#
#   Hangman version 2: h8.py (Fall 2025, CSCI 1470.1)
#   Two built-in modules may be needed.
import sys
import random

def populate_words(infile_name = 'hangman_words.txt'):
    """
    Read the file infile_name that contains one word per line.
    Strip away any trailing white spaces.
    Return a list of words.
    """
    words = []
    with open(infile_name, 'r') as file:
        words= [line.rstrip() for line in file]
    return words

#   The number of guesses is set to 13. Captial letters are used for constants.
NUM_GUESSES = 13   

def get_a_word(words):
    """
    Return a random word from words, which is a list of words.
    """
    return random.choice(words)
    
def get_alphabet_from_user(prompt):
    """
    Prompts the user to enter a single alphabetical character and returns it.
    Includes validation to ensure only a single letter is entered.
    """
    while True:
        user_input = input(prompt).strip().lower()

        if len(user_input) == 1 and user_input.isalpha():
            return user_input
        else:
            print("Invalid input. Please enter exactly one alphabetical character.")
 
def get_yes_no_answer(prompt):
    """ 
        Prompt the user to enter a yes no answer.
        Return True if yes, False if no.
    """
    while True:
        user_input = input(prompt).strip().lower()
        if user_input in ('y', 'yes'):
            return True
        elif user_input in ('n', 'no'):
            return False
        else:
            print("Invalid input. Please enter 'yes' or 'no'.")
            
def play_one_game(word):
    """ Play one hangman game. 
        The parameter word is the answer word.
    """

    hidden_word = "-" * len(word)
    guess = 1
    #   guessed_chars is a set variable to keep track
    #   of what characters have already been guessed.
    guessed_chars = set()

    while guess <= NUM_GUESSES and "-" in hidden_word:
        print(f"The hidden word: {hidden_word}")
        while True:
            user_input = get_alphabet_from_user(f"Enter a character (guess #{guess}): ")
            if user_input in guessed_chars:
                print("You have already entered this character. Please input a new one.")
            else:
                guessed_chars.add(user_input)
                break

        if len(user_input) == 1:
            # Count the number of times the character occurs in the word
            num_occurrences = word.count(user_input)

            # Replace the appropriate position(s) in hidden_word with the actual character.
            position = -1
            for occurrence in range(num_occurrences):
                position = word.find(user_input, position +
                                     1)  # Find the position of the next occurrence
                hidden_word = (hidden_word[:position] + user_input +
                               hidden_word[position + 1:]
                               )  # Rebuild the hidden word string

            guess += 1

    if not "-" in hidden_word:
        print("Winner!", end=" ")
    else:
        print("Loser!", end=" ")

    print(f"The word was {word}.")

def main(): 
    #   populate words dictionary
    words = []
    try:
        infile_name = 'hangman_words.txt'
        words = populate_words()
    except FileNotFoundError:
        print(f"Error: The file '{infile_name}' was not found.")
        sys.exit(1)
    except Exception as e:
        print(f"An error occurred: {e}")
        sys.exit(1)
    
    #   Print a welcome and introduction to the game.
    print(f"""
Welcome to the hangman game to guess a hidden word.
The hidden word is initially displayed as a sequence of - of the length of the word.
You may make a guess of a character. If the character is in the word,
the corresponding - is replaced by the word.

You can make up to {NUM_GUESSES} guesses.
""")
    
    #  Play games as many times as the user like.
    while True:
        word = get_a_word(words)
        play_one_game(word)
        if not get_yes_no_answer('\nPlayer another game [y/n]:  '):
            break;
            
    #   print 
    print("\nBye, see you later.")    

if __name__ == "__main__":
    main()