#!/usr/local/bin/ruby -w

# $Id$

class Marcov
	def initialize(ary, cont = 2)
		raise "continous must be > 1" if cont < 2
		@ary = ary
		@chain = Hash.new([])
		(@ary.size - cont + 2).times do |i|
			@chain[@ary[i..(i + cont - 2)]] += [@ary[(i + 1)..(i + cont - 1)]]
		end
	end

	def chain(seed0 = nil)
		if seed0
			seed = @chain.keys.find {|x| p x; x[0] == seed0 }
			raise "couldn't start from #{seed0}" unless seed
		else
			seed = @chain.keys[rand(@chain.keys.size)]
		#	seed = @chain.keys[0]
		end
		r = [seed[0]]
		while true
			n = @chain[seed][rand(@chain[seed].size)]
			if n == nil || n.size < 1
				r += seed[1..-1] if seed.size > 1
				break
			end
			r += [n[0]]
			seed = n
		end
		r
	end
end

if $0 == __FILE__
	Mix = Struct.new("Mix", "split", "join")
	Letter = Mix.new(//, "")
	Word = Mix.new(/[ \t]/, " ")
	mix = Letter

	chain = 4
	while true
		case ARGV[0]
		when /-([0-9]+)/
			ARGV.shift
			chain = $1.to_i
		when /-e/
			ARGV.shift
			chain = 2 unless chain == 2
			mix = Word
		when /-j/
			ARGV.shift
			chain = 4 unless chain == 4
			mix = Letter
		else
			break
		end
	end
	splitter, joinner = mix.split, mix.join
	a = []
	debug = false
	if debug
		10.times do a << rand(8) end
		chain = 3
	else
		while (buf = gets) != nil
			a += buf.split(splitter)
		end
	end
	m = Marcov.new(a, chain)
	if debug
		p m
		p m.chain(1)
	else
		puts m.chain.join(joinner)
	end
end