caesarCipher.py

import art
print(art.logo)

alphabet = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

# def encrypt(original_text, shift_amount):
#     cipher_text = ""
#     for letter in original_text:
#         shifted_position = alphabet.index(letter) + shift_amount
#         shifted_position %= len(alphabet)
#         cipher_text += alphabet[shifted_position]
#     print(f"Here is the encoded result: {cipher_text}")
#
#
# def decrypt(encrypted_text, shift_amount):
#     cipher_text = ""
#     for letter in encrypted_text:
#         shifted_position = alphabet.index(letter) - shift_amount
#         cipher_text += alphabet[shifted_position]
#     print(f"Your decrypted text is : {cipher_text}")
#
# encrypt(original_text=text, shift_amount=shift)
# decrypt(text,shift)

def caesar(original_text, shift_amount , encode_or_decode):
    output_text = ""

    if encode_or_decode == "decode":
        shift_amount *= -1


    for letter in original_text:

        if letter not in alphabet: #checks if character is not an alphabet
            output_text += letter  #adds the character as it is to the output_text. hence symbol remains as expected
            continue

        shifted_position = alphabet.index(letter) + shift_amount
        shifted_position %= len(alphabet)
        output_text += alphabet[shifted_position]

    print(f"Here is your {encode_or_decode}d result: {output_text}")


should_user_continue = True
while should_user_continue:
    direction = input("Type 'encode' to encrypt, type 'decode' to decrypt:\n").lower()
    text = input("Type your message:\n").lower()
    shift = int(input("Type the shift number:\n"))

    caesar(text,shift,direction)
    continue_or_not = input("Do you want to do this again? Type 'yes' to continue, type 'no' to end\n").lower()

    if continue_or_not == "no":
        should_user_continue = False
        print("Goodbye then!")