package platform

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

func FormatCZK(amountMinor int64) string {
	sign := ""
	if amountMinor < 0 {
		sign = "-"
		amountMinor = -amountMinor
	}

	whole := amountMinor / 100
	fraction := amountMinor % 100

	return fmt.Sprintf("%s%s,%02d CZK", sign, formatThousands(whole), fraction)
}

func ParseCZK(input string) (int64, error) {
	clean := strings.TrimSpace(strings.ReplaceAll(input, " ", ""))
	clean = strings.ReplaceAll(clean, ",", ".")
	if clean == "" {
		return 0, fmt.Errorf("amount is required")
	}

	parts := strings.Split(clean, ".")
	if len(parts) > 2 {
		return 0, fmt.Errorf("invalid amount")
	}

	whole, err := strconv.ParseInt(parts[0], 10, 64)
	if err != nil {
		return 0, fmt.Errorf("invalid whole amount")
	}

	var fraction int64
	if len(parts) == 2 {
		frac := parts[1]
		if len(frac) > 2 {
			return 0, fmt.Errorf("too many decimal places")
		}
		if len(frac) == 1 {
			frac += "0"
		}
		if len(frac) == 0 {
			frac = "00"
		}

		fraction, err = strconv.ParseInt(frac, 10, 64)
		if err != nil {
			return 0, fmt.Errorf("invalid decimal amount")
		}
	}

	if whole < 0 || fraction < 0 {
		return 0, fmt.Errorf("amount must be positive")
	}

	return whole*100 + fraction, nil
}

func formatThousands(value int64) string {
	plain := strconv.FormatInt(value, 10)
	if len(plain) <= 3 {
		return plain
	}

	var parts []string
	for len(plain) > 3 {
		parts = append([]string{plain[len(plain)-3:]}, parts...)
		plain = plain[:len(plain)-3]
	}
	parts = append([]string{plain}, parts...)

	return strings.Join(parts, " ")
}