package firstrechargereward

import (
	"fmt"
	"math"
	"strconv"
	"strings"
)

func parseAmountCents(raw string) (int64, error) {
	value := strings.TrimSpace(raw)
	if value == "" {
		return 0, nil
	}
	value = strings.TrimPrefix(value, "$")
	parsed, err := strconv.ParseFloat(value, 64)
	if err != nil {
		return 0, err
	}
	if parsed < 0 {
		return 0, fmt.Errorf("amount must not be negative")
	}
	return int64(math.Round(parsed * 100)), nil
}

func formatAmountCents(cents int64) string {
	if cents <= 0 {
		return "0.00"
	}
	return fmt.Sprintf("%.2f", float64(cents)/100)
}