Network days function (ruby)

network_days.rb

require 'date'

def network_days(start_date, end_date)
  days_between = (end_date - start_date).to_i
  whole_weeks, extra_days = days_between.divmod(7)

  unless extra_days.zero?
    extra_days -= if (start_date + 1).wday <= end_date.wday
                    [(start_date + 1).sunday?, end_date.saturday?].count(true)
                  else
                    2
                  end
  end

  (whole_weeks * 5) + extra_days + 1
end

start_date = Date.new(2015,07,13)
end_date = Date.new(2015,07,20)
puts network_days(start_date, end_date)