list_cipher.py

"""A module to encode secret messages into null ciphers using word lists."""

import random


def load_file(file_name: str) -> list:
    """
    Load a text file and return a list of lowercase, stripped strings.

    Args:
        file_name (str): The path to the dictionary file.

    Returns:
        list: A list of words from the file.
    """
    with open(file_name, "r", encoding="utf-8") as file:
        content = file.read().split("\n")
        content = [x.lower().strip() for x in content]
        return content


def write_null_cipher(secret_message: str, dict_path: str, key: int) -> list:
    """Generate a list of words where the nth letter of each word spells out the secret message."""
    content = load_file(dict_path)
    secret_message = secret_message.lower().replace(" ", "")

    usable_words = [w for w in content if len(w) >= key]

    message_list = []

    for char in secret_message:
        choices = [w for w in usable_words if w[key - 1] == char]

        if choices:
            message_list.append(random.choice(choices))
        else:
            message_list.append(f"MISSING_WORD_FOR_{char.upper()}")
    # print(f"len list: {len(message_list)}")
    # print(f"len secret_message: {len(secret_message)}")
    return message_list


def main():
    """Execute the null cipher encoding function."""
    secret_message = "Panel at east end of chapel slides"
    print(write_null_cipher(secret_message, "dict.txt", 3))


if __name__ == "__main__":
    main()