import time

import pytest
import jwt

from Crypto.PublicKey import RSA
from jwkest.jwk import RSAKey

from util.security.jwtutil import (decode, exp_max_s_option, jwk_dict_to_public_key,
                                   InvalidTokenError, InvalidAlgorithmError)


@pytest.fixture(scope="session")
def private_key():
  return RSA.generate(2048)


@pytest.fixture(scope="session")
def private_key_pem(private_key):
  return private_key.exportKey('PEM')


@pytest.fixture(scope="session")
def public_key(private_key):
  return private_key.publickey().exportKey('PEM')


def _token_data(audience, subject, iss, iat=None, exp=None, nbf=None):
  return {
    'iss': iss,
    'aud': audience,
    'nbf': nbf() if nbf is not None else int(time.time()),
    'iat': iat() if iat is not None else int(time.time()),
    'exp': exp() if exp is not None else int(time.time() + 3600),
    'sub': subject,
  }


@pytest.mark.parametrize('aud, iss, nbf, iat, exp, expected_exception', [
  pytest.param('invalidaudience', 'someissuer', None, None, None, 'Invalid audience',
               id='invalid audience'),
  pytest.param('someaudience', 'invalidissuer', None, None, None, 'Invalid issuer',
               id='invalid issuer'),
  pytest.param('someaudience', 'someissuer', lambda: time.time() + 120, None, None,
               'The token is not yet valid',
               id='invalid not before'),
  pytest.param('someaudience', 'someissuer', None, lambda: time.time() + 120, None,
               'Issued At claim',
               id='issued at in future'),
  pytest.param('someaudience', 'someissuer', None, None, lambda: time.time() - 100,
               'Signature has expired',
               id='already expired'),
  pytest.param('someaudience', 'someissuer', None, None, lambda: time.time() + 10000,
               'Token was signed for more than',
               id='expiration too far in future'),

  pytest.param('someaudience', 'someissuer', lambda: time.time() + 10, None, None,
               None,
               id='not before in future by within leeway'),
  pytest.param('someaudience', 'someissuer', None, lambda: time.time() + 10, None,
               None,
               id='issued at in future but within leeway'),
  pytest.param('someaudience', 'someissuer', None, None, lambda: time.time() - 10,
               None,
               id='expiration in past but within leeway'),
])
def test_decode_jwt_validation(aud, iss, nbf, iat, exp, expected_exception, private_key_pem,
                               public_key):
  token = jwt.encode(_token_data(aud, 'subject', iss, iat, exp, nbf), private_key_pem, 'RS256')

  if expected_exception is not None:
    with pytest.raises(InvalidTokenError) as ite:
      max_exp = exp_max_s_option(3600)
      decode(token, public_key, algorithms=['RS256'], audience='someaudience',
             issuer='someissuer', options=max_exp, leeway=60)
    assert ite.match(expected_exception)
  else:
    max_exp = exp_max_s_option(3600)
    decode(token, public_key, algorithms=['RS256'], audience='someaudience',
           issuer='someissuer', options=max_exp, leeway=60)


def test_decode_jwt_invalid_key(private_key_pem):
  # Encode with the test private key.
  token = jwt.encode(_token_data('aud', 'subject', 'someissuer'), private_key_pem, 'RS256')

  # Try to decode with a different public key.
  another_public_key = RSA.generate(2048).publickey().exportKey('PEM')
  with pytest.raises(InvalidTokenError) as ite:
    max_exp = exp_max_s_option(3600)
    decode(token, another_public_key, algorithms=['RS256'], audience='aud',
           issuer='someissuer', options=max_exp, leeway=60)
  assert ite.match('Signature verification failed')


def test_decode_jwt_invalid_algorithm(private_key_pem, public_key):
  # Encode with the test private key.
  token = jwt.encode(_token_data('aud', 'subject', 'someissuer'), private_key_pem, 'RS256')

  # Attempt to decode but only with a different algorithm than that used.
  with pytest.raises(InvalidAlgorithmError) as ite:
    max_exp = exp_max_s_option(3600)
    decode(token, public_key, algorithms=['ES256'], audience='aud',
           issuer='someissuer', options=max_exp, leeway=60)
  assert ite.match('are not whitelisted')


def test_jwk_dict_to_public_key(private_key, private_key_pem):
  public_key = private_key.publickey()
  jwk = RSAKey(key=private_key.publickey()).serialize()
  converted = jwk_dict_to_public_key(jwk)

  # Encode with the test private key.
  token = jwt.encode(_token_data('aud', 'subject', 'someissuer'), private_key_pem, 'RS256')

  # Decode with the converted key.
  max_exp = exp_max_s_option(3600)
  decode(token, converted, algorithms=['RS256'], audience='aud',
         issuer='someissuer', options=max_exp, leeway=60)