improve the tax calculation based on given income/expenses

.env.example

@@ -4,7 +4,7 @@
 
 APP_NAME=swis-api
 APP_ROOT=/opt/${APP_NAME}
-APP_VERSION=5.11.6
+APP_VERSION=5.11.7
 
 
 #

main.go

@@ -1,5 +1,5 @@
 // @title swis-api (swapi) v5
-// @version 5.11.6
+// @version 5.11.7
 // @description sakalWeb Information System v5 RESTful API documentation
 // @termsOfService http://swagger.io/terms/
 

pkg/finance/controllers.go

@@ -342,8 +342,17 @@ func DoTaxesByOwner(ctx *gin.Context) {
 			}
 		}
 	}
-
-	tax.Base += tax.IncomeTotal - tax.ExpenseTotal
+
+	// define the tax constants
+	const incTaxRate = 0.15
+	const expRate60 = 0.60
+
+	// calculate the base for the income tax
+	tax.Base = tax.IncomeTotal - tax.ExpenseTotal
+
+	// calculate two estimations of the income tax
+	tax.IncomeTaxEstAbs = tax.Base * (1 - incTaxRate)
+	tax.IncomeTaxEst60 = (tax.IncomeTotal * (1 - expRate60) * (1 - incTaxRate))
 
 	ctx.IndentedJSON(http.StatusOK, gin.H{
 		"code":     http.StatusOK,

pkg/finance/models.go

@@ -73,4 +73,10 @@ type Tax struct {
 
 	// Difference between incomes and expenses. Base for income tax.
 	Base float64 `json:"base_sum"`
+
+	// Absolute estimation of the income tax per year, from given totals.
+	IncomeTaxEstAbs float64 `json:"income_tax_estimation_abs"`
+
+	// Weighted estimation of the income tax, where 60% of income are meant as expenses.
+	IncomeTaxEst60 float64 `json:"income_tax_estimation_60"`
 }