import sys, re, operator, string
from abc import ABCMeta

#
# The classes
#
class TFExercise(object):
    __metaclass__ = ABCMeta

    def info(self):
        return self.__class__.__name__ + ": No major data structure"

class DataStorageManager(TFExercise):
    """ Models the contents of the file """
    _data = ''
    def __init__(self, path_to_file):
        f = open(path_to_file)
        self._data = f.read()
        f.close()
        self.__filter_chars()
        self.__normalize()

    def __filter_chars(self):
        """
        Takes a string and returns a copy with all nonalphanumeric chars
        replaced by white space
        """
        pattern = re.compile('[\W_]+')
        self._data = pattern.sub(' ', self._data)

    def __normalize(self):
        """
        Takes a string and returns a copy with all characters in lower case
        """
        self._data = self._data.lower()

    def words(self):
        """
        Returns the list words in storage
        """
        data_str = ''.join(self._data)
        return data_str.split()

    def info(self):
        return self.__class__.__name__ + ": My major data structure is a " + self._data.__class__.__name__

class StopWordManager(TFExercise):
    """ Models the stop word filter """
    _stop_words = []
    def __init__(self):
        f = open('../stop_words.txt')
        self._stop_words = f.read().split(',')
        f.close()
        # add single-letter words
        self._stop_words.extend(list(string.ascii_lowercase))

    def is_stop_word(self, word):
        return word in self._stop_words

    def info(self):
        return self.__class__.__name__ + ": My major data structure is a " + self._stop_words.__class__.__name__

class WordFrequencyManager(TFExercise):
    """ Keeps the word frequency data """
    _word_freqs = {}

    def increment_count(self, word):
        if word in self._word_freqs:
            self._word_freqs[word] += 1
        else:
            self._word_freqs[word] = 1

    def sorted(self):
        return sorted(self._word_freqs.iteritems(), key=operator.itemgetter(1), reverse=True)

    def info(self):
        return self.__class__.__name__ + ": My major data structure is a " + self._word_freqs.__class__.__name__


class WordFrequencyController(TFExercise):
    def __init__(self, path_to_file):
        self._storage_manager = DataStorageManager(path_to_file)
        self._stop_word_manager = StopWordManager()
        self._word_freq_manager = WordFrequencyManager()

    def run(self):
        for w in self._storage_manager.words():
            if not self._stop_word_manager.is_stop_word(w):
                self._word_freq_manager.increment_count(w)

        word_freqs = self._word_freq_manager.sorted()
        for tf in word_freqs[0:25]:
            print tf[0], ' - ', tf[1]

#
# The main function
#
WordFrequencyController(sys.argv[1]).run()