# Copyright 2019 Canonical Ltd
#
# 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
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import unittest

from unittest import mock

import reactive.cinder_backup_swift_handlers as handlers


_when_args = {}
_when_not_args = {}


def mock_hook_factory(d):

    def mock_hook(*args, **kwargs):

        def inner(f):
            # remember what we were passed.  Note that we can't actually
            # determine the class we're attached to, as the decorator only gets
            # the function.
            try:
                d[f.__name__].append(dict(args=args, kwargs=kwargs))
            except KeyError:
                d[f.__name__] = [dict(args=args, kwargs=kwargs)]
            return f
        return inner
    return mock_hook


class TestCinderBackupSwiftHandlers(unittest.TestCase):

    @classmethod
    def setUpClass(cls):
        cls._patched_when = mock.patch('charms.reactive.when',
                                       mock_hook_factory(_when_args))
        cls._patched_when_started = cls._patched_when.start()
        cls._patched_when_not = mock.patch('charms.reactive.when_not',
                                           mock_hook_factory(_when_not_args))
        cls._patched_when_not_started = cls._patched_when_not.start()
        # force requires to rerun the mock_hook decorator:
        # try except is Python2/Python3 compatibility as Python3 has moved
        # reload to importlib.
        try:
            reload(handlers)
        except NameError:
            import importlib
            importlib.reload(handlers)

    @classmethod
    def tearDownClass(cls):
        cls._patched_when.stop()
        cls._patched_when_started = None
        cls._patched_when = None
        cls._patched_when_not.stop()
        cls._patched_when_not_started = None
        cls._patched_when_not = None
        # and fix any breakage we did to the module
        try:
            reload(handlers)
        except NameError:
            import importlib
            importlib.reload(handlers)

    def setUp(self):
        self._patches = {}
        self._patches_start = {}

    def tearDown(self):
        for k, v in self._patches.items():
            v.stop()
            setattr(self, k, None)
        self._patches = None
        self._patches_start = None

    def patch(self, obj, attr, return_value=None):
        mocked = mock.patch.object(obj, attr)
        self._patches[attr] = mocked
        started = mocked.start()
        started.return_value = return_value
        self._patches_start[attr] = started
        setattr(self, attr, started)

    def test_registered_hooks(self):
        # test that the hooks actually registered the relation expressions that
        # are meaningful for this interface: this is to handle regressions.
        # The keys are the function names that the hook attaches to.
        when_patterns = {
            'configure_cinder_backup': [
                ('backup-backend.available', )],
        }

        # check the when hooks are attached to the expected functions
        for t, p in [(_when_args, when_patterns),
                     ]:

            for f, args in t.items():
                # check that function is in patterns
                self.assertIn(f, p.keys())