# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2018 New Vector Ltd
#
# 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.

""" This module contains REST servlets to do with rooms: /rooms/<paths> """
import logging
import re
from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
from urllib import parse as urlparse

from synapse.api.constants import EventContentFields, EventTypes, Membership
from synapse.api.errors import (
    AuthError,
    Codes,
    InvalidClientCredentialsError,
    ShadowBanError,
    SynapseError,
)
from synapse.api.filtering import Filter
from synapse.appservice import ApplicationService
from synapse.events.utils import format_event_for_client_v2
from synapse.http.servlet import (
    RestServlet,
    assert_params_in_dict,
    parse_boolean,
    parse_integer,
    parse_json_object_from_request,
    parse_string,
    parse_strings_from_args,
)
from synapse.http.site import SynapseRequest
from synapse.logging.opentracing import set_tag
from synapse.rest.client.transactions import HttpTransactionCache
from synapse.rest.client.v2_alpha._base import client_patterns
from synapse.storage.state import StateFilter
from synapse.streams.config import PaginationConfig
from synapse.types import (
    JsonDict,
    Requester,
    RoomAlias,
    RoomID,
    StreamToken,
    ThirdPartyInstanceID,
    UserID,
    create_requester,
)
from synapse.util import json_decoder
from synapse.util.stringutils import parse_and_validate_server_name, random_string

if TYPE_CHECKING:
    from synapse.server import HomeServer

logger = logging.getLogger(__name__)


class TransactionRestServlet(RestServlet):
    def __init__(self, hs):
        super().__init__()
        self.txns = HttpTransactionCache(hs)


class RoomCreateRestServlet(TransactionRestServlet):
    # No PATTERN; we have custom dispatch rules here

    def __init__(self, hs):
        super().__init__(hs)
        self._room_creation_handler = hs.get_room_creation_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        PATTERNS = "/createRoom"
        register_txn_path(self, PATTERNS, http_server)

    def on_PUT(self, request, txn_id):
        set_tag("txn_id", txn_id)
        return self.txns.fetch_or_execute_request(request, self.on_POST, request)

    async def on_POST(self, request):
        requester = await self.auth.get_user_by_req(request)

        info, _ = await self._room_creation_handler.create_room(
            requester, self.get_room_config(request)
        )

        return 200, info

    def get_room_config(self, request):
        user_supplied_config = parse_json_object_from_request(request)
        return user_supplied_config


# TODO: Needs unit testing for generic events
class RoomStateEventRestServlet(TransactionRestServlet):
    def __init__(self, hs):
        super().__init__(hs)
        self.event_creation_handler = hs.get_event_creation_handler()
        self.room_member_handler = hs.get_room_member_handler()
        self.message_handler = hs.get_message_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        # /room/$roomid/state/$eventtype
        no_state_key = "/rooms/(?P<room_id>[^/]*)/state/(?P<event_type>[^/]*)$"

        # /room/$roomid/state/$eventtype/$statekey
        state_key = (
            "/rooms/(?P<room_id>[^/]*)/state/"
            "(?P<event_type>[^/]*)/(?P<state_key>[^/]*)$"
        )

        http_server.register_paths(
            "GET",
            client_patterns(state_key, v1=True),
            self.on_GET,
            self.__class__.__name__,
        )
        http_server.register_paths(
            "PUT",
            client_patterns(state_key, v1=True),
            self.on_PUT,
            self.__class__.__name__,
        )
        http_server.register_paths(
            "GET",
            client_patterns(no_state_key, v1=True),
            self.on_GET_no_state_key,
            self.__class__.__name__,
        )
        http_server.register_paths(
            "PUT",
            client_patterns(no_state_key, v1=True),
            self.on_PUT_no_state_key,
            self.__class__.__name__,
        )

    def on_GET_no_state_key(self, request, room_id, event_type):
        return self.on_GET(request, room_id, event_type, "")

    def on_PUT_no_state_key(self, request, room_id, event_type):
        return self.on_PUT(request, room_id, event_type, "")

    async def on_GET(self, request, room_id, event_type, state_key):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        format = parse_string(
            request, "format", default="content", allowed_values=["content", "event"]
        )

        msg_handler = self.message_handler
        data = await msg_handler.get_room_data(
            user_id=requester.user.to_string(),
            room_id=room_id,
            event_type=event_type,
            state_key=state_key,
        )

        if not data:
            raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)

        if format == "event":
            event = format_event_for_client_v2(data.get_dict())
            return 200, event
        elif format == "content":
            return 200, data.get_dict()["content"]

    async def on_PUT(self, request, room_id, event_type, state_key, txn_id=None):
        requester = await self.auth.get_user_by_req(request)

        if txn_id:
            set_tag("txn_id", txn_id)

        content = parse_json_object_from_request(request)

        event_dict = {
            "type": event_type,
            "content": content,
            "room_id": room_id,
            "sender": requester.user.to_string(),
        }

        if state_key is not None:
            event_dict["state_key"] = state_key

        try:
            if event_type == EventTypes.Member:
                membership = content.get("membership", None)
                event_id, _ = await self.room_member_handler.update_membership(
                    requester,
                    target=UserID.from_string(state_key),
                    room_id=room_id,
                    action=membership,
                    content=content,
                )
            else:
                (
                    event,
                    _,
                ) = await self.event_creation_handler.create_and_send_nonmember_event(
                    requester, event_dict, txn_id=txn_id
                )
                event_id = event.event_id
        except ShadowBanError:
            event_id = "$" + random_string(43)

        set_tag("event_id", event_id)
        ret = {"event_id": event_id}
        return 200, ret


# TODO: Needs unit testing for generic events + feedback
class RoomSendEventRestServlet(TransactionRestServlet):
    def __init__(self, hs):
        super().__init__(hs)
        self.event_creation_handler = hs.get_event_creation_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        # /rooms/$roomid/send/$event_type[/$txn_id]
        PATTERNS = "/rooms/(?P<room_id>[^/]*)/send/(?P<event_type>[^/]*)"
        register_txn_path(self, PATTERNS, http_server, with_get=True)

    async def on_POST(self, request, room_id, event_type, txn_id=None):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        content = parse_json_object_from_request(request)

        event_dict = {
            "type": event_type,
            "content": content,
            "room_id": room_id,
            "sender": requester.user.to_string(),
        }

        if b"ts" in request.args and requester.app_service:
            event_dict["origin_server_ts"] = parse_integer(request, "ts", 0)

        try:
            (
                event,
                _,
            ) = await self.event_creation_handler.create_and_send_nonmember_event(
                requester, event_dict, txn_id=txn_id
            )
            event_id = event.event_id
        except ShadowBanError:
            event_id = "$" + random_string(43)

        set_tag("event_id", event_id)
        return 200, {"event_id": event_id}

    def on_GET(self, request, room_id, event_type, txn_id):
        return 200, "Not implemented"

    def on_PUT(self, request, room_id, event_type, txn_id):
        set_tag("txn_id", txn_id)

        return self.txns.fetch_or_execute_request(
            request, self.on_POST, request, room_id, event_type, txn_id
        )


class RoomBatchSendEventRestServlet(TransactionRestServlet):
    """
    API endpoint which can insert a chunk of events historically back in time
    next to the given `prev_event`.

    `chunk_id` comes from `next_chunk_id `in the response of the batch send
    endpoint and is derived from the "insertion" events added to each chunk.
    It's not required for the first batch send.

    `state_events_at_start` is used to define the historical state events
    needed to auth the events like join events. These events will float
    outside of the normal DAG as outlier's and won't be visible in the chat
    history which also allows us to insert multiple chunks without having a bunch
    of `@mxid joined the room` noise between each chunk.

    `events` is chronological chunk/list of events you want to insert.
    There is a reverse-chronological constraint on chunks so once you insert
    some messages, you can only insert older ones after that.
    tldr; Insert chunks from your most recent history -> oldest history.

    POST /_matrix/client/unstable/org.matrix.msc2716/rooms/<roomID>/batch_send?prev_event=<eventID>&chunk_id=<chunkID>
    {
        "events": [ ... ],
        "state_events_at_start": [ ... ]
    }
    """

    PATTERNS = (
        re.compile(
            "^/_matrix/client/unstable/org.matrix.msc2716"
            "/rooms/(?P<room_id>[^/]*)/batch_send$"
        ),
    )

    def __init__(self, hs):
        super().__init__(hs)
        self.hs = hs
        self.store = hs.get_datastore()
        self.state_store = hs.get_storage().state
        self.event_creation_handler = hs.get_event_creation_handler()
        self.room_member_handler = hs.get_room_member_handler()
        self.auth = hs.get_auth()

    async def _inherit_depth_from_prev_ids(self, prev_event_ids) -> int:
        (
            most_recent_prev_event_id,
            most_recent_prev_event_depth,
        ) = await self.store.get_max_depth_of(prev_event_ids)

        # We want to insert the historical event after the `prev_event` but before the successor event
        #
        # We inherit depth from the successor event instead of the `prev_event`
        # because events returned from `/messages` are first sorted by `topological_ordering`
        # which is just the `depth` and then tie-break with `stream_ordering`.
        #
        # We mark these inserted historical events as "backfilled" which gives them a
        # negative `stream_ordering`. If we use the same depth as the `prev_event`,
        # then our historical event will tie-break and be sorted before the `prev_event`
        # when it should come after.
        #
        # We want to use the successor event depth so they appear after `prev_event` because
        # it has a larger `depth` but before the successor event because the `stream_ordering`
        # is negative before the successor event.
        successor_event_ids = await self.store.get_successor_events(
            [most_recent_prev_event_id]
        )

        # If we can't find any successor events, then it's a forward extremity of
        # historical messages and we can just inherit from the previous historical
        # event which we can already assume has the correct depth where we want
        # to insert into.
        if not successor_event_ids:
            depth = most_recent_prev_event_depth
        else:
            (
                _,
                oldest_successor_depth,
            ) = await self.store.get_min_depth_of(successor_event_ids)

            depth = oldest_successor_depth

        return depth

    def _create_insertion_event_dict(
        self, sender: str, room_id: str, origin_server_ts: int
    ):
        """Creates an event dict for an "insertion" event with the proper fields
        and a random chunk ID.

        Args:
            sender: The event author MXID
            room_id: The room ID that the event belongs to
            origin_server_ts: Timestamp when the event was sent

        Returns:
            Tuple of event ID and stream ordering position
        """

        next_chunk_id = random_string(8)
        insertion_event = {
            "type": EventTypes.MSC2716_INSERTION,
            "sender": sender,
            "room_id": room_id,
            "content": {
                EventContentFields.MSC2716_NEXT_CHUNK_ID: next_chunk_id,
                EventContentFields.MSC2716_HISTORICAL: True,
            },
            "origin_server_ts": origin_server_ts,
        }

        return insertion_event

    async def _create_requester_for_user_id_from_app_service(
        self, user_id: str, app_service: ApplicationService
    ) -> Requester:
        """Creates a new requester for the given user_id
        and validates that the app service is allowed to control
        the given user.

        Args:
            user_id: The author MXID that the app service is controlling
            app_service: The app service that controls the user

        Returns:
            Requester object
        """

        await self.auth.validate_appservice_can_control_user_id(app_service, user_id)

        return create_requester(user_id, app_service=app_service)

    async def on_POST(self, request, room_id):
        requester = await self.auth.get_user_by_req(request, allow_guest=False)

        if not requester.app_service:
            raise AuthError(
                403,
                "Only application services can use the /batchsend endpoint",
            )

        body = parse_json_object_from_request(request)
        assert_params_in_dict(body, ["state_events_at_start", "events"])

        prev_events_from_query = parse_strings_from_args(request.args, "prev_event")
        chunk_id_from_query = parse_string(request, "chunk_id")

        if prev_events_from_query is None:
            raise SynapseError(
                400,
                "prev_event query parameter is required when inserting historical messages back in time",
                errcode=Codes.MISSING_PARAM,
            )

        # For the event we are inserting next to (`prev_events_from_query`),
        # find the most recent auth events (derived from state events) that
        # allowed that message to be sent. We will use that as a base
        # to auth our historical messages against.
        (
            most_recent_prev_event_id,
            _,
        ) = await self.store.get_max_depth_of(prev_events_from_query)
        # mapping from (type, state_key) -> state_event_id
        prev_state_map = await self.state_store.get_state_ids_for_event(
            most_recent_prev_event_id
        )
        # List of state event ID's
        prev_state_ids = list(prev_state_map.values())
        auth_event_ids = prev_state_ids

        state_events_at_start = []
        for state_event in body["state_events_at_start"]:
            assert_params_in_dict(
                state_event, ["type", "origin_server_ts", "content", "sender"]
            )

            logger.debug(
                "RoomBatchSendEventRestServlet inserting state_event=%s, auth_event_ids=%s",
                state_event,
                auth_event_ids,
            )

            event_dict = {
                "type": state_event["type"],
                "origin_server_ts": state_event["origin_server_ts"],
                "content": state_event["content"],
                "room_id": room_id,
                "sender": state_event["sender"],
                "state_key": state_event["state_key"],
            }

            # Mark all events as historical
            event_dict["content"][EventContentFields.MSC2716_HISTORICAL] = True

            # Make the state events float off on their own
            fake_prev_event_id = "$" + random_string(43)

            # TODO: This is pretty much the same as some other code to handle inserting state in this file
            if event_dict["type"] == EventTypes.Member:
                membership = event_dict["content"].get("membership", None)
                event_id, _ = await self.room_member_handler.update_membership(
                    await self._create_requester_for_user_id_from_app_service(
                        state_event["sender"], requester.app_service
                    ),
                    target=UserID.from_string(event_dict["state_key"]),
                    room_id=room_id,
                    action=membership,
                    content=event_dict["content"],
                    outlier=True,
                    prev_event_ids=[fake_prev_event_id],
                    # Make sure to use a copy of this list because we modify it
                    # later in the loop here. Otherwise it will be the same
                    # reference and also update in the event when we append later.
                    auth_event_ids=auth_event_ids.copy(),
                )
            else:
                # TODO: Add some complement tests that adds state that is not member joins
                # and will use this code path. Maybe we only want to support join state events
                # and can get rid of this `else`?
                (
                    event,
                    _,
                ) = await self.event_creation_handler.create_and_send_nonmember_event(
                    await self._create_requester_for_user_id_from_app_service(
                        state_event["sender"], requester.app_service
                    ),
                    event_dict,
                    outlier=True,
                    prev_event_ids=[fake_prev_event_id],
                    # Make sure to use a copy of this list because we modify it
                    # later in the loop here. Otherwise it will be the same
                    # reference and also update in the event when we append later.
                    auth_event_ids=auth_event_ids.copy(),
                )
                event_id = event.event_id

            state_events_at_start.append(event_id)
            auth_event_ids.append(event_id)

        events_to_create = body["events"]

        inherited_depth = await self._inherit_depth_from_prev_ids(
            prev_events_from_query
        )

        # Figure out which chunk to connect to. If they passed in
        # chunk_id_from_query let's use it. The chunk ID passed in comes
        # from the chunk_id in the "insertion" event from the previous chunk.
        last_event_in_chunk = events_to_create[-1]
        chunk_id_to_connect_to = chunk_id_from_query
        base_insertion_event = None
        if chunk_id_from_query:
            #  All but the first base insertion event should point at a fake
            #  event, which causes the HS to ask for the state at the start of
            #  the chunk later.
            prev_event_ids = [fake_prev_event_id]
            # TODO: Verify the chunk_id_from_query corresponds to an insertion event
            pass
        # Otherwise, create an insertion event to act as a starting point.
        #
        # We don't always have an insertion event to start hanging more history
        # off of (ideally there would be one in the main DAG, but that's not the
        # case if we're wanting to add history to e.g. existing rooms without
        # an insertion event), in which case we just create a new insertion event
        # that can then get pointed to by a "marker" event later.
        else:
            prev_event_ids = prev_events_from_query

            base_insertion_event_dict = self._create_insertion_event_dict(
                sender=requester.user.to_string(),
                room_id=room_id,
                origin_server_ts=last_event_in_chunk["origin_server_ts"],
            )
            base_insertion_event_dict["prev_events"] = prev_event_ids.copy()

            (
                base_insertion_event,
                _,
            ) = await self.event_creation_handler.create_and_send_nonmember_event(
                await self._create_requester_for_user_id_from_app_service(
                    base_insertion_event_dict["sender"],
                    requester.app_service,
                ),
                base_insertion_event_dict,
                prev_event_ids=base_insertion_event_dict.get("prev_events"),
                auth_event_ids=auth_event_ids,
                historical=True,
                depth=inherited_depth,
            )

            chunk_id_to_connect_to = base_insertion_event["content"][
                EventContentFields.MSC2716_NEXT_CHUNK_ID
            ]

        # Connect this current chunk to the insertion event from the previous chunk
        chunk_event = {
            "type": EventTypes.MSC2716_CHUNK,
            "sender": requester.user.to_string(),
            "room_id": room_id,
            "content": {
                EventContentFields.MSC2716_CHUNK_ID: chunk_id_to_connect_to,
                EventContentFields.MSC2716_HISTORICAL: True,
            },
            # Since the chunk event is put at the end of the chunk,
            # where the newest-in-time event is, copy the origin_server_ts from
            # the last event we're inserting
            "origin_server_ts": last_event_in_chunk["origin_server_ts"],
        }
        # Add the chunk event to the end of the chunk (newest-in-time)
        events_to_create.append(chunk_event)

        # Add an "insertion" event to the start of each chunk (next to the oldest-in-time
        # event in the chunk) so the next chunk can be connected to this one.
        insertion_event = self._create_insertion_event_dict(
            sender=requester.user.to_string(),
            room_id=room_id,
            # Since the insertion event is put at the start of the chunk,
            # where the oldest-in-time event is, copy the origin_server_ts from
            # the first event we're inserting
            origin_server_ts=events_to_create[0]["origin_server_ts"],
        )
        # Prepend the insertion event to the start of the chunk (oldest-in-time)
        events_to_create = [insertion_event] + events_to_create

        event_ids = []
        events_to_persist = []
        for ev in events_to_create:
            assert_params_in_dict(ev, ["type", "origin_server_ts", "content", "sender"])

            event_dict = {
                "type": ev["type"],
                "origin_server_ts": ev["origin_server_ts"],
                "content": ev["content"],
                "room_id": room_id,
                "sender": ev["sender"],  # requester.user.to_string(),
                "prev_events": prev_event_ids.copy(),
            }

            # Mark all events as historical
            event_dict["content"][EventContentFields.MSC2716_HISTORICAL] = True

            event, context = await self.event_creation_handler.create_event(
                await self._create_requester_for_user_id_from_app_service(
                    ev["sender"], requester.app_service
                ),
                event_dict,
                prev_event_ids=event_dict.get("prev_events"),
                auth_event_ids=auth_event_ids,
                historical=True,
                depth=inherited_depth,
            )
            logger.debug(
                "RoomBatchSendEventRestServlet inserting event=%s, prev_event_ids=%s, auth_event_ids=%s",
                event,
                prev_event_ids,
                auth_event_ids,
            )

            assert self.hs.is_mine_id(event.sender), "User must be our own: %s" % (
                event.sender,
            )

            events_to_persist.append((event, context))
            event_id = event.event_id

            event_ids.append(event_id)
            prev_event_ids = [event_id]

        # Persist events in reverse-chronological order so they have the
        # correct stream_ordering as they are backfilled (which decrements).
        # Events are sorted by (topological_ordering, stream_ordering)
        # where topological_ordering is just depth.
        for (event, context) in reversed(events_to_persist):
            ev = await self.event_creation_handler.handle_new_client_event(
                await self._create_requester_for_user_id_from_app_service(
                    event["sender"], requester.app_service
                ),
                event=event,
                context=context,
            )

        # Add the base_insertion_event to the bottom of the list we return
        if base_insertion_event is not None:
            event_ids.append(base_insertion_event.event_id)

        return 200, {
            "state_events": state_events_at_start,
            "events": event_ids,
            "next_chunk_id": insertion_event["content"][
                EventContentFields.MSC2716_NEXT_CHUNK_ID
            ],
        }

    def on_GET(self, request, room_id):
        return 501, "Not implemented"

    def on_PUT(self, request, room_id):
        return self.txns.fetch_or_execute_request(
            request, self.on_POST, request, room_id
        )


# TODO: Needs unit testing for room ID + alias joins
class JoinRoomAliasServlet(TransactionRestServlet):
    def __init__(self, hs):
        super().__init__(hs)
        self.room_member_handler = hs.get_room_member_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        # /join/$room_identifier[/$txn_id]
        PATTERNS = "/join/(?P<room_identifier>[^/]*)"
        register_txn_path(self, PATTERNS, http_server)

    async def on_POST(
        self,
        request: SynapseRequest,
        room_identifier: str,
        txn_id: Optional[str] = None,
    ):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)

        try:
            content = parse_json_object_from_request(request)
        except Exception:
            # Turns out we used to ignore the body entirely, and some clients
            # cheekily send invalid bodies.
            content = {}

        if RoomID.is_valid(room_identifier):
            room_id = room_identifier

            # twisted.web.server.Request.args is incorrectly defined as Optional[Any]
            args: Dict[bytes, List[bytes]] = request.args  # type: ignore

            remote_room_hosts = parse_strings_from_args(
                args, "server_name", required=False
            )
        elif RoomAlias.is_valid(room_identifier):
            handler = self.room_member_handler
            room_alias = RoomAlias.from_string(room_identifier)
            room_id_obj, remote_room_hosts = await handler.lookup_room_alias(room_alias)
            room_id = room_id_obj.to_string()
        else:
            raise SynapseError(
                400, "%s was not legal room ID or room alias" % (room_identifier,)
            )

        await self.room_member_handler.update_membership(
            requester=requester,
            target=requester.user,
            room_id=room_id,
            action="join",
            txn_id=txn_id,
            remote_room_hosts=remote_room_hosts,
            content=content,
            third_party_signed=content.get("third_party_signed", None),
        )

        return 200, {"room_id": room_id}

    def on_PUT(self, request, room_identifier, txn_id):
        set_tag("txn_id", txn_id)

        return self.txns.fetch_or_execute_request(
            request, self.on_POST, request, room_identifier, txn_id
        )


# TODO: Needs unit testing
class PublicRoomListRestServlet(TransactionRestServlet):
    PATTERNS = client_patterns("/publicRooms$", v1=True)

    def __init__(self, hs):
        super().__init__(hs)
        self.hs = hs
        self.auth = hs.get_auth()

    async def on_GET(self, request):
        server = parse_string(request, "server")

        try:
            await self.auth.get_user_by_req(request, allow_guest=True)
        except InvalidClientCredentialsError as e:
            # Option to allow servers to require auth when accessing
            # /publicRooms via CS API. This is especially helpful in private
            # federations.
            if not self.hs.config.allow_public_rooms_without_auth:
                raise

            # We allow people to not be authed if they're just looking at our
            # room list, but require auth when we proxy the request.
            # In both cases we call the auth function, as that has the side
            # effect of logging who issued this request if an access token was
            # provided.
            if server:
                raise e

        limit: Optional[int] = parse_integer(request, "limit", 0)
        since_token = parse_string(request, "since")

        if limit == 0:
            # zero is a special value which corresponds to no limit.
            limit = None

        handler = self.hs.get_room_list_handler()
        if server and server != self.hs.config.server_name:
            # Ensure the server is valid.
            try:
                parse_and_validate_server_name(server)
            except ValueError:
                raise SynapseError(
                    400,
                    "Invalid server name: %s" % (server,),
                    Codes.INVALID_PARAM,
                )

            data = await handler.get_remote_public_room_list(
                server, limit=limit, since_token=since_token
            )
        else:
            data = await handler.get_local_public_room_list(
                limit=limit, since_token=since_token
            )

        return 200, data

    async def on_POST(self, request):
        await self.auth.get_user_by_req(request, allow_guest=True)

        server = parse_string(request, "server")
        content = parse_json_object_from_request(request)

        limit: Optional[int] = int(content.get("limit", 100))
        since_token = content.get("since", None)
        search_filter = content.get("filter", None)

        include_all_networks = content.get("include_all_networks", False)
        third_party_instance_id = content.get("third_party_instance_id", None)

        if include_all_networks:
            network_tuple = None
            if third_party_instance_id is not None:
                raise SynapseError(
                    400, "Can't use include_all_networks with an explicit network"
                )
        elif third_party_instance_id is None:
            network_tuple = ThirdPartyInstanceID(None, None)
        else:
            network_tuple = ThirdPartyInstanceID.from_string(third_party_instance_id)

        if limit == 0:
            # zero is a special value which corresponds to no limit.
            limit = None

        handler = self.hs.get_room_list_handler()
        if server and server != self.hs.config.server_name:
            # Ensure the server is valid.
            try:
                parse_and_validate_server_name(server)
            except ValueError:
                raise SynapseError(
                    400,
                    "Invalid server name: %s" % (server,),
                    Codes.INVALID_PARAM,
                )

            data = await handler.get_remote_public_room_list(
                server,
                limit=limit,
                since_token=since_token,
                search_filter=search_filter,
                include_all_networks=include_all_networks,
                third_party_instance_id=third_party_instance_id,
            )

        else:
            data = await handler.get_local_public_room_list(
                limit=limit,
                since_token=since_token,
                search_filter=search_filter,
                network_tuple=network_tuple,
            )

        return 200, data


# TODO: Needs unit testing
class RoomMemberListRestServlet(RestServlet):
    PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/members$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.message_handler = hs.get_message_handler()
        self.auth = hs.get_auth()
        self.store = hs.get_datastore()

    async def on_GET(self, request, room_id):
        # TODO support Pagination stream API (limit/tokens)
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        handler = self.message_handler

        # request the state as of a given event, as identified by a stream token,
        # for consistency with /messages etc.
        # useful for getting the membership in retrospect as of a given /sync
        # response.
        at_token_string = parse_string(request, "at")
        if at_token_string is None:
            at_token = None
        else:
            at_token = await StreamToken.from_string(self.store, at_token_string)

        # let you filter down on particular memberships.
        # XXX: this may not be the best shape for this API - we could pass in a filter
        # instead, except filters aren't currently aware of memberships.
        # See https://github.com/matrix-org/matrix-doc/issues/1337 for more details.
        membership = parse_string(request, "membership")
        not_membership = parse_string(request, "not_membership")

        events = await handler.get_state_events(
            room_id=room_id,
            user_id=requester.user.to_string(),
            at_token=at_token,
            state_filter=StateFilter.from_types([(EventTypes.Member, None)]),
        )

        chunk = []

        for event in events:
            if (membership and event["content"].get("membership") != membership) or (
                not_membership and event["content"].get("membership") == not_membership
            ):
                continue
            chunk.append(event)

        return 200, {"chunk": chunk}


# deprecated in favour of /members?membership=join?
# except it does custom AS logic and has a simpler return format
class JoinedRoomMemberListRestServlet(RestServlet):
    PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/joined_members$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.message_handler = hs.get_message_handler()
        self.auth = hs.get_auth()

    async def on_GET(self, request, room_id):
        requester = await self.auth.get_user_by_req(request)

        users_with_profile = await self.message_handler.get_joined_members(
            requester, room_id
        )

        return 200, {"joined": users_with_profile}


# TODO: Needs better unit testing
class RoomMessageListRestServlet(RestServlet):
    PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/messages$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.pagination_handler = hs.get_pagination_handler()
        self.auth = hs.get_auth()
        self.store = hs.get_datastore()

    async def on_GET(self, request, room_id):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        pagination_config = await PaginationConfig.from_request(
            self.store, request, default_limit=10
        )
        as_client_event = b"raw" not in request.args
        filter_str = parse_string(request, "filter", encoding="utf-8")
        if filter_str:
            filter_json = urlparse.unquote(filter_str)
            event_filter: Optional[Filter] = Filter(json_decoder.decode(filter_json))
            if (
                event_filter
                and event_filter.filter_json.get("event_format", "client")
                == "federation"
            ):
                as_client_event = False
        else:
            event_filter = None

        msgs = await self.pagination_handler.get_messages(
            room_id=room_id,
            requester=requester,
            pagin_config=pagination_config,
            as_client_event=as_client_event,
            event_filter=event_filter,
        )

        return 200, msgs


# TODO: Needs unit testing
class RoomStateRestServlet(RestServlet):
    PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/state$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.message_handler = hs.get_message_handler()
        self.auth = hs.get_auth()

    async def on_GET(self, request, room_id):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        # Get all the current state for this room
        events = await self.message_handler.get_state_events(
            room_id=room_id,
            user_id=requester.user.to_string(),
            is_guest=requester.is_guest,
        )
        return 200, events


# TODO: Needs unit testing
class RoomInitialSyncRestServlet(RestServlet):
    PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/initialSync$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.initial_sync_handler = hs.get_initial_sync_handler()
        self.auth = hs.get_auth()
        self.store = hs.get_datastore()

    async def on_GET(self, request, room_id):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        pagination_config = await PaginationConfig.from_request(self.store, request)
        content = await self.initial_sync_handler.room_initial_sync(
            room_id=room_id, requester=requester, pagin_config=pagination_config
        )
        return 200, content


class RoomEventServlet(RestServlet):
    PATTERNS = client_patterns(
        "/rooms/(?P<room_id>[^/]*)/event/(?P<event_id>[^/]*)$", v1=True
    )

    def __init__(self, hs):
        super().__init__()
        self.clock = hs.get_clock()
        self.event_handler = hs.get_event_handler()
        self._event_serializer = hs.get_event_client_serializer()
        self.auth = hs.get_auth()

    async def on_GET(self, request, room_id, event_id):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        try:
            event = await self.event_handler.get_event(
                requester.user, room_id, event_id
            )
        except AuthError:
            # This endpoint is supposed to return a 404 when the requester does
            # not have permission to access the event
            # https://matrix.org/docs/spec/client_server/r0.5.0#get-matrix-client-r0-rooms-roomid-event-eventid
            raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)

        time_now = self.clock.time_msec()
        if event:
            event = await self._event_serializer.serialize_event(event, time_now)
            return 200, event

        return SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)


class RoomEventContextServlet(RestServlet):
    PATTERNS = client_patterns(
        "/rooms/(?P<room_id>[^/]*)/context/(?P<event_id>[^/]*)$", v1=True
    )

    def __init__(self, hs):
        super().__init__()
        self.clock = hs.get_clock()
        self.room_context_handler = hs.get_room_context_handler()
        self._event_serializer = hs.get_event_client_serializer()
        self.auth = hs.get_auth()

    async def on_GET(self, request, room_id, event_id):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)

        limit = parse_integer(request, "limit", default=10)

        # picking the API shape for symmetry with /messages
        filter_str = parse_string(request, "filter", encoding="utf-8")
        if filter_str:
            filter_json = urlparse.unquote(filter_str)
            event_filter: Optional[Filter] = Filter(json_decoder.decode(filter_json))
        else:
            event_filter = None

        results = await self.room_context_handler.get_event_context(
            requester, room_id, event_id, limit, event_filter
        )

        if not results:
            raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)

        time_now = self.clock.time_msec()
        results["events_before"] = await self._event_serializer.serialize_events(
            results["events_before"], time_now
        )
        results["event"] = await self._event_serializer.serialize_event(
            results["event"], time_now
        )
        results["events_after"] = await self._event_serializer.serialize_events(
            results["events_after"], time_now
        )
        results["state"] = await self._event_serializer.serialize_events(
            results["state"],
            time_now,
            # No need to bundle aggregations for state events
            bundle_aggregations=False,
        )

        return 200, results


class RoomForgetRestServlet(TransactionRestServlet):
    def __init__(self, hs):
        super().__init__(hs)
        self.room_member_handler = hs.get_room_member_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        PATTERNS = "/rooms/(?P<room_id>[^/]*)/forget"
        register_txn_path(self, PATTERNS, http_server)

    async def on_POST(self, request, room_id, txn_id=None):
        requester = await self.auth.get_user_by_req(request, allow_guest=False)

        await self.room_member_handler.forget(user=requester.user, room_id=room_id)

        return 200, {}

    def on_PUT(self, request, room_id, txn_id):
        set_tag("txn_id", txn_id)

        return self.txns.fetch_or_execute_request(
            request, self.on_POST, request, room_id, txn_id
        )


# TODO: Needs unit testing
class RoomMembershipRestServlet(TransactionRestServlet):
    def __init__(self, hs):
        super().__init__(hs)
        self.room_member_handler = hs.get_room_member_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        # /rooms/$roomid/[invite|join|leave]
        PATTERNS = (
            "/rooms/(?P<room_id>[^/]*)/"
            "(?P<membership_action>join|invite|leave|ban|unban|kick)"
        )
        register_txn_path(self, PATTERNS, http_server)

    async def on_POST(self, request, room_id, membership_action, txn_id=None):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)

        if requester.is_guest and membership_action not in {
            Membership.JOIN,
            Membership.LEAVE,
        }:
            raise AuthError(403, "Guest access not allowed")

        try:
            content = parse_json_object_from_request(request)
        except Exception:
            # Turns out we used to ignore the body entirely, and some clients
            # cheekily send invalid bodies.
            content = {}

        if membership_action == "invite" and self._has_3pid_invite_keys(content):
            try:
                await self.room_member_handler.do_3pid_invite(
                    room_id,
                    requester.user,
                    content["medium"],
                    content["address"],
                    content["id_server"],
                    requester,
                    txn_id,
                    content.get("id_access_token"),
                )
            except ShadowBanError:
                # Pretend the request succeeded.
                pass
            return 200, {}

        target = requester.user
        if membership_action in ["invite", "ban", "unban", "kick"]:
            assert_params_in_dict(content, ["user_id"])
            target = UserID.from_string(content["user_id"])

        event_content = None
        if "reason" in content:
            event_content = {"reason": content["reason"]}

        try:
            await self.room_member_handler.update_membership(
                requester=requester,
                target=target,
                room_id=room_id,
                action=membership_action,
                txn_id=txn_id,
                third_party_signed=content.get("third_party_signed", None),
                content=event_content,
            )
        except ShadowBanError:
            # Pretend the request succeeded.
            pass

        return_value = {}

        if membership_action == "join":
            return_value["room_id"] = room_id

        return 200, return_value

    def _has_3pid_invite_keys(self, content):
        for key in {"id_server", "medium", "address"}:
            if key not in content:
                return False
        return True

    def on_PUT(self, request, room_id, membership_action, txn_id):
        set_tag("txn_id", txn_id)

        return self.txns.fetch_or_execute_request(
            request, self.on_POST, request, room_id, membership_action, txn_id
        )


class RoomRedactEventRestServlet(TransactionRestServlet):
    def __init__(self, hs):
        super().__init__(hs)
        self.event_creation_handler = hs.get_event_creation_handler()
        self.auth = hs.get_auth()

    def register(self, http_server):
        PATTERNS = "/rooms/(?P<room_id>[^/]*)/redact/(?P<event_id>[^/]*)"
        register_txn_path(self, PATTERNS, http_server)

    async def on_POST(self, request, room_id, event_id, txn_id=None):
        requester = await self.auth.get_user_by_req(request)
        content = parse_json_object_from_request(request)

        try:
            (
                event,
                _,
            ) = await self.event_creation_handler.create_and_send_nonmember_event(
                requester,
                {
                    "type": EventTypes.Redaction,
                    "content": content,
                    "room_id": room_id,
                    "sender": requester.user.to_string(),
                    "redacts": event_id,
                },
                txn_id=txn_id,
            )
            event_id = event.event_id
        except ShadowBanError:
            event_id = "$" + random_string(43)

        set_tag("event_id", event_id)
        return 200, {"event_id": event_id}

    def on_PUT(self, request, room_id, event_id, txn_id):
        set_tag("txn_id", txn_id)

        return self.txns.fetch_or_execute_request(
            request, self.on_POST, request, room_id, event_id, txn_id
        )


class RoomTypingRestServlet(RestServlet):
    PATTERNS = client_patterns(
        "/rooms/(?P<room_id>[^/]*)/typing/(?P<user_id>[^/]*)$", v1=True
    )

    def __init__(self, hs: "HomeServer"):
        super().__init__()
        self.hs = hs
        self.presence_handler = hs.get_presence_handler()
        self.auth = hs.get_auth()

        # If we're not on the typing writer instance we should scream if we get
        # requests.
        self._is_typing_writer = (
            hs.config.worker.writers.typing == hs.get_instance_name()
        )

    async def on_PUT(self, request, room_id, user_id):
        requester = await self.auth.get_user_by_req(request)

        if not self._is_typing_writer:
            raise Exception("Got /typing request on instance that is not typing writer")

        room_id = urlparse.unquote(room_id)
        target_user = UserID.from_string(urlparse.unquote(user_id))

        content = parse_json_object_from_request(request)

        await self.presence_handler.bump_presence_active_time(requester.user)

        # Limit timeout to stop people from setting silly typing timeouts.
        timeout = min(content.get("timeout", 30000), 120000)

        # Defer getting the typing handler since it will raise on workers.
        typing_handler = self.hs.get_typing_writer_handler()

        try:
            if content["typing"]:
                await typing_handler.started_typing(
                    target_user=target_user,
                    requester=requester,
                    room_id=room_id,
                    timeout=timeout,
                )
            else:
                await typing_handler.stopped_typing(
                    target_user=target_user, requester=requester, room_id=room_id
                )
        except ShadowBanError:
            # Pretend this worked without error.
            pass

        return 200, {}


class RoomAliasListServlet(RestServlet):
    PATTERNS = [
        re.compile(
            r"^/_matrix/client/unstable/org\.matrix\.msc2432"
            r"/rooms/(?P<room_id>[^/]*)/aliases"
        ),
    ] + list(client_patterns("/rooms/(?P<room_id>[^/]*)/aliases$", unstable=False))

    def __init__(self, hs: "HomeServer"):
        super().__init__()
        self.auth = hs.get_auth()
        self.directory_handler = hs.get_directory_handler()

    async def on_GET(self, request, room_id):
        requester = await self.auth.get_user_by_req(request)

        alias_list = await self.directory_handler.get_aliases_for_room(
            requester, room_id
        )

        return 200, {"aliases": alias_list}


class SearchRestServlet(RestServlet):
    PATTERNS = client_patterns("/search$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.search_handler = hs.get_search_handler()
        self.auth = hs.get_auth()

    async def on_POST(self, request):
        requester = await self.auth.get_user_by_req(request)

        content = parse_json_object_from_request(request)

        batch = parse_string(request, "next_batch")
        results = await self.search_handler.search(requester.user, content, batch)

        return 200, results


class JoinedRoomsRestServlet(RestServlet):
    PATTERNS = client_patterns("/joined_rooms$", v1=True)

    def __init__(self, hs):
        super().__init__()
        self.store = hs.get_datastore()
        self.auth = hs.get_auth()

    async def on_GET(self, request):
        requester = await self.auth.get_user_by_req(request, allow_guest=True)

        room_ids = await self.store.get_rooms_for_user(requester.user.to_string())
        return 200, {"joined_rooms": list(room_ids)}


def register_txn_path(servlet, regex_string, http_server, with_get=False):
    """Registers a transaction-based path.

    This registers two paths:
        PUT regex_string/$txnid
        POST regex_string

    Args:
        regex_string (str): The regex string to register. Must NOT have a
        trailing $ as this string will be appended to.
        http_server : The http_server to register paths with.
        with_get: True to also register respective GET paths for the PUTs.
    """
    http_server.register_paths(
        "POST",
        client_patterns(regex_string + "$", v1=True),
        servlet.on_POST,
        servlet.__class__.__name__,
    )
    http_server.register_paths(
        "PUT",
        client_patterns(regex_string + "/(?P<txn_id>[^/]*)$", v1=True),
        servlet.on_PUT,
        servlet.__class__.__name__,
    )
    if with_get:
        http_server.register_paths(
            "GET",
            client_patterns(regex_string + "/(?P<txn_id>[^/]*)$", v1=True),
            servlet.on_GET,
            servlet.__class__.__name__,
        )


class RoomSpaceSummaryRestServlet(RestServlet):
    PATTERNS = (
        re.compile(
            "^/_matrix/client/unstable/org.matrix.msc2946"
            "/rooms/(?P<room_id>[^/]*)/spaces$"
        ),
    )

    def __init__(self, hs: "HomeServer"):
        super().__init__()
        self._auth = hs.get_auth()
        self._space_summary_handler = hs.get_space_summary_handler()

    async def on_GET(
        self, request: SynapseRequest, room_id: str
    ) -> Tuple[int, JsonDict]:
        requester = await self._auth.get_user_by_req(request, allow_guest=True)

        return 200, await self._space_summary_handler.get_space_summary(
            requester.user.to_string(),
            room_id,
            suggested_only=parse_boolean(request, "suggested_only", default=False),
            max_rooms_per_space=parse_integer(request, "max_rooms_per_space"),
        )

    # TODO When switching to the stable endpoint, remove the POST handler.
    async def on_POST(
        self, request: SynapseRequest, room_id: str
    ) -> Tuple[int, JsonDict]:
        requester = await self._auth.get_user_by_req(request, allow_guest=True)
        content = parse_json_object_from_request(request)

        suggested_only = content.get("suggested_only", False)
        if not isinstance(suggested_only, bool):
            raise SynapseError(
                400, "'suggested_only' must be a boolean", Codes.BAD_JSON
            )

        max_rooms_per_space = content.get("max_rooms_per_space")
        if max_rooms_per_space is not None and not isinstance(max_rooms_per_space, int):
            raise SynapseError(
                400, "'max_rooms_per_space' must be an integer", Codes.BAD_JSON
            )

        return 200, await self._space_summary_handler.get_space_summary(
            requester.user.to_string(),
            room_id,
            suggested_only=suggested_only,
            max_rooms_per_space=max_rooms_per_space,
        )


class RoomHierarchyRestServlet(RestServlet):
    PATTERNS = (
        re.compile(
            "^/_matrix/client/unstable/org.matrix.msc2946"
            "/rooms/(?P<room_id>[^/]*)/hierarchy$"
        ),
    )

    def __init__(self, hs: "HomeServer"):
        super().__init__()
        self._auth = hs.get_auth()
        self._space_summary_handler = hs.get_space_summary_handler()

    async def on_GET(
        self, request: SynapseRequest, room_id: str
    ) -> Tuple[int, JsonDict]:
        requester = await self._auth.get_user_by_req(request, allow_guest=True)

        max_depth = parse_integer(request, "max_depth")
        if max_depth is not None and max_depth < 0:
            raise SynapseError(
                400, "'max_depth' must be a non-negative integer", Codes.BAD_JSON
            )

        limit = parse_integer(request, "limit")
        if limit is not None and limit <= 0:
            raise SynapseError(
                400, "'limit' must be a positive integer", Codes.BAD_JSON
            )

        return 200, await self._space_summary_handler.get_room_hierarchy(
            requester.user.to_string(),
            room_id,
            suggested_only=parse_boolean(request, "suggested_only", default=False),
            max_depth=max_depth,
            limit=limit,
            from_token=parse_string(request, "from"),
        )


def register_servlets(hs: "HomeServer", http_server, is_worker=False):
    msc2716_enabled = hs.config.experimental.msc2716_enabled

    RoomStateEventRestServlet(hs).register(http_server)
    RoomMemberListRestServlet(hs).register(http_server)
    JoinedRoomMemberListRestServlet(hs).register(http_server)
    RoomMessageListRestServlet(hs).register(http_server)
    JoinRoomAliasServlet(hs).register(http_server)
    RoomMembershipRestServlet(hs).register(http_server)
    RoomSendEventRestServlet(hs).register(http_server)
    if msc2716_enabled:
        RoomBatchSendEventRestServlet(hs).register(http_server)
    PublicRoomListRestServlet(hs).register(http_server)
    RoomStateRestServlet(hs).register(http_server)
    RoomRedactEventRestServlet(hs).register(http_server)
    RoomTypingRestServlet(hs).register(http_server)
    RoomEventContextServlet(hs).register(http_server)
    RoomSpaceSummaryRestServlet(hs).register(http_server)
    RoomHierarchyRestServlet(hs).register(http_server)
    RoomEventServlet(hs).register(http_server)
    JoinedRoomsRestServlet(hs).register(http_server)
    RoomAliasListServlet(hs).register(http_server)
    SearchRestServlet(hs).register(http_server)

    # Some servlets only get registered for the main process.
    if not is_worker:
        RoomCreateRestServlet(hs).register(http_server)
        RoomForgetRestServlet(hs).register(http_server)


def register_deprecated_servlets(hs, http_server):
    RoomInitialSyncRestServlet(hs).register(http_server)