add a helper function 'TruncateDecimalString' to format amounts to specified decimal places

store/tokens.go

@@ -3,6 +3,7 @@ package store
 import (
 	"context"
 	"errors"
+	"fmt"
 	"math/big"
 	"reflect"
 	"strconv"
@@ -20,6 +21,27 @@ type TransactionData struct {
 	ActiveAddress  string
 }
 
+// TruncateDecimalString safely truncates the input amount to the specified decimal places
+func TruncateDecimalString(input string, decimalPlaces int) (string, error) {
+	num, ok := new(big.Float).SetString(input)
+	if !ok {
+		return "", fmt.Errorf("invalid input")
+	}
+
+	// Multiply by 10^decimalPlaces
+	scale := new(big.Float).SetInt(new(big.Int).Exp(big.NewInt(10), big.NewInt(int64(decimalPlaces)), nil))
+	scaled := new(big.Float).Mul(num, scale)
+
+	// Truncate by converting to int (chops off decimals)
+	intPart, _ := scaled.Int(nil)
+
+	// Divide back to get truncated float
+	truncated := new(big.Float).Quo(new(big.Float).SetInt(intPart), scale)
+
+	// Format with fixed decimals
+	return truncated.Text('f', decimalPlaces), nil
+}
+
 func ParseAndScaleAmount(storedAmount, activeDecimal string) (string, error) {
 	// Parse token decimal
 	tokenDecimal, err := strconv.Atoi(activeDecimal)