feat: add total income calculation

Author: morremeyer

pkg/models/budget.go

@@ -81,3 +81,28 @@ func (b Budget) Income(t time.Time) (decimal.Decimal, error) {
 
 	return income.Decimal, nil
 }
+
+// TotalIncome calculates the total income over all time.
+func (b Budget) TotalIncome() (decimal.Decimal, error) {
+	var income decimal.NullDecimal
+	err := database.DB.
+		Select("SUM(amount)").
+		Joins("JOIN accounts source_account ON transactions.source_account_id = source_account.id AND source_account.deleted_at IS NULL").
+		Joins("JOIN accounts destination_account ON transactions.destination_account_id = destination_account.id AND destination_account.deleted_at IS NULL").
+		Where("source_account.external = 1").
+		Where("destination_account.external = 0").
+		Where("transactions.envelope_id IS NULL").
+		Table("transactions").
+		Find(&income).
+		Error
+	if err != nil {
+		return decimal.Zero, err
+	}
+
+	// If no transactions are found, the value is nil
+	if !income.Valid {
+		return decimal.NewFromFloat(0), nil
+	}
+
+	return income.Decimal, nil
+}

pkg/models/budget_test.go

@@ -92,14 +92,30 @@ func (suite *TestSuiteEnv) TestBudgetCalculations() {
 			SourceAccountID:      employerAccount.ID,
 			DestinationAccountID: bankAccount.ID,
 			Reconciled:           true,
-			Amount:               decimal.NewFromFloat(2857.51),
+			Amount:               decimal.NewFromFloat(2800),
 		},
 	}
 	err = database.DB.Save(&salaryTransaction).Error
 	if err != nil {
 		suite.Assert().Fail("Resource could not be saved", err)
 	}
 
+	salaryTransactionApril := models.Transaction{
+		TransactionCreate: models.TransactionCreate{
+			Date:                 marchFifteenthTwentyTwentyTwo.AddDate(0, 1, 0),
+			BudgetID:             budget.ID,
+			EnvelopeID:           nil,
+			SourceAccountID:      employerAccount.ID,
+			DestinationAccountID: bankAccount.ID,
+			Reconciled:           true,
+			Amount:               decimal.NewFromFloat(2800),
+		},
+	}
+	err = database.DB.Save(&salaryTransactionApril).Error
+	if err != nil {
+		suite.Assert().Fail("Resource could not be saved", err)
+	}
+
 	outgoingTransactionBank := models.Transaction{
 		TransactionCreate: models.TransactionCreate{
 			BudgetID:             budget.ID,
@@ -130,11 +146,40 @@ func (suite *TestSuiteEnv) TestBudgetCalculations() {
 
 	budget = budget.WithCalculations()
 
-	shouldBalance := decimal.NewFromFloat(2746.89)
+	shouldBalance := decimal.NewFromFloat(5489.38)
 	assert.True(suite.T(), budget.Balance.Equal(shouldBalance), "Balance for budget is not correct. Should be %s, is %s", shouldBalance, budget.Balance)
 
-	shouldIncome := decimal.NewFromFloat(2857.51)
+	shouldIncome := decimal.NewFromFloat(2800)
 	income, err := budget.Income(marchFifteenthTwentyTwentyTwo)
 	assert.Nil(suite.T(), err)
 	assert.True(suite.T(), income.Equal(shouldIncome), "Income is %s, should be %s", income, shouldIncome)
+
+	shouldIncomeTotal := decimal.NewFromFloat(5600)
+	income, err = budget.TotalIncome()
+	assert.Nil(suite.T(), err)
+	assert.True(suite.T(), income.Equal(shouldIncomeTotal), "Income is %s, should be %s", income, shouldIncomeTotal)
+}
+
+func (suite *TestSuiteEnv) TestMonthIncomeNoTransactions() {
+	budget := models.Budget{}
+	err := database.DB.Save(&budget).Error
+	if err != nil {
+		suite.Assert().Fail("Resource could not be saved", err)
+	}
+
+	income, err := budget.Income(time.Date(2022, 3, 15, 0, 0, 0, 0, time.UTC))
+	assert.Nil(suite.T(), err)
+	assert.True(suite.T(), income.IsZero(), "Income is %s, should be 0", income)
+}
+
+func (suite *TestSuiteEnv) TestTotalIncomeNoTransactions() {
+	budget := models.Budget{}
+	err := database.DB.Save(&budget).Error
+	if err != nil {
+		suite.Assert().Fail("Resource could not be saved", err)
+	}
+
+	income, err := budget.TotalIncome()
+	assert.Nil(suite.T(), err)
+	assert.True(suite.T(), income.IsZero(), "Income is %s, should be 0", income)
 }