Financial Service

In this task, you will enhance a FinancialService class by implementing two core functionalities: transferring funds between accounts and converting currency amounts. The base code provides the structure and some placeholder logic. Your goal is to implement the logic within the transferFunds and convertCurrency methods, and create required value classes.

Task Requirements

1. Transfer Funds Between Accounts:

   • Implement the transferFunds method to simulate transferring money from a source account to a destination account. This method accepts account numbers for both the source and destination, the amount to be transferred, the currency code of the amount, and a transaction ID.
   • Your implementation should return a confirmation message summarizing the transaction, including the amount transferred, the currency code, and the transaction ID.
   • For this task, you do not need to interact with a real database; simply simulate the transaction logic and return the confirmation message.

2. Convert Currency:

   • Implement the convertCurrency method to simulate converting a given amount from one currency to another. This method takes an amount, a source currency code, and a destination currency code as inputs.
   • Use the provided getExchangeRate method to determine the exchange rate between the two currencies. Then, calculate the converted amount and return it as a CurrencyAmount.
   • The getExchangeRate method includes placeholder logic with predefined rates for USD to EUR and USD to GBP conversions. Assume a 1:1 rate for any other currency conversions not explicitly defined.

3. Create the following inline value classes with validation:

   • CurrencyAmount: Represents a monetary amount. Should ensure the amount is non-negative.
   • CurrencyCode: Represents a currency code. Should be a 3-letter uppercase code (e.g., USD, EUR).
   • AccountNumber: Represents an account number. Should be a 10-digit string.
   • TransactionId: Represents a transaction ID. Should ensure the ID is not empty.

Example Usage

val financialService = FinancialService()
val transferMessage = financialService.transferFunds(
    source = AccountNumber("1234567890"),
    destination = AccountNumber("0987654321"),
    amount = CurrencyAmount(100.0),
    currencyCode = CurrencyCode("USD"),
    transactionId = TransactionId("TX12345")
)
println(transferMessage)
// Expected output: "Transferred 100.0 USD from 1234567890 to 0987654321. Transaction ID: TX12345"

val convertedAmount = financialService.convertCurrency(
    amount = CurrencyAmount(100.0),
    fromCurrency = CurrencyCode("USD"),
    toCurrency = CurrencyCode("EUR")
)
println("Converted amount: ${convertedAmount.amount} EUR")
// Expected output: "Converted amount: 93.0 EUR"