/// <summary>
/// Merges the given string into the "formatted_dest" pattern using the
/// set of provided characters.
/// </summary>
/// <param name="inputString"></param>
/// <param name="parsedInput"></param>
/// <param name="padCharacter"></param>
/// <returns></returns>
private string MergeToFormattedOutput(string inputString, FpeParseModel parsedInput, string padCharacter)
{
var ptChars = parsedInput.StringTemplate.ToCharArray();
var inputChars = inputString.ToCharArray();
var d = ptChars.Length - 1;
var s = inputString.Length - 1;
var padChar = padCharacter.ToCharArray()[0];
while (s >= 0 && d >= 0)
{
// Find the first available destination character
while (d >= 0 && ptChars[d] != padChar)
{
d--;
}
// Copy the encrypted text into the formatted output string
if (d >= 0)
{
ptChars[d] = inputChars[s];
}
s--;
d--;
}
return(new string(ptChars));
}
private FpeParseModel ParseInput(string input, FfsConfigurationResponse ffs, bool encrypt)
{
var inputRgxPattern = $"[{RegexEscape(ffs.InputCharacters)}]";
var firstCharacter = ffs.OutputCharacters.Substring(0, 1);
var invalidRgxPattern = $"[{RegexEscape(ffs.InputCharacters)}{RegexEscape(ffs.Passthrough)}]";
if (!encrypt)
{
inputRgxPattern = $"[{RegexEscape(ffs.OutputCharacters)}]";
firstCharacter = ffs.InputCharacters.Substring(0, 1);
invalidRgxPattern = $"[{RegexEscape(ffs.OutputCharacters)}{RegexEscape(ffs.Passthrough)}]";
}
var inputRgx = new Regex(inputRgxPattern);
var inputMatches = inputRgx.Matches(input);
var formattedPassthroughCharacters = Regex.Replace(input, inputRgxPattern, firstCharacter);
if (encrypt)
{
var invalidRgx = new Regex(invalidRgxPattern);
MatchCollection invalidMatch = invalidRgx.Matches(input);
if (invalidMatch.Count != input.Length)
{
throw new ArgumentOutOfRangeException("invalid character found in the input");
}
}
var inputSb = new StringBuilder();
foreach (Match group in inputMatches)
{
inputSb.Append(group.Value);
}
var result = new FpeParseModel
{
StringTemplate = formattedPassthroughCharacters,
Trimmed = inputSb.ToString(),
};
return(result);
}
