# -*- 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.

from twisted.internet import defer

from synapse.api.errors import SynapseError, AuthError
from synapse.util.logcontext import (
    PreserveLoggingContext, preserve_fn, preserve_context_over_deferred,
)
from synapse.util.metrics import Measure
from synapse.types import UserID, get_domain_from_id

import logging

from collections import namedtuple
import ujson as json

logger = logging.getLogger(__name__)


# A tiny object useful for storing a user's membership in a room, as a mapping
# key
RoomMember = namedtuple("RoomMember", ("room_id", "user_id"))


class TypingHandler(object):
    def __init__(self, hs):
        self.store = hs.get_datastore()
        self.server_name = hs.config.server_name
        self.auth = hs.get_auth()
        self.is_mine_id = hs.is_mine_id
        self.notifier = hs.get_notifier()
        self.state = hs.get_state_handler()

        self.clock = hs.get_clock()

        self.federation = hs.get_replication_layer()

        self.federation.register_edu_handler("m.typing", self._recv_edu)

        hs.get_distributor().observe("user_left_room", self.user_left_room)

        self._member_typing_until = {}  # clock time we expect to stop
        self._member_typing_timer = {}  # deferreds to manage theabove

        # map room IDs to serial numbers
        self._room_serials = {}
        self._latest_room_serial = 0
        # map room IDs to sets of users currently typing
        self._room_typing = {}

    def tearDown(self):
        """Cancels all the pending timers.
        Normally this shouldn't be needed, but it's required from unit tests
        to avoid a "Reactor was unclean" warning."""
        for t in self._member_typing_timer.values():
            self.clock.cancel_call_later(t)

    @defer.inlineCallbacks
    def started_typing(self, target_user, auth_user, room_id, timeout):
        target_user_id = target_user.to_string()
        auth_user_id = auth_user.to_string()

        if not self.is_mine_id(target_user_id):
            raise SynapseError(400, "User is not hosted on this Home Server")

        if target_user_id != auth_user_id:
            raise AuthError(400, "Cannot set another user's typing state")

        yield self.auth.check_joined_room(room_id, target_user_id)

        logger.debug(
            "%s has started typing in %s", target_user_id, room_id
        )

        until = self.clock.time_msec() + timeout
        member = RoomMember(room_id=room_id, user_id=target_user_id)

        was_present = member in self._member_typing_until

        if member in self._member_typing_timer:
            self.clock.cancel_call_later(self._member_typing_timer[member])

        def _cb():
            logger.debug(
                "%s has timed out in %s", target_user.to_string(), room_id
            )
            self._stopped_typing(member)

        self._member_typing_until[member] = until
        self._member_typing_timer[member] = self.clock.call_later(
            timeout / 1000.0, _cb
        )

        if was_present:
            # No point sending another notification
            defer.returnValue(None)

        yield self._push_update(
            room_id=room_id,
            user_id=target_user_id,
            typing=True,
        )

    @defer.inlineCallbacks
    def stopped_typing(self, target_user, auth_user, room_id):
        target_user_id = target_user.to_string()
        auth_user_id = auth_user.to_string()

        if not self.is_mine_id(target_user_id):
            raise SynapseError(400, "User is not hosted on this Home Server")

        if target_user_id != auth_user_id:
            raise AuthError(400, "Cannot set another user's typing state")

        yield self.auth.check_joined_room(room_id, target_user_id)

        logger.debug(
            "%s has stopped typing in %s", target_user_id, room_id
        )

        member = RoomMember(room_id=room_id, user_id=target_user_id)

        if member in self._member_typing_timer:
            self.clock.cancel_call_later(self._member_typing_timer[member])
            del self._member_typing_timer[member]

        yield self._stopped_typing(member)

    @defer.inlineCallbacks
    def user_left_room(self, user, room_id):
        user_id = user.to_string()
        if self.is_mine_id(user_id):
            member = RoomMember(room_id=room_id, user_id=user_id)
            yield self._stopped_typing(member)

    @defer.inlineCallbacks
    def _stopped_typing(self, member):
        if member not in self._member_typing_until:
            # No point
            defer.returnValue(None)

        yield self._push_update(
            room_id=member.room_id,
            user_id=member.user_id,
            typing=False,
        )

        del self._member_typing_until[member]

        if member in self._member_typing_timer:
            # Don't cancel it - either it already expired, or the real
            # stopped_typing() will cancel it
            del self._member_typing_timer[member]

    @defer.inlineCallbacks
    def _push_update(self, room_id, user_id, typing):
        users = yield self.state.get_current_user_in_room(room_id)
        domains = set(get_domain_from_id(u) for u in users)

        deferreds = []
        for domain in domains:
            if domain == self.server_name:
                preserve_fn(self._push_update_local)(
                    room_id=room_id,
                    user_id=user_id,
                    typing=typing
                )
            else:
                deferreds.append(preserve_fn(self.federation.send_edu)(
                    destination=domain,
                    edu_type="m.typing",
                    content={
                        "room_id": room_id,
                        "user_id": user_id,
                        "typing": typing,
                    },
                    key=(room_id, user_id),
                ))

        yield preserve_context_over_deferred(
            defer.DeferredList(deferreds, consumeErrors=True)
        )

    @defer.inlineCallbacks
    def _recv_edu(self, origin, content):
        room_id = content["room_id"]
        user_id = content["user_id"]

        # Check that the string is a valid user id
        user = UserID.from_string(user_id)

        if user.domain != origin:
            logger.info(
                "Got typing update from %r with bad 'user_id': %r",
                origin, user_id,
            )
            return

        users = yield self.state.get_current_user_in_room(room_id)
        domains = set(get_domain_from_id(u) for u in users)

        if self.server_name in domains:
            self._push_update_local(
                room_id=room_id,
                user_id=user_id,
                typing=content["typing"]
            )

    def _push_update_local(self, room_id, user_id, typing):
        room_set = self._room_typing.setdefault(room_id, set())
        if typing:
            room_set.add(user_id)
        else:
            room_set.discard(user_id)

        self._latest_room_serial += 1
        self._room_serials[room_id] = self._latest_room_serial

        with PreserveLoggingContext():
            self.notifier.on_new_event(
                "typing_key", self._latest_room_serial, rooms=[room_id]
            )

    def get_all_typing_updates(self, last_id, current_id):
        # TODO: Work out a way to do this without scanning the entire state.
        if last_id == current_id:
            return []

        rows = []
        for room_id, serial in self._room_serials.items():
            if last_id < serial and serial <= current_id:
                typing = self._room_typing[room_id]
                typing_bytes = json.dumps(list(typing), ensure_ascii=False)
                rows.append((serial, room_id, typing_bytes))
        rows.sort()
        return rows


class TypingNotificationEventSource(object):
    def __init__(self, hs):
        self.hs = hs
        self.clock = hs.get_clock()
        # We can't call get_typing_handler here because there's a cycle:
        #
        #   Typing -> Notifier -> TypingNotificationEventSource -> Typing
        #
        self.get_typing_handler = hs.get_typing_handler

    def _make_event_for(self, room_id):
        typing = self.get_typing_handler()._room_typing[room_id]
        return {
            "type": "m.typing",
            "room_id": room_id,
            "content": {
                "user_ids": list(typing),
            },
        }

    def get_new_events(self, from_key, room_ids, **kwargs):
        with Measure(self.clock, "typing.get_new_events"):
            from_key = int(from_key)
            handler = self.get_typing_handler()

            events = []
            for room_id in room_ids:
                if room_id not in handler._room_serials:
                    continue
                if handler._room_serials[room_id] <= from_key:
                    continue

                events.append(self._make_event_for(room_id))

            return events, handler._latest_room_serial

    def get_current_key(self):
        return self.get_typing_handler()._latest_room_serial

    def get_pagination_rows(self, user, pagination_config, key):
        return ([], pagination_config.from_key)
