add main.py with basic matrix client implementation

main.py

@@ -0,0 +1,38 @@
+import asyncio
+import tomllib
+
+from nio import AsyncClient, MatrixRoom, RoomMessageText, RoomMemberEvent
+
+
+async def message_callback(room: MatrixRoom, event: RoomMessageText) -> None:
+    print(
+        f"Message received in room {room.display_name}\n"
+        f"{room.user_name(event.sender)} | {event.body}"
+    )
+
+
+async def membership_callback(room: MatrixRoom, event: RoomMemberEvent) -> None:
+    print(f"Room member event on room '{repr(room)}': {repr(event)}\n")
+
+    if event.content["membership"] == "join":
+        print(f"{event.content['displayname']} joined room")
+
+
+async def main() -> None:
+    with open("credentials.toml", "rb") as f:
+        config = tomllib.load(f)
+
+    server = config["credentials"]["server"]
+    username = config["credentials"]["username"]
+    password = config["credentials"]["password"]
+
+    client = AsyncClient(server, username)
+    client.add_event_callback(message_callback, RoomMessageText)
+    client.add_event_callback(membership_callback, RoomMemberEvent)
+
+    print(await client.login(password))
+
+    await client.sync_forever(timeout=30000)  # milliseconds
+
+
+asyncio.run(main())