Pirate Scrabble word finder

pirates.rb

#!/usr/bin/env ruby
#
# Usage: ruby [filename] [word]
#    Will return a list of up to ten words from the system dictionary
#    that could be played before the provided word. It is up to the user
#    to manually filter for "root" constraints.
# e.g.
#    ruby pirates.rb marquisotte

class Yarr
	def initialize(word)
		@word = word.downcase
		@sorted_word = sorted_word(@word)
	end

	def ideas
		candidates = filter_dictionary
		candidates[0...10]
	end

	def filter_dictionary
		candidates = []
		File.open('/usr/share/dict/words').each_line do |line|
			candidate = line.strip.downcase
			if valid_word?(candidate)
				candidates << Candidate.new(candidate, @word)
			end
		end
		candidates.sort_by!(&:size).reverse!
		candidates
	end

	def valid_word?(candidate)
		sorted_candidate = sorted_word(candidate)
		regex = Regexp.new(sorted_candidate.split('').join('.*'))
		# test that @word contains all candidate letters, but not in the candidate's exact order
		!@sorted_word[regex].nil? && @word[candidate].nil?
	end

	def sorted_word(word)
		word.split('').sort.join
	end
end

class Candidate
	def initialize(word, target)
		@word = word
		@target = target
	end

	def needs
		target_letters = @target.split('')
		@word.each_char do |char|
			index = target_letters.find_index(char)
			unless index.nil?
				target_letters.delete_at(index)
			end
		end
		target_letters.sort
	end

	def to_s
		"#{@word} needs #{needs.join(', ')}"
	end

	def size
		@word.size
	end
end

puts Yarr.new(ARGV[0]).ideas