cart and checkout

pkg/cart/tax_nordic.go

@@ -0,0 +1,55 @@
+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]
+}