# Copyright 2017 Google 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 datetime
import itertools
import re

import mock
import pytest

from google.api.core import exceptions
from google.api.core import retry


def test_if_exception_type():
    predicate = retry.if_exception_type(ValueError)

    assert predicate(ValueError())
    assert not predicate(TypeError())


def test_if_exception_type_multiple():
    predicate = retry.if_exception_type(ValueError, TypeError)

    assert predicate(ValueError())
    assert predicate(TypeError())
    assert not predicate(RuntimeError())


def test_if_transient_error():
    assert retry.if_transient_error(exceptions.InternalServerError(''))
    assert retry.if_transient_error(exceptions.TooManyRequests(''))
    assert not retry.if_transient_error(exceptions.InvalidArgument(''))


# Make uniform return half of its maximum, which will be the calculated
# sleep time.
@mock.patch('random.uniform', autospec=True, side_effect=lambda m, n: n/2.0)
def test_exponential_sleep_generator_base_2(uniform):
    gen = retry.exponential_sleep_generator(
        1, 60, multiplier=2)

    result = list(itertools.islice(gen, 8))
    assert result == [1, 2, 4, 8, 16, 32, 60, 60]


@mock.patch('time.sleep', autospec=True)
@mock.patch(
    'google.api.core.helpers.datetime_helpers.utcnow',
    return_value=datetime.datetime.min,
    autospec=True)
def test_retry_target_success(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    call_count = [0]

    def target():
        call_count[0] += 1
        if call_count[0] < 3:
            raise ValueError()
        return 42

    result = retry.retry_target(target, predicate, range(10), None)

    assert result == 42
    assert call_count[0] == 3
    sleep.assert_has_calls([mock.call(0), mock.call(1)])


@mock.patch('time.sleep', autospec=True)
@mock.patch(
    'google.api.core.helpers.datetime_helpers.utcnow',
    return_value=datetime.datetime.min,
    autospec=True)
def test_retry_target_non_retryable_error(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    exception = TypeError()
    target = mock.Mock(side_effect=exception)

    with pytest.raises(TypeError) as exc_info:
        retry.retry_target(target, predicate, range(10), None)

    assert exc_info.value == exception
    sleep.assert_not_called()


@mock.patch('time.sleep', autospec=True)
@mock.patch(
    'google.api.core.helpers.datetime_helpers.utcnow', autospec=True)
def test_retry_target_deadline_exceeded(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    exception = ValueError('meep')
    target = mock.Mock(side_effect=exception)
    # Setup the timeline so that the first call takes 5 seconds but the second
    # call takes 6, which puts the retry over the deadline.
    utcnow.side_effect = [
        # The first call to utcnow establishes the start of the timeline.
        datetime.datetime.min,
        datetime.datetime.min + datetime.timedelta(seconds=5),
        datetime.datetime.min + datetime.timedelta(seconds=11)]

    with pytest.raises(exceptions.RetryError) as exc_info:
        retry.retry_target(target, predicate, range(10), deadline=10)

    assert exc_info.value.cause == exception
    assert exc_info.match('Deadline of 10.0s exceeded')
    assert exc_info.match('last exception: meep')
    assert target.call_count == 2


def test_retry_target_bad_sleep_generator():
    with pytest.raises(ValueError, match='Sleep generator'):
        retry.retry_target(
            mock.sentinel.target, mock.sentinel.predicate, [], None)


class TestRetry(object):
    def test_constructor_defaults(self):
        retry_ = retry.Retry()
        assert retry_._predicate == retry.if_transient_error
        assert retry_._initial == 1
        assert retry_._maximum == 60
        assert retry_._multiplier == 2
        assert retry_._deadline == 120

    def test_constructor_options(self):
        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4)
        assert retry_._predicate == mock.sentinel.predicate
        assert retry_._initial == 1
        assert retry_._maximum == 2
        assert retry_._multiplier == 3
        assert retry_._deadline == 4

    def test_with_deadline(self):
        retry_ = retry.Retry()
        new_retry = retry_.with_deadline(42)
        assert retry_ is not new_retry
        assert new_retry._deadline == 42

    def test_with_predicate(self):
        retry_ = retry.Retry()
        new_retry = retry_.with_predicate(mock.sentinel.predicate)
        assert retry_ is not new_retry
        assert new_retry._predicate == mock.sentinel.predicate

    def test_with_delay_noop(self):
        retry_ = retry.Retry()
        new_retry = retry_.with_delay()
        assert retry_ is not new_retry
        assert new_retry._initial == retry_._initial
        assert new_retry._maximum == retry_._maximum
        assert new_retry._multiplier == retry_._multiplier

    def test_with_delay(self):
        retry_ = retry.Retry()
        new_retry = retry_.with_delay(
            initial=1, maximum=2, multiplier=3)
        assert retry_ is not new_retry
        assert new_retry._initial == 1
        assert new_retry._maximum == 2
        assert new_retry._multiplier == 3

    def test___str__(self):
        retry_ = retry.Retry()
        assert re.match((
            r'<Retry predicate=<function.*?if_exception_type.*?>, '
            r'initial=1.0, maximum=60.0, multiplier=2.0, deadline=120.0>'),
            str(retry_))

    @mock.patch('time.sleep', autospec=True)
    def test___call___and_execute_success(self, sleep):
        retry_ = retry.Retry()
        target = mock.Mock(spec=['__call__'], return_value=42)
        # __name__ is needed by functools.partial.
        target.__name__ = 'target'

        decorated = retry_(target)
        target.assert_not_called()

        result = decorated('meep')

        assert result == 42
        target.assert_called_once_with('meep')
        sleep.assert_not_called()

    # Make uniform return half of its maximum, which will be the calculated
    # sleep time.
    @mock.patch(
        'random.uniform', autospec=True, side_effect=lambda m, n: n/2.0)
    @mock.patch('time.sleep', autospec=True)
    def test___call___and_execute_retry(self, sleep, uniform):
        retry_ = retry.Retry(predicate=retry.if_exception_type(ValueError))
        target = mock.Mock(spec=['__call__'], side_effect=[ValueError(), 42])
        # __name__ is needed by functools.partial.
        target.__name__ = 'target'

        decorated = retry_(target)
        target.assert_not_called()

        result = decorated('meep')

        assert result == 42
        assert target.call_count == 2
        target.assert_has_calls([mock.call('meep'), mock.call('meep')])
        sleep.assert_called_once_with(retry_._initial)
