# -*- coding: utf-8 -*-
# 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.

"""Contains functions for performing events on rooms."""
import itertools
import logging
import math
import string
from collections import OrderedDict

from six import string_types

from twisted.internet import defer

from synapse.api.constants import (
    DEFAULT_ROOM_VERSION,
    KNOWN_ROOM_VERSIONS,
    EventTypes,
    JoinRules,
    RoomCreationPreset,
)
from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError
from synapse.storage.state import StateFilter
from synapse.types import RoomAlias, RoomID, RoomStreamToken, StreamToken, UserID
from synapse.util import stringutils
from synapse.util.async_helpers import Linearizer
from synapse.visibility import filter_events_for_client

from ._base import BaseHandler

logger = logging.getLogger(__name__)

id_server_scheme = "https://"


class RoomCreationHandler(BaseHandler):

    PRESETS_DICT = {
        RoomCreationPreset.PRIVATE_CHAT: {
            "join_rules": JoinRules.INVITE,
            "history_visibility": "shared",
            "original_invitees_have_ops": False,
            "guest_can_join": True,
        },
        RoomCreationPreset.TRUSTED_PRIVATE_CHAT: {
            "join_rules": JoinRules.INVITE,
            "history_visibility": "shared",
            "original_invitees_have_ops": True,
            "guest_can_join": True,
        },
        RoomCreationPreset.PUBLIC_CHAT: {
            "join_rules": JoinRules.PUBLIC,
            "history_visibility": "shared",
            "original_invitees_have_ops": False,
            "guest_can_join": False,
        },
    }

    def __init__(self, hs):
        super(RoomCreationHandler, self).__init__(hs)

        self.spam_checker = hs.get_spam_checker()
        self.event_creation_handler = hs.get_event_creation_handler()
        self.room_member_handler = hs.get_room_member_handler()

        # linearizer to stop two upgrades happening at once
        self._upgrade_linearizer = Linearizer("room_upgrade_linearizer")

    @defer.inlineCallbacks
    def upgrade_room(self, requester, old_room_id, new_version):
        """Replace a room with a new room with a different version

        Args:
            requester (synapse.types.Requester): the user requesting the upgrade
            old_room_id (unicode): the id of the room to be replaced
            new_version (unicode): the new room version to use

        Returns:
            Deferred[unicode]: the new room id
        """
        yield self.ratelimit(requester)

        user_id = requester.user.to_string()

        with (yield self._upgrade_linearizer.queue(old_room_id)):
            # start by allocating a new room id
            r = yield self.store.get_room(old_room_id)
            if r is None:
                raise NotFoundError("Unknown room id %s" % (old_room_id,))
            new_room_id = yield self._generate_room_id(
                creator_id=user_id, is_public=r["is_public"],
            )

            # we create and auth the tombstone event before properly creating the new
            # room, to check our user has perms in the old room.
            tombstone_event, tombstone_context = (
                yield self.event_creation_handler.create_event(
                    requester, {
                        "type": EventTypes.Tombstone,
                        "state_key": "",
                        "room_id": old_room_id,
                        "sender": user_id,
                        "content": {
                            "body": "This room has been replaced",
                            "replacement_room": new_room_id,
                        }
                    },
                    token_id=requester.access_token_id,
                )
            )
            yield self.auth.check_from_context(tombstone_event, tombstone_context)

            yield self.clone_exiting_room(
                requester,
                old_room_id=old_room_id,
                new_room_id=new_room_id,
                new_room_version=new_version,
                tombstone_event_id=tombstone_event.event_id,
            )

            # now send the tombstone
            yield self.event_creation_handler.send_nonmember_event(
                requester, tombstone_event, tombstone_context,
            )

            # XXX send a power_levels in the old room, if possible

        defer.returnValue(new_room_id)

    @defer.inlineCallbacks
    def clone_exiting_room(
            self, requester, old_room_id, new_room_id, new_room_version,
            tombstone_event_id,
    ):
        """Populate a new room based on an old room

        Args:
            requester (synapse.types.Requester): the user requesting the upgrade
            old_room_id (unicode): the id of the room to be replaced
            new_room_id (unicode): the id to give the new room (should already have been
                created with _gemerate_room_id())
            new_room_version (unicode): the new room version to use
            tombstone_event_id (unicode|str): the ID of the tombstone event in the old
                room.
        Returns:
            Deferred[None]
        """
        user_id = requester.user.to_string()

        if not self.spam_checker.user_may_create_room(user_id):
            raise SynapseError(403, "You are not permitted to create rooms")

        # XXX check alias is free
        # canonical_alias = None

        # XXX create association in directory handler
        # XXX preset

        preset_config = RoomCreationPreset.PRIVATE_CHAT

        creation_content = {
            "room_version": new_room_version,
            "predecessor": {
                "room_id": old_room_id,
                "event_id": tombstone_event_id,
            }
        }

        initial_state = OrderedDict()

        yield self._send_events_for_new_room(
            requester,
            new_room_id,
            preset_config=preset_config,
            invite_list=[],
            initial_state=initial_state,
            creation_content=creation_content,
        )

        # XXX name
        # XXX topic
        # XXX invites/joins
        # XXX 3pid invites
        # XXX directory_handler.send_room_alias_update_event

    @defer.inlineCallbacks
    def create_room(self, requester, config, ratelimit=True,
                    creator_join_profile=None):
        """ Creates a new room.

        Args:
            requester (synapse.types.Requester):
                The user who requested the room creation.
            config (dict) : A dict of configuration options.
            ratelimit (bool): set to False to disable the rate limiter

            creator_join_profile (dict|None):
                Set to override the displayname and avatar for the creating
                user in this room. If unset, displayname and avatar will be
                derived from the user's profile. If set, should contain the
                values to go in the body of the 'join' event (typically
                `avatar_url` and/or `displayname`.

        Returns:
            Deferred[dict]:
                a dict containing the keys `room_id` and, if an alias was
                requested, `room_alias`.
        Raises:
            SynapseError if the room ID couldn't be stored, or something went
            horribly wrong.
            ResourceLimitError if server is blocked to some resource being
            exceeded
        """
        user_id = requester.user.to_string()

        self.auth.check_auth_blocking(user_id)

        if not self.spam_checker.user_may_create_room(user_id):
            raise SynapseError(403, "You are not permitted to create rooms")

        if ratelimit:
            yield self.ratelimit(requester)

        room_version = config.get("room_version", DEFAULT_ROOM_VERSION)
        if not isinstance(room_version, string_types):
            raise SynapseError(
                400,
                "room_version must be a string",
                Codes.BAD_JSON,
            )

        if room_version not in KNOWN_ROOM_VERSIONS:
            raise SynapseError(
                400,
                "Your homeserver does not support this room version",
                Codes.UNSUPPORTED_ROOM_VERSION,
            )

        if "room_alias_name" in config:
            for wchar in string.whitespace:
                if wchar in config["room_alias_name"]:
                    raise SynapseError(400, "Invalid characters in room alias")

            room_alias = RoomAlias(
                config["room_alias_name"],
                self.hs.hostname,
            )
            mapping = yield self.store.get_association_from_room_alias(
                room_alias
            )

            if mapping:
                raise SynapseError(
                    400,
                    "Room alias already taken",
                    Codes.ROOM_IN_USE
                )
        else:
            room_alias = None

        invite_list = config.get("invite", [])
        for i in invite_list:
            try:
                UserID.from_string(i)
            except Exception:
                raise SynapseError(400, "Invalid user_id: %s" % (i,))

        yield self.event_creation_handler.assert_accepted_privacy_policy(
            requester,
        )

        invite_3pid_list = config.get("invite_3pid", [])

        visibility = config.get("visibility", None)
        is_public = visibility == "public"

        room_id = yield self._generate_room_id(creator_id=user_id, is_public=is_public)

        if room_alias:
            directory_handler = self.hs.get_handlers().directory_handler
            yield directory_handler.create_association(
                requester=requester,
                room_id=room_id,
                room_alias=room_alias,
                servers=[self.hs.hostname],
                send_event=False,
            )

        preset_config = config.get(
            "preset",
            RoomCreationPreset.PRIVATE_CHAT
            if visibility == "private"
            else RoomCreationPreset.PUBLIC_CHAT
        )

        raw_initial_state = config.get("initial_state", [])

        initial_state = OrderedDict()
        for val in raw_initial_state:
            initial_state[(val["type"], val.get("state_key", ""))] = val["content"]

        creation_content = config.get("creation_content", {})

        # override any attempt to set room versions via the creation_content
        creation_content["room_version"] = room_version

        yield self._send_events_for_new_room(
            requester,
            room_id,
            preset_config=preset_config,
            invite_list=invite_list,
            initial_state=initial_state,
            creation_content=creation_content,
            room_alias=room_alias,
            power_level_content_override=config.get("power_level_content_override"),
            creator_join_profile=creator_join_profile,
        )

        if "name" in config:
            name = config["name"]
            yield self.event_creation_handler.create_and_send_nonmember_event(
                requester,
                {
                    "type": EventTypes.Name,
                    "room_id": room_id,
                    "sender": user_id,
                    "state_key": "",
                    "content": {"name": name},
                },
                ratelimit=False)

        if "topic" in config:
            topic = config["topic"]
            yield self.event_creation_handler.create_and_send_nonmember_event(
                requester,
                {
                    "type": EventTypes.Topic,
                    "room_id": room_id,
                    "sender": user_id,
                    "state_key": "",
                    "content": {"topic": topic},
                },
                ratelimit=False)

        for invitee in invite_list:
            content = {}
            is_direct = config.get("is_direct", None)
            if is_direct:
                content["is_direct"] = is_direct

            yield self.room_member_handler.update_membership(
                requester,
                UserID.from_string(invitee),
                room_id,
                "invite",
                ratelimit=False,
                content=content,
            )

        for invite_3pid in invite_3pid_list:
            id_server = invite_3pid["id_server"]
            address = invite_3pid["address"]
            medium = invite_3pid["medium"]
            yield self.hs.get_room_member_handler().do_3pid_invite(
                room_id,
                requester.user,
                medium,
                address,
                id_server,
                requester,
                txn_id=None,
            )

        result = {"room_id": room_id}

        if room_alias:
            result["room_alias"] = room_alias.to_string()
            yield directory_handler.send_room_alias_update_event(
                requester, room_id
            )

        defer.returnValue(result)

    @defer.inlineCallbacks
    def _send_events_for_new_room(
            self,
            creator,  # A Requester object.
            room_id,
            preset_config,
            invite_list,
            initial_state,
            creation_content,
            room_alias=None,
            power_level_content_override=None,
            creator_join_profile=None,
    ):
        def create(etype, content, **kwargs):
            e = {
                "type": etype,
                "content": content,
            }

            e.update(event_keys)
            e.update(kwargs)

            return e

        @defer.inlineCallbacks
        def send(etype, content, **kwargs):
            event = create(etype, content, **kwargs)
            yield self.event_creation_handler.create_and_send_nonmember_event(
                creator,
                event,
                ratelimit=False
            )

        config = RoomCreationHandler.PRESETS_DICT[preset_config]

        creator_id = creator.user.to_string()

        event_keys = {
            "room_id": room_id,
            "sender": creator_id,
            "state_key": "",
        }

        creation_content.update({"creator": creator_id})
        yield send(
            etype=EventTypes.Create,
            content=creation_content,
        )

        yield self.room_member_handler.update_membership(
            creator,
            creator.user,
            room_id,
            "join",
            ratelimit=False,
            content=creator_join_profile,
        )

        # We treat the power levels override specially as this needs to be one
        # of the first events that get sent into a room.
        pl_content = initial_state.pop((EventTypes.PowerLevels, ''), None)
        if pl_content is not None:
            yield send(
                etype=EventTypes.PowerLevels,
                content=pl_content,
            )
        else:
            power_level_content = {
                "users": {
                    creator_id: 100,
                },
                "users_default": 0,
                "events": {
                    EventTypes.Name: 50,
                    EventTypes.PowerLevels: 100,
                    EventTypes.RoomHistoryVisibility: 100,
                    EventTypes.CanonicalAlias: 50,
                    EventTypes.RoomAvatar: 50,
                },
                "events_default": 0,
                "state_default": 50,
                "ban": 50,
                "kick": 50,
                "redact": 50,
                "invite": 0,
            }

            if config["original_invitees_have_ops"]:
                for invitee in invite_list:
                    power_level_content["users"][invitee] = 100

            if power_level_content_override:
                power_level_content.update(power_level_content_override)

            yield send(
                etype=EventTypes.PowerLevels,
                content=power_level_content,
            )

        if room_alias and (EventTypes.CanonicalAlias, '') not in initial_state:
            yield send(
                etype=EventTypes.CanonicalAlias,
                content={"alias": room_alias.to_string()},
            )

        if (EventTypes.JoinRules, '') not in initial_state:
            yield send(
                etype=EventTypes.JoinRules,
                content={"join_rule": config["join_rules"]},
            )

        if (EventTypes.RoomHistoryVisibility, '') not in initial_state:
            yield send(
                etype=EventTypes.RoomHistoryVisibility,
                content={"history_visibility": config["history_visibility"]}
            )

        if config["guest_can_join"]:
            if (EventTypes.GuestAccess, '') not in initial_state:
                yield send(
                    etype=EventTypes.GuestAccess,
                    content={"guest_access": "can_join"}
                )

        for (etype, state_key), content in initial_state.items():
            yield send(
                etype=etype,
                state_key=state_key,
                content=content,
            )

    @defer.inlineCallbacks
    def _generate_room_id(self, creator_id, is_public):
        # autogen room IDs and try to create it. We may clash, so just
        # try a few times till one goes through, giving up eventually.
        attempts = 0
        while attempts < 5:
            try:
                random_string = stringutils.random_string(18)
                gen_room_id = RoomID(
                    random_string,
                    self.hs.hostname,
                ).to_string()
                if isinstance(gen_room_id, bytes):
                    gen_room_id = gen_room_id.decode('utf-8')
                yield self.store.store_room(
                    room_id=gen_room_id,
                    room_creator_user_id=creator_id,
                    is_public=is_public,
                )
                defer.returnValue(gen_room_id)
            except StoreError:
                attempts += 1
        raise StoreError(500, "Couldn't generate a room ID.")


class RoomContextHandler(object):
    def __init__(self, hs):
        self.hs = hs
        self.store = hs.get_datastore()

    @defer.inlineCallbacks
    def get_event_context(self, user, room_id, event_id, limit, event_filter):
        """Retrieves events, pagination tokens and state around a given event
        in a room.

        Args:
            user (UserID)
            room_id (str)
            event_id (str)
            limit (int): The maximum number of events to return in total
                (excluding state).
            event_filter (Filter|None): the filter to apply to the events returned
                (excluding the target event_id)

        Returns:
            dict, or None if the event isn't found
        """
        before_limit = math.floor(limit / 2.)
        after_limit = limit - before_limit

        users = yield self.store.get_users_in_room(room_id)
        is_peeking = user.to_string() not in users

        def filter_evts(events):
            return filter_events_for_client(
                self.store,
                user.to_string(),
                events,
                is_peeking=is_peeking
            )

        event = yield self.store.get_event(event_id, get_prev_content=True,
                                           allow_none=True)
        if not event:
            defer.returnValue(None)
            return

        filtered = yield(filter_evts([event]))
        if not filtered:
            raise AuthError(
                403,
                "You don't have permission to access that event."
            )

        results = yield self.store.get_events_around(
            room_id, event_id, before_limit, after_limit, event_filter
        )

        results["events_before"] = yield filter_evts(results["events_before"])
        results["events_after"] = yield filter_evts(results["events_after"])
        results["event"] = event

        if results["events_after"]:
            last_event_id = results["events_after"][-1].event_id
        else:
            last_event_id = event_id

        if event_filter and event_filter.lazy_load_members():
            state_filter = StateFilter.from_lazy_load_member_list(
                ev.sender
                for ev in itertools.chain(
                    results["events_before"],
                    (results["event"],),
                    results["events_after"],
                )
            )
        else:
            state_filter = StateFilter.all()

        # XXX: why do we return the state as of the last event rather than the
        # first? Shouldn't we be consistent with /sync?
        # https://github.com/matrix-org/matrix-doc/issues/687

        state = yield self.store.get_state_for_events(
            [last_event_id], state_filter=state_filter,
        )
        results["state"] = list(state[last_event_id].values())

        # We use a dummy token here as we only care about the room portion of
        # the token, which we replace.
        token = StreamToken.START

        results["start"] = token.copy_and_replace(
            "room_key", results["start"]
        ).to_string()

        results["end"] = token.copy_and_replace(
            "room_key", results["end"]
        ).to_string()

        defer.returnValue(results)


class RoomEventSource(object):
    def __init__(self, hs):
        self.store = hs.get_datastore()

    @defer.inlineCallbacks
    def get_new_events(
            self,
            user,
            from_key,
            limit,
            room_ids,
            is_guest,
            explicit_room_id=None,
    ):
        # We just ignore the key for now.

        to_key = yield self.get_current_key()

        from_token = RoomStreamToken.parse(from_key)
        if from_token.topological:
            logger.warn("Stream has topological part!!!! %r", from_key)
            from_key = "s%s" % (from_token.stream,)

        app_service = self.store.get_app_service_by_user_id(
            user.to_string()
        )
        if app_service:
            # We no longer support AS users using /sync directly.
            # See https://github.com/matrix-org/matrix-doc/issues/1144
            raise NotImplementedError()
        else:
            room_events = yield self.store.get_membership_changes_for_user(
                user.to_string(), from_key, to_key
            )

            room_to_events = yield self.store.get_room_events_stream_for_rooms(
                room_ids=room_ids,
                from_key=from_key,
                to_key=to_key,
                limit=limit or 10,
                order='ASC',
            )

            events = list(room_events)
            events.extend(e for evs, _ in room_to_events.values() for e in evs)

            events.sort(key=lambda e: e.internal_metadata.order)

            if limit:
                events[:] = events[:limit]

            if events:
                end_key = events[-1].internal_metadata.after
            else:
                end_key = to_key

        defer.returnValue((events, end_key))

    def get_current_key(self):
        return self.store.get_room_events_max_id()

    def get_current_key_for_room(self, room_id):
        return self.store.get_room_events_max_id(room_id)

    @defer.inlineCallbacks
    def get_pagination_rows(self, user, config, key):
        events, next_key = yield self.store.paginate_room_events(
            room_id=key,
            from_key=config.from_key,
            to_key=config.to_key,
            direction=config.direction,
            limit=config.limit,
        )

        defer.returnValue((events, next_key))