From c02d6d7bf88947bab266383a9d5b09a13649919c Mon Sep 17 00:00:00 2001
From: Davide Casale <davi0kprogramsthings@gmail.com>
Date: Thu, 26 Oct 2023 05:57:10 +0200
Subject: [PATCH] Fix bug in module bfxapi.websocket._event_emitter.

---
 .../websocket/_client/bfx_websocket_client.py |  2 +-
 .../_event_emitter/bfx_event_emitter.py       | 49 +++++++++++--------
 2 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/bfxapi/websocket/_client/bfx_websocket_client.py b/bfxapi/websocket/_client/bfx_websocket_client.py
index a8831c0..eb7d9ab 100644
--- a/bfxapi/websocket/_client/bfx_websocket_client.py
+++ b/bfxapi/websocket/_client/bfx_websocket_client.py
@@ -335,4 +335,4 @@ class BfxWebSocketClient(Connection):
             [ 0, event, None, data], cls=JSONEncoder))
 
     def on(self, event, f = None):
-        return self.__event_emitter.on(event, f=f)
+        return self.__event_emitter.on(event, f)
diff --git a/bfxapi/websocket/_event_emitter/bfx_event_emitter.py b/bfxapi/websocket/_event_emitter/bfx_event_emitter.py
index 31ee983..27f00d0 100644
--- a/bfxapi/websocket/_event_emitter/bfx_event_emitter.py
+++ b/bfxapi/websocket/_event_emitter/bfx_event_emitter.py
@@ -1,6 +1,7 @@
 from typing import \
-    Callable, List, Dict, \
-    Optional, Any
+    TypeVar, Callable, List, \
+    Dict, Union, Optional, \
+    Any
 
 from collections import defaultdict
 from asyncio import AbstractEventLoop
@@ -8,6 +9,8 @@ from pyee.asyncio import AsyncIOEventEmitter
 
 from bfxapi.websocket.exceptions import UnknownEventError
 
+_Handler = TypeVar("_Handler", bound=Callable[..., None])
+
 _ONCE_PER_CONNECTION = [
     "open", "authenticated", "order_snapshot",
     "position_snapshot", "funding_offer_snapshot", "funding_credit_snapshot",
@@ -21,19 +24,19 @@ _ONCE_PER_SUBSCRIPTION = [
 ]
 
 _COMMON = [
-    "error", "disconnected", "t_ticker_update",
-    "f_ticker_update", "t_trade_execution", "t_trade_execution_update",
-    "f_trade_execution", "f_trade_execution_update", "t_book_update",
-    "f_book_update", "t_raw_book_update", "f_raw_book_update",
-    "candles_update", "derivatives_status_update", "liquidation_feed_update",
-    "order_new", "order_update", "order_cancel",
-    "position_new", "position_update", "position_close",
-    "funding_offer_new", "funding_offer_update", "funding_offer_cancel",
-    "funding_credit_new", "funding_credit_update", "funding_credit_close",
-    "funding_loan_new", "funding_loan_update", "funding_loan_close",
-    "trade_execution", "trade_execution_update", "wallet_update",
-    "notification", "on-req-notification", "ou-req-notification",
-    "oc-req-notification", "fon-req-notification", "foc-req-notification"
+    "disconnected", "t_ticker_update", "f_ticker_update",
+    "t_trade_execution", "t_trade_execution_update", "f_trade_execution",
+    "f_trade_execution_update", "t_book_update", "f_book_update",
+    "t_raw_book_update", "f_raw_book_update", "candles_update",
+    "derivatives_status_update", "liquidation_feed_update", "order_new",
+    "order_update", "order_cancel", "position_new",
+    "position_update", "position_close", "funding_offer_new",
+    "funding_offer_update", "funding_offer_cancel", "funding_credit_new",
+    "funding_credit_update", "funding_credit_close", "funding_loan_new",
+    "funding_loan_update", "funding_loan_close", "trade_execution",
+    "trade_execution_update", "wallet_update", "notification",
+    "on-req-notification", "ou-req-notification", "oc-req-notification",
+    "fon-req-notification", "foc-req-notification"
 ]
 
 class BfxEventEmitter(AsyncIOEventEmitter):
@@ -49,10 +52,12 @@ class BfxEventEmitter(AsyncIOEventEmitter):
         self._subscriptions: Dict[str, List[str]] = \
             defaultdict(lambda: [ ])
 
-    def emit(self,
-             event: str,
-             *args: Any,
-             **kwargs: Any) -> bool:
+    def emit(
+        self,
+        event: str,
+        *args: Any,
+        **kwargs: Any
+    ) -> bool:
         if event in _ONCE_PER_CONNECTION:
             if event in self._connection:
                 return self._has_listeners(event)
@@ -69,12 +74,14 @@ class BfxEventEmitter(AsyncIOEventEmitter):
 
         return super().emit(event, *args, **kwargs)
 
-    def _add_event_handler(self, event: str, k: Callable, v: Callable):
+    def on(
+        self, event: str, f: Optional[_Handler] = None
+    ) -> Union[_Handler, Callable[[_Handler], _Handler]]:
         if event not in BfxEventEmitter._EVENTS:
             raise UnknownEventError(f"Can't register to unknown event: <{event}> " + \
                 "(to get a full list of available events see https://docs.bitfinex.com/).")
 
-        super()._add_event_handler(event, k, v)
+        return super().on(event, f)
 
     def _has_listeners(self, event: str) -> bool:
         with self._lock: