# Copyright 2021 The Matrix.org Foundation C.I.C.
#
# 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.

from unittest.mock import Mock

import yaml

from twisted.internet.defer import Deferred, ensureDeferred
from twisted.test.proto_helpers import MemoryReactor

from synapse.server import HomeServer
from synapse.storage.background_updates import BackgroundUpdater
from synapse.types import JsonDict
from synapse.util import Clock

from tests import unittest
from tests.test_utils import make_awaitable, simple_async_mock
from tests.unittest import override_config


class BackgroundUpdateTestCase(unittest.HomeserverTestCase):
    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
        self.updates: BackgroundUpdater = self.hs.get_datastores().main.db_pool.updates
        # the base test class should have run the real bg updates for us
        self.assertTrue(
            self.get_success(self.updates.has_completed_background_updates())
        )

        self.update_handler = Mock()
        self.updates.register_background_update_handler(
            "test_update", self.update_handler
        )
        self.store = self.hs.get_datastores().main

    async def update(self, progress: JsonDict, count: int) -> int:
        duration_ms = 10
        await self.clock.sleep((count * duration_ms) / 1000)
        progress = {"my_key": progress["my_key"] + 1}
        await self.store.db_pool.runInteraction(
            "update_progress",
            self.updates._background_update_progress_txn,
            "test_update",
            progress,
        )
        return count

    def test_do_background_update(self) -> None:
        # the time we claim it takes to update one item when running the update
        duration_ms = 10

        # the target runtime for each bg update
        target_background_update_duration_ms = 100

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        self.update_handler.side_effect = self.update
        self.update_handler.reset_mock()
        res = self.get_success(
            self.updates.do_next_background_update(False),
            by=0.02,
        )
        self.assertFalse(res)

        # on the first call, we should get run with the default background update size
        self.update_handler.assert_called_once_with(
            {"my_key": 1}, self.updates.default_background_batch_size
        )

        # second step: complete the update
        # we should now get run with a much bigger number of items to update
        async def update(progress: JsonDict, count: int) -> int:
            self.assertEqual(progress, {"my_key": 2})
            self.assertAlmostEqual(
                count,
                target_background_update_duration_ms / duration_ms,
                places=0,
            )
            await self.updates._end_background_update("test_update")
            return count

        self.update_handler.side_effect = update
        self.update_handler.reset_mock()
        result = self.get_success(self.updates.do_next_background_update(False))
        self.assertFalse(result)
        self.update_handler.assert_called_once()

        # third step: we don't expect to be called any more
        self.update_handler.reset_mock()
        result = self.get_success(self.updates.do_next_background_update(False))
        self.assertTrue(result)
        self.assertFalse(self.update_handler.called)

    @override_config(
        yaml.safe_load(
            """
            background_updates:
                default_batch_size: 20
            """
        )
    )
    def test_background_update_default_batch_set_by_config(self) -> None:
        """
        Test that the background update is run with the default_batch_size set by the config
        """

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        self.update_handler.side_effect = self.update
        self.update_handler.reset_mock()
        res = self.get_success(
            self.updates.do_next_background_update(False),
            by=0.01,
        )
        self.assertFalse(res)

        # on the first call, we should get run with the default background update size specified in the config
        self.update_handler.assert_called_once_with({"my_key": 1}, 20)

    def test_background_update_default_sleep_behavior(self) -> None:
        """
        Test default background update behavior, which is to sleep
        """

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        self.update_handler.side_effect = self.update
        self.update_handler.reset_mock()
        self.updates.start_doing_background_updates()

        # 2: advance the reactor less than the default sleep duration (1000ms)
        self.reactor.pump([0.5])
        # check that an update has not been run
        self.update_handler.assert_not_called()

        # advance reactor past default sleep duration
        self.reactor.pump([1])
        # check that update has been run
        self.update_handler.assert_called()

    @override_config(
        yaml.safe_load(
            """
            background_updates:
                sleep_duration_ms: 500
            """
        )
    )
    def test_background_update_sleep_set_in_config(self) -> None:
        """
        Test that changing the sleep time in the config changes how long it sleeps
        """

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        self.update_handler.side_effect = self.update
        self.update_handler.reset_mock()
        self.updates.start_doing_background_updates()

        # 2: advance the reactor less than the configured sleep duration (500ms)
        self.reactor.pump([0.45])
        # check that an update has not been run
        self.update_handler.assert_not_called()

        # advance reactor past config sleep duration but less than default duration
        self.reactor.pump([0.75])
        # check that update has been run
        self.update_handler.assert_called()

    @override_config(
        yaml.safe_load(
            """
            background_updates:
                sleep_enabled: false
            """
        )
    )
    def test_disabling_background_update_sleep(self) -> None:
        """
        Test that disabling sleep in the config results in bg update not sleeping
        """

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        self.update_handler.side_effect = self.update
        self.update_handler.reset_mock()
        self.updates.start_doing_background_updates()

        # 2: advance the reactor very little
        self.reactor.pump([0.025])
        # check that an update has run
        self.update_handler.assert_called()

    @override_config(
        yaml.safe_load(
            """
            background_updates:
                background_update_duration_ms: 500
            """
        )
    )
    def test_background_update_duration_set_in_config(self) -> None:
        """
        Test that the desired duration set in the config is used in determining batch size
        """
        # Duration of one background update item
        duration_ms = 10

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        self.update_handler.side_effect = self.update
        self.update_handler.reset_mock()
        res = self.get_success(
            self.updates.do_next_background_update(False),
            by=0.02,
        )
        self.assertFalse(res)

        # the first update was run with the default batch size, this should be run with 500ms as the
        # desired duration
        async def update(progress: JsonDict, count: int) -> int:
            self.assertEqual(progress, {"my_key": 2})
            self.assertAlmostEqual(
                count,
                500 / duration_ms,
                places=0,
            )
            await self.updates._end_background_update("test_update")
            return count

        self.update_handler.side_effect = update
        self.get_success(self.updates.do_next_background_update(False))

    @override_config(
        yaml.safe_load(
            """
            background_updates:
                min_batch_size: 5
            """
        )
    )
    def test_background_update_min_batch_set_in_config(self) -> None:
        """
        Test that the minimum batch size set in the config is used
        """
        # a very long-running individual update
        duration_ms = 50

        self.get_success(
            self.store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": '{"my_key": 1}'},
            )
        )

        # Run the update with the long-running update item
        async def update_long(progress: JsonDict, count: int) -> int:
            await self.clock.sleep((count * duration_ms) / 1000)
            progress = {"my_key": progress["my_key"] + 1}
            await self.store.db_pool.runInteraction(
                "update_progress",
                self.updates._background_update_progress_txn,
                "test_update",
                progress,
            )
            return count

        self.update_handler.side_effect = update_long
        self.update_handler.reset_mock()
        res = self.get_success(
            self.updates.do_next_background_update(False),
            by=1,
        )
        self.assertFalse(res)

        # the first update was run with the default batch size, this should be run with minimum batch size
        # as the first items took a very long time
        async def update_short(progress: JsonDict, count: int) -> int:
            self.assertEqual(progress, {"my_key": 2})
            self.assertEqual(count, 5)
            await self.updates._end_background_update("test_update")
            return count

        self.update_handler.side_effect = update_short
        self.get_success(self.updates.do_next_background_update(False))


class BackgroundUpdateControllerTestCase(unittest.HomeserverTestCase):
    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
        self.updates: BackgroundUpdater = self.hs.get_datastores().main.db_pool.updates
        # the base test class should have run the real bg updates for us
        self.assertTrue(
            self.get_success(self.updates.has_completed_background_updates())
        )

        self.update_deferred: Deferred[int] = Deferred()
        self.update_handler = Mock(return_value=self.update_deferred)
        self.updates.register_background_update_handler(
            "test_update", self.update_handler
        )

        # Mock out the AsyncContextManager
        class MockCM:
            __aenter__ = simple_async_mock(return_value=None)
            __aexit__ = simple_async_mock(return_value=None)

        self._update_ctx_manager = MockCM

        # Mock out the `update_handler` callback
        self._on_update = Mock(return_value=self._update_ctx_manager())

        # Define a default batch size value that's not the same as the internal default
        # value (100).
        self._default_batch_size = 500

        # Register the callbacks with more mocks
        self.hs.get_module_api().register_background_update_controller_callbacks(
            on_update=self._on_update,
            min_batch_size=Mock(return_value=make_awaitable(self._default_batch_size)),
            default_batch_size=Mock(
                return_value=make_awaitable(self._default_batch_size),
            ),
        )

    def test_controller(self) -> None:
        store = self.hs.get_datastores().main
        self.get_success(
            store.db_pool.simple_insert(
                "background_updates",
                values={"update_name": "test_update", "progress_json": "{}"},
            )
        )

        # Set the return value for the context manager.
        enter_defer: Deferred[int] = Deferred()
        self._update_ctx_manager.__aenter__ = Mock(return_value=enter_defer)

        # Start the background update.
        do_update_d = ensureDeferred(self.updates.do_next_background_update(True))

        self.pump()

        # `run_update` should have been called, but the update handler won't be
        # called until the `enter_defer` (returned by `__aenter__`) is resolved.
        self._on_update.assert_called_once_with(
            "test_update",
            "master",
            False,
        )
        self.assertFalse(do_update_d.called)
        self.assertFalse(self.update_deferred.called)

        # Resolving the `enter_defer` should call the update handler, which then
        # blocks.
        enter_defer.callback(100)
        self.pump()
        self.update_handler.assert_called_once_with({}, self._default_batch_size)
        self.assertFalse(self.update_deferred.called)
        self._update_ctx_manager.__aexit__.assert_not_called()

        # Resolving the update handler deferred should cause the
        # `do_next_background_update` to finish and return
        self.update_deferred.callback(100)
        self.pump()
        self._update_ctx_manager.__aexit__.assert_called()
        self.get_success(do_update_d)