From b3f03d307d35e37ad1507f3da92ba5865812261b Mon Sep 17 00:00:00 2001
From: strawberry <strawberry@puppygock.gay>
Date: Mon, 22 Apr 2024 00:44:35 -0400
Subject: [PATCH] try finding more servers for federation hierarchy instead of
 room ID server name

just the room ID server name is terrible

Signed-off-by: strawberry <strawberry@puppygock.gay>
---
 src/service/rooms/spaces/mod.rs | 53 ++++++++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 11 deletions(-)

diff --git a/src/service/rooms/spaces/mod.rs b/src/service/rooms/spaces/mod.rs
index 8cdd2d22..714da443 100644
--- a/src/service/rooms/spaces/mod.rs
+++ b/src/service/rooms/spaces/mod.rs
@@ -30,9 +30,9 @@ use ruma::{
 	OwnedRoomId, OwnedServerName, RoomId, ServerName, UInt, UserId,
 };
 use tokio::sync::Mutex;
-use tracing::{debug, error, warn};
+use tracing::{debug, error, info, warn};
 
-use crate::{services, Error, Result};
+use crate::{debug_info, services, Error, Result};
 
 pub struct CachedSpaceHierarchySummary {
 	summary: SpaceHierarchyParentSummary,
@@ -425,8 +425,36 @@ impl Service {
 	}
 
 	async fn get_summary_and_children_federation(
-		&self, current_room: &OwnedRoomId, suggested_only: bool, user_id: &UserId, via: &Vec<OwnedServerName>,
+		&self, current_room: &OwnedRoomId, suggested_only: bool, user_id: &UserId, via: &[OwnedServerName],
 	) -> Result<Option<SummaryAccessibility>> {
+		// try to find more servers to fetch hierachy from if the only
+		// choice is the room ID's server name (usually dead)
+		//
+		// all spaces are normal rooms, so they should always have at least
+		// 1 admin in it which has a far higher chance of their server still
+		// being alive
+		let power_levels: ruma::events::room::power_levels::RoomPowerLevelsEventContent = services()
+			.rooms
+			.state_accessor
+			.room_state_get(current_room, &StateEventType::RoomPowerLevels, "")?
+			.map(|ev| {
+				serde_json::from_str(ev.content.get())
+					.map_err(|_| Error::bad_database("invalid m.room.power_levels event"))
+			})
+			.transpose()?
+			.unwrap_or_default();
+
+		// add server names of the list of admins in the room for backfill server
+		via.to_owned().extend(
+			power_levels
+				.users
+				.iter()
+				.filter(|(_, level)| **level > power_levels.users_default)
+				.map(|(user_id, _)| user_id.server_name())
+				.filter(|server| server != &services().globals.server_name())
+				.map(ToOwned::to_owned),
+		);
+
 		for server in via {
 			debug!("Asking {server} for /hierarchy");
 			if let Ok(response) = services()
@@ -440,7 +468,7 @@ impl Service {
 				)
 				.await
 			{
-				debug!("Got response from {server} for /hierarchy\n{response:?}");
+				debug_info!("Got response from {server} for /hierarchy\n{response:?}");
 				let summary = response.room.clone();
 
 				self.roomid_spacehierarchy_cache.lock().await.insert(
@@ -511,7 +539,7 @@ impl Service {
 	}
 
 	async fn get_summary_and_children_client(
-		&self, current_room: &OwnedRoomId, suggested_only: bool, user_id: &UserId, via: &Vec<OwnedServerName>,
+		&self, current_room: &OwnedRoomId, suggested_only: bool, user_id: &UserId, via: &[OwnedServerName],
 	) -> Result<Option<SummaryAccessibility>> {
 		if let Ok(Some(response)) = self
 			.get_summary_and_children_local(current_room, Identifier::UserId(user_id))
@@ -625,13 +653,16 @@ impl Service {
 		&self, sender_user: &UserId, room_id: &RoomId, limit: usize, skip: usize, max_depth: usize,
 		suggested_only: bool,
 	) -> Result<client::space::get_hierarchy::v1::Response> {
-		let via = match room_id.server_name() {
-			Some(server_name) => vec![server_name.to_owned()],
-			None => vec![],
-		};
-
 		match self
-			.get_summary_and_children_client(&room_id.to_owned(), suggested_only, sender_user, &via)
+			.get_summary_and_children_client(
+				&room_id.to_owned(),
+				suggested_only,
+				sender_user,
+				&match room_id.server_name() {
+					Some(server_name) => vec![server_name.to_owned()],
+					None => vec![],
+				},
+			)
 			.await?
 		{
 			Some(SummaryAccessibility::Accessible(summary)) => {