DateNavigation.rb

require 'rubygems'
require 'active_support/core_ext/date/calculations.rb'

WORKDAY_STOP  = 16

module DateCalculation
  def weekend?
    self.wday.to_s =~ /[6,0]/
  end

  # Counts workdays between two Dates
  def count_weekdays(startdate,stopdate)
    raise "Expected both to be Date: (#{startdate.class},#{stopdate.class})"    unless (startdate.class == Date && stopdate.class == Date)
    @workdays = 0
    startdate.to_date.upto(stopdate.to_date) do |date|
      @workdays +=1 if date.wday.to_s =~ /[1,2,3,5]/
    end
    @workdays
  end
end



module DateNavigation

  def one_week_before(start)
    current_date = start
    7.times do |d|
      current_date = current_date.yesterday
    end
    current_date
  end

  # Returns the previous monday, calculated from current date.
  def previous_monday(calculation_day = DateTime.now)
    until calculation_day.wday == 1
      calculation_day = calculation_day.yesterday
    end
    calculation_day
  end
  
  # The monday we´re counting hours from till friday. This monday is not the monday the calculation is executed on.
  def start_of_calculation_week
    monday = one_week_before(previous_monday)
  end
  
  def end_of_calculation_week
    friday = find_end_of_week(start_of_calculation_week)
  end

  def find_end_of_week(date)
    yr,mon,day,hr,min = ParseDate.parsedate date.to_s
    end_of_week = Time.utc(yr,mon,day,WORKDAY_STOP)       
    until end_of_week.wday == 5
      end_of_week = end_of_week.tomorrow
    end
    end_of_week
  end

  def start_of_previous_week
    one_week_before(previous_monday)
  end

  def end_of_previous_week
    find_end_of_week(start_of_previous_week)
  end
end


class DateTime
  def time_to_date
    Date.new(self.year,self.month,self.day)
  end  
end

class Time
  include DateCalculation
  def time_to_date
    Date.new(self.year,self.month,self.day)
  end  
end
  
class Date
  include DateCalculation
end

class Fixnum
  include DateCalculation
  def weekend?
    date = Date.new(self)
    date.wday.to_s =~ /[6,0]/
  end
end