public static IEnumerable <Message> GetAllInRadius(double latitude, double longitude, int radius)
{
if (Collection == null)
{
throw new NullReferenceException("Collection could not be found: " + CollectionName);
}
var messages = Collection.FindAllAs <Message>();
var filteredMessags = MessageFilter.GetFilteredMessages(messages, latitude, longitude, radius);
var firstMessages = filteredMessags.OrderBy(msg => msg.SendTime).GroupBy(item => item.GroupId).Select(grp => grp.First());
DateTime now = DateTime.Now;
var lastTwentyFourHoursMessages = firstMessages.Where(msg => msg.SendTime > now.AddHours(-24) && msg.SendTime <= now);
return(lastTwentyFourHoursMessages);
}