# Copyright 2014 Facebook, Inc.

# You are hereby granted a non-exclusive, worldwide, royalty-free license to
# use, copy, modify, and distribute this software in source code or binary
# form for use in connection with the web services and APIs provided by
# Facebook.

# As with any software that integrates with the Facebook platform, your use
# of this software is subject to the Facebook Developer Principles and
# Policies [http://developers.facebook.com/policy/]. This copyright notice
# shall be included in all copies or substantial portions of the software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.

import hmac
import hashlib
import os
import sys

class Util:

    @staticmethod
    def async_requests_available():
        return sys.version_info >= (3, 5, 3)

    @staticmethod
    def ca_bundle_path():
        return os.path.join(
            os.path.dirname(__file__),
            '..',
            '..',
            'fb_ca_chain_bundle.crt',
        )

    @staticmethod
    def appsecret_proof(appsecret, access_token):
        hmac_object = hmac.new(
            appsecret.encode('utf-8'),
            msg=access_token.encode('utf-8'),
            digestmod=hashlib.sha256
        )

        return hmac_object.hexdigest()