# Copyright 2013 Rackspace, Inc.
#
# 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 mock
from oslotest import base as test_base
from stevedore import extension

from ironic_python_agent import errors
from ironic_python_agent import hardware


def counted(fn):
    def wrapper(*args, **kwargs):
        wrapper.called += 1
        return fn(*args, **kwargs)
    wrapper.called = 0
    wrapper.__name__ = fn.__name__
    return wrapper


class FakeGenericHardwareManager(hardware.HardwareManager):
    @counted
    def generic_only(self):
        return True

    @counted
    def specific_only(self):
        raise Exception("Test fail: This method should not be called")

    @counted
    def mainline_fail(self):
        return True

    @counted
    def both_succeed(self):
        return True

    @counted
    def unexpected_fail(self):
        raise Exception("Test fail: This method should not be called")

    @counted
    def evaluate_hardware_support(self):
        return hardware.HardwareSupport.GENERIC


class FakeMainlineHardwareManager(hardware.HardwareManager):
    @counted
    def specific_only(self):
        return True

    @counted
    def mainline_fail(self):
        raise errors.IncompatibleHardwareMethodError

    @counted
    def both_succeed(self):
        return True

    @counted
    def unexpected_fail(self):
        raise RuntimeError('A problem was encountered')

    @counted
    def evaluate_hardware_support(self):
        return hardware.HardwareSupport.MAINLINE


class TestMultipleHardwareManagerLoading(test_base.BaseTestCase):
    def setUp(self):
        super(TestMultipleHardwareManagerLoading, self).setUp()
        fake_ep = mock.Mock()
        fake_ep.module_name = 'fake'
        fake_ep.attrs = ['fake attrs']
        ext1 = extension.Extension('fake_generic', fake_ep, None,
                FakeGenericHardwareManager())
        ext2 = extension.Extension('fake_mainline', fake_ep, None,
                FakeMainlineHardwareManager())
        self.fake_ext_mgr = extension.ExtensionManager.make_test_instance([
                ext1, ext2
        ])

        self.extension_mgr_patcher = mock.patch('stevedore.ExtensionManager')
        self.mocked_extension_mgr = self.extension_mgr_patcher.start()
        self.mocked_extension_mgr.return_value = self.fake_ext_mgr
        hardware._global_managers = None

    def tearDown(self):
        super(TestMultipleHardwareManagerLoading, self).tearDown()
        self.extension_mgr_patcher.stop()

    def test_mainline_method_only(self):
        hardware.dispatch_to_managers('specific_only')

        self.assertEqual(1, FakeMainlineHardwareManager.specific_only.called)

    def test_generic_method_only(self):
        hardware.dispatch_to_managers('generic_only')

        self.assertEqual(1, FakeGenericHardwareManager.generic_only.called)

    def test_both_succeed(self):
        """In the case where both managers will work; only the most specific
        manager should have it's function called.
        """
        hardware.dispatch_to_managers('both_succeed')

        self.assertEqual(1, FakeMainlineHardwareManager.both_succeed.called)
        self.assertEqual(0, FakeGenericHardwareManager.both_succeed.called)

    def test_mainline_fails(self):
        """Ensure that if the mainline manager is unable to run the method
        that we properly fall back to generic.
        """
        hardware.dispatch_to_managers('mainline_fail')

        self.assertEqual(1, FakeMainlineHardwareManager.mainline_fail.called)
        self.assertEqual(1, FakeGenericHardwareManager.mainline_fail.called)

    def test_manager_method_not_found(self):
        self.assertRaises(errors.HardwareManagerMethodNotFound,
                          hardware.dispatch_to_managers,
                          'fake_method')

    def test_method_fails(self):
        self.assertRaises(RuntimeError,
                          hardware.dispatch_to_managers,
                          'unexpected_fail')


class TestNoHardwareManagerLoading(test_base.BaseTestCase):
    def setUp(self):
        super(TestNoHardwareManagerLoading, self).setUp()
        self.empty_ext_mgr = extension.ExtensionManager.make_test_instance([])

    @mock.patch('stevedore.ExtensionManager')
    def test_no_managers_found(self, mocked_extension_mgr_constructor):
        mocked_extension_mgr_constructor.return_value = self.empty_ext_mgr
        hardware._global_managers = None

        self.assertRaises(errors.HardwareManagerNotFound,
                          hardware.dispatch_to_managers,
                          'some_method')