import os
import pickle
import sys

DEBUG = os.environ.get('DEBUG', '') == '1'


class Trie:
    def __init__(self, value):
        self.value = value
        self.children = []
        self.is_leaf = False

    def add(self, value):
        node = self
        for ch in value:
            child_matches = False
            for child in node.children:
                if child.value == value:
                    node = child
                    child_matches = True
                    break
            if not child_matches:
                to_add = Trie(value)
                node.children.append(to_add)
                node = to_add
        node.is_leaf = True

    def __contains__(self, search):
        node = self
        if not self.children:
            return False
        for ch in search:
            found = False
            for child in node.children:
                if child.value == ch:
                    found = True
                    node = child
                    break
            if not found:
                return False
        return True


def main():
    words_file = os.environ.get('WORDS', 'words-en.txt')
    words_dat_file = os.environ.get('WORDS_DAT', 'words-en.dat')
    words_size_range = range(*(
        map(lambda s: int(s),
            os.environ.get('WORDS_SIZE_RANGE', '2-15').split('-'))))

    valid_words = Trie('')

    with open(words_file) as inwords:
        debug('reading from {!r}'.format(words_file))
        for word in inwords.read().split():
            if len(word) not in words_size_range:
                continue

            debug('adding {!r} to valid words'.format(word))
            valid_words.add(word)

    with open(words_dat_file, 'wb') as outdat:
        debug('writing valid words to {!r}'.format(words_dat_file))
        pickle.dump(valid_words, outdat)

    return 0


def debug(msg):
    if not DEBUG:
        return
    print(msg, file=sys.stderr)


if __name__ == '__main__':
    sys.exit(main())