# standard imports
import os
import logging

from Crypto.Cipher import AES
from Crypto.Util import Counter

logg = logging.getLogger(__name__)


class Encrypt:

    aesBlockSize = 1 << 7

    def __init__(self, secret, db_dir):
        fp = os.path.join(db_dir, '.aes_ctr_iv')
        try:
            f = open(fp, 'rb')
            self.iv = f.read()
        except FileNotFoundError:
            logg.debug('generating new iv for aes-ctr')
            self.iv = os.urandom(8)
            f = open(fp, 'wb')
            f.write(self.iv)

        f.close()

        iv_num = int.from_bytes(self.iv, 'big')
        self.ctr = Counter.new(aesBlockSize, initial_value=iv_num)
        self.cipher = AES.new(secret, AES.MODE_CTR, counter=self.ctr)


    def encrypt(self, v):
        return self.cipher.encrypt(v)
       

    def decrypt(self, v):
        return self.cipher.decrypt(v)