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from logging import getLogger
from asyncio import AbstractEventLoop, create_task
from aiohttp import WSMsgType, WSMessage
from aiohttp.web import Application, WebSocketResponse, Request, Response, get
from enum import IntEnum
from typing import Callable, Coroutine, Dict, Any, cast, TypeVar
from traceback import format_exc
from .helpers import get_csrf_token
class MessageType(IntEnum):
ERROR = -1
# Call-reply, Frontend -> Backend -> Frontend
CALL = 0
REPLY = 1
# Pub/Sub, Backend -> Frontend
EVENT = 3
# WSMessage with slightly better typings
class WSMessageExtra(WSMessage):
# TODO message typings here too
data: Any # pyright: ignore [reportIncompatibleVariableOverride]
type: WSMsgType # pyright: ignore [reportIncompatibleVariableOverride]
# see wsrouter.ts for typings
DataType = TypeVar("DataType")
Route = Callable[..., Coroutine[Any, Any, Any]]
class WSRouter:
def __init__(self, loop: AbstractEventLoop, server_instance: Application) -> None:
self.loop = loop
self.ws: WebSocketResponse | None = None
self.instance_id = 0
self.routes: Dict[str, Route] = {}
# self.subscriptions: Dict[str, Callable[[Any]]] = {}
self.logger = getLogger("WSRouter")
server_instance.add_routes([
get("/ws", self.handle)
])
async def write(self, data: Dict[str, Any]):
if self.ws != None:
await self.ws.send_json(data)
else:
self.logger.warn("Dropping message as there is no connected socket: %s", data)
def add_route(self, name: str, route: Route):
self.routes[name] = route
def remove_route(self, name: str):
del self.routes[name]
async def _call_route(self, route: str, args: ..., call_id: int):
instance_id = self.instance_id
error = None
try:
res = await self.routes[route](*args)
except Exception as err:
error = {"name":err.__class__.__name__, "message":str(err), "traceback":format_exc()}
res = None
if instance_id != self.instance_id:
try:
self.logger.warn("Ignoring %s reply from stale instance %d with args %s and response %s", route, instance_id, args, res)
except:
self.logger.warn("Ignoring %s reply from stale instance %d (failed to log event data)", route, instance_id)
finally:
return
if error:
await self.write({"type": MessageType.ERROR.value, "id": call_id, "error": error})
else:
await self.write({"type": MessageType.REPLY.value, "id": call_id, "result": res})
async def handle(self, request: Request):
# Auth is a query param as JS WebSocket doesn't support headers
if request.rel_url.query["auth"] != get_csrf_token():
return Response(text='Forbidden', status=403)
self.logger.debug('Websocket connection starting')
ws = WebSocketResponse()
await ws.prepare(request)
self.instance_id += 1
self.logger.debug('Websocket connection ready')
if self.ws != None:
try:
await self.ws.close()
except:
pass
self.ws = None
self.ws = ws
try:
async for msg in ws:
msg = cast(WSMessageExtra, msg)
if msg.type == WSMsgType.TEXT:
if msg.data == 'close':
# TODO DO NOT RELY ON THIS!
break
else:
data = msg.json()
match data["type"]:
case MessageType.CALL.value:
# do stuff with the message
if data["route"] in self.routes:
self.logger.debug(f'Started PY call {data["route"]} ID {data["id"]}')
create_task(self._call_route(data["route"], data["args"], data["id"]))
else:
error = {"error":f'Route {data["route"]} does not exist.', "name": "RouteNotFoundError", "traceback": None}
create_task(self.write({"type": MessageType.ERROR.value, "id": data["id"], "error": error}))
case _:
self.logger.error("Unknown message type", data)
finally:
try:
await ws.close()
self.ws = None
except:
pass
self.logger.debug('Websocket connection closed')
return ws
async def emit(self, event: str, *args: Any):
self.logger.debug(f'Firing frontend event {event} with args {args}')
await self.write({ "type": MessageType.EVENT.value, "event": event, "args": args })
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