namespace FinancialApi.Application;

public record Account(int Id, decimal Balance)
{
    public Account ApplyFee(decimal amount)
    {
        if (amount <= 0) 
            throw new ArgumentException("Fee must be positive.");
            
        if (Balance - amount < 0)
            throw new InvalidOperationException("Insufficient funds.");

        // Returns a brand new record with the updated balance
        return this with { Balance = Balance - amount };
    }
}