# 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 typing import TYPE_CHECKING, Iterator, Tuple

import attr

from synapse.handlers.account_data import AccountDataEventSource
from synapse.handlers.presence import PresenceEventSource
from synapse.handlers.receipts import ReceiptEventSource
from synapse.handlers.room import RoomEventSource
from synapse.handlers.typing import TypingNotificationEventSource
from synapse.streams import EventSource
from synapse.types import StreamToken

if TYPE_CHECKING:
    from synapse.server import HomeServer


@attr.s(frozen=True, slots=True, auto_attribs=True)
class _EventSourcesInner:
    room: RoomEventSource
    presence: PresenceEventSource
    typing: TypingNotificationEventSource
    receipt: ReceiptEventSource
    account_data: AccountDataEventSource

    def get_sources(self) -> Iterator[Tuple[str, EventSource]]:
        for attribute in attr.fields(_EventSourcesInner):
            yield attribute.name, getattr(self, attribute.name)


class EventSources:
    def __init__(self, hs: "HomeServer"):
        self.sources = _EventSourcesInner(
            # mypy thinks attribute.type is `Optional`, but we know it's never `None` here since
            # all the attributes of `_EventSourcesInner` are annotated.
            *(attribute.type(hs) for attribute in attr.fields(_EventSourcesInner))  # type: ignore[misc]
        )
        self.store = hs.get_datastores().main

    def get_current_token(self) -> StreamToken:
        push_rules_key = self.store.get_max_push_rules_stream_id()
        to_device_key = self.store.get_to_device_stream_token()
        device_list_key = self.store.get_device_stream_token()

        token = StreamToken(
            room_key=self.sources.room.get_current_key(),
            presence_key=self.sources.presence.get_current_key(),
            typing_key=self.sources.typing.get_current_key(),
            receipt_key=self.sources.receipt.get_current_key(),
            account_data_key=self.sources.account_data.get_current_key(),
            push_rules_key=push_rules_key,
            to_device_key=to_device_key,
            device_list_key=device_list_key,
            # Groups key is unused.
            groups_key=0,
        )
        return token

    async def get_current_token_for_pagination(self, room_id: str) -> StreamToken:
        """Get the current token for a given room to be used to paginate
        events.

        The returned token does not have the current values for fields other
        than `room`, since they are not used during pagination.

        Returns:
            The current token for pagination.
        """
        token = StreamToken(
            room_key=await self.sources.room.get_current_key_for_room(room_id),
            presence_key=0,
            typing_key=0,
            receipt_key=0,
            account_data_key=0,
            push_rules_key=0,
            to_device_key=0,
            device_list_key=0,
            groups_key=0,
        )
        return token
