package analyzer

import (
	"math"
	"os"
	"regexp"
	"strings"

	"golang.org/x/text/currency"
	"golang.org/x/text/language"
	"golang.org/x/text/message"
)

type Amount float64

var localizedLanguagePrinter = func() *message.Printer {
	_newLocalizedLanguage := func() (language.Tag, bool) {
		environmentLang := os.Getenv("LANG")
		if environmentLang == "" {
			return language.Tag{}, false
		}
		regexp := regexp.MustCompile(`^([a-z]+)_([A-Z]+)\.[A-Z0-9-]+$`)
		results := regexp.FindAllStringSubmatch(environmentLang, -1)
		if len(results) != 1 || len(results[0]) != 3 {
			return language.Tag{}, false
		}

		base, err := language.ParseBase(results[0][1])
		if err != nil {
			return language.Tag{}, false
		}
		region, err := language.ParseRegion(results[0][2])
		if err != nil {
			return language.Tag{}, false
		}
		result, err := language.Compose(base, region)
		return result, err == nil
	}

	result, ok := _newLocalizedLanguage()
	if !ok {
		return message.NewPrinter(language.AmericanEnglish)
	}
	return message.NewPrinter(result)
}()

// Rounded rounds a float to the number of places specified.
func (amount Amount) Rounded(places int) Amount {
	p := math.Pow10(places)
	return Amount(math.Round(float64(amount)*p) / p)
}

// FormatUSD formats Amount as a string in US dollars.
func (amount Amount) FormatUSD() string {
	rounded := amount.Rounded(2)
	prefix := ""
	if rounded < 0 {
		prefix = "-"
		rounded *= -1.0
	}

	roundedAsCurrency := currency.NarrowSymbol(currency.USD.Amount(float32(rounded)))
	resultWithSpaceAfterDollarSign := localizedLanguagePrinter.Sprintf("%s%.2f", prefix, roundedAsCurrency)
	return strings.Replace(resultWithSpaceAfterDollarSign, "$ ", "$", 1)
}