Re-enable copypasting URLs from other participants

[cbachhuber]

#163 broke the copy-link-to-join ability, as now the link contains the session ID. If I copypaste a user's URL, I'm treated as the same user. I need to be a separate user.

[cbachhuber]

I had a brief look into this issue and streamlit's caching offerings. I think we might be able to use context objects such as cookies. Cookies contain ajs_anonymous_id, which is the (hopefully persistent on streamlit.com) identifier of a session.

My solution comes down to

diff --git a/src/open_cups/session_state.py b/src/open_cups/session_state.py
index 626c159..c1d19e9 100644
--- a/src/open_cups/session_state.py
+++ b/src/open_cups/session_state.py
@@ -12,9 +12,7 @@ class SessionState:
 
     def __init__(self) -> None:
         if "session_id" not in st.session_state:
-            existing = st.query_params.get("session_id")
-            st.session_state.session_id = existing or str(uuid.uuid4())
-        st.query_params["session_id"] = st.session_state.session_id
+            st.session_state.session_id = st.context.cookies["ajs_anonymous_id"]
 
     @property
     def session_id(self) -> str:

We could just give this a try on our main branch, if you want. I'm not entirely sure whether ajs_anonymous_id survives the streamlit reconnect.

If that doesn't work, st.context has more options to offer, among them the user's IP address.

I don't think we're getting into dangerous territory here: we'd just use what streamlit anyways offers, and we don't publish that data to other users.

[BayerC]

lets try it! can you make a PR, we merge it and see how it behaves

[BayerC]

seems cookie doesnt work :/

[cbachhuber]

I think this relates to streamlit/streamlit#10041. Shall we try the solution proposed in the original message of that issue?

An alternative would be Device Fingerprinting: Generate a hash from screen size, fonts, canvas using libraries like FingerprintJS. Not sure how unique that is given the relatively few iPhone models out there, for example.

[BayerC]

I think we can try it!

Device Fingerprinting sounds very briddle

[cbachhuber]

If we stick with the cookie option, we might need to implement a cookie banner :/

Let's see if we can avoid that.

[BayerC]

didne work for me your branch