caesar-cipher.py

import argparse
import string
'''
!! TODO !!
1. Add a feature to output cipher text to file
2. Add a deciphering feature
'''
def main():
    
    Lowercase_Letters = string.ascii_lowercase # string of lowercase letters
    Uppercase_Letters = string.ascii_uppercase # string of uppercase letters


    parser = argparse.ArgumentParser(description="This converts your text to a caesar cipher text. You can specify the shift value from 1 - 25")
    parser.add_argument("-o", required=False, type=str, help="Output the ciphered text to a specified text file")
    parser.add_argument("-f", required=False, type=str, help="Indicate the path to the text file")
    parser.add_argument("-t", required=False, type=str, help="Indicate the text you want shift the values")
    parser.add_argument("-s", required=True, type=int, help="Specify the shift value E.g. 3 to shift letter to 3 spaces. You can only have 1 - 25 as shift value")
    args = parser.parse_args()

    cipherText = [] # This stores the ciphered text
    
    # This parses the arguments and performs the shifting of the values
    if(args.t != None):
        for i in args.t:
            try:
                if i.isupper(): # check if its an uppercase letter
                    index = Uppercase_Letters.index(i) # 
                    newChar = Uppercase_Letters[index + args.s]
                    cipherText.append(newChar)
                else:
                    index = Lowercase_Letters.index(i)
                    newChar = Lowercase_Letters[index + args.s]
                    cipherText.append(newChar)
            except:
                if i.isupper(): # Check if its in lowercase
                    currentIndex = Uppercase_Letters.index(i) + 1
                    remainingNumberOfLetters = 26 - currentIndex
                    newChar = Uppercase_Letters[args.s - remainingNumberOfLetters - 1]
                    cipherText.append(newChar)
                else: 
                    currentIndex = Lowercase_Letters.index(i) + 1
                    remainingNumberOfLetters = 26 - currentIndex
                    newChar = Lowercase_Letters[args.s - remainingNumberOfLetters - 1]
                    cipherText.append(newChar)




    elif(args.f != None):
        path = args.f
        with open(path, "r") as file:
            for i in file:
                for char in i:
                    try:
                        if char.isupper(): # check if its an uppercase letter
                            index = Uppercase_Letters.index(char) # 
                            newChar = Uppercase_Letters[index + args.s]
                            cipherText.append(newChar)
                        else:
                            index = Lowercase_Letters.index(char)
                            newChar = Lowercase_Letters[index + args.s]
                            cipherText.append(newChar)
                    except:
                        if i.isupper(): # Check if its in lowercase
                            currentIndex = Uppercase_Letters.index(char) + 1
                            remainingNumberOfLetters = 26 - currentIndex
                            newChar = Uppercase_Letters[args.s - remainingNumberOfLetters - 1]
                            cipherText.append(newChar)
                        else: 
                            currentIndex = Lowercase_Letters.index(char) + 1
                            remainingNumberOfLetters = 26 - currentIndex
                            newChar = Lowercase_Letters[args.s - remainingNumberOfLetters - 1]
                            cipherText.append(newChar)
    # if the user specified an output file path
    if args.o != None:
        with open(args.o, "w") as f:
            f.write(''.join(cipherText))
    else:
        print(''.join(cipherText))


main()