Financial Service

In this task, you will enhance a FinancialService class by implementing two essential functionalities: transferring funds between accounts and converting currency amounts. The base code lays out the structure and provides some placeholder logic. The objective is to execute the logic within the transferFunds and convertCurrency methods and establish the required value classes.

Task Requirements

1. Transfer Funds Between Accounts:

   • Implement the transferFunds method to simulate money transfer from a source to a destination account. This method requires account numbers for both the source and destination, the amount to be transferred, the currency code of the amount, and a transaction ID.
   • Upon completion, return a confirmation message summarizing the transaction, including details such as the amount transferred, currency code, and transaction ID.
   • In this task, interaction with an actual database isn't necessary; 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 getExchangeRate method provided to determine the exchange rate between the two currencies. Then, calculate the converted amount and return it as a CurrencyAmount.
   • Placeholder logic exists within the getExchangeRate method, offering 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. Creation of Inline Value Classes with Validation:

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

Example

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"