public void GetLoanInfo_ValidInput_ShouldReturnCorrectInfo()
{
var log = new InMemoryLog();
var strategy = new CompoundInterestCalculationStrategy();
var engine = new LoanCalculationEngine(strategy, log);
double amount = 100000;
double interest = 5.5;
double downpayment = 20000;
int term = 30;
var loanInfo = engine.GetLoanInfo(amount, downpayment, interest, term);
Assert.IsNotNull(loanInfo);
Assert.AreEqual(loanInfo.Amount, amount);
Assert.AreEqual(loanInfo.AnnualInterestRate, interest);
Assert.AreEqual(loanInfo.DownPayment, downpayment);
Assert.AreEqual(loanInfo.Terms, term);
Assert.AreEqual(loanInfo.MonthlyPayment, 454.23);
Assert.AreEqual(loanInfo.Principle, 80000);
Assert.AreEqual(loanInfo.TotalInterest, 83522.8);
Assert.AreEqual(loanInfo.TotalPayment, 163522.8);
}
public static void Main(string[] args)
{
System.Console.WriteLine("Loan Calculator");
System.Console.WriteLine("Please Enter loan information");
System.Console.WriteLine("amount, interest, downpayment, and term");
System.Console.WriteLine("==========================================");
bool amountSet = false, interestSet = false, downPaymentSet = false, termSet = false;
double amount = 0;
double interest = 0;
double downpayment = 0;
int term = 0;
try
{
// since its a demo we can just do a quick in place parsing
// but there are so many good cmd libraries out there can do the job in cleaner way
string inputLine = string.Empty;
while (!string.IsNullOrEmpty(inputLine = System.Console.ReadLine()) ||
(amountSet && interestSet && downPaymentSet && termSet) == false)
{
inputLine = inputLine.ToLower();
var values = inputLine.Split(':');
if (values.Length != 2)
{
System.Console.WriteLine("Enter valid format <key>:<value>");
}
if (values[0].Equals("amount"))
{
if (!double.TryParse(values[1], out amount))
{
System.Console.WriteLine("Enter valid <amount>");
}
else
{
amountSet = true;
}
}
else if (values[0].Equals("interest"))
{
string val = values[1].TrimEnd('%');
if (!double.TryParse(val, out interest))
{
System.Console.WriteLine("Enter valid <interest>");
}
else
{
interestSet = true;
}
}
else if (values[0].Equals("downpayment"))
{
if (!double.TryParse(values[1], out downpayment))
{
System.Console.WriteLine("Enter valid <downpayment>");
}
else
{
downPaymentSet = true;
}
}
else if (values[0].Equals("term"))
{
if (!int.TryParse(values[1], out term))
{
System.Console.WriteLine("Enter valid <term>");
}
else
{
termSet = true;
}
}
else
{
System.Console.WriteLine("Invalid value, please enter valid loan value or blank line to calculate");
}
}
// loan calcualtion
var log = new InMemoryLog();
var strategy = new CompoundInterestCalculationStrategy();
var engine = new LoanCalculationEngine(strategy, log);
var loanInfo = engine.GetLoanInfo(amount, downpayment, interest, term);
if (loanInfo == null)
{
System.Console.WriteLine("Failed to calcualte loan info");
foreach (var message in log)
{
System.Console.WriteLine($"Error: {message}");
}
}
else
{
var loanJson = JsonConvert.SerializeObject(loanInfo);
System.Console.WriteLine("Loan Info:");
System.Console.WriteLine(loanJson);
}
}
catch (Exception ex)
{
System.Console.WriteLine($"Error occured: {ex}");
}
System.Console.WriteLine("Press any key to exit");
System.Console.ReadLine();
}
