import random
###################################FUNCTION###################################################
def encryption_and_decryption(chos):
    if chos=="e":
        e=random.randint(0,24)
        letters="abcdefghijklmnopqrstuvwxyz"
        encryp_dic={letters[i]:letters[(i+e)%len(letters)] for i in range(len(letters))}
    elif chos=="d":
        d=random.randint(0,24)
        letters="abcdefghijklmnopqrstuvwxyz"
        encryp_dic={letters[i]:letters[(i+d)%len(letters)] for i in range(len(letters))}
    return encryp_dic
###################################FUNCTION###################################################
def ignore_not_alpha(lst):
    lst1=[]
    lst2=[]
    for i in lst:
        for j in range(len(lst)):
            a=lst[j]
            a=a.replace("\n","")
            a=a.replace("-"," ")
            lst1.append(a)
    for i in lst1:
        flag=""
        for x in i:
            if x.isalpha() or x.isspace():
                flag+=x
        flag=flag.lower()
        lst2.append(flag)
    return lst2
###################################FUNCTION###################################################
def choose_e(chos):
    encrypt=(encryption_and_decryption(chos))
    plaintext=open("plaintext.txt","r")
    lst=plaintext.readlines()
    plaintext.close()
    cipher=(ignore_not_alpha(lst))
    ciphertext=open("ciphertext.txt","w")
    keytext=open("key.txt","w")
    keys=[i for i in encrypt.values()]
    lst_secret=[]
    for val in cipher:
        secret=""
        for n in range(len(val)):
            if val[n]==" ":
                secret+=val[n]
            else:
                code=val[n]
                secret+=(encrypt[code])
        lst_secret.append(secret)

    for index in lst_secret:
        ciphertext.write(index)
        ciphertext.write("\n")
    ciphertext.close()
    for i in keys:
        keytext.write(i)
    keytext.close()
###################################FUNCTION###################################################
def choose_d(chos):
    choose_e(chos)
    dictionary=(encryption_and_decryption(chos))
    keytext=open("key.txt","r").read()
    value=[i for i in keytext]
    keys=[i for i in dictionary]
    decrypt=(dictionary_swap(value, keys))
    ciphertext=open("ciphertext.txt","r")
    lst1=ciphertext.readlines()
    cipher=[]
    for i in range(len(lst1)):
        val=lst1[i].replace("\n","")
        cipher.append(val)
    translation=(decrypt_file(cipher, decrypt))
    decrypted_text=open("decrypted.txt","w")
    for i in translation:
        decrypted_text.write(i)
        decrypted_text.write("\n")
    decrypted_text.close()

def dictionary_swap(lst1, lst2):
    new_dic={}
    for i in range(len(lst1)):
        new_dic[lst1[i]] = lst2[i]
    return new_dic
###################################FUNCTION###################################################
def decrypt_file(decryp, dictionary):
    decoding=[]
    for val in decryp:
        translate=""
        for x in range(len(val)):
            if val[x]==" ":
                translate+=val[x]
            else:
                code=val[x]
                translate+=(dictionary[code])
        decoding.append(translate)
    return decoding
###################################FUNCTION###################################################
###################################main#######################################################
choice=input("please enter the letter 'e' for encrypt, or 'd' for decrypt : " )
if choice == "e":
   encrypt=(choose_e(choice))
elif choice=="d":
    decrypt=(choose_d(choice))
else:
    print("we are done")