# -*- coding: utf-8 -*-
# Copyright 2014 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.util.logutils import log_function

from ._base import BaseHandler

import logging


logger = logging.getLogger(__name__)


class EventStreamHandler(BaseHandler):

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

        # Count of active streams per user
        self._streams_per_user = {}
        # Grace timers per user to delay the "stopped" signal
        self._stop_timer_per_user = {}

        self.distributor = hs.get_distributor()
        self.distributor.declare("started_user_eventstream")
        self.distributor.declare("stopped_user_eventstream")

        self.clock = hs.get_clock()

        self.notifier = hs.get_notifier()

    @defer.inlineCallbacks
    @log_function
    def get_stream(self, auth_user_id, pagin_config, timeout=0):
        auth_user = self.hs.parse_userid(auth_user_id)

        try:
            if auth_user not in self._streams_per_user:
                self._streams_per_user[auth_user] = 0
                if auth_user in self._stop_timer_per_user:
                    self.clock.cancel_call_later(
                        self._stop_timer_per_user.pop(auth_user))
                else:
                    self.distributor.fire(
                        "started_user_eventstream", auth_user
                    )
            self._streams_per_user[auth_user] += 1

            if pagin_config.from_token is None:
                pagin_config.from_token = None

            rm_handler = self.hs.get_handlers().room_member_handler
            room_ids = yield rm_handler.get_rooms_for_user(auth_user)

            events, tokens = yield self.notifier.get_events_for(
                auth_user, room_ids, pagin_config, timeout
            )

            chunks = [self.hs.serialize_event(e) for e in events]

            chunk = {
                "chunk": chunks,
                "start": tokens[0].to_string(),
                "end": tokens[1].to_string(),
            }

            defer.returnValue(chunk)

        finally:
            self._streams_per_user[auth_user] -= 1
            if not self._streams_per_user[auth_user]:
                del self._streams_per_user[auth_user]

                # 10 seconds of grace to allow the client to reconnect again
                #   before we think they're gone
                def _later():
                    logger.debug(
                        "_later stopped_user_eventstream %s", auth_user
                    )
                    self.distributor.fire(
                        "stopped_user_eventstream", auth_user
                    )
                    del self._stop_timer_per_user[auth_user]

                logger.debug("Scheduling _later: for %s", auth_user)
                self._stop_timer_per_user[auth_user] = (
                    self.clock.call_later(30, _later)
                )


class EventHandler(BaseHandler):

    @defer.inlineCallbacks
    def get_event(self, user, event_id):
        """Retrieve a single specified event.

        Args:
            user (synapse.types.UserID): The user requesting the event
            event_id (str): The event ID to obtain.
        Returns:
            dict: An event, or None if there is no event matching this ID.
        Raises:
            SynapseError if there was a problem retrieving this event, or
            AuthError if the user does not have the rights to inspect this
            event.
        """
        event = yield self.store.get_event(event_id)

        if not event:
            defer.returnValue(None)
            return

        if hasattr(event, "room_id"):
            yield self.auth.check_joined_room(event.room_id, user.to_string())

        defer.returnValue(event)
