module CalendarTextBuilder
  def get_databinder(events, check_exceptions, &cell_text_builder)
    cell_text_builder ||= lambda {|d| nil}
    @databinder = lambda do |d|
      cell_text = "#{d.mday}<br />"
      cell_attrs = {:class => 'day'}
      curdate = Time.local(d.year, d.month, d.mday)
      events.each do |e|
        # Start at the starting day of the event
        workdate = Time.local(e.startdate.year, e.startdate.month, e.startdate.mday)
        if !e.enddate.nil?
          enddate = Time.local(e.enddate.year, e.enddate.month, e.enddate.mday)
        else
          enddate = Time.gm(Event::FOREVER)
        end
        # Work forward and figure out if a repeating event falls on this day
        case e.repeat
          when Event::REP_DAILY
            workdate += e.repeat_interval.days while (workdate < curdate) && (workdate < enddate)

          when Event::REP_WEEKLY
            if e.repeats_on_day?(curdate.wday)
              # Set the workdate to be the right day of the week, moving forward
              workdate += ((curdate.wday - workdate.wday) % 7).days
              workdate += e.repeat_interval.weeks while (workdate < curdate) && (workdate < enddate)
            end

          when Event::REP_MONTHLY
            # Event repeats by date
            if e.repeats_by_date? && (e.startdate.mday == curdate.mday)
              workdate = Time.local(workdate.year, workdate.month + e.repeat_interval, workdate.mday) while (workdate < curdate) && (workdate < enddate)
            # Event repeats by day
            elsif (e.startdate.wday == curdate.wday) && (curdate <= enddate)
              # First figure out which of that weekday (first? second?) of the month
              # both the event and the current day fall on
              c_ordday = get_ordday_of_month(curdate)
              e_ordday = get_ordday_of_month(workdate)
              # If it's the first through third, and they're the same, we have
              # a match for this day
              if (c_ordday < 4)
                 workdate = curdate if c_ordday == e_ordday
              # If it's marked as repeating on the fourth day, check for a match
              elsif !e.repeats_on_last_day?
                 workdate = curdate if c_ordday == 4
              # If it's marked as repeating on the last day, see if we have
              # another of this day in this month; if we don't, it's a match
              else
                 tempdate = curdate + 1.week
                 workdate = curdate if tempdate.month != curdate.month
              end
            end

          when Event::REP_YEARLY
            workdate += e.repeat_interval.years while (workdate < curdate) && (workdate < enddate)
        end

        # Does the calculated date falls on the current date?
        if (workdate == curdate) && (workdate <= enddate)
          found_exc = false
          # Check for an exception first, unless told not to
          if check_exceptions
            e.event_exceptions.each do |exception|
              found_exc = true if workdate == Time.local(exception.date.year, exception.date.month, exception.date.mday)
            end
          end
          if !found_exc
            # This one is good to go, get the controller to give us some text
            addl_cell_text, cell_attrs = cell_text_builder.call(e, workdate)
            cell_text << addl_cell_text
          end
        end
      end
      [cell_text, cell_attrs]
    end
  end

  def get_ordday_of_month(findDate)
    c_ordday = 1
    tempdate = Time.local(findDate.year, findDate.month, findDate.mday)
    while (tempdate.month == findDate.month)
      tempdate -= 7.days
      c_ordday += 1 if tempdate.month == findDate.month
    end
    return c_ordday
  end
end