from cryptography.fernet import Fernet
from cryptography.fernet import InvalidToken
from pathlib import Path
import settings
import string
import secrets
import sys
import os


# Check if encryption key already exists
enckey = Path(settings.ENCKEY_PATH)
if enckey.is_file():
    print("Encryption key found.")
else:
    print("Encryption key not found.")
    print("Generating key...")
    key = Fernet.generate_key()
    with open(settings.ENCKEY_PATH, "wb") as key_file:
        key_file.write(key)
    print("Encryption key generated and stored in secret.key.")


# Load encryption key
def load_key():
    with open(settings.ENCKEY_PATH, "rb") as kf:
        kdata = kf.read()
    return kdata


# Encrypting and storing of key
def encrypt_key(message):
    key = load_key()
    keyf = Fernet(key)

    with open('uploadkeys', 'a+') as uploadkeys:
        print(str(token), file=uploadkeys)

    with open("uploadkeys", "rb") as keyfile:
        keyfile_data = keyfile.read()

    encrypted_data = keyf.encrypt(keyfile_data)

    with open("uploadkeys", "wb") as keyfile:
        keyfile.write(encrypted_data)


def ask_yn(msg):
    resps = {"y": True, "n": False}
    ask = True
    while ask:
        proceedraw = input(msg)
        if proceedraw.lower() in resps.keys():
            proceed = resps[proceedraw]
            ask = False
        else:
            print("Invalid response.")
    return proceed


start = ask_yn("Have you run this program as the correct user (for example, nginx uses www-data)? [y/n] ")
if not start:
    print("Please run this as the correct user with: sudo su [user] -s /bin/sh -c 'python3 keygen/py'")

else:

    N = 64  # Size of token

    # Generate key
    token = ''.join(secrets.choice(string.ascii_letters + string.digits) for i in range(N))

    # Decrypt the existing keyfile
    key = load_key()
    keyf = Fernet(key)

    genkey = True
    uploadkeysp = Path("uploadkeys")
    if not uploadkeysp.is_file():
        uploadkeysp.touch()
    else:
        with open("uploadkeys", "rb") as ukf:
            # read the encrypted data
            encrypted_data = ukf.read()

        try:
            decrypted_data = keyf.decrypt(encrypted_data)  # decrypt data
            with open("uploadkeys", "wb") as ukf:
                ukf.write(decrypted_data)  # write the original file
        except InvalidToken:
            print("The encrypted key data is invalid and cannot be read.")
            print("It may be necessary to clear the file entirely, which will invalidate all tokens.")
            proceed = ask_yn("Do you wish to proceed to clearing the uploadkeys file? [y/n] ")

            if proceed:
                os.remove("uploadkeys")
                print("Removed uploadkeys file.")
                proceed2 = ask_yn("Would you like to continue and generate a new token? [y/n] ")
                if not proceed2:
                    genkey = False

    if genkey:
        print("Your new token is: " + str(token))  # Print token
        encrypt_key(str(token))  # Encrypt the key and save