/// <summary>
/// Tries to create an Unused Short Code by creating a Random AlphaNumeric
/// sequence based on the ShortCodeLenth within X number of tries given
/// by the ShortCodeTriesBeforeFail variable
/// </summary>
/// <returns></returns>
private static string CreateUnusedShortCode()
{
DbContext dbContext = new DbContext();
for (int x = 0; x < ShortCodeTriesBeforeFail; x++)
{
string newKey = CreateRandomAlphaNumericSequence(ShortCodeLength);
if (dbContext.Links.Where(i => i.ShortCode == newKey).Count() == 0)
return newKey;
}
throw new Exception();
}
/// <summary>
/// Gets the ShortCode and tries to find a RedirectUrl based on that code
/// </summary>
/// <param name="shortCode"></param>
/// <returns></returns>
public static string GetRedirectUrlFromShortCode(string shortCode)
{
DbContext dbContext = new DbContext();
var link = dbContext.Links.Where(l => l.ShortCode == shortCode).First();
link.DateOfLastVisit = DateTime.Now;
link.VisitCount++;
dbContext.SubmitChanges();
return link.RedirectUrl;
}
/// <summary>
/// Logs an authentication error to the database to prevent future requests until the wait time has lapsed
/// </summary>
/// <param name="ipAddress"></param>
/// <param name="lastAttemptDate"></param>
/// <param name="SecondsUntilNextAttempt"></param>
public static void LogAuthorizationError(string ipAddress, out DateTime lastAttemptDate, out long SecondsUntilNextAttempt)
{
Attempt a = null;
DbContext dbContext = new DbContext();
lastAttemptDate = DateTime.Now;
var allAttempts = dbContext.Attempts.Where(i => i.IPAddress == ipAddress);
if (allAttempts.Count() == 0)
{
a = new Attempt();
a.DateOfLastAttempt = lastAttemptDate;
a.IPAddress = ipAddress;
a.NumberOfAttemptsSinceLastSuccess = 1;
a.SecondsUntilNextAttempt = Convert.ToInt64(FailWaitExtenderLength);
dbContext.Attempts.InsertOnSubmit(a);
}
else
{
a = allAttempts.First();
a.DateOfLastAttempt = lastAttemptDate;
a.NumberOfAttemptsSinceLastSuccess++;
var power = Math.Pow(FailWaitExtenderLength, a.NumberOfAttemptsSinceLastSuccess);
a.SecondsUntilNextAttempt = Convert.ToInt64(power);
}
dbContext.SubmitChanges();
//return seconds until when they can try again
SecondsUntilNextAttempt = a.SecondsUntilNextAttempt;
}
/// <summary>
/// Creates a link in the database based on the IPAddress of the requestor and the RedirectUrl
/// </summary>
/// <param name="ipAddress"></param>
/// <param name="redirectUrl"></param>
/// <returns></returns>
public static string AddLink(string ipAddress, string redirectUrl)
{
try
{
DbContext dbContext = new DbContext();
var newLink = new Link();
newLink.Id = Guid.NewGuid();
newLink.DateCreated = DateTime.Now;
newLink.RedirectUrl = redirectUrl;
newLink.ShortCode = CreateUnusedShortCode();
newLink.VisitCount = 0;
dbContext.Links.InsertOnSubmit(newLink);
dbContext.SubmitChanges();
return newLink.ShortCode;
}
catch
{
throw new Exception();
}
}