tracks/app/models/recurring_todos/monthly_repeat_pattern.rb

module RecurringTodos

  class MonthlyRepeatPattern < AbstractRepeatPattern

    def initialize(user)
      super user
    end

    def recurrence_selector
      get :recurrence_selector
    end

    def every_x_day?
      get(:recurrence_selector) == 0
    end

    def every_x_day
      get(:every_other1)
    end

    def every_xth_day?
      get(:recurrence_selector) == 1
    end

    def every_x_month
      # in case monthly pattern is every day x, return every_other2 otherwise
      # return a default value
      get(:recurrence_selector) == 0 ? get(:every_other2) : 1
    end

    def every_x_month2
      # in case monthly pattern is every xth day, return every_other2 otherwise
      # return a default value
      get(:recurrence_selector) == 1 ? get(:every_other2) : 1
    end

    def every_xth_day(default=nil)
      get(:every_other3) || default
    end

    def day_of_week
      get :every_count
    end

    def recurrence_pattern
      if recurrence_selector == 0
        recurrence_pattern_for_specific_day
      else
        recurrence_pattern_for_relative_day_in_month
      end
    end

    def validate
      super

      case recurrence_selector
      when 0 # 'monthly_every_x_day'
        validate_not_blank(every_x_month, "Every other nth month may not be empty for recurrence setting")
      when 1 # 'monthly_every_xth_day'
        validate_not_blank(every_x_month2, "Every other nth month may not be empty for recurrence setting")
        validate_not_blank(day_of_week, "The day of the month may not be empty for recurrence setting")
      else
        raise Exception.new, "unexpected value of recurrence selector '#{recurrence_selector}'"
      end
    end

    def get_next_date(previous)
      start = determine_start(previous)
      day = every_x_day
      n = get(:every_other2)

      case recurrence_selector
      when 0 # specific day of the month
        if (previous && start.mday >= day) || (previous.nil? && start.mday > day)
          # there is no next day n in this month, search in next month
          #
          #  start += n.months
          #
          # The above seems to not work. Fiddle with timezone. Looks like we hit a
          # bug in rails here where 2008-12-01 +0100 plus 1.month becomes
          # 2008-12-31 +0100. For now, just calculate in UTC and convert back to
          # local timezone.
          #
          #  TODO: recheck if future rails versions have this problem too
          start = Time.utc(start.year, start.month, start.day)+n.months
          start = Time.zone.local(start.year, start.month, start.day)

          # go back to day
        end
        Time.zone.local(start.year, start.month, day)

      when 1 # relative weekday of a month
        the_next = get_xth_day_of_month(every_xth_day, day_of_week, start.month, start.year)
        if the_next.nil? || the_next <= start
          # the nth day is already passed in this month, go to next month and try
          # again

          # fiddle with timezone. Looks like we hit a bug in rails here where
          # 2008-12-01 +0100 plus 1.month becomes 2008-12-31 +0100. For now, just
          # calculate in UTC and convert back to local timezone.
          #  TODO: recheck if future rails versions have this problem too
          the_next = Time.utc(the_next.year, the_next.month, the_next.day)+n.months
          the_next = Time.zone.local(the_next.year, the_next.month, the_next.day)

          # TODO: if there is still no match, start will be set to nil. if we ever
          # support 5th day of the month, we need to handle this case
          the_next = get_xth_day_of_month(every_xth_day, day_of_week, the_next.month, the_next.year)
        end
        the_next
      else
        raise Exception.new, "unknown monthly recurrence selection (#{self.recurrence_selector})"
      end
    end

    private

    def recurrence_pattern_for_specific_day
      on_day = " #{I18n.t('todos.recurrence.pattern.on_day_n', :n => every_x_day)}"
      if every_xth_day(0) > 1
        I18n.t("todos.recurrence.pattern.every_n_months", :n => every_xth_day) + on_day
      else
        I18n.t("todos.recurrence.pattern.every_month") + on_day
      end
    end

    def recurrence_pattern_for_relative_day_in_month
      n_months = if every_x_month2 > 1
                   "#{every_x_month2} #{I18n.t('common.months')}"
                 else
                   I18n.t('common.month')
                 end
      I18n.t('todos.recurrence.pattern.every_xth_day_of_every_n_months',
        x:        xth(every_xth_day), 
        day:      day_of_week_as_text(day_of_week), 
        n_months: n_months)
    end

  end
  
end