#    Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
#
#    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 collections
import logging
from unittest import mock

import fixtures
from oslotest import base

from testtools import matchers

from taskflow import exceptions
from taskflow.tests import fixtures as taskflow_fixtures
from taskflow.tests import utils


class FailureRegexpMatcher:
    """Matches if the failure was caused by the given exception and message.

    This will match if a given failure contains and exception of the given
    class type and if its string message matches to the given regular
    expression pattern.
    """

    def __init__(self, exc_class, pattern):
        self.exc_class = exc_class
        self.pattern = pattern

    def match(self, failure):
        for cause in failure:
            if cause.check(self.exc_class) is not None:
                return matchers.MatchesRegex(
                    self.pattern).match(cause.exception_str)
        return matchers.Mismatch("The `%s` wasn't caused by the `%s`" %
                                 (failure, self.exc_class))


class TestCase(base.BaseTestCase):
    """Test case base class for all taskflow unit tests."""

    def setUp(self):
        super().setUp()
        self.useFixture(taskflow_fixtures.WarningsFixture())

    def makeTmpDir(self):
        t_dir = self.useFixture(fixtures.TempDir())
        return t_dir.path

    def assertRaisesAttrAccess(self, exc_class, obj, attr_name):

        def access_func():
            getattr(obj, attr_name)

        self.assertRaises(exc_class, access_func)

    def assertIsSuperAndSubsequence(self, super_seq, sub_seq, msg=None):
        super_seq = list(super_seq)
        sub_seq = list(sub_seq)
        current_tail = super_seq
        for sub_elem in sub_seq:
            try:
                super_index = current_tail.index(sub_elem)
            except ValueError:
                # element not found
                if msg is None:
                    msg = ("%r is not subsequence of %r: "
                           "element %r not found in tail %r"
                           % (sub_seq, super_seq, sub_elem, current_tail))
                self.fail(msg)
            else:
                current_tail = current_tail[super_index + 1:]

    def assertFailuresRegexp(self, exc_class, pattern, callable_obj, *args,
                             **kwargs):
        """Asserts the callable failed with the given exception and message."""
        try:
            with utils.wrap_all_failures():
                callable_obj(*args, **kwargs)
        except exceptions.WrappedFailure as e:
            self.assertThat(e, FailureRegexpMatcher(exc_class, pattern))


class MockTestCase(TestCase):

    def setUp(self):
        super().setUp()
        self.master_mock = mock.Mock(name='master_mock')

    def patch(self, target, autospec=True, **kwargs):
        """Patch target and attach it to the master mock."""
        f = self.useFixture(fixtures.MockPatch(target,
                                               autospec=autospec, **kwargs))
        mocked = f.mock
        attach_as = kwargs.pop('attach_as', None)
        if attach_as is not None:
            self.master_mock.attach_mock(mocked, attach_as)
        return mocked

    def patchClass(self, module, name, autospec=True, attach_as=None):
        """Patches a modules class.

        This will create a class instance mock (using the provided name to
        find the class in the module) and attach a mock class the master mock
        to be cleaned up on test exit.
        """
        if autospec:
            instance_mock = mock.Mock(spec_set=getattr(module, name))
        else:
            instance_mock = mock.Mock()

        f = self.useFixture(fixtures.MockPatchObject(module, name,
                                                     autospec=autospec))
        class_mock = f.mock
        class_mock.return_value = instance_mock

        if attach_as is None:
            attach_class_as = name
            attach_instance_as = name.lower()
        else:
            attach_class_as = attach_as + '_class'
            attach_instance_as = attach_as

        self.master_mock.attach_mock(class_mock, attach_class_as)
        self.master_mock.attach_mock(instance_mock, attach_instance_as)
        return class_mock, instance_mock

    def resetMasterMock(self):
        self.master_mock.reset_mock()


class CapturingLoggingHandler(logging.Handler):
    """A handler that saves record contents for post-test analysis."""

    def __init__(self, level=logging.DEBUG):
        # It seems needed to use the old style of base class calling, we
        # can remove this old style when we only support py3.x
        logging.Handler.__init__(self, level=level)
        self._records = []

    @property
    def counts(self):
        """Returns a dictionary with the number of records at each level."""
        self.acquire()
        try:
            captured = collections.defaultdict(int)
            for r in self._records:
                captured[r.levelno] += 1
            return captured
        finally:
            self.release()

    @property
    def messages(self):
        """Returns a dictionary with list of record messages at each level."""
        self.acquire()
        try:
            captured = collections.defaultdict(list)
            for r in self._records:
                captured[r.levelno].append(r.getMessage())
            return captured
        finally:
            self.release()

    @property
    def exc_infos(self):
        """Returns a list of all the record exc_info tuples captured."""
        self.acquire()
        try:
            captured = []
            for r in self._records:
                if r.exc_info:
                    captured.append(r.exc_info)
            return captured
        finally:
            self.release()

    def emit(self, record):
        self.acquire()
        try:
            self._records.append(record)
        finally:
            self.release()

    def reset(self):
        """Resets *all* internally captured state."""
        self.acquire()
        try:
            self._records = []
        finally:
            self.release()

    def close(self):
        logging.Handler.close(self)
        self.reset()