update

region/config.go

@@ -0,0 +1,101 @@
+// Package region provides a first-class region configuration for the commerce
+// platform. It maps country codes to their associated currency, locale, and
+// other market-specific settings, replacing the hardcoded getCurrency/getLocale
+// helpers that were duplicated across services.
+//
+// Usage:
+//
+//	cfg, err := region.LoadConfig("data/regions.json")
+//	currency := cfg.CurrencyOf("no")  // "NOK"
+//	locale   := cfg.LocaleOf("no")    // "nb-no"
+//	country  := cfg.CountryFromCurrency("NOK") // "no"
+package region
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// Region defines the market configuration for a single country.
+type Region struct {
+	CountryCode string `json:"countryCode"` // ISO 3166-1 alpha-2 lowercase, e.g. "se", "no", "dk", "fi"
+	Currency    string `json:"currency"`    // ISO 4217, e.g. "SEK", "NOK", "DKK", "EUR"
+	Locale      string `json:"locale"`      // IETF BCP 47, e.g. "sv-se", "nb-no", "da-dk", "fi-fi"
+}
+
+// Config holds the full set of region definitions.
+type Config struct {
+	Regions []Region `json:"regions"`
+}
+
+// LoadConfig reads a region configuration from a JSON file. An absent file
+// returns a default Config with only SE configured, matching the legacy
+// hardcoded behaviour.
+func LoadConfig(path string) (*Config, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return DefaultConfig(), nil
+		}
+		return nil, fmt.Errorf("region: open %s: %w", path, err)
+	}
+	defer f.Close()
+
+	var cfg Config
+	if err := json.NewDecoder(f).Decode(&cfg); err != nil {
+		return nil, fmt.Errorf("region: decode %s: %w", path, err)
+	}
+	// Normalise country codes to lowercase.
+	for i := range cfg.Regions {
+		cfg.Regions[i].CountryCode = strings.ToLower(cfg.Regions[i].CountryCode)
+	}
+	return &cfg, nil
+}
+
+// DefaultConfig returns the built-in default with SE and NO configured.
+func DefaultConfig() *Config {
+	return &Config{
+		Regions: []Region{
+			{CountryCode: "se", Currency: "SEK", Locale: "sv-se"},
+			{CountryCode: "no", Currency: "NOK", Locale: "nb-no"},
+		},
+	}
+}
+
+// CurrencyOf returns the ISO 4217 currency code for the given country.
+// Returns "SEK" if the country is not configured.
+func (c *Config) CurrencyOf(country string) string {
+	cc := strings.ToLower(country)
+	for _, r := range c.Regions {
+		if r.CountryCode == cc {
+			return r.Currency
+		}
+	}
+	return "SEK"
+}
+
+// LocaleOf returns the IETF BCP 47 locale tag for the given country.
+// Returns "sv-se" if the country is not configured.
+func (c *Config) LocaleOf(country string) string {
+	cc := strings.ToLower(country)
+	for _, r := range c.Regions {
+		if r.CountryCode == cc {
+			return r.Locale
+		}
+	}
+	return "sv-se"
+}
+
+// CountryFromCurrency is the reverse of CurrencyOf — it returns the country
+// code that uses the given currency. Returns "se" for unknown currencies.
+func (c *Config) CountryFromCurrency(currency string) string {
+	curr := strings.ToUpper(currency)
+	for _, r := range c.Regions {
+		if strings.EqualFold(r.Currency, curr) {
+			return r.CountryCode
+		}
+	}
+	return "se"
+}