ipp3_0_palingrams

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Filename: ipp3_0_palingrams.py
# Version: 1.0.0
# Author: Jeoi Reqi

"""
Description:
    - This script demonstrates "Chapter 2: Project #3 - Finding Palingrams" from the book "Impractical Python Projects" by Lee Vaughan.
    - The script searches an English language dictionary file for palingrams (phrases that can be read both forward and backward, ignoring spaces and punctuation) and prints them out.

Requirements:
    - Python 3.x
    - The following modules:
        - sys module
        - requests module
        - time module

Functions:
    - download_dictionary(url, file_name):
        - Description:
            - Downloads a dictionary file from a given URL.
            - Parameters:
                - url (str): The URL from which to download the dictionary file.
                - file_name (str): The name to save the downloaded file as.

    - load_dictionary(file):
        - Description:
            - Opens a text file and turns its contents into a list of lowercase strings.
            - Parameters:
                - file (str): The name of the file to open.
            - Returns:
                - list: A list of lowercase strings containing the words from the file.

    - find_palingrams():
        - Description:
            - Finds palingrams in a list of words loaded from a dictionary file.
            - Prints the number of palingrams found and the runtime of the search.
            - Prompts the user to save the list of palingrams to a file.

    - save_to_file(pali_list):
        - Description:
            - Saves a list of palingrams to a file.
            - Parameters:
                - pali_list (list): A list of tuples containing pairs of palingrams.

Usage:
    - Ensure you have Python 3.x installed on your system.
    - Save the script to a file, for example, `palingrams.py`.
    - Run the script using the command: python palingrams.py.

Running the Script:
    - Open a terminal or command prompt.
    - Navigate to the directory where the script is saved.
    - Run the script using the command: python palingrams.py.

Output:
    - Upon running the script, any palingrams found in the dictionary file will be printed to the console.
    - The number of palingrams found and the runtime of the search will be displayed.
    - The list of palingrams will be saved to a file named 'palingrams_list.txt'.
"""

import sys
import requests
import time

def download_dictionary(url, file_name):
    """Download a dictionary file from a URL."""
    try:
        response = requests.get(url)  # Sending a GET request to the specified URL
        with open(file_name, 'wb') as f:  # Opening the file in binary write mode
            f.write(response.content)  # Writing the content of the response to the file
    except requests.RequestException as e:
        # Handling exceptions that may occur during the request
        print("Error downloading dictionary from {}: {}".format(url, e))
        sys.exit(1)  # Exiting the program with an error code if an exception occurs

def load_dictionary(file):
    """Open a text file & turn contents into a list of lowercase strings."""
    try:
        with open(file, encoding='utf-8') as in_file:
            # Opening the file with utf-8 encoding and reading its contents
            loaded_txt = in_file.read().strip().split('\n')  # Splitting the text into lines
            loaded_txt = [x.lower() for x in loaded_txt]  # Converting all words to lowercase
            return loaded_txt  # Returning the list of lowercase words
    except IOError as e:
        # Handling IO errors that may occur during file operations
        print("{}\nError opening {}. Terminating program.".format(e, file))
        sys.exit(1)  # Exiting the program with an error code if an exception occurs

def find_palingrams():
    """Find dictionary palingrams."""
    start_time = time.time()  # Getting the current time to measure the runtime
    dictionary_url = "https://inventwithpython.com/dictionary.txt"
    dictionary_file = "dictionary.txt"
    download_dictionary(dictionary_url, dictionary_file)  # Downloading the dictionary file
    word_list = load_dictionary(dictionary_file)  # Loading the dictionary into a list
    pali_list = []  # Initializing a list to store palingrams
    words = set(word_list)  # Converting the list of words into a set for faster lookup
    for word in words:
        end = len(word)
        rev_word = word[::-1]
        if end > 1:
            for i in range(end):
                if word[i:] == rev_word[:end-i] and rev_word[end-i:] in words:
                    pali_list.append((word, rev_word[end-i:]))
                if word[:i] == rev_word[end-i:] and rev_word[:end-i] in words:
                    pali_list.append((rev_word[:end-i], word))
    end_time = time.time()  # Getting the current time after finding palingrams
    print("\nNumber of palingrams = {}\n".format(len(pali_list)))  # Printing the number of palingrams found
    print("Runtime for finding palingrams was {} seconds.".format(end_time - start_time))  # Printing the runtime
    save_option = input("\nDo you want to save the list of palingrams to a file? (y/n): ")
    if save_option.lower() == "y":
        save_to_file(pali_list)  # Prompting the user to save the list if desired

def save_to_file(pali_list):
    """Save list of palingrams to a file."""
    try:
        with open("palingrams_list.txt", "w", encoding="utf-8") as f:
            for palingram in pali_list:
                f.write("{} {}\n".format(palingram[0], palingram[1]))
        print("\nPalingrams list saved to 'palingrams_list.txt'.")
    except IOError as e:
        print("\nError saving palingrams list: {}".format(e))

if __name__ == "__main__":
    find_palingrams()  # Calling the find_palingrams function when the script is executed