# -*- 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."""
from twisted.internet import defer

from ._base import BaseHandler

from synapse.types import UserID, RoomAlias, RoomID, RoomStreamToken
from synapse.api.constants import (
    EventTypes, JoinRules, RoomCreationPreset
)
from synapse.api.errors import AuthError, StoreError, SynapseError
from synapse.util import stringutils
from synapse.visibility import filter_events_for_client

from collections import OrderedDict

import logging
import math
import string

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,
            "encryption_alg": "m.megolm.v1.aes-sha2",
        },
        RoomCreationPreset.TRUSTED_PRIVATE_CHAT: {
            "join_rules": JoinRules.INVITE,
            "history_visibility": "shared",
            "original_invitees_have_ops": True,
            "guest_can_join": True,
            "encryption_alg": "m.megolm.v1.aes-sha2",
        },
        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()

    @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.
        """
        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")

        if ratelimit:
            yield self.ratelimit(requester)

        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")
        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"

        # 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
        room_id = None
        while attempts < 5:
            try:
                random_string = stringutils.random_string(18)
                gen_room_id = RoomID(
                    random_string,
                    self.hs.hostname,
                )
                yield self.store.store_room(
                    room_id=gen_room_id.to_string(),
                    room_creator_user_id=user_id,
                    is_public=is_public
                )
                room_id = gen_room_id.to_string()
                break
            except StoreError:
                attempts += 1
        if not room_id:
            raise StoreError(500, "Couldn't generate a room ID.")

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

        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", {})

        room_member_handler = self.hs.get_room_member_handler()

        yield self._send_events_for_new_room(
            requester,
            room_id,
            room_member_handler,
            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 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, user_id, room_id
            )

        defer.returnValue(result)

    @defer.inlineCallbacks
    def _send_events_for_new_room(
            self,
            creator,  # A Requester object.
            room_id,
            room_member_handler,
            preset_config,
            invite_list,
            initial_state,
            creation_content,
            room_alias,
            power_level_content_override,
            creator_join_profile,
    ):
        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 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

            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,
            )

        if "encryption_alg" in config:
            send(
                etype=EventTypes.Encryption,
                state_key="",
                content={
                    'algorithm': config["encryption_alg"],
                }
            )


class RoomContextHandler(BaseHandler):
    @defer.inlineCallbacks
    def get_event_context(self, user, room_id, event_id, limit):
        """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).

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

        now_token = yield self.hs.get_event_sources().get_current_token()

        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
        )

        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

        state = yield self.store.get_state_for_events(
            [last_event_id], None
        )
        results["state"] = list(state[last_event_id].values())

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

        results["end"] = now_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))