From: Keith Fahlgren <keith@...>
Date: 2007-04-06T23:13:31+09:00
Subject: Re: Calculating Business Hours Left

On 4/5/07, Phrogz <gavin@refinery.com> wrote:
>   current_time = Time.new
>   due_time = # ... some Time instance in the future
>   work_hours_left_before_I_am_screwed = # ... calculate
>
> I'm writing a little task-tracking app to help me put out the most
> urgent fires. As above, given any two Time instances, I'd like to know
> how many hours are left to perform the task. This should skip weekends
> and hours outside of specified start- and end-hours for a work day.
>
> Anyone got such code handy? Or feel like writing it for me? :)

Hmm... no idea if this works, but it might be a start:

#!/usr/bin/env ruby
class WorkHours
  SECONDS_IN_HOUR = 3600
  HOURS_I_WORK = (7..16)
  DAYS_I_WORK = (1..5)
  def self.diff_times(a, b)
    hours = []
    (a.to_i..b.to_i).step(SECONDS_IN_HOUR) {|t|
      time = Time.at(t)
      hours << t if DAYS_I_WORK.include?(time.wday) &&
HOURS_I_WORK.include?(time.hour)
    }
    return hours.length
  end
end
nil

now = Time.now
=> Fri Apr 06 07:12:08 PDT 2007
twenty_days_from_now = now + 1728000
=> Thu Apr 26 07:12:08 PDT 2007
one_day_from_now = now + 86400
=> Sat Apr 07 07:12:08 PDT 2007
WorkHours.diff_times(now, twenty_days_from_now)
=> 141
WorkHours.diff_times(now, one_day_from_now)
=> 10


HTH,
Keith