grapevine/src/api/client_server/sync/msc4186.rs

//! [MSC4186], aka Simplified Sliding Sync, aka Simplified [MSC3575], support
//!
//! [MSC4186]: https://github.com/matrix-org/matrix-spec-proposals/pull/4186
//! [MSC3575]: https://github.com/matrix-org/matrix-spec-proposals/pull/3575

use std::{
    collections::{BTreeMap, BTreeSet, HashSet},
    time::Duration,
};

use ruma::{
    api::client::{
        sync::sync_events::{
            self,
            v5::{request::ListFilters, response::Hero},
            DeviceLists, UnreadNotificationsCount,
        },
        uiaa::UiaaResponse,
    },
    events::{
        direct::DirectEventContent,
        room::{
            create::RoomCreateEventContent,
            encryption::PossiblyRedactedRoomEncryptionEventContent,
            member::{MembershipState, RoomMemberEventContent},
        },
        AnyStrippedStateEvent, PossiblyRedactedStateEventContent,
        StateEventType, StrippedStateEvent, TimelineEventType,
    },
    room::RoomType,
    serde::Raw,
    uint, JsOption, OwnedRoomId, RoomId, UInt, UserId,
};
use serde::de::DeserializeOwned;
use tracing::{debug, error, field, trace, warn};

use super::{load_timeline, share_encrypted_room};
use crate::{
    service::{
        account_data,
        rooms::{
            short::ShortStateHash, state::ExtractType, timeline::PduCount,
        },
        users::ConnectionKey,
    },
    services, utils, Ar, Error, Ra, Result,
};

#[derive(Debug)]
enum RequiredStateKeys {
    All,
    Selected(BTreeSet<String>),
}
impl RequiredStateKeys {
    fn merge(&mut self, key: String) {
        match self {
            RequiredStateKeys::All => {
                // nothing to do, we're already getting all keys
            }
            RequiredStateKeys::Selected(keys) => {
                if key == "*" {
                    *self = RequiredStateKeys::All;
                } else {
                    keys.insert(key);
                }
            }
        }
    }
}

#[derive(Debug)]
struct RequiredState {
    /// Indicates that a `("*", "*")` tuple was present in `required_state`.
    /// When `true`, all state events are sent by default, except for state
    /// event types that are present in `filters`, for which only the
    /// request state keys are sent.
    all_events: bool,
    filters: BTreeMap<StateEventType, RequiredStateKeys>,
}
impl RequiredState {
    fn update(
        &mut self,
        required_state: Vec<(StateEventType, String)>,
        sender_user: &UserId,
    ) {
        let contains_wildcard = required_state
            .iter()
            .any(|(typ, key)| typ.to_string() == "*" && key == "*");

        let mut old_filters = None;
        if contains_wildcard {
            if self.all_events {
                // filters already contains existing negative filters, remember
                // them and only apply new filters that were
                // already there previously
                old_filters = Some(std::mem::take(&mut self.filters));
            } else {
                // clear existing positive filters
                self.filters = BTreeMap::new();
            }

            self.all_events = true;
        } else if self.all_events {
            // all events were requested previously, don't add any additional
            // positive filters
            return;
        }

        for (typ, mut key) in required_state {
            if typ.to_string() == "*" {
                continue;
            }
            if key == "$ME" {
                key = sender_user.to_string();
            }

            if let Some(old_filters) = old_filters.as_mut() {
                // re-insert the old negative filter if it matches the new
                // negative filter exactly
                if let Some(old_filter) = old_filters.remove(&typ) {
                    if let RequiredStateKeys::Selected(state_keys) = &old_filter
                    {
                        if state_keys.len() == 1 && state_keys.contains(&key) {
                            self.filters.insert(typ, old_filter);
                        }
                    }
                }
            } else {
                // add the key to the filter for this event type
                self.filters
                    .entry(typ)
                    .or_insert_with(|| {
                        RequiredStateKeys::Selected(BTreeSet::new())
                    })
                    .merge(key);
            }
        }
    }

    fn matches(&self, typ: &StateEventType, key: &str) -> bool {
        match self.filters.get(typ) {
            Some(keys) => match keys {
                RequiredStateKeys::All => true,
                RequiredStateKeys::Selected(keys) => keys.contains(key),
            },
            None => self.all_events,
        }
    }
}

#[derive(Debug)]
struct TodoRoom {
    required_state: RequiredState,
    timeline_limit: u64,
    roomsince: u64,
}
impl TodoRoom {
    fn update(
        &mut self,
        required_state: Vec<(StateEventType, String)>,
        timeline_limit: UInt,
        known_rooms: &BTreeMap<OwnedRoomId, u64>,
        room_id: &RoomId,
        sender_user: &UserId,
    ) {
        self.required_state.update(required_state, sender_user);

        self.timeline_limit =
            self.timeline_limit.max(u64::from(timeline_limit).min(100));
        // 0 means unknown because it got out of date
        self.roomsince =
            self.roomsince.min(known_rooms.get(room_id).copied().unwrap_or(0));
    }
}
impl Default for TodoRoom {
    fn default() -> Self {
        Self {
            required_state: RequiredState {
                all_events: false,
                filters: BTreeMap::new(),
            },
            timeline_limit: 0,
            roomsince: u64::MAX,
        }
    }
}

fn is_dm_room(user: &UserId, room: &RoomId) -> Result<bool> {
    let Some(event) =
        services().account_data.get_global::<DirectEventContent>(user)?
    else {
        return Ok(false);
    };

    let event = event
        .deserialize()
        .map_err(|_| Error::bad_database("Invalid m.direct event"))?;

    Ok(event.values().flatten().any(|r| r == room))
}

fn is_encrypted_room(current_shortstatehash: ShortStateHash) -> Result<bool> {
    Ok(services()
        .rooms
        .state_accessor
        .state_get(current_shortstatehash, &StateEventType::RoomEncryption, "")?
        .is_some())
}

fn get_invite_state<T>(
    invite_state: &[Raw<AnyStrippedStateEvent>],
) -> Option<StrippedStateEvent<T>>
where
    T: PossiblyRedactedStateEventContent + DeserializeOwned,
{
    invite_state
        .iter()
        .find_map(|ev| ev.deserialize_as::<StrippedStateEvent<T>>().ok())
}

#[derive(Debug)]
struct RoomData {
    id: OwnedRoomId,
    current_shortstatehash: ShortStateHash,
    is_dm: bool,
    is_encrypted: bool,
    is_invite: bool,
    room_type: Option<RoomType>,
}

impl RoomData {
    #[tracing::instrument]
    fn new(
        id: OwnedRoomId,
        user: &UserId,
        invite_state: Option<&[Raw<AnyStrippedStateEvent>]>,
    ) -> Result<Self> {
        let current_shortstatehash = services()
            .rooms
            .state
            .get_room_shortstatehash(&id)?
            .ok_or_else(|| Error::bad_database("Room has no state"))?;

        let room_type = if let Some(invite_state) = &invite_state {
            get_invite_state::<RoomCreateEventContent>(invite_state)
                .and_then(|e| e.content.room_type)
        } else {
            services().rooms.state.get_create_content::<ExtractType>(&id)?
        };

        let is_dm = match is_dm_room(user, &id) {
            Ok(x) => x,
            Err(error) => {
                error!(%error, %user, "Invalid m.direct account data event");
                false
            }
        };
        let is_encrypted = if let Some(invite_state) = &invite_state {
            get_invite_state::<PossiblyRedactedRoomEncryptionEventContent>(
                invite_state,
            )
            .is_some()
        } else {
            is_encrypted_room(current_shortstatehash)?
        };
        let is_invite = invite_state.is_some();

        Ok(Self {
            id,
            current_shortstatehash,
            is_dm,
            is_encrypted,
            is_invite,
            room_type,
        })
    }

    #[tracing::instrument(skip(self), fields(room_id = self.id.as_str()))]
    fn matches_filter(&self, filter_data: &ListFilters) -> Result<bool> {
        if let Some(is_dm) = filter_data.is_dm {
            if self.is_dm != is_dm {
                return Ok(false);
            }
        }
        if let Some(is_encrypted) = filter_data.is_encrypted {
            if self.is_encrypted != is_encrypted {
                return Ok(false);
            }
        }
        if let Some(is_invite) = filter_data.is_invite {
            if self.is_invite != is_invite {
                return Ok(false);
            }
        }

        let room_type = self.room_type.clone().into();
        if filter_data.not_room_types.contains(&room_type) {
            return Ok(false);
        }
        if !filter_data.room_types.is_empty()
            && !filter_data.room_types.contains(&room_type)
        {
            return Ok(false);
        }

        Ok(true)
    }
}

#[tracing::instrument(skip_all)]
fn joined_rooms_data(sender_user: &UserId) -> Vec<RoomData> {
    services()
        .rooms
        .state_cache
        .rooms_joined(sender_user)
        .filter_map(Result::ok)
        .filter_map(move |id| {
            RoomData::new(id.clone(), sender_user, None)
                .inspect_err(|error| {
                    error!(%error, room_id = %id, "Failed to get data for room, skipping");
                })
                .ok()
        }).collect()
}

#[tracing::instrument(skip_all)]
fn invited_rooms_data(sender_user: &UserId) -> Vec<RoomData> {
    services()
        .rooms
        .state_cache
        .rooms_invited(sender_user)
        .filter_map(Result::ok)
        .filter_map(move |(id, invite_state)| {
            RoomData::new(id.clone(), sender_user, Some(&invite_state))
                .inspect_err(|error| {
                    error!(
                        %error, room_id = %id, "Failed to get data for room, skipping"
                    );
                })
                .ok()
        })
        .collect()
}

#[allow(clippy::too_many_lines)]
#[tracing::instrument(skip_all, fields(
    pos,
    next_batch,
    connection_id = ?body.conn_id,
))]
pub(crate) async fn sync_events_v5_route(
    body: Ar<sync_events::v5::Request>,
) -> Result<Ra<sync_events::v5::Response>, Ra<UiaaResponse>> {
    let current_span = tracing::Span::current();

    let sender_user = body.sender_user.expect("user is authenticated");
    let sender_device = body.sender_device.expect("user is authenticated");
    let body = body.body;
    // Setup watchers, so if there's no response, we can wait for them
    let watcher = services().globals.watch(&sender_user, &sender_device);

    let next_batch = services().globals.next_count()?;
    current_span.record("next_batch", field::display(&next_batch));

    current_span.record("pos", field::debug(&body.pos));
    let globalsince =
        body.pos.as_ref().and_then(|string| string.parse().ok()).unwrap_or(0);

    let connection_key = ConnectionKey {
        user: sender_user.clone(),
        device: sender_device.clone(),
        connection: body.conn_id.clone(),
    };

    if globalsince == 0 {
        services().users.forget_sync_request_connection(&connection_key);
    }

    let known_rooms = services()
        .users
        .get_rooms_in_connection(connection_key.clone(), globalsince);

    let all_joined_rooms = joined_rooms_data(&sender_user);

    if body.extensions.to_device.enabled.unwrap_or(false) {
        services().users.remove_to_device_events(
            &sender_user,
            &sender_device,
            globalsince,
        )?;
    }

    #[allow(clippy::if_then_some_else_none)]
    let e2ee = if body.extensions.e2ee.enabled == Some(true) {
        Some(sync_events::v5::response::E2EE {
            device_lists: get_e2ee_data(
                &sender_user,
                globalsince,
                &all_joined_rooms,
            )
            .await?,
            device_one_time_keys_count: services()
                .users
                .count_one_time_keys(&sender_user, &sender_device)?,
            // Fallback keys are not yet supported
            device_unused_fallback_key_types: None,
        })
    } else {
        None
    };

    let mut all_rooms = all_joined_rooms;
    all_rooms.extend(invited_rooms_data(&sender_user));

    let all_room_ids: Vec<_> = all_rooms.iter().map(|r| r.id.clone()).collect();
    let all_room_ids: Vec<_> = all_room_ids.iter().map(|id| &**id).collect();

    let mut todo_rooms: BTreeMap<OwnedRoomId, TodoRoom> = BTreeMap::new();

    let lists = body
        .lists
        .into_iter()
        .map(|(list_id, list)| {
            let rooms = rooms_in_list(
                &list_id,
                list,
                &all_rooms,
                &all_room_ids,
                &known_rooms,
                &mut todo_rooms,
                &sender_user,
            );
            (list_id, rooms)
        })
        .collect();

    for (room_id, room) in &body.room_subscriptions {
        if !services().rooms.metadata.exists(room_id)? {
            warn!(room_id = room_id.as_str(), "Subscribed room does not exist");
            continue;
        }
        todo_rooms.entry(room_id.clone()).or_default().update(
            room.required_state.clone(),
            room.timeline_limit,
            &known_rooms,
            room_id,
            &sender_user,
        );
    }

    services().users.update_sync_known_rooms(
        connection_key.clone(),
        todo_rooms.keys().cloned().collect(),
        globalsince,
        next_batch,
    );

    let to_device = if body.extensions.to_device.enabled == Some(true) {
        let events = services()
            .users
            .get_to_device_events(&sender_user, &sender_device)?;
        if !events.is_empty() {
            debug!(
                events = utils::debug_slice_truncated(&events, 3),
                "Got new to-device events"
            );
        }

        Some(sync_events::v5::response::ToDevice {
            events,
            next_batch: next_batch.to_string(),
        })
    } else {
        None
    };

    let mut rooms = BTreeMap::new();
    for (room_id, todo_room) in todo_rooms {
        if let Some(room) = process_room(&sender_user, &room_id, &todo_room)? {
            rooms.insert(room_id.clone(), room);
        }
    }

    if rooms
        .iter()
        .all(|(_, r)| r.timeline.is_empty() && r.required_state.is_empty())
    {
        // Hang a few seconds so requests are not spammed
        // Stop hanging if new info arrives
        let mut duration = body.timeout.unwrap_or(Duration::from_secs(30));
        if duration.as_secs() > 30 {
            duration = Duration::from_secs(30);
        }
        match tokio::time::timeout(duration, watcher).await {
            Ok(x) => x.expect("watcher should succeed"),
            Err(error) => debug!(%error, "Timed out"),
        };
    }

    Ok(Ra(sync_events::v5::Response {
        txn_id: body.txn_id.clone(),
        pos: next_batch.to_string(),
        lists,
        rooms,
        extensions: sync_events::v5::response::Extensions {
            to_device,
            e2ee: e2ee.unwrap_or_default(),
            account_data: sync_events::v5::response::AccountData {
                global: if body.extensions.account_data.enabled.unwrap_or(false)
                {
                    services()
                        .account_data
                        .global_changes_since(&sender_user, globalsince)?
                        .into_iter()
                        .map(|(event_type, content)| {
                            account_data::raw_global_event_from_parts(
                                &event_type,
                                &content,
                            )
                        })
                        .collect()
                } else {
                    Vec::new()
                },
                rooms: BTreeMap::new(),
            },
            receipts: sync_events::v5::response::Receipts {
                rooms: BTreeMap::new(),
            },
            typing: sync_events::v5::response::Typing {
                rooms: BTreeMap::new(),
            },
        },
    }))
}

#[allow(clippy::too_many_lines)]
#[tracing::instrument(skip_all)]
async fn get_e2ee_data(
    sender_user: &UserId,
    globalsince: u64,
    all_joined_rooms: &[RoomData],
) -> Result<DeviceLists> {
    // Users that have left any encrypted rooms the sender was in
    let mut left_encrypted_users = HashSet::new();

    // Look for device list updates of this account
    let mut device_list_changes: HashSet<_> = services()
        .users
        .keys_changed(sender_user.as_ref(), globalsince, None)
        .filter_map(Result::ok)
        .collect();

    for RoomData {
        id: room_id,
        current_shortstatehash,
        is_encrypted,
        ..
    } in all_joined_rooms
    {
        let since_shortstatehash = services()
            .rooms
            .user
            .get_token_shortstatehash(room_id, globalsince)?;

        let since_sender_member: Option<RoomMemberEventContent> =
            since_shortstatehash
                .and_then(|shortstatehash| {
                    services()
                        .rooms
                        .state_accessor
                        .state_get(
                            shortstatehash,
                            &StateEventType::RoomMember,
                            sender_user.as_str(),
                        )
                        .transpose()
                })
                .transpose()?
                .and_then(|pdu| {
                    serde_json::from_str(pdu.content.get())
                        .map_err(|_| {
                            Error::bad_database("Invalid PDU in database.")
                        })
                        .ok()
                });

        if let Some(since_shortstatehash) = since_shortstatehash {
            // Skip if there are only timeline changes
            if since_shortstatehash == *current_shortstatehash {
                continue;
            }

            let since_encryption = services().rooms.state_accessor.state_get(
                since_shortstatehash,
                &StateEventType::RoomEncryption,
                "",
            )?;

            let joined_since_last_sync =
                since_sender_member.is_none_or(|member| {
                    member.membership != MembershipState::Join
                });

            let new_encrypted_room =
                *is_encrypted && since_encryption.is_none();
            if *is_encrypted {
                let current_state_ids = services()
                    .rooms
                    .state_accessor
                    .state_full_ids(*current_shortstatehash)
                    .await?;
                let since_state_ids = services()
                    .rooms
                    .state_accessor
                    .state_full_ids(since_shortstatehash)
                    .await?;

                for (key, event_id) in current_state_ids {
                    if since_state_ids.get(&key) != Some(&event_id) {
                        let Some(pdu) =
                            services().rooms.timeline.get_pdu(&event_id)?
                        else {
                            error!(%event_id, "Event in state not found");
                            continue;
                        };
                        if pdu.kind == TimelineEventType::RoomMember {
                            if let Some(state_key) = &pdu.state_key {
                                let user_id = UserId::parse(state_key.clone())
                                    .map_err(|_| {
                                        Error::bad_database(
                                            "Invalid UserId in member PDU.",
                                        )
                                    })?;

                                if user_id == sender_user {
                                    continue;
                                }

                                let new_membership = serde_json::from_str::<
                                    RoomMemberEventContent,
                                >(
                                    pdu.content.get()
                                )
                                .map_err(|_| {
                                    Error::bad_database(
                                        "Invalid PDU in database.",
                                    )
                                })?
                                .membership;

                                match new_membership {
                                    MembershipState::Join => {
                                        // A new user joined an encrypted
                                        // room
                                        if !share_encrypted_room(
                                            sender_user,
                                            &user_id,
                                            room_id,
                                        )? {
                                            device_list_changes.insert(user_id);
                                        }
                                    }
                                    MembershipState::Leave => {
                                        // Write down users that have left
                                        // encrypted rooms we are in
                                        left_encrypted_users.insert(user_id);
                                    }
                                    _ => {}
                                }
                            }
                        }
                    }
                }
                if joined_since_last_sync || new_encrypted_room {
                    // If the user is in a new encrypted room, give them all
                    // joined users
                    device_list_changes.extend(
                        services()
                            .rooms
                            .state_cache
                            .room_members(room_id)
                            .flatten()
                            .filter(|user_id| {
                                // Don't send key updates from the sender to
                                // the sender
                                sender_user != user_id
                            })
                            .filter(|user_id| {
                                // Only send keys if the sender doesn't
                                // share an encrypted room with the target
                                // already
                                !share_encrypted_room(
                                    sender_user,
                                    user_id,
                                    room_id,
                                )
                                .unwrap_or(false)
                            }),
                    );
                }
            }
        }
        // Look for device list updates in this room
        device_list_changes.extend(
            services()
                .users
                .keys_changed(room_id.as_ref(), globalsince, None)
                .filter_map(Result::ok),
        );
    }

    let mut device_list_left = HashSet::new();
    for user_id in left_encrypted_users {
        let dont_share_encrypted_room = services()
            .rooms
            .user
            .get_shared_rooms(vec![sender_user.to_owned(), user_id.clone()])?
            .filter_map(Result::ok)
            .filter_map(|other_room_id| {
                Some(
                    services()
                        .rooms
                        .state_accessor
                        .room_state_get(
                            &other_room_id,
                            &StateEventType::RoomEncryption,
                            "",
                        )
                        .ok()?
                        .is_some(),
                )
            })
            .all(|encrypted| !encrypted);
        // If the user doesn't share an encrypted room with the target
        // anymore, we need to tell them
        if dont_share_encrypted_room {
            device_list_left.insert(user_id);
        }
    }

    Ok(DeviceLists {
        changed: device_list_changes.into_iter().collect(),
        left: device_list_left.into_iter().collect(),
    })
}

#[tracing::instrument(
    skip_all,
    fields(list_id = list_id, ?list),
)]
fn rooms_in_list(
    list_id: &str,
    list: sync_events::v5::request::List,
    all_rooms: &[RoomData],
    all_room_ids: &[&RoomId],
    known_rooms: &BTreeMap<OwnedRoomId, u64>,
    todo_rooms: &mut BTreeMap<OwnedRoomId, TodoRoom>,
    sender_user: &UserId,
) -> sync_events::v5::response::List {
    trace!(list_id, ?list, "Collecting rooms in list");

    let matching_room_ids_buf: Vec<&RoomId>;
    let matching_room_ids = if let Some(filters) = list.filters.as_ref() {
        matching_room_ids_buf = all_rooms
            .iter()
            .filter_map(|r| {
                match r.matches_filter(filters) {
                    Ok(pass) => pass.then_some(&*r.id),
                    Err(error) => {
                        warn!(%error, ?filters, room_id=r.id.as_str(), "Failed to evaluate list filter, skipping room");
                        None
                    }
                }
            })
            .collect();
        matching_room_ids_buf.as_slice()
    } else {
        all_room_ids
    };

    if !matching_room_ids.is_empty() {
        let mut list_room_ids: BTreeSet<&RoomId> = BTreeSet::new();
        for (from, to) in list.ranges {
            let from = usize::try_from(from)
                .unwrap_or(usize::MAX)
                .clamp(0, matching_room_ids.len() - 1);
            let to = usize::try_from(to)
                .unwrap_or(usize::MAX)
                .clamp(from, matching_room_ids.len() - 1);
            list_room_ids.extend(&matching_room_ids[from..=to]);
        }
        for room_id in list_room_ids {
            todo_rooms.entry(room_id.to_owned()).or_default().update(
                list.room_details.required_state.clone(),
                list.room_details.timeline_limit,
                known_rooms,
                room_id,
                sender_user,
            );
        }
    }

    let num_rooms = matching_room_ids.len();
    trace!(list_id, num_rooms, "Done collecting rooms");

    sync_events::v5::response::List {
        count: UInt::try_from(num_rooms).unwrap_or(UInt::MAX),
    }
}

#[allow(clippy::too_many_lines)]
#[tracing::instrument(skip(sender_user))]
fn process_room(
    sender_user: &UserId,
    room_id: &RoomId,
    todo_room: &TodoRoom,
) -> Result<Option<sync_events::v5::response::Room>> {
    let roomsincecount = PduCount::Normal(todo_room.roomsince);

    let (timeline_pdus, limited) = load_timeline(
        sender_user,
        room_id,
        roomsincecount,
        todo_room.timeline_limit,
    )?;

    if todo_room.roomsince != 0 && timeline_pdus.is_empty() {
        return Ok(None);
    }

    let prev_batch = timeline_pdus
        .first()
        .map(|(pdu_count, _)| match pdu_count {
            PduCount::Backfilled(_) => {
                error!("Timeline in backfill state?!");
                "0".to_owned()
            }
            PduCount::Normal(c) => c.to_string(),
        })
        .or_else(|| {
            (todo_room.roomsince != 0).then(|| todo_room.roomsince.to_string())
        });

    // TODO: consider only message-like PDUs here, rather than all PDUs
    let bump_stamp = match services()
        .rooms
        .timeline
        .last_timeline_count(sender_user, room_id)?
    {
        PduCount::Backfilled(n) | PduCount::Normal(n) => {
            Some(UInt::new_saturating(n))
        }
    };

    let room_events: Vec<_> =
        timeline_pdus.iter().map(|(_, pdu)| pdu.to_sync_room_event()).collect();

    let Some(current_shortstatehash) =
        services().rooms.state.get_room_shortstatehash(room_id)?
    else {
        error!(%room_id, "Room has no state");
        return Ok(None);
    };

    let need_scan = todo_room.required_state.all_events
        || todo_room
            .required_state
            .filters
            .iter()
            .any(|(_, keys)| matches!(keys, RequiredStateKeys::All));
    let required_state = if need_scan {
        let full_state = services()
            .rooms
            .state_compressor
            .load_shortstatehash_info(current_shortstatehash)?
            .pop()
            .expect("there is always one layer")
            .full_state;
        full_state
            .iter()
            .filter_map(|compressed| {
                let Ok((typ, key)) = services()
                    .rooms
                    .short
                    .get_statekey_from_short(compressed.state)
                else {
                    warn!(
                        ?compressed,
                        "Failed to get info for shortstatekey, skipping"
                    );
                    return None;
                };

                if !todo_room.required_state.matches(&typ, &key) {
                    return None;
                }

                let shorteventid = compressed.event;
                let pdu = match services()
                    .rooms
                    .short
                    .get_eventid_from_short(shorteventid)
                {
                    Ok(event_id) => {
                        services().rooms.timeline.get_pdu(&event_id)
                    }
                    Err(error) => {
                        warn!(
                            %error,
                            %typ,
                            key,
                            ?shorteventid,
                            "Failed to get event ID from short event ID"
                        );
                        return None;
                    }
                };
                match pdu {
                    Ok(Some(pdu)) => Some(pdu.to_sync_state_event()),
                    Ok(None) => None,
                    Err(error) => {
                        warn!(%error, %typ, key, "Failed to get state PDU");
                        None
                    }
                }
            })
            .collect()
    } else {
        todo_room
            .required_state
            .filters
            .iter()
            .flat_map(|(typ, keys)| {
                let RequiredStateKeys::Selected(keys) = keys else {
                    panic!(
                        "wildcard key should have triggered a full state scan"
                    );
                };
                keys.iter().filter_map(move |key| {
                    match services().rooms.state_accessor.state_get(
                        current_shortstatehash,
                        typ,
                        key,
                    ) {
                        Ok(Some(pdu)) => Some(pdu.to_sync_state_event()),
                        Ok(None) => None,
                        Err(error) => {
                            warn!(%error, %typ, key, "Failed to get state PDU");
                            None
                        }
                    }
                })
            })
            .collect()
    };

    let name = services().rooms.state_accessor.get_name(room_id)?;
    let heroes = name.is_none().then(|| {
        services()
            .rooms
            .state_cache
            .room_members(room_id)
            .filter_map(Result::ok)
            .filter(|member| member != sender_user)
            .filter_map(|member| {
                services()
                    .rooms
                    .state_accessor
                    .get_member(room_id, &member)
                    .ok()
                    .flatten()
                    .map(|memberevent| Hero {
                        user_id: member,
                        name: memberevent.displayname,
                        avatar: memberevent.avatar_url,
                    })
            })
            .take(5)
            .collect::<Vec<_>>()
    });

    let room = sync_events::v5::response::Room {
        name,
        avatar: match services().rooms.state_accessor.get_avatar(room_id)? {
            JsOption::Some(avatar) => JsOption::from_option(avatar.url),
            JsOption::Null => JsOption::Null,
            JsOption::Undefined => JsOption::Undefined,
        },
        initial: Some(todo_room.roomsince == 0),
        is_dm: None,
        invite_state: None,
        unread_notifications: UnreadNotificationsCount {
            highlight_count: Some(
                services()
                    .rooms
                    .user
                    .highlight_count(sender_user, room_id)?
                    .try_into()
                    .expect("notification count can't go that high"),
            ),
            notification_count: Some(
                services()
                    .rooms
                    .user
                    .notification_count(sender_user, room_id)?
                    .try_into()
                    .expect("notification count can't go that high"),
            ),
        },
        timeline: room_events,
        required_state,
        prev_batch,
        limited,
        joined_count: Some(
            services()
                .rooms
                .state_cache
                .room_joined_count(room_id)?
                .map(UInt::new_saturating)
                .unwrap_or(uint!(0)),
        ),
        invited_count: Some(
            services()
                .rooms
                .state_cache
                .room_invited_count(room_id)?
                .map(UInt::new_saturating)
                .unwrap_or(uint!(0)),
        ),
        // Count events in timeline greater than global sync counter
        num_live: None,
        bump_stamp,
        heroes,
    };
    trace!(?room, "Built room data");

    Ok(Some(room))
}