#!/usr/bin/env python
import sys, re, operator, string

#
# The Quarantine class for this example
#
class TFQuarantine:
    def __init__(self):
        self._funcs = []

    def bind(self, func):
        self._funcs.append(func)
        return self

    def execute(self):
        value = lambda : None
        for func in self._funcs:
            value = func(value())
        print value()

#
# The functions
#
def get_input(arg):
    def _f():
        return sys.argv[1]
    return _f

def read_file(path_to_file):
    def _f():
        with open(path_to_file) as f:
            data = f.read()
        return data
    return _f

def filter_chars(str_data):
    def _f():
        pattern = re.compile('[\W_]+')
        return pattern.sub(' ', str_data)
    return _f

def normalize(str_data):
    def _f():
        return str_data.lower()
    return _f

def scan(str_data):
    def _f():
        return str_data.split()
    return _f

def remove_stop_words(word_list):
    def _f():
        with open('../stop_words.txt') as f:
            stop_words = f.read().split(',')
        # add single-letter words
        stop_words.extend(list(string.ascii_lowercase))
        return [w for w in word_list if not w in stop_words]
    return _f

def frequencies(word_list):
    def _f():
        word_freqs = {}
        for w in word_list:
            if w in word_freqs:
                word_freqs[w] += 1
            else:
                word_freqs[w] = 1
        return word_freqs
    return _f

def sort(word_freq):
    def _f():
        return sorted(word_freq.iteritems(), key=operator.itemgetter(1), reverse=True)
    return _f

def top25_freqs(word_freqs):
    def _f():
        top25 = ""
        for tf in word_freqs[0:25]:
            top25 += str(tf[0]) + ' - ' + str(tf[1]) + '\n'
        return top25
    return _f

#
# The main function
#
quarantine = TFQuarantine()
quarantine.bind(get_input).bind(read_file).bind(filter_chars).bind(normalize).bind(scan).bind(remove_stop_words).bind(frequencies).bind(sort).bind(top25_freqs)
quarantine.execute()