# This program reads an input file of thesaurus data
# and allows the user to look up synonyms for words.
# It stores words in a nested dictionary of lists,
# where each key is a word and its value is a list
# of synonyms of that word from the thesaurus file.

import random

# Reads the given input file and converts its data
# into a dictionary where each key is a word and each
# value is a list of synonyms for that word.
def read_thesaurus(filename):
    thesaurus = {}
    with open(filename) as file:
        lines = file.readlines()
        for i in range(0, len(lines) - 3, 4):
            word = lines[i].strip()
            synonyms = lines[i + 2].strip().split("|")
            thesaurus[word] = synonyms
    return thesaurus

# Looks up and prints a randomly chosen synonym
# for the given word in the given thesaurus.
# If the word is not found, prints an error message.
def find_random_synonym(thesaurus, word):
    if word in thesaurus:
        synonyms = thesaurus[word]
        syn = random.choice(synonyms)
        print("A synonym for", word, "is", syn)
    else:
        print(word, "not found.")

def main():
    # introduction
    print("This program looks up random synonyms")
    print("for you from a thesaurus.")
    print()
    
    # read thesaurus into a dictionary
    thesaurus = read_thesaurus("thesaurus.txt")
    
    # look up random synonyms
    word = input("Word to look up (Enter to quit)? ")
    while word != "":
        find_random_synonym(thesaurus, word)
        word = input("Word to look up (Enter to quit)? ")

    print("Goodbye.")

main()