import hmac
import json
from base64 import b64encode, urlsafe_b64encode
from hashlib import sha256


def sha256_base64(payload):
    out = payload.encode('utf-8')
    out = sha256(out).digest()
    out = b64encode(out)
    return out.decode('utf-8')


def hmac_sha256(key, message):
    hm = hmac.new(key.encode('utf-8'), digestmod=sha256)
    hm.update(message.encode('utf-8'))
    digest = hm.digest()
    return urlsafe_b64encode(digest).decode('utf-8').replace('=', '')


class RequestFailure(Exception):
    def __init__(self, message, ans, error_code=None):
        super().__init__(message)
        self.ans = ans
        self.error_code = error_code