public static IAd GetAd(AdRepo repo, iDateTime dateTime, string zoneName)
{
// Get the given zone
var zone = repo.Zones.FirstOrDefault(z => z.Name.ToLower() == zoneName.ToLower());
if (zone == null)
{
throw new Exception("Zone not found");
}
// Get all ads that have a time span covering now
var now = dateTime.Now();
var ads = zone.Ads.Where(a => a.StartDate < now && a.EndDate > now).ToList();
//if (ads.Count == 0)
//{
// // return Error ad, or blank ad
// return new DummyAd(
//}
// Get the sum of all rotation values
var sum = ads.Sum(a => a.Rotation);
// Select one at random, weighted by rotation
var randomSelector = r.Next(0, sum);
var counter = 0;
while (randomSelector > -1)
{
if (ads[counter].Rotation > randomSelector)
{
return ads[counter];
}
randomSelector -= ads[counter].Rotation;
counter++;
}
throw new Exception("this should never happen, probably an off by 1 error. r = " + randomSelector);
}