# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
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# distributed under the License is distributed on an "AS IS" BASIS,
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# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import pytest

from cryptography import utils
from cryptography.exceptions import UnsupportedAlgorithm
from cryptography.hazmat.bindings.openssl.backend import backend, Backend
from cryptography.hazmat.primitives import interfaces
from cryptography.hazmat.primitives.ciphers import Cipher
from cryptography.hazmat.primitives.ciphers.algorithms import AES
from cryptography.hazmat.primitives.ciphers.modes import CBC


class DummyMode(object):
    pass


@utils.register_interface(interfaces.CipherAlgorithm)
class DummyCipher(object):
    pass


class TestOpenSSL(object):
    def test_backend_exists(self):
        assert backend

    def test_openssl_version_text(self):
        """
        This test checks the value of OPENSSL_VERSION_TEXT.

        Unfortunately, this define does not appear to have a
        formal content definition, so for now we'll test to see
        if it starts with OpenSSL as that appears to be true
        for every OpenSSL.
        """
        assert backend.openssl_version_text().startswith("OpenSSL")

    def test_supports_cipher(self):
        assert backend.cipher_supported(None, None) is False

    def test_register_duplicate_cipher_adapter(self):
        with pytest.raises(ValueError):
            backend.register_cipher_adapter(AES, CBC, None)

    def test_instances_share_ffi(self):
        b = Backend()
        assert b.ffi is backend.ffi
        assert b.lib is backend.lib

    def test_nonexistent_cipher(self):
        b = Backend()
        b.register_cipher_adapter(
            DummyCipher,
            DummyMode,
            lambda backend, cipher, mode: backend.ffi.NULL
        )
        cipher = Cipher(
            DummyCipher(), DummyMode(), backend=b,
        )
        with pytest.raises(UnsupportedAlgorithm):
            cipher.encryptor()