class Chronic::Repeater < Chronic::Tag #:nodoc:
	def self.scan(tokens, options)
		# for each token
		tokens.each_index do |i|
			if t = self.scan_for_season_names(tokens[i]) then tokens[i].tag(t); next end
			if t = self.scan_for_month_names(tokens[i]) then tokens[i].tag(t); next end
			if t = self.scan_for_day_names(tokens[i]) then tokens[i].tag(t); next end
			if t = self.scan_for_day_portions(tokens[i]) then tokens[i].tag(t); next end
			if t = self.scan_for_times(tokens[i], options) then tokens[i].tag(t); next end
			if t = self.scan_for_units(tokens[i]) then tokens[i].tag(t); next end
			if t = self.scan_for_decades(tokens[i]) then tokens[i].tag(t); next end
		end
		tokens
	end

	def self.scan_for_season_names(token)
		scanner = {/^springs?$/i => :spring,
			/^summers?$/i => :summer,
			/^(autumn)|(fall)s?$/i => :autumn,
			/^winters?$/i => :winter}
		scanner.keys.each do |scanner_item|
			return Chronic::RepeaterSeasonName.new(scanner[scanner_item]) if scanner_item =~ token.word
		end

		return nil
	end

	def self.scan_for_month_names(token)
		scanner = {/^jan\.?(uary)?$/i => :january,
			/^feb\.?(ruary)?$/i => :february,
			/^mar\.?(ch)?$/i => :march,
			/^apr\.?(il)?$/i => :april,
			/^may$/i => :may,
			/^jun\.?e?$/i => :june,
			/^jul\.?y?$/i => :july,
			/^aug\.?(ust)?$/i => :august,
			/^sep\.?(t\.?|tember)?$/i => :september,
			/^oct\.?(ober)?$/i => :october,
			/^nov\.?(ember)?$/i => :november,
			/^dec\.?(ember)?$/i => :december}
		scanner.keys.each do |scanner_item|
			return Chronic::RepeaterMonthName.new(scanner[scanner_item]) if scanner_item =~ token.word
		end
		return nil
	end

	def self.scan_for_day_names(token)
		scanner = {/^m[ou]n(day)?$/i => :monday,
			/^t(ue|eu|oo|u|)s(day)?$/i => :tuesday,
			/^tue$/i => :tuesday,
			/^we(dnes|nds|nns)day$/i => :wednesday,
			/^wed$/i => :wednesday,
			/^th(urs|ers)day$/i => :thursday,
			/^thu$/i => :thursday,
			/^fr[iy](day)?$/i => :friday,
			/^sat(t?[ue]rday)?$/i => :saturday,
			/^su[nm](day)?$/i => :sunday}
		scanner.keys.each do |scanner_item|
			return Chronic::RepeaterDayName.new(scanner[scanner_item]) if scanner_item =~ token.word
		end
		return nil
	end

	def self.scan_for_day_portions(token)
		puts "scan_for_day_portions -- #{token}" if Chronic.debug
		scanner = {/^ams?$/i => :am,
			/^pms?$/i => :pm,
			/^mornings?$/i => :morning,
			/^afternoons?$/i => :afternoon,
			/^evenings?$/i => :evening,
			/^(night|nite)s?$/i => :night}
		scanner.keys.each do |scanner_item|
			return Chronic::RepeaterDayPortion.new(scanner[scanner_item]) if scanner_item =~ token.word
		end
		return nil
	end

	def self.scan_for_times(token, options)
		if token.word =~ /^\d{1,2}(:?\d{2})?([\.:]?\d{2})?$/
			return Chronic::RepeaterTime.new(token.word, options)
		end
		return nil
	end

	def self.scan_for_decades(token)
		if token.word =~ Chronic::RepeaterDecade::DECADE_PATTERN
			return Chronic::RepeaterDecade.new(token.word)
		end
		return nil
	end

	def self.scan_for_units(token)
		scanner = {/^years?$/i => :year,
			/^seasons?$/i => :season,
			/^months?$/i => :month,
			/^fortnights?$/i => :fortnight,
			/^weeks?$/i => :week,
			/^weekends?$/i => :weekend,
			/^(week|business)days?$/i => :weekday,
			/^days?$/i => :day,
			/^hours?$/i => :hour,
			/^minutes?$/i => :minute,
			/^seconds?$/i => :second,
		}
		scanner.keys.each do |scanner_item|
			if scanner_item =~ token.word
				klass_name = 'Chronic::Repeater' + scanner[scanner_item].to_s.capitalize
				klass = eval(klass_name)
				return klass.new(scanner[scanner_item])
			end
		end
		return nil
	end

	def <=>(other)
		width <=> other.width
	end

	# returns the width (in seconds or months) of this repeatable.
	def width
		raise("Repeatable#width must be overridden in subclasses")
	end

	# returns the next occurance of this repeatable.
	def next(pointer)
		!@now.nil? || raise("Start point must be set before calling #next")
		[:future, :none, :past].include?(pointer) || raise("First argument 'pointer' must be one of :past or :future")
		#raise("Repeatable#next must be overridden in subclasses")
	end

	def this(pointer)
		!@now.nil? || raise("Start point must be set before calling #this")
		[:future, :past, :none].include?(pointer) || raise("First argument 'pointer' must be one of :past, :future, :none")
	end

	def to_s
		'repeater'
	end
end