package cart

// NordicTaxProvider implements TaxProvider for the Nordic countries
// (SE, NO, DK, FI). It encodes the standard statutory VAT rates:
//
//	SE:  25 % (standard), 12 % (food, hotels), 6 % (books, transport)
//	NO:  25 % (standard), 15 % (food),        12 %
//	DK:  25 % (standard)
//	FI:  25 % (standard; actual rate is 25.5 % as of 2026)
//
// All rates are raw percent (25 = 25 %). Fractional rates (FI 25.5) are
// truncated to the nearest integer per the raw-percent convention.
//
// NordicTaxProvider does not make network calls — all logic is local math.
// An external provider (Avalara, TaxJar) can be added by implementing
// TaxProvider and switching on TAX_PROVIDER.
type NordicTaxProvider struct {
	defaultCountry string
}

// NewNordicTaxProvider returns a NordicTaxProvider. defaultCountry is used
// when DefaultTaxRate is called with an empty country code; it defaults to
// "SE" if empty.
func NewNordicTaxProvider(defaultCountry string) *NordicTaxProvider {
	if defaultCountry == "" {
		defaultCountry = "SE"
	}
	return &NordicTaxProvider{defaultCountry: defaultCountry}
}

var _ TaxProvider = (*NordicTaxProvider)(nil)

func (p *NordicTaxProvider) Name() string { return "nordic" }

func (p *NordicTaxProvider) ComputeTax(total int64, taxRate int) int64 {
	return ComputeTax(total, taxRate)
}

// nordicStandardRates maps country code → default standard VAT rate (raw percent).
var nordicStandardRates = map[string]int{
	"SE": 25,
	"NO": 25,
	"DK": 25,
	"FI": 25,
}

func (p *NordicTaxProvider) DefaultTaxRate(country string) int {
	if country == "" {
		country = p.defaultCountry
	}
	if rate, ok := nordicStandardRates[country]; ok {
		return rate
	}
	return nordicStandardRates[p.defaultCountry]
}