# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket 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,
        },
        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()

    @defer.inlineCallbacks
    def create_room(self, requester, config, ratelimit=True):
        """ Creates a new room.

        Args:
            requester (Requester): The user who requested the room creation.
            config (dict) : A dict of configuration options.
        Returns:
            The new room ID.
        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,))

        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", {})

        msg_handler = self.hs.get_handlers().message_handler
        room_member_handler = self.hs.get_handlers().room_member_handler

        yield self._send_events_for_new_room(
            requester,
            room_id,
            msg_handler,
            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", {})
        )

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

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

        for invitee in invite_list:
            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_handlers().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,
            msg_handler,
            room_member_handler,
            preset_config,
            invite_list,
            initial_state,
            creation_content,
            room_alias,
            power_level_content_override,
    ):
        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 msg_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,
        )

        # 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,
            )


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"] = 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:
            events, end_key = yield self.store.get_appservice_room_stream(
                service=app_service,
                from_key=from_key,
                to_key=to_key,
                limit=limit,
            )
        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))
