import os
import random
 
if os.name == "nt":
    os.system("color 48")
    os.system("title Encryptor/Decryptor")
    def clear():
        os.system("cls")
else:
    def clear():
        os.system("clear")
 
def menu():
    clear()
    print ("")
    print ("Encryptor/Decryptor")
    print ("-------------------")
    print ("1) Encrypt Message ")
    print ("2) Decrypt Message ")
    print ("-------------------")
    menu_choice = input ("Choose one: ")
 
    if menu_choice != "1":
        if menu_choice != "2":
            clear()
            print ("")
            print ("Please type a valid choice!")
            input ()
            menu()
 
    if menu_choice == "1": encrypt()
    if menu_choice == "2": decrypt()
 
def encrypt():
    clear()
    print ("")
    print ("------------------------------------")
    print ("1) Use computer generated number key")
    print ("2) Manually key                     ")
    print ("------------------------------------")
    encrypt_choice = input ("Choose one: ")
 
    if encrypt_choice == "1":
        key = list(str(random.random()).split(".")[1])
    else:
        clear()
        print ("")
        key = list(str(input("Please type key: ")))
 
    show = ""
    while 1:
        clear()
        print ("")
        print (show)
        print ("Type S to show key, H to hide key  ")
        print ("Type R to change key               ")
        print ("-----------------------------------")
        message = list(input ("Please type a message to be encrypted: "))
 
        if "".join(message).lower() == "s":
            show = str("Key is: " + str("".join(key)))
            continue
        if "".join(message).lower() == "r":
            encrypt()
        if "".join(message).lower() == "h":
            show = ""
            continue
 
        break
 
 
    while len(key) < len(message):
        key += key
 
    spaces = 0
    encrypt_list = []
    shift = 1
    for loop in range((len(message))):
        shift += 1
        if str(message[loop]) == ' ':
                spaces += 1
        else:
            if str(message[loop]) == '  ':
                spaces += 1
            ''
        if str(message[loop]) != ' ':
            if str(message[loop]) != '  ':
                if str(message[loop]) == str(key[loop-spaces]):
                    encrypt_list.append(message[loop])
                else:
                    if (shift % 2) == 0:
                        loop_ord = str(chr(ord(key[loop-spaces])+ord(message[loop])))
                    else:
                        if ord(str(message[loop])) < ord(str(key[loop-spaces])):
                            loop_ord = "9u" + str(chr(ord(key[loop-spaces])-ord(message[loop])))
                        else:
                            loop_ord = chr(ord(message[loop])-ord(key[loop-spaces]))
                    encrypt_list.append(loop_ord)
 
    print ("")
    print ("Encrypted message is: ", "".join(encrypt_list))
    if show == "":
        print ("")
        ask = input ("Show key before leaving(Y/N): ")
        if ask.lower() == "y":
            print ("")
            print ("Key is: " + str("".join(key)))
    input ()
    menu()
 
def decrypt():
    menu()
 
menu()