Calendar week calculations

calendar_week.rb

require 'active_support/core_ext'

def calendar_week(week)
  now = Date.current
  year = now.cweek < week ? now.year : now.year + 1
  Date.commercial(year, week, 1)
end

p calendar_week(49)
# => Mon, 02 Dec 2013

p calendar_week(1)
# => Mon, 30 Dec 2013 # don't know if that's the way calendar weeks are counted

p calendar_week(27)
# => Mon, 30 Jun 2014