaction_test.go b/pkg/models/transaction_test.go
index a68f3641..ac8d399a 100644
--- a/pkg/models/transaction_test.go
+++ b/pkg/models/transaction_test.go
@@ -5,6 +5,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/envelope-zero/backend/v3/internal/types"
 	"github.com/envelope-zero/backend/v3/pkg/models"
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
@@ -120,3 +121,24 @@ func (suite *TestSuiteStandard) TestTransactionReconciled() {
 func (suite *TestSuiteStandard) TestTransactionSelf() {
 	assert.Equal(suite.T(), "Transaction", models.Transaction{}.Self())
 }
+
+// Regression test for https://github.com/envelope-zero/backend/issues/768
+func (suite *TestSuiteStandard) TestTransactionAvailableFromDate() {
+	budget := suite.createTestBudget(models.BudgetCreate{})
+	internalAccount := suite.createTestAccount(models.AccountCreate{External: false, BudgetID: budget.ID})
+	externalAccount := suite.createTestAccount(models.AccountCreate{External: true, BudgetID: budget.ID})
+
+	transaction := models.Transaction{
+		TransactionCreate: models.TransactionCreate{
+			SourceAccountID:      externalAccount.ID,
+			DestinationAccountID: internalAccount.ID,
+			Note:                 "TestTransactionAvailableFromDate",
+			AvailableFrom:        types.NewMonth(2023, 9),
+			Date:                 time.Date(2023, 10, 7, 0, 0, 0, 0, time.UTC),
+		},
+	}
+
+	err := suite.db.Save(&transaction).Error
+	suite.Assert().NotNil(err, "Saving a transaction with an AvailableFrom date in a month before the transaction date should not be possible")
+	suite.Assert().Contains(err.Error(), "availability month must not be earlier than the month of the transaction")
+}