require 'hiccup/enumerable/schedule_enumerator'

module Hiccup
  module Enumerable
    class MonthlyEnumerator < ScheduleEnumerator
      
      def self.for(schedule)
        if schedule.monthly_pattern.all? { |occurrence| Fixnum === occurrence }
          MonthlyDateEnumerator
        else
          self
        end
      end
      
      
      
      def started?
        !@position.nil?
      end
      
      
      
    protected
      
      attr_reader :year, :month, :cycle, :last_day_of_month
      
      
      
      def advance!
        @position += 1
        next_month if @position >= cycle.length
        
        day = cycle[@position]
        return self.next if day > last_day_of_month
        Date.new(year, month, day)
      end
      
      def rewind!
        @position -= 1
        prev_month if @position < 0
        
        day = cycle[@position]
        return self.prev if day > last_day_of_month
        Date.new(year, month, day)
      end
      
      
      
      def first_occurrence_on_or_after(date)
        @year, @month = date.year, date.month
        get_context
        
        @position = cycle.index { |day| day >= date.day }
        next_month unless @position
        
        day = cycle[@position]
        return self.next if day > last_day_of_month
        Date.new(year, month, day)
      end
      
      def first_occurrence_on_or_before(date)
        @year, @month = date.year, date.month
        get_context
        
        @position = cycle.index { |day| day <= date.day }
        prev_month unless @position
        
        day = cycle[@position]
        return self.prev if day > last_day_of_month
        Date.new(year, month, day)
      end
      
      
      
      def occurrences_in_month(year, month)
        wday_of_first_of_month = Date.new(year, month, 1).wday
        monthly_pattern.map do |occurrence|
          if occurrence.is_a?(Array)
            ordinal, weekday = occurrence
            wday = Date::DAYNAMES.index(weekday)
            day = wday
            day = day + 7 if (wday < wday_of_first_of_month)
            day = day - wday_of_first_of_month
            day = day + (ordinal * 7) - 6
            day
          else
            occurrence
          end
        end
      end
      
      
      
      def next_month
        @position = 0
        @month += skip
        @year, @month = year + 1, month - 12 if month > 12
        get_context
      end
      
      def prev_month
        @position = @cycle.length - 1
        @month -= skip
        @year, @month = year - 1, month + 12 if month < 1
        get_context
      end
      
      def get_context
        @last_day_of_month = [4, 6, 9, 11].member?(month) ? 30 : 31
        @last_day_of_month = leap_year?(year) ? 29 : 28 if month == 2
        @cycle = occurrences_in_month(year, month).sort
      end
      
      
      
    end
  end
end

require "hiccup/enumerable/monthly_date_enumerator"