import string
import re
import random
import sys

CHAIN_LENGTH = int(raw_input("Chain Length: "))
MIN_WORD_LEN = int(raw_input("Mininum Word Length: "))
MAX_WORD_LEN = int(raw_input("Maximum Word Length: "))
PREFIX = str(raw_input("Enter letters to start the word with (blank for random): "))
print "Parsing corpus..."

def strings(len):
    if len == 0:
        return []
    if len == 1:
        return list(string.lowercase)
    return elem_add(strings(len-1), list(string.lowercase))

def elem_add(list1, list2):
    ret = []
    for x in list1:
        for y in list2:
            ret.append(x + y)
    return ret

dict = {}
dict = dict.fromkeys(strings(CHAIN_LENGTH), 0)

file = file("comc.txt")    
text = re.sub("[^a-zA-Z\s]", "", file.read())
text = text.lower()
words = text.split()

for word in words:
    begin = -1
    while 1:
        begin = begin + 1
        end = begin + CHAIN_LENGTH 
        if end > len(word):
            break
        dict[word[begin:end]] += 1

sum = sum(dict.values())
for k in dict.keys():
    dict[k] = float(dict[k]) / float(sum)


# make a random word!
print "Press enter for random word."
while 1:
    raw_input()
    word_len = random.randint(MIN_WORD_LEN, MAX_WORD_LEN) 
    if PREFIX == "":
        start = random.choice(list(string.lowercase)) 
    else:
        start = PREFIX
    letters = list(start) 
    while len(letters) < word_len:
        total = 0
        for k, v in dict.iteritems():
            if k[0] == letters[-1]:
                total += v
        running_sum = 0
        rand = random.uniform(0, total)
        for k, v in dict.iteritems():
            if k[0] == letters[-1]:
                running_sum += v
                if running_sum > rand:
                    letters.extend(list(k)[1:])
                    break
    print "".join(letters)