import string
import whrandom

class WordList:
	"""Read in a list of words and divide according to length.

	Only words with only lower case letters are used."""

	def __init__(self, filename):
		self.words = {}
		trans = string.maketrans('', '')
		f = open(filename)
		while 1:
			line = f.readline()
			if not line:
				break
			word = string.strip(line)

			# Delete all lower case characters and ignore
			# the word if any bad characters remain
			bad = string.translate(word, trans, string.lowercase)
			if len(bad) > 0:
				continue

			# Must be a good word.  Add it to our list of
			# words of the same length.  If this word is the
			# first one of its length, the exception case will
			# used.
			try:
				self.words[len(word)].append(word)
			except KeyError:
				self.words[len(word)] = [ word ]
		f.close()

	def selectWord(self, length=-1):
		"""Select a word of given length.

		If no length is given, a random length is selected.
		If no words of the given length is available, a
		KeyError is raised."""

		if length < 0:
			length = whrandom.choice(self.words.keys())
		return whrandom.choice(self.words[length])

class BigWordList(WordList):
	"""List of big (>7 characters) words."""

	def selectWord(self):
		"""Select a big word."""

		keys = filter(lambda length: length > 7, self.words.keys())
		return WordList.selectWord(self, whrandom.choice(keys))

if __name__ == '__main__':
	wl = WordList('words')
	print wl.selectWord()
	print wl.selectWord(1)
	print wl.selectWord(3)
	print wl.selectWord(5)
	print wl.selectWord(7)