feat: support /make_join and /send_join for restricted rooms

from https://gitlab.com/famedly/conduit/-/merge_requests/618

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/service/rooms/state_accessor/mod.rs

@@ -13,6 +13,7 @@ use ruma::{
 			history_visibility::{HistoryVisibility, RoomHistoryVisibilityEventContent},
 			member::{MembershipState, RoomMemberEventContent},
 			name::RoomNameEventContent,
+			power_levels::RoomPowerLevelsEventContent,
 		},
 		StateEventType,
 	},
@@ -139,6 +140,18 @@ impl Service {
 		Ok(visibility)
 	}
 
+	/// Whether a user's power level is sufficient to invite other users
+	pub fn user_can_invite(&self, user_id: &UserId, room_id: &RoomId) -> Result<bool> {
+		self.room_state_get(room_id, &StateEventType::RoomPowerLevels, "")?
+			.map(|pdu_event| {
+				serde_json::from_str(pdu_event.content.get()).map(|content: RoomPowerLevelsEventContent| {
+					content.users.get(user_id).unwrap_or(&content.users_default) >= &content.invite
+				})
+			})
+			.unwrap_or(Ok(false))
+			.map_err(|_| Error::bad_database("Invalid history visibility event in database."))
+	}
+
 	/// Whether a user is allowed to see an event, based on
 	/// the room's history_visibility at that event's state.
 	#[tracing::instrument(skip(self, user_id, room_id, event_id))]