def vigenere_en(ptext, vk):
    result = ""
    ptext = ptext.upper()
    vk = vk.upper()

    kl = len(vk) ## key length

    for i in range(len(ptext)):
        ch = ptext[i]
        if 32 <= ord(ch) <= 47:
            result += ch
        elif 65 <= ord(ch) <= 90:
            shift = (ord(vk[i % kl]) - ord('A')) % 26
            result += chr((ord(ch) - ord('A') + shift) % 26 + ord('A'))
        else:
            result += ch

    return result


def vigenere_de(ctext, vk):
    result = ""
    ctext = ctext.upper()
    vk = vk.upper()

    kl = len(vk)

    for i in range(len(ctext)):
        ch = ctext[i]
        if 32 <= ord(ch) <= 47:
            result += ch
        elif 65 <= ord(ch) <= 90:
            shift = (ord(vk[i % kl]) - ord('A')) % 26
            result += chr((ord(ch) - ord('A') - shift + 26) % 26 + ord('A'))
        else:
            result += ch

    return result


def autokey_en(ptext, ak):
    result = ""
    ptext = ptext.upper()
    current_key = ak

    for i in range(len(ptext)):
        ch = ptext[i]
        if 32 <= ord(ch) <= 47:
            result += ch
        elif 65 <= ord(ch) <= 90:
            shift = (current_key - ord('A')) % 26
            cipher_char = chr((ord(ch) - ord('A') + shift) % 26 + ord('A'))
            result += cipher_char
            current_key = ord(cipher_char)
        else:
            result += ch

    return result

def autokey_de(ctext, ak):
    result = ""
    ctext = ctext.upper()
    current_key = ak

    for i in range(len(ctext)):
        ch = ctext[i]
        if 32 <= ord(ch) <= 47:
            result += ch
        elif 65 <= ord(ch) <= 90:
            shift = (current_key - ord('A')) % 26
            plain_char = chr((ord(ch) - ord('A') - shift + 26) % 26 + ord('A'))
            result += plain_char
            current_key = ord(plain_char)
        else:
            result += ch

    return result

def operator(argument,ptext,ak,vk):
    match argument:
        case '1':
            print("Vigenere Cipher")
            print("Plaintext: ", ptext)
            print("Vigenere Key: ", vk)
            ctext = vigenere_en(ptext, vk)
            print("Ciphertext: ", ctext)
            print("Decrypted Text: ", vigenere_de(ctext, vk))
        case '2':
            print("Autokey Cipher")
            print("Plaintext: ", ptext)
            print("Auto Key: ", ak)
            ctext = autokey_en(ptext, ak)
            print("Ciphertext: ", ctext)
            print("Decrypted Text: ", autokey_de(ctext, ak))
        case '3':
            print("Goodbye")
            exit()
        case _:
            print("Invalid Choice, please try again.")

def main():
    ptext = input("Kindly enter your desired plaintext: ")
    vk = input("Kindly enter the Vigenere Key: ")
    ak = int(input("Kindly enter the Autokey: "))

    print("Welcome to the Autokey cipher system.")
    print("Enter your choice of algorithm")
    print("1. Vigenere Cipher")
    print("2. Autokey Cipher")
    print("3. Exit")

    while True:
        op = input("Enter your choice of operation: ")
        operator(op, ptext, ak, vk)


if __name__ == '__main__':
    main()