"""
 This file is part of nucypher.

 nucypher is free software: you can redistribute it and/or modify
 it under the terms of the GNU Affero General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 nucypher is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU Affero General Public License for more details.

 You should have received a copy of the GNU Affero General Public License
 along with nucypher.  If not, see <https://www.gnu.org/licenses/>.
"""

import builtins
import pytest

from nucypher.exceptions import DevelopmentInstallationRequired


class TestsImportMocker:

    REAL_IMPORT = builtins.__import__
    __active = False

    def mock_import(self, name, *args, **kwargs):
        if 'tests' in name and self.__active:
            raise ImportError
        return self.REAL_IMPORT(name, *args, **kwargs)

    def start(self):
        builtins.__import__ = self.mock_import
        self.__active = True

    def stop(self):
        builtins.__import__ = self.REAL_IMPORT
        self.__active = False

    def __enter__(self):
        self.start()

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.stop()


@pytest.fixture(scope='function')
def import_mocker():
    mock = TestsImportMocker()
    try:
        yield mock
    finally:
        mock.stop()


def test_use_vladimir_without_development_installation(import_mocker, mocker):

    # Expected error message (Related object)
    from tests.utils.middleware import EvilMiddleWare
    import_path = f'{EvilMiddleWare.__module__}.{EvilMiddleWare.__name__}'
    message = DevelopmentInstallationRequired.MESSAGE.format(importable_name=import_path)
    del EvilMiddleWare

    with import_mocker:
        from nucypher.characters.unlawful import Vladimir                    # Import OK
        with pytest.raises(DevelopmentInstallationRequired, match=message):  # Expect lazy failure
            Vladimir.from_target_ursula(target_ursula=mocker.Mock())


def test_get_pyevm_backend_without_development_installation(import_mocker):

    # Expected error message (Related object)
    from tests import constants
    import_path = f'{constants.__name__}'
    message = DevelopmentInstallationRequired.MESSAGE.format(importable_name=import_path)
    del constants

    with import_mocker:
        from nucypher.blockchain.eth.providers import _get_pyevm_test_backend   # Import OK
        with pytest.raises(DevelopmentInstallationRequired, match=message):     # Expect lazy failure
            _get_pyevm_test_backend()


def test_rpc_test_client_without_development_installation(import_mocker, mocker):

    # Expected error message (Related object)
    from tests.utils.controllers import JSONRPCTestClient
    import_path = f'{JSONRPCTestClient.__module__}.{JSONRPCTestClient.__name__}'
    message = DevelopmentInstallationRequired.MESSAGE.format(importable_name=import_path)
    del JSONRPCTestClient

    with import_mocker:
        from nucypher.characters.control.controllers import JSONRPCController  # Import OK
        with pytest.raises(DevelopmentInstallationRequired, match=message):    # Expect lazy failure
            JSONRPCController.test_client(self=mocker.Mock())