var Now = DateTime.Now;
DateTime StartDate = DateTime.Now.AddDays(-30);
List<ApplicationInstance> UsersAndApps = new List<ApplicationInstance>();
var Application = from A in ApplicationInstances
where A.Session.User.UserName != null && A.Application.Name != null && (A.StartDate > StartDate)
select new {UserName = A.Session.User.UserName, A.Application.Name,A.StartDate,A.EndDate,DGName = A.Session.Machine.DesktopGroup.Name};

foreach(var User in Application.ToList().GroupBy(u=>u.UserName))
{
 	foreach(var App in User.GroupBy(u=>u.Name))
	{
		
		if(App.ToList().Count >1)
		{
			int Duration =0 ;
			int launch =0;
			foreach(var app in App)
			{
				DateTime EndDate ;
				if(app.EndDate == null)
				EndDate = Now;
				else
				EndDate = (DateTime)app.EndDate;				
				Duration += (int)((TimeSpan)(EndDate - app.StartDate)).TotalMinutes;
				launch++;
			}
			
			UsersAndApps.Add(new ApplicationInstance((String)App.ToList()[0].Name,(String)App.ToList()[0].UserName,Duration,launch,App.ToList()[0].DGName));
			
		}
		else
		{
			DateTime EndDate;
			if(App.ToList()[0].EndDate == null)
			EndDate = Now;
			else
			EndDate = (DateTime)App.ToList()[0].EndDate;
		
			UsersAndApps.Add(new ApplicationInstance((String)App.ToList()[0].Name,(String)App.ToList()[0].UserName,(int)((TimeSpan)(EndDate-App.ToList()[0].StartDate)).TotalMinutes,1,App.ToList()[0].DGName));
			
		}
		
		
	}
}
Console.WriteLine(UsersAndApps.OrderBy(u=>u.UserName).ToList());
}
public class ApplicationInstance
{
public String UserName;
public String AppName;
public int Duration;
public int Launches;
public string DeliveryGroup;

public  ApplicationInstance(String AppName,String UserName,int Duration,int Launches, string DeliveryGroup)
{
	this.AppName = AppName;
this.UserName = UserName;
this.Duration = Duration;
this.Launches = Launches;
this.DeliveryGroup = DeliveryGroup;

}