Define domain service

domain/services.go

@@ -0,0 +1,22 @@
+package domain
+
+
+// CurrencyConverter is a domain service for currency conversion operations
+type CurrencyConverter struct{}
+
+// NewCurrencyConverter creates a new CurrencyConverter
+func NewCurrencyConverter() *CurrencyConverter {
+	return &CurrencyConverter{}
+}
+
+// Convert converts money from one currency to another using the provided rate
+func (c *CurrencyConverter) Convert(money Money, rate Rate) (Money, error) {
+	if money.Currency.Code != rate.From.Code {
+		return Money{}, ErrCurrencyMismatch
+	}
+
+	convertedAmount := money.Amount.Mul(rate.Value)
+
+	return NewMoneyFromDecimal(convertedAmount, rate.To)
+}
+