python-aternos/python_aternos/atwss.py

"""Connects to Aternos API websocket
for real-time information"""

import enum
import json
import asyncio
import logging
import websockets
from typing import Union, Any
from typing import Dict, Tuple
from typing import Callable, Coroutine
from typing import TYPE_CHECKING

from .atconnect import REQUA
if TYPE_CHECKING:
    from .atserver import AternosServer

OneArgT = Callable[[Any], Coroutine[Any, Any, None]]
TwoArgT = Callable[[Any, Tuple[Any, ...]], Coroutine[Any, Any, None]]
FunctionT = Union[OneArgT, TwoArgT]
ArgsTuple = Tuple[FunctionT, Tuple[Any, ...]]


class Streams(enum.Enum):

    """WebSocket streams types"""

    status = (0, None)
    queue = (1, None)
    console = (2, 'console')
    ram = (3, 'heap')
    tps = (4, 'tick')
    none = (-1, None)

    def __init__(self, num: int, stream: str) -> None:
        self.num = num
        self.stream = stream


class AternosWss:

    """Class for managing websocket connection

    :param atserv: :class:`python_aternos.atserver.AternosServer` instance
    :type atserv: python_aternos.atserver.AternosServer
    :param autoconfirm: Automatically start server status listener
    when AternosWss connects to API to confirm
    server launching, defaults to `False`
    :type autoconfirm: bool, optional
    """

    def __init__(
            self,
            atserv: 'AternosServer',
            autoconfirm: bool = False) -> None:

        self.atserv = atserv
        self.cookies = atserv.atconn.session.cookies
        self.session = self.cookies['ATERNOS_SESSION']
        self.servid = atserv.servid

        recvtype = Dict[Streams, ArgsTuple]
        self.recv: recvtype = {}
        self.autoconfirm = autoconfirm
        self.confirmed = False

        self.socket: Any
        self.keep: asyncio.Task
        self.msgs: asyncio.Task

    async def confirm(self) -> None:

        """Simple way to call AternosServer.confirm from this class"""

        self.atserv.confirm()

    def wssreceiver(
            self,
            stream: Streams,
            *args: Any) -> Callable[[FunctionT], Any]:

        """Decorator that marks your function as a stream receiver.
        When websocket receives message from the specified stream,
        it calls all listeners created with this decorator.

        :param stream: Stream that your function should listen
        :type stream: python_aternos.atwss.Streams
        :param args: Arguments which will be passed to your function
        :type args: tuple, optional
        :return: ...
        :rtype: Callable[[Callable[[Any], Coroutine[Any, Any, None]]], Any]
        """

        def decorator(func: FunctionT) -> None:
            self.recv[stream] = (func, args)
        return decorator

    async def connect(self) -> None:

        """Connect to the websocket server and start all stream listeners"""

        headers = [
            ('Host', 'aternos.org'),
            ('User-Agent', REQUA),
            (
                'Cookie',
                f'ATERNOS_SESSION={self.session}; '
                f'ATERNOS_SERVER={self.servid}'
            )
        ]
        self.socket = await websockets.connect(  # type: ignore
            'wss://aternos.org/hermes/',
            origin='https://aternos.org',
            extra_headers=headers
        )

        @self.wssreceiver(Streams.status)
        async def confirmfunc(msg):

            """Automatically confirm Minecraft server launching"""

            if not self.autoconfirm:
                return

            in_queue = (msg['class'] == 'queueing')
            pending = (msg['queue']['pending'] == 'pending')
            confirmation = in_queue and pending

            if confirmation and not self.confirmed:
                self.confirm()

        @self.wssreceiver(Streams.status)
        async def streamsfunc(msg):

            """Automatically starts streams. Detailed description:

            According to the websocket messages from the web site,
            Aternos can't receive any data from a stream (e.g. console) until
            it requests this stream via the special message
            to the websocket server: `{"stream":"console","type":"start"}`
            on which the server responses with: `{"type":"connected"}`
            Also, there are RAM (used heap) and TPS (ticks per second)
            streams that must be enabled before trying to get information.
            Enabling the stream for listening the server status is not needed,
            these data is sent from API by default, so there's None value in
            the second item of its stream type tuple
            (`<Streams.status: (0, None)>`).
            https://github.com/DarkCat09/python-aternos/issues/22#issuecomment-1146788496
            """

            if msg['status'] == 2:
                # Automatically start streams
                for strm in self.recv:

                    if not isinstance(strm, Streams):
                        continue

                    if strm.stream:
                        logging.debug(f'Enabling {strm.stream} stream')
                        await self.send({
                            'stream': strm.stream,
                            'type': 'start'
                        })

        await self.wssworker()

    async def close(self) -> None:

        """Closes websocket connection and stops all listeners"""

        self.keep.cancel()
        self.msgs.cancel()
        await self.socket.close()
        del self.socket

    async def send(self, obj: Union[Dict[str, Any], str]) -> None:

        """Sends a message to websocket server

        :param obj: Message, may be a string or a dict
        :type obj: Union[Dict[str, Any],str]
        """

        if isinstance(obj, dict):
            obj = json.dumps(obj)

        await self.socket.send(obj)

    async def wssworker(self) -> None:

        """Starts async tasks in background
        for receiving websocket messages
        and sending keepalive ping"""

        self.keep = asyncio.create_task(self.keepalive())
        self.msgs = asyncio.create_task(self.receiver())

    async def keepalive(self) -> None:

        """Each 49 seconds sends keepalive ping to websocket server"""

        try:
            while True:
                await asyncio.sleep(49)
                await self.socket.send('{"type":"\u2764"}')

        except asyncio.CancelledError:
            pass

    async def receiver(self) -> None:

        """Receives messages from websocket servers
        and calls user's streams listeners"""

        while True:
            try:
                data = await self.socket.recv()
                obj = json.loads(data)
                msgtype = Streams.none

                if obj['type'] == 'line':
                    msgtype = Streams.console
                    msg = obj['data'].strip('\r\n ')

                elif obj['type'] == 'heap':
                    msgtype = Streams.ram
                    msg = int(obj['data']['usage'])

                elif obj['type'] == 'tick':
                    msgtype = Streams.tps
                    ticks = 1000 / obj['data']['averageTickTime']
                    msg = 20 if ticks > 20 else ticks

                elif obj['type'] == 'status':
                    msgtype = Streams.status
                    msg = json.loads(obj['message'])

                if msgtype in self.recv:

                    # function info tuple
                    func: ArgsTuple = self.recv[msgtype]

                    # if arguments is not empty
                    if func[1]:
                        # call the function with args
                        coro = func[0](msg, func[1])  # type: ignore
                    else:
                        # mypy error: Too few arguments
                        # looks like bug, so it is ignored
                        coro = func[0](msg)  # type: ignore
                    # run
                    asyncio.create_task(coro)

            except asyncio.CancelledError:
                break