# -*- coding: utf-8 -*-
# Copyright 2014, 2015 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.constants import EventTypes, Membership
from synapse.api.errors import RoomError, SynapseError
from synapse.streams.config import PaginationConfig
from synapse.events.utils import serialize_event
from synapse.events.validator import EventValidator
from synapse.util import unwrapFirstError
from synapse.util.logcontext import PreserveLoggingContext
from synapse.types import UserID, RoomStreamToken

from ._base import BaseHandler

import logging

logger = logging.getLogger(__name__)


class MessageHandler(BaseHandler):

    def __init__(self, hs):
        super(MessageHandler, self).__init__(hs)
        self.hs = hs
        self.state = hs.get_state_handler()
        self.clock = hs.get_clock()
        self.validator = EventValidator()

    @defer.inlineCallbacks
    def get_message(self, msg_id=None, room_id=None, sender_id=None,
                    user_id=None):
        """ Retrieve a message.

        Args:
            msg_id (str): The message ID to obtain.
            room_id (str): The room where the message resides.
            sender_id (str): The user ID of the user who sent the message.
            user_id (str): The user ID of the user making this request.
        Returns:
            The message, or None if no message exists.
        Raises:
            SynapseError if something went wrong.
        """
        yield self.auth.check_joined_room(room_id, user_id)

        # Pull out the message from the db
#        msg = yield self.store.get_message(
#            room_id=room_id,
#            msg_id=msg_id,
#            user_id=sender_id
#        )

        # TODO (erikj): Once we work out the correct c-s api we need to think
        # on how to do this.

        defer.returnValue(None)

    @defer.inlineCallbacks
    def get_messages(self, user_id=None, room_id=None, pagin_config=None,
                     feedback=False, as_client_event=True):
        """Get messages in a room.

        Args:
            user_id (str): The user requesting messages.
            room_id (str): The room they want messages from.
            pagin_config (synapse.api.streams.PaginationConfig): The pagination
            config rules to apply, if any.
            feedback (bool): True to get compressed feedback with the messages
            as_client_event (bool): True to get events in client-server format.
        Returns:
            dict: Pagination API results
        """
        yield self.auth.check_joined_room(room_id, user_id)

        data_source = self.hs.get_event_sources().sources["room"]

        if not pagin_config.from_token:
            pagin_config.from_token = (
                yield self.hs.get_event_sources().get_current_token(
                    direction='b'
                )
            )

        room_token = RoomStreamToken.parse(pagin_config.from_token.room_key)
        if room_token.topological is None:
            raise SynapseError(400, "Invalid token")

        yield self.hs.get_handlers().federation_handler.maybe_backfill(
            room_id, room_token.topological
        )

        user = UserID.from_string(user_id)

        events, next_key = yield data_source.get_pagination_rows(
            user, pagin_config.get_source_config("room"), room_id
        )

        next_token = pagin_config.from_token.copy_and_replace(
            "room_key", next_key
        )

        if not events:
            defer.returnValue({
                "chunk": [],
                "start": pagin_config.from_token.to_string(),
                "end": next_token.to_string(),
            })

        events = yield self._filter_events_for_client(user_id, room_id, events)

        time_now = self.clock.time_msec()

        chunk = {
            "chunk": [
                serialize_event(e, time_now, as_client_event)
                for e in events
            ],
            "start": pagin_config.from_token.to_string(),
            "end": next_token.to_string(),
        }

        defer.returnValue(chunk)

    @defer.inlineCallbacks
    def _filter_events_for_client(self, user_id, room_id, events):
        event_id_to_state = yield self.store.get_state_for_events(
            room_id, frozenset(e.event_id for e in events),
            types=(
                (EventTypes.RoomHistoryVisibility, ""),
                (EventTypes.Member, user_id),
            )
        )

        def allowed(event_and_state):
            event, state = event_and_state

            if event.type == EventTypes.RoomHistoryVisibility:
                return True

            membership_ev = state.get((EventTypes.Member, user_id), None)
            if membership_ev:
                membership = membership_ev.membership
            else:
                membership = Membership.LEAVE

            if membership == Membership.JOIN:
                return True

            history = state.get((EventTypes.RoomHistoryVisibility, ''), None)
            if history:
                visibility = history.content.get("history_visibility", "shared")
            else:
                visibility = "shared"

            if visibility == "public":
                return True
            elif visibility == "shared":
                return True
            elif visibility == "joined":
                return membership == Membership.JOIN
            elif visibility == "invited":
                return membership == Membership.INVITE

            return True

        event_and_state = filter(
            allowed,
            [
                (e, event_id_to_state[e.event_id])
                for e in events
            ]
        )

        defer.returnValue([
            ev
            for ev, _ in event_and_state
        ])

    @defer.inlineCallbacks
    def create_and_send_event(self, event_dict, ratelimit=True,
                              client=None, txn_id=None):
        """ Given a dict from a client, create and handle a new event.

        Creates an FrozenEvent object, filling out auth_events, prev_events,
        etc.

        Adds display names to Join membership events.

        Persists and notifies local clients and federation.

        Args:
            event_dict (dict): An entire event
        """
        builder = self.event_builder_factory.new(event_dict)

        self.validator.validate_new(builder)

        if ratelimit:
            self.ratelimit(builder.user_id)
        # TODO(paul): Why does 'event' not have a 'user' object?
        user = UserID.from_string(builder.user_id)
        assert self.hs.is_mine(user), "User must be our own: %s" % (user,)

        if builder.type == EventTypes.Member:
            membership = builder.content.get("membership", None)
            if membership == Membership.JOIN:
                joinee = UserID.from_string(builder.state_key)
                # If event doesn't include a display name, add one.
                yield self.distributor.fire(
                    "collect_presencelike_data",
                    joinee,
                    builder.content
                )

        if client is not None:
            if client.token_id is not None:
                builder.internal_metadata.token_id = client.token_id
            if client.device_id is not None:
                builder.internal_metadata.device_id = client.device_id

        if txn_id is not None:
            builder.internal_metadata.txn_id = txn_id

        event, context = yield self._create_new_client_event(
            builder=builder,
        )

        if event.type == EventTypes.Member:
            member_handler = self.hs.get_handlers().room_member_handler
            yield member_handler.change_membership(event, context)
        else:
            yield self.handle_new_client_event(
                event=event,
                context=context,
            )

        if event.type == EventTypes.Message:
            presence = self.hs.get_handlers().presence_handler
            with PreserveLoggingContext():
                presence.bump_presence_active_time(user)

        defer.returnValue(event)

    @defer.inlineCallbacks
    def get_room_data(self, user_id=None, room_id=None,
                      event_type=None, state_key=""):
        """ Get data from a room.

        Args:
            event : The room path event
        Returns:
            The path data content.
        Raises:
            SynapseError if something went wrong.
        """
        have_joined = yield self.auth.check_joined_room(room_id, user_id)
        if not have_joined:
            raise RoomError(403, "User not in room.")

        data = yield self.state_handler.get_current_state(
            room_id, event_type, state_key
        )
        defer.returnValue(data)

    @defer.inlineCallbacks
    def get_feedback(self, event_id):
        # yield self.auth.check_joined_room(room_id, user_id)

        # Pull out the feedback from the db
        fb = yield self.store.get_feedback(event_id)

        if fb:
            defer.returnValue(fb)
        defer.returnValue(None)

    @defer.inlineCallbacks
    def get_state_events(self, user_id, room_id):
        """Retrieve all state events for a given room.

        Args:
            user_id(str): The user requesting state events.
            room_id(str): The room ID to get all state events from.
        Returns:
            A list of dicts representing state events. [{}, {}, {}]
        """
        yield self.auth.check_joined_room(room_id, user_id)

        # TODO: This is duplicating logic from snapshot_all_rooms
        current_state = yield self.state_handler.get_current_state(room_id)
        now = self.clock.time_msec()
        defer.returnValue(
            [serialize_event(c, now) for c in current_state.values()]
        )

    @defer.inlineCallbacks
    def snapshot_all_rooms(self, user_id=None, pagin_config=None,
                           feedback=False, as_client_event=True):
        """Retrieve a snapshot of all rooms the user is invited or has joined.

        This snapshot may include messages for all rooms where the user is
        joined, depending on the pagination config.

        Args:
            user_id (str): The ID of the user making the request.
            pagin_config (synapse.api.streams.PaginationConfig): The pagination
            config used to determine how many messages *PER ROOM* to return.
            feedback (bool): True to get feedback along with these messages.
            as_client_event (bool): True to get events in client-server format.
        Returns:
            A list of dicts with "room_id" and "membership" keys for all rooms
            the user is currently invited or joined in on. Rooms where the user
            is joined on, may return a "messages" key with messages, depending
            on the specified PaginationConfig.
        """
        room_list = yield self.store.get_rooms_for_user_where_membership_is(
            user_id=user_id,
            membership_list=[Membership.INVITE, Membership.JOIN]
        )

        user = UserID.from_string(user_id)

        rooms_ret = []

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

        presence_stream = self.hs.get_event_sources().sources["presence"]
        pagination_config = PaginationConfig(from_token=now_token)
        presence, _ = yield presence_stream.get_pagination_rows(
            user, pagination_config.get_source_config("presence"), None
        )

        receipt_stream = self.hs.get_event_sources().sources["receipt"]
        receipt, _ = yield receipt_stream.get_pagination_rows(
            user, pagination_config.get_source_config("receipt"), None
        )

        public_room_ids = yield self.store.get_public_room_ids()

        limit = pagin_config.limit
        if limit is None:
            limit = 10

        @defer.inlineCallbacks
        def handle_room(event):
            d = {
                "room_id": event.room_id,
                "membership": event.membership,
                "visibility": (
                    "public" if event.room_id in public_room_ids
                    else "private"
                ),
            }

            if event.membership == Membership.INVITE:
                d["inviter"] = event.sender

            rooms_ret.append(d)

            if event.membership != Membership.JOIN:
                return
            try:
                (messages, token), current_state = yield defer.gatherResults(
                    [
                        self.store.get_recent_events_for_room(
                            event.room_id,
                            limit=limit,
                            end_token=now_token.room_key,
                        ),
                        self.state_handler.get_current_state(
                            event.room_id
                        ),
                    ]
                ).addErrback(unwrapFirstError)

                messages = yield self._filter_events_for_client(
                    user_id, event.room_id, messages
                )

                start_token = now_token.copy_and_replace("room_key", token[0])
                end_token = now_token.copy_and_replace("room_key", token[1])
                time_now = self.clock.time_msec()

                d["messages"] = {
                    "chunk": [
                        serialize_event(m, time_now, as_client_event)
                        for m in messages
                    ],
                    "start": start_token.to_string(),
                    "end": end_token.to_string(),
                }

                d["state"] = [
                    serialize_event(c, time_now, as_client_event)
                    for c in current_state.values()
                ]
            except:
                logger.exception("Failed to get snapshot")

        yield defer.gatherResults(
            [handle_room(e) for e in room_list],
            consumeErrors=True
        ).addErrback(unwrapFirstError)

        ret = {
            "rooms": rooms_ret,
            "presence": presence,
            "receipts": receipt,
            "end": now_token.to_string(),
        }

        defer.returnValue(ret)

    @defer.inlineCallbacks
    def room_initial_sync(self, user_id, room_id, pagin_config=None,
                          feedback=False):
        current_state = yield self.state.get_current_state(
            room_id=room_id,
        )

        yield self.auth.check_joined_room(
            room_id, user_id,
            current_state=current_state
        )

        # TODO(paul): I wish I was called with user objects not user_id
        #   strings...
        auth_user = UserID.from_string(user_id)

        # TODO: These concurrently
        time_now = self.clock.time_msec()
        state = [
            serialize_event(x, time_now)
            for x in current_state.values()
        ]

        member_event = current_state.get((EventTypes.Member, user_id,))

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

        limit = pagin_config.limit if pagin_config else None
        if limit is None:
            limit = 10

        room_members = [
            m for m in current_state.values()
            if m.type == EventTypes.Member
            and m.content["membership"] == Membership.JOIN
        ]

        presence_handler = self.hs.get_handlers().presence_handler

        @defer.inlineCallbacks
        def get_presence():
            presence_defs = yield defer.DeferredList(
                [
                    presence_handler.get_state(
                        target_user=UserID.from_string(m.user_id),
                        auth_user=auth_user,
                        as_event=True,
                        check_auth=False,
                    )
                    for m in room_members
                ],
                consumeErrors=True,
            )

            defer.returnValue([p for success, p in presence_defs if success])

        receipts_handler = self.hs.get_handlers().receipts_handler

        presence, receipts, (messages, token) = yield defer.gatherResults(
            [
                get_presence(),
                receipts_handler.get_receipts_for_room(room_id, now_token.receipt_key),
                self.store.get_recent_events_for_room(
                    room_id,
                    limit=limit,
                    end_token=now_token.room_key,
                )
            ],
            consumeErrors=True,
        ).addErrback(unwrapFirstError)

        messages = yield self._filter_events_for_client(
            user_id, room_id, messages
        )

        start_token = now_token.copy_and_replace("room_key", token[0])
        end_token = now_token.copy_and_replace("room_key", token[1])

        time_now = self.clock.time_msec()

        defer.returnValue({
            "membership": member_event.membership,
            "room_id": room_id,
            "messages": {
                "chunk": [serialize_event(m, time_now) for m in messages],
                "start": start_token.to_string(),
                "end": end_token.to_string(),
            },
            "state": state,
            "presence": presence,
            "receipts": receipts,
        })