#!/usr/bin/env python3
from sys import argv
from string import ascii_letters
from random import choice


def get_word_list(text):
    # Define a set of allowed letters
    allowed_letters = ascii_letters + "áàéèíìóòúù" + "ÁÀÉÈÍÌÓÒÚÙ" + "'."
    # Keep only the allowed replacing the others with a space
    text = "".join(c.lower()
                   if c in allowed_letters else " "
                   for c in text)
    # Split by words, using space as separator
    return text.split()


def get_associations(word_list):
    # Build a dictionary where each word is a key, and the values are the list
    # of the words that follow the key one
    # ['a', 'b', 'a',  'c']  became {'a': ['b', 'c'], 'b': ['a']}
    associations = {}
    for i, word in enumerate(word_list[:-1]):
        if word not in associations:
            associations[word] = []
        associations[word].append(word_list[i+1])
    return associations


def generate(text, max_words=100):
    word_list = get_word_list(text)
    associations = get_associations(word_list)
    out_list = []
    current_word = choice(word_list)

    for i in range(max_words):
        out_list.append(current_word)
        choice_list = associations.get(current_word, word_list)
        if current_word.endswith("."):
            break
        current_word = choice(choice_list)

    out_string = " ".join(out_list)
    out_string = out_string.replace(" .", ".")
    out_string = out_string[0].upper() + out_string[1:]

    return out_string


if __name__ == '__main__':
    if argv[1:]:
        with open(argv[1]) as f:
            print(generate(f.read()))
    else:
        print('Usage:', argv[0], 'something_antani.txt')