Automatically deduct breaks from total time worked?

Hi folks.

I’m working on a Job Record app that (in it’s simplest form) will log:

  • Date
  • Employee Name
  • Job Name
  • Job Type
  • Start Time
  • Finish Time
  • Total Hours

My question is, start and finish times vary, so how would I make it automatically deduct if it should cross over:

  • Morning tea - 15mins (10:30-10:45)
  • Lunch - 1hr (12:30-1:30)
  • Afternoon Tea - 15mins (3:30-3:45)

For example, some jobs might start at 8:30 and finish at 10:00. No deduction…
Others might start at 9:00 and finish at 11:30 and there we have a deduction for morning tea.

What if I start a job just after morning tea and finish it at 5:30pm? That should automatically deduct Lunch (1hr) and Afternoon Tea (15mins). See what I mean?

Do I need to set multiple triggers for each break start and finish? That’s at least 12 triggers and would be a lot of messing around. Something easier maybe?

Thanks in advance, my head is sore thinking about it!!!