import base64
import urllib.parse
from random import Random


class ETkObject(object):
    def __init__(self, etk):
        self.uid = ''
        self.decrypt_uid(etk)

    def decrypt_uid(self, etk):
        try:
            c = base64.b64decode(etk)
            c = c[2:-2]
            c = urllib.parse.unquote(c.decode('utf-8'))
            c = base64.b64decode(c)
            uid = c.decode('utf-8')
            assert len(uid) == 20 or len(uid) == 14
            self.uid = uid
        except Exception as e:
            print(repr(e))

    def encrypt_uid(self, data):
        s = data.encode()
        s = base64.b64encode(s)
        startStr = self.generate_random()
        endStr = self.generate_random()
        s = '{startStr}{s}{endStr}'.format(startStr=startStr, s=s.decode('utf-8'), endStr=endStr)
        s = base64.b64encode(s.encode())
        s = s.decode('utf-8')
        return s

    @staticmethod
    def generate_random():
        characterSet = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0123456789'
        length = len(characterSet) - 1
        random = Random()
        ss = ''
        for index in range(2):
            ss += characterSet[random.randint(0, length)]
        return ss