public class CardValidator
{
public string CardType { get; private set; }
public bool IsValid { get; private set; }
public string ResultingError { get; private set; }
public string CardNumber { get; set; }
public DateTime CardExpiration { get; set; }
public void Validate()
{
IsValid = false;
if (string.IsNullOrEmpty(CardNumber))
{
ResultingError = "Card number empty....";
return;
}
if (CardNumber.Length > 16)
{
ResultingError = "Card number too long";
return;
}
foreach (char digit in CardNumber)
{
if (!char.IsDigit(digit))
{
ResultingError = "Card number contains invalid characters";
return;
}
}
if (CardExpiration < DateTime.Now)
{
ResultingError = "Card has expired.";
return;
}
int sum = 0;
for (int i = CardNumber.Length - 1; i >= 0; i--)
{
if (i % 2 == CardNumber.Length % 2)
{
int n = int.Parse(CardNumber.Substring(i, 1)) * 2;
sum += (n / 10) + (n % 10);
}
else
{
sum += int.Parse(CardNumber.Substring(i, 1));
}
}
IsValid = (sum % 10 == 0);
if (IsValid == true)
{
switch (CardNumber.Substring(0, 1))
{
case "3":
CardType = "AMEX/Diners Club/JCB";
break;
case "4":
CardType = "VISA";
break;
case "5":
CardType = "MasterCard";
break;
case "6":
CardType = "Discover";
break;
default:
CardType = "Unknown";
break;
}
}
else
{
CardType = "Invalid";
}
}
}
