public string Encrypt(string s)
{
sb.Clear();
if (s == null)
{
return(null);
}
sb.Capacity = s.Length;
for (int i = 0; i < s.Length; i++)
{
if (IsSymbol(s[i]))
{
sb.Append(s[i]); // ignore symbols
continue;
}
if (shiftedCache.ContainsKey(s[i]))
{
sb.Append(shiftedCache[s[i]]);
}
else
{
CharDetails cd = GetCharDetails(s[i]);
char shiftedChar = GetShiftedCharacter(cd);
sb.Append(shiftedChar);
shiftedCache[cd.AsciiCode] = shiftedChar;
}
}
return(sb.ToString());
}
private char GetShiftedCharacter(CharDetails cd)
{
// no need to check for symbols as we filter those out already
int shiftedResult = cd.AsciiCode + shift;
if (cd.CharType == CharType.Number && shiftedResult > AsciiConstants.CeilNumber)
{
int overflowShift = GetOverflowShift(AsciiConstants.FloorNumber, shiftedResult, NumberDivider);
shiftedResult = overflowShift;
}
else if (cd.CharType == CharType.Lower && shiftedResult > AsciiConstants.CeilLowerCase)
{
int overflowShift = GetOverflowShift(AsciiConstants.FloorLowerCase, shiftedResult, LetterDivider);
shiftedResult = overflowShift;
}
else if (cd.CharType == CharType.Upper && shiftedResult > AsciiConstants.CeilUpperCase)
{
int overflowShift = GetOverflowShift(AsciiConstants.FloorUpperCase, shiftedResult, LetterDivider);
shiftedResult = overflowShift;
}
return(Convert.ToChar(shiftedResult));
}