SQL Server在不同的行之间找到datediff，sum

I am trying to build a query that analyzes data in our time tracking system. Every time a user swipes in or out, it makes a row recording the swipe time and On or Off site (entry or exit). In user 'Joe Bloggs' case there are 4 rows, which I want to pair and calculate a total time spent on site for Joe Bloggs.I am trying to build a query that analyzes data