from typing import Callable, Collection
from unittest import mock
from unittest.mock import AsyncMock, Mock

from twisted.internet.testing import MemoryReactor

from synapse.api.constants import EventTypes
from synapse.events import EventBase
from synapse.federation.sender import (
    FederationSender,
    PerDestinationQueue,
    TransactionManager,
)
from synapse.federation.units import Edu, Transaction
from synapse.rest import admin
from synapse.rest.client import login, room
from synapse.server import HomeServer
from synapse.types import JsonDict
from synapse.util.clock import Clock
from synapse.util.retryutils import NotRetryingDestination

from tests.test_utils import event_injection
from tests.unittest import FederatingHomeserverTestCase


class FederationCatchUpTestCases(FederatingHomeserverTestCase):
    """
    Tests cases of catching up over federation.

    By default for test cases federation sending is disabled. This Test class has it
    re-enabled for the main process.
    """

    servlets = [
        admin.register_servlets,
        room.register_servlets,
        login.register_servlets,
    ]

    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
        self.federation_transport_client = Mock(spec=["send_transaction"])
        return self.setup_test_homeserver(
            federation_transport_client=self.federation_transport_client,
        )

    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
        # stub out get_current_hosts_in_room
        state_storage_controller = hs.get_storage_controllers().state

        # This mock is crucial for destination_rooms to be populated.
        # TODO: this seems to no longer be the case---tests pass with this mock
        # commented out.
        state_storage_controller.get_current_hosts_in_room = AsyncMock(  # type: ignore[method-assign]
            return_value={"test", "host2"}
        )

        # whenever send_transaction is called, record the pdu data
        self.pdus: list[JsonDict] = []
        self.failed_pdus: list[JsonDict] = []
        self.is_online = True
        self.federation_transport_client.send_transaction.side_effect = (
            self.record_transaction
        )

        federation_sender = hs.get_federation_sender()
        assert isinstance(federation_sender, FederationSender)
        self.federation_sender = federation_sender

    def default_config(self) -> JsonDict:
        config = super().default_config()
        config["federation_sender_instances"] = None
        return config

    async def record_transaction(
        self, txn: Transaction, json_cb: Callable[[], JsonDict] | None
    ) -> JsonDict:
        if json_cb is None:
            # The tests seem to expect that this method raises in this situation.
            raise Exception("Blank json_cb")
        elif self.is_online:
            data = json_cb()
            self.pdus.extend(data["pdus"])
            return {}
        else:
            data = json_cb()
            self.failed_pdus.extend(data["pdus"])
            raise NotRetryingDestination(0, 24 * 60 * 60 * 1000, txn.destination)

    def get_destination_room(self, room: str, destination: str = "host2") -> dict:
        """
        Gets the destination_rooms entry for a (destination, room_id) pair.

        Args:
            room: room ID
            destination: what destination, default is "host2"

        Returns:
            Dictionary of { event_id: str, stream_ordering: int }
        """
        event_id, stream_ordering = self.get_success(
            self.hs.get_datastores().main.db_pool.execute(
                "test:get_destination_rooms",
                """
                SELECT event_id, stream_ordering
                    FROM destination_rooms dr
                    JOIN events USING (stream_ordering)
                    WHERE dr.destination = ? AND dr.room_id = ?
                """,
                destination,
                room,
            )
        )[0]
        return {"event_id": event_id, "stream_ordering": stream_ordering}

    def test_catch_up_destination_rooms_tracking(self) -> None:
        """
        Tests that we populate the `destination_rooms` table as needed.
        """
        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room = self.helper.create_room_as("u1", tok=u1_token)

        self.get_success(
            event_injection.inject_member_event(self.hs, room, "@user:host2", "join")
        )

        event_id_1 = self.helper.send(room, "wombats!", tok=u1_token)["event_id"]

        row_1 = self.get_destination_room(room)

        event_id_2 = self.helper.send(room, "rabbits!", tok=u1_token)["event_id"]

        row_2 = self.get_destination_room(room)

        # check: events correctly registered in order
        self.assertEqual(row_1["event_id"], event_id_1)
        self.assertEqual(row_2["event_id"], event_id_2)
        self.assertEqual(row_1["stream_ordering"], row_2["stream_ordering"] - 1)

    def test_catch_up_last_successful_stream_ordering_tracking(self) -> None:
        """
        Tests that we populate the `destination_rooms` table as needed.
        """
        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room = self.helper.create_room_as("u1", tok=u1_token)

        # take the remote offline
        self.is_online = False

        self.get_success(
            event_injection.inject_member_event(self.hs, room, "@user:host2", "join")
        )

        self.helper.send(room, "wombats!", tok=u1_token)
        self.pump()

        lsso_1 = self.get_success(
            self.hs.get_datastores().main.get_destination_last_successful_stream_ordering(
                "host2"
            )
        )

        self.assertIsNone(
            lsso_1,
            "There should be no last successful stream ordering for an always-offline destination",
        )

        # bring the remote online
        self.is_online = True

        event_id_2 = self.helper.send(room, "rabbits!", tok=u1_token)["event_id"]

        lsso_2 = self.get_success(
            self.hs.get_datastores().main.get_destination_last_successful_stream_ordering(
                "host2"
            )
        )
        row_2 = self.get_destination_room(room)

        self.assertEqual(
            self.pdus[0]["content"]["body"],
            "rabbits!",
            "Test fault: didn't receive the right PDU",
        )
        self.assertEqual(
            row_2["event_id"],
            event_id_2,
            "Test fault: destination_rooms not updated correctly",
        )
        self.assertEqual(
            lsso_2,
            row_2["stream_ordering"],
            "Send succeeded but not marked as last_successful_stream_ordering",
        )

    def test_catch_up_from_blank_state(self) -> None:
        """
        Runs an overall test of federation catch-up from scratch.
        Further tests will focus on more narrow aspects and edge-cases, but I
        hope to provide an overall view with this test.
        """
        # bring the other server online
        self.is_online = True

        # let's make some events for the other server to receive
        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room_1 = self.helper.create_room_as("u1", tok=u1_token)
        room_2 = self.helper.create_room_as("u1", tok=u1_token)

        # also critical to federate
        self.get_success(
            event_injection.inject_member_event(self.hs, room_1, "@user:host2", "join")
        )
        self.get_success(
            event_injection.inject_member_event(self.hs, room_2, "@user:host2", "join")
        )

        self.helper.send_state(
            room_1, event_type="m.room.topic", body={"topic": "wombat"}, tok=u1_token
        )

        # check: PDU received for topic event
        self.assertEqual(len(self.pdus), 1)
        self.assertEqual(self.pdus[0]["type"], "m.room.topic")

        # take the remote offline
        self.is_online = False

        # send another event
        self.helper.send(room_1, "hi user!", tok=u1_token)

        # check: things didn't go well since the remote is down
        self.assertEqual(len(self.failed_pdus), 1)
        self.assertEqual(self.failed_pdus[0]["content"]["body"], "hi user!")

        # let's delete the federation transmission queue
        # (this pretends we are starting up fresh.)
        self.assertFalse(
            self.federation_sender._per_destination_queues[
                "host2"
            ].transmission_loop_running
        )
        del self.federation_sender._per_destination_queues["host2"]

        # let's also clear any backoffs
        self.get_success(
            self.hs.get_datastores().main.set_destination_retry_timings(
                "host2", None, 0, 0
            )
        )

        # bring the remote online and clear the received pdu list
        self.is_online = True
        self.pdus = []

        # now we need to initiate a federation transaction somehow…
        # to do that, let's send another event (because it's simple to do)
        # (do it to another room otherwise the catch-up logic decides it doesn't
        # need to catch up room_1 — something I overlooked when first writing
        # this test)
        self.helper.send(room_2, "wombats!", tok=u1_token)

        # we should now have received both PDUs
        self.assertEqual(len(self.pdus), 2)
        self.assertEqual(self.pdus[0]["content"]["body"], "hi user!")
        self.assertEqual(self.pdus[1]["content"]["body"], "wombats!")

    def make_fake_destination_queue(
        self, destination: str = "host2"
    ) -> tuple[PerDestinationQueue, list[EventBase]]:
        """
        Makes a fake per-destination queue.
        """
        transaction_manager = TransactionManager(self.hs)
        per_dest_queue = PerDestinationQueue(self.hs, transaction_manager, destination)
        results_list = []

        async def fake_send(
            destination_tm: str,
            pending_pdus: list[EventBase],
            _pending_edus: list[Edu],
        ) -> None:
            assert destination == destination_tm
            results_list.extend(pending_pdus)

        transaction_manager.send_new_transaction = fake_send  # type: ignore[assignment]

        return per_dest_queue, results_list

    def test_catch_up_loop(self) -> None:
        """
        Tests the behaviour of _catch_up_transmission_loop.
        """

        # ARRANGE:
        #  - a local user (u1)
        #  - 3 rooms which u1 is joined to (and remote user @user:host2 is
        #    joined to)
        #  - some events (1 to 5) in those rooms
        #      we have 'already sent' events 1 and 2 to host2
        per_dest_queue, sent_pdus = self.make_fake_destination_queue()

        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room_1 = self.helper.create_room_as("u1", tok=u1_token)
        room_2 = self.helper.create_room_as("u1", tok=u1_token)
        room_3 = self.helper.create_room_as("u1", tok=u1_token)
        self.get_success(
            event_injection.inject_member_event(self.hs, room_1, "@user:host2", "join")
        )
        self.get_success(
            event_injection.inject_member_event(self.hs, room_2, "@user:host2", "join")
        )
        self.get_success(
            event_injection.inject_member_event(self.hs, room_3, "@user:host2", "join")
        )

        # create some events
        self.helper.send(room_1, "you hear me!!", tok=u1_token)
        event_id_2 = self.helper.send(room_2, "wombats!", tok=u1_token)["event_id"]
        self.helper.send(room_3, "Matrix!", tok=u1_token)
        event_id_4 = self.helper.send(room_2, "rabbits!", tok=u1_token)["event_id"]
        event_id_5 = self.helper.send(room_3, "Synapse!", tok=u1_token)["event_id"]

        # destination_rooms should already be populated, but let us pretend that we already
        # sent (successfully) up to and including event id 2
        event_2 = self.get_success(self.hs.get_datastores().main.get_event(event_id_2))

        # also fetch event 5 so we know its last_successful_stream_ordering later
        event_5 = self.get_success(self.hs.get_datastores().main.get_event(event_id_5))

        assert event_2.internal_metadata.stream_ordering is not None
        self.get_success(
            self.hs.get_datastores().main.set_destination_last_successful_stream_ordering(
                "host2", event_2.internal_metadata.stream_ordering
            )
        )

        # ACT
        self.get_success(per_dest_queue._catch_up_transmission_loop())

        # ASSERT, noticing in particular:
        # - event 3 not sent out, because event 5 replaces it
        # - order is least recent first, so event 5 comes after event 4
        # - catch-up is completed
        self.assertEqual(len(sent_pdus), 2)
        self.assertEqual(sent_pdus[0].event_id, event_id_4)
        self.assertEqual(sent_pdus[1].event_id, event_id_5)
        self.assertFalse(per_dest_queue._catching_up)
        self.assertEqual(
            per_dest_queue._last_successful_stream_ordering,
            event_5.internal_metadata.stream_ordering,
        )

    def test_catch_up_on_synapse_startup(self) -> None:
        """
        Tests the behaviour of get_catch_up_outstanding_destinations and
            _wake_destinations_needing_catchup.
        """

        # list of sorted server names (note that there are more servers than the batch
        # size used in get_catch_up_outstanding_destinations).
        server_names = ["server%02d" % number for number in range(42)] + ["zzzerver"]

        # ARRANGE:
        #  - a local user (u1)
        #  - a room which u1 is joined to (and remote users @user:serverXX are
        #    joined to)

        # mark the remotes as online
        self.is_online = True

        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room_id = self.helper.create_room_as("u1", tok=u1_token)

        for server_name in server_names:
            self.get_success(
                event_injection.inject_member_event(
                    self.hs, room_id, "@user:%s" % server_name, "join"
                )
            )

        # create an event
        self.helper.send(room_id, "deary me!", tok=u1_token)

        # ASSERT:
        # - All servers are up to date so none should have outstanding catch-up
        outstanding_when_successful = self.get_success(
            self.hs.get_datastores().main.get_catch_up_outstanding_destinations(None)
        )
        self.assertEqual(outstanding_when_successful, [])

        # ACT:
        # - Make the remote servers unreachable
        self.is_online = False

        # - Mark zzzerver as being backed-off from
        now = self.clock.time_msec()
        self.get_success(
            self.hs.get_datastores().main.set_destination_retry_timings(
                "zzzerver",
                now,
                now,
                24 * 60 * 60 * 1000,  # retry in 1 day
            )
        )

        # - Send an event
        self.helper.send(room_id, "can anyone hear me?", tok=u1_token)

        # ASSERT (get_catch_up_outstanding_destinations):
        # - all remotes are outstanding
        # - they are returned in batches of 25, in order
        outstanding_1 = self.get_success(
            self.hs.get_datastores().main.get_catch_up_outstanding_destinations(None)
        )

        self.assertEqual(len(outstanding_1), 25)
        self.assertEqual(outstanding_1, server_names[0:25])

        outstanding_2 = self.get_success(
            self.hs.get_datastores().main.get_catch_up_outstanding_destinations(
                outstanding_1[-1]
            )
        )
        self.assertNotIn("zzzerver", outstanding_2)
        self.assertEqual(len(outstanding_2), 17)
        self.assertEqual(outstanding_2, server_names[25:-1])

        # ACT: call _wake_destinations_needing_catchup

        # patch wake_destination to just count the destinations instead
        woken = set()

        def wake_destination_track(destination: str) -> None:
            woken.add(destination)

        self.federation_sender.wake_destination = wake_destination_track  # type: ignore[method-assign]

        # We wait quite long so that all dests can be woken up, since there is a delay
        # between them.
        self.pump(by=5.0)

        # ASSERT (_wake_destinations_needing_catchup):
        # - all remotes are woken up, save for zzzerver
        self.assertNotIn("zzzerver", woken)
        # - all destinations are woken, potentially more than once, since the
        # wake up is called regularly and we don't ack in this test that a transaction
        # has been successfully sent.
        self.assertCountEqual(woken, set(server_names[:-1]))

    def test_not_latest_event(self) -> None:
        """Test that we send the latest event in the room even if its not ours."""

        per_dest_queue, sent_pdus = self.make_fake_destination_queue()

        # Make a room with a local user, and two servers. One will go offline
        # and one will send some events.
        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room_1 = self.helper.create_room_as("u1", tok=u1_token)

        self.get_success(
            event_injection.inject_member_event(self.hs, room_1, "@user:host2", "join")
        )
        event_1 = self.get_success(
            event_injection.inject_member_event(self.hs, room_1, "@user:host3", "join")
        )

        # First we send something from the local server, so that we notice the
        # remote is down and go into catchup mode.
        self.helper.send(room_1, "you hear me!!", tok=u1_token)

        # Now simulate us receiving an event from the still online remote.
        event_2 = self.get_success(
            event_injection.inject_event(
                self.hs,
                type=EventTypes.Message,
                sender="@user:host3",
                room_id=room_1,
                content={"msgtype": "m.text", "body": "Hello"},
            )
        )

        assert event_1.internal_metadata.stream_ordering is not None
        self.get_success(
            self.hs.get_datastores().main.set_destination_last_successful_stream_ordering(
                "host2", event_1.internal_metadata.stream_ordering
            )
        )

        self.get_success(per_dest_queue._catch_up_transmission_loop())

        # We expect only the last message from the remote, event_2, to have been
        # sent, rather than the last *local* event that was sent.
        self.assertEqual(len(sent_pdus), 1)
        self.assertEqual(sent_pdus[0].event_id, event_2.event_id)
        self.assertFalse(per_dest_queue._catching_up)

    def test_catch_up_is_not_blocked_by_remote_event_in_partial_state_room(
        self,
    ) -> None:
        """Detects (part of?) https://github.com/matrix-org/synapse/issues/15220."""
        # ARRANGE:
        # - a local user (u1)
        # - a room which contains u1 and two remote users, @u2:host2 and @u3:other
        # - events in that room such that
        #   - history visibility is restricted
        #   - u1 sent message events e1 and e2
        #   - afterwards, u3 sent a remote event e3
        # - catchup to begin for host2; last successfully sent event was e1
        per_dest_queue, sent_pdus = self.make_fake_destination_queue()

        self.register_user("u1", "you the one")
        u1_token = self.login("u1", "you the one")
        room = self.helper.create_room_as("u1", tok=u1_token)
        self.helper.send_state(
            room_id=room,
            event_type="m.room.history_visibility",
            body={"history_visibility": "joined"},
            tok=u1_token,
        )
        self.get_success(
            event_injection.inject_member_event(self.hs, room, "@u2:host2", "join")
        )
        self.get_success(
            event_injection.inject_member_event(self.hs, room, "@u3:other", "join")
        )

        # create some events
        event_id_1 = self.helper.send(room, "hello", tok=u1_token)["event_id"]
        event_id_2 = self.helper.send(room, "world", tok=u1_token)["event_id"]
        # pretend that u3 changes their displayname
        event_id_3 = self.get_success(
            event_injection.inject_member_event(self.hs, room, "@u3:other", "join")
        ).event_id

        # destination_rooms should already be populated, but let us pretend that we already
        # sent (successfully) up to and including event id 1
        event_1 = self.get_success(self.hs.get_datastores().main.get_event(event_id_1))
        assert event_1.internal_metadata.stream_ordering is not None
        self.get_success(
            self.hs.get_datastores().main.set_destination_last_successful_stream_ordering(
                "host2", event_1.internal_metadata.stream_ordering
            )
        )

        # also fetch event 2 so we can compare its stream ordering to the sender's
        # last_successful_stream_ordering later
        event_2 = self.get_success(self.hs.get_datastores().main.get_event(event_id_2))

        # Mock event 3 as having partial state
        self.get_success(
            event_injection.mark_event_as_partial_state(self.hs, event_id_3, room)
        )

        # Fail the test if we block on full state for event 3.
        async def mock_await_full_state(event_ids: Collection[str]) -> None:
            if event_id_3 in event_ids:
                raise AssertionError("Tried to await full state for event_id_3")

        # ACT
        with mock.patch.object(
            self.hs.get_storage_controllers().state._partial_state_events_tracker,
            "await_full_state",
            mock_await_full_state,
        ):
            self.get_success(per_dest_queue._catch_up_transmission_loop())

        # ASSERT
        # We should have:
        # - not sent event 3: it's not ours, and the room is partial stated
        # - fallen back to sending event 2: it's the most recent event in the room
        #   we tried to send to host2
        # - completed catch-up
        self.assertEqual(len(sent_pdus), 1)
        self.assertEqual(sent_pdus[0].event_id, event_id_2)
        self.assertFalse(per_dest_queue._catching_up)
        self.assertEqual(
            per_dest_queue._last_successful_stream_ordering,
            event_2.internal_metadata.stream_ordering,
        )
