feat(ffi): expose join_rules in OtherState::RoomJoinRules (#5863)

Expose the room join rules in the `OtherState::RoomJoinRules` event 
for the FFI timeline.

It reuses the existing `JoinRules` type from the client module and
converts the event content accordingly. This allows clients to inspect
the room’s current join rule directly from the event. Like `m.federate`,
this field was previously unavailable in the FFI variant of the SDK.

---------

Signed-off-by: JoFrost <[email protected]>

Author: JoFrost

bindings/matrix-sdk-ffi/CHANGELOG.md

@@ -81,6 +81,7 @@ All notable changes to this project will be documented in this file.
 - Add new API to decline calls ([MSC4310](https://github.com/matrix-org/matrix-spec-proposals/pull/4310)): `Room::decline_call` and `Room::subscribe_to_call_decline_events`
   ([#5614](https://github.com/matrix-org/matrix-rust-sdk/pull/5614))
 - Expose `m.federate` in `OtherState::RoomCreate` and `history_visibility` in `OtherState::RoomHistoryVisibility`, allowing clients to know whether a room federates and how its history is shared in the appropriate timeline events.
+- Expose `join_rule` in `OtherState::RoomJoinRules`, allowing clients to know the join rules of a room from the appropriate timeline events.
 
 ### Changes
 

bindings/matrix-sdk-ffi/src/timeline/content.rs

@@ -20,7 +20,7 @@ use ruma::events::{
     room::history_visibility::HistoryVisibility as RumaHistoryVisibility, FullStateEventContent,
 };
 
-use crate::{timeline::msg_like::MsgLikeContent, utils::Timestamp};
+use crate::{client::JoinRule, timeline::msg_like::MsgLikeContent, utils::Timestamp};
 
 impl From<matrix_sdk_ui::timeline::TimelineItemContent> for TimelineItemContent {
     fn from(value: matrix_sdk_ui::timeline::TimelineItemContent) -> Self {
@@ -254,7 +254,7 @@ pub enum OtherState {
     RoomEncryption,
     RoomGuestAccess,
     RoomHistoryVisibility { history_visibility: Option<HistoryVisibility> },
-    RoomJoinRules,
+    RoomJoinRules { join_rule: Option<JoinRule> },
     RoomName { name: Option<String> },
     RoomPinnedEvents { change: RoomPinnedEventsChange },
     RoomPowerLevels { users: HashMap<String, i64>, previous: Option<HashMap<String, i64>> },
@@ -305,7 +305,21 @@ impl From<&matrix_sdk_ui::timeline::AnyOtherFullStateEventContent> for OtherStat
                 };
                 Self::RoomHistoryVisibility { history_visibility }
             }
-            Content::RoomJoinRules(_) => Self::RoomJoinRules,
+            Content::RoomJoinRules(c) => {
+                let join_rule = match c {
+                    FullContent::Original { content, .. } => {
+                        match content.join_rule.clone().try_into() {
+                            Ok(jr) => Some(jr),
+                            Err(err) => {
+                                tracing::error!("Failed to convert join rule: {}", err);
+                                None
+                            }
+                        }
+                    }
+                    FullContent::Redacted(_) => None,
+                };
+                Self::RoomJoinRules { join_rule }
+            }
             Content::RoomName(c) => {
                 let name = match c {
                     FullContent::Original { content, .. } => Some(content.name.clone()),