package core

import (
	"fmt"
	"strings"
)

func FormatEuros(balance int64) string {
	prefix := ""
	if balance < 0 {
		prefix = "- "
		balance = -balance
	}

	n := float64(balance) / 100
	s := fmt.Sprintf("%.2f", n) // "1234567.89"

	parts := strings.Split(s, ".")
	intPart := parts[0]
	fracPart := parts[1]

	var result strings.Builder
	numberOfSeperators := len(intPart) % 3
	if numberOfSeperators == 0 {
		result.WriteString(intPart)
	} else {
		for i := range intPart {
			if i > 0 && (i-numberOfSeperators)%3 == 0 {
				result.WriteString(",")
			}
			result.WriteByte(intPart[i])
		}
	}

	return prefix + result.String() + "." + fracPart + " €"
}