experiments with pgtype numeric

pgutils/pgutils.go

@@ -2,19 +2,21 @@ package pgutils
 
 import (
 	"log/slog"
+	"math"
+	"math/big"
 	"strconv"
 
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
 func NumericToFloat64(n pgtype.Numeric) float64 {
-	value, err := n.Value()
+	val, err := n.Value()
 	if err != nil {
 		slog.Error("error getting numeric value", "error", err)
 		return 0
 	}
 
-	strValue, ok := value.(string)
+	strValue, ok := val.(string)
 	if !ok {
 		slog.Error("error converting numeric value to string")
 		return 0
@@ -29,10 +31,70 @@ func NumericToFloat64(n pgtype.Numeric) float64 {
 	return floatValue
 }
 
-func FloatToNumeric(number float64) (value pgtype.Numeric) {
-	parse := strconv.FormatFloat(number, 'f', -1, 64)
+func NumericToInt64(n pgtype.Numeric) int64 {
+	return n.Int.Int64() * int64(math.Pow(10, float64(n.Exp)))
+}
+
+func FloatToNumeric(number float64, precision int) (value pgtype.Numeric) {
+	parse := strconv.FormatFloat(number, 'f', precision, 64)
+	slog.Info("parse", "parse", parse)
+
 	if err := value.Scan(parse); err != nil {
-		slog.Error("error scanning float to numeric", "error", err)
+		slog.Error("error scanning numeric", "error", err)
 	}
 	return value
 }
+
+func AddNumeric(a, b pgtype.Numeric) pgtype.Numeric {
+	minExp := a.Exp
+	if b.Exp < minExp {
+		minExp = b.Exp
+	}
+
+	aInt := new(big.Int).Set(a.Int)
+	bInt := new(big.Int).Set(b.Int)
+
+	for a.Exp > minExp {
+		aInt.Mul(aInt, big.NewInt(10))
+		a.Exp--
+	}
+	for b.Exp > minExp {
+		bInt.Mul(bInt, big.NewInt(10))
+		b.Exp--
+	}
+
+	resultado := new(big.Int).Add(aInt, bInt)
+
+	return pgtype.Numeric{
+		Int:   resultado,
+		Exp:   minExp,
+		Valid: true,
+	}
+}
+
+func SubtractNumeric(a, b pgtype.Numeric) pgtype.Numeric {
+	minExp := a.Exp
+	if b.Exp < minExp {
+		minExp = b.Exp
+	}
+
+	aInt := new(big.Int).Set(a.Int)
+	bInt := new(big.Int).Set(b.Int)
+
+	for a.Exp > minExp {
+		aInt.Mul(aInt, big.NewInt(10))
+		a.Exp--
+	}
+	for b.Exp > minExp {
+		bInt.Mul(bInt, big.NewInt(10))
+		b.Exp--
+	}
+
+	resultado := new(big.Int).Sub(aInt, bInt)
+
+	return pgtype.Numeric{
+		Int:   resultado,
+		Exp:   minExp,
+		Valid: true,
+	}
+}