sliding-sync/sync3/room.go

package sync3

import (
	"encoding/json"

	"github.com/matrix-org/sliding-sync/internal"

	"github.com/matrix-org/sliding-sync/sync3/caches"
)

type Room struct {
	Name              string            `json:"name,omitempty"`
	AvatarChange      AvatarChange      `json:"avatar,omitempty"`
	Heroes            []internal.Hero   `json:"heroes,omitempty"`
	RequiredState     []json.RawMessage `json:"required_state,omitempty"`
	Timeline          []json.RawMessage `json:"timeline,omitempty"`
	InviteState       []json.RawMessage `json:"invite_state,omitempty"`
	NotificationCount int64             `json:"notification_count"`
	HighlightCount    int64             `json:"highlight_count"`
	Initial           bool              `json:"initial,omitempty"`
	IsDM              bool              `json:"is_dm,omitempty"`
	JoinedCount       int               `json:"joined_count,omitempty"`
	InvitedCount      *int              `json:"invited_count,omitempty"`
	PrevBatch         string            `json:"prev_batch,omitempty"`
	NumLive           int               `json:"num_live,omitempty"`
	Timestamp         uint64            `json:"timestamp,omitempty"`
}

// RoomConnMetadata represents a room as seen by one specific connection (hence one
// specific device).
type RoomConnMetadata struct {
	// We enclose copies of the data kept in the global and user caches. These snapshots
	// represent the state we reported to the connection the last time they requested
	// a sync. Note that we are free to tweak fields within these copies if we want, to
	// report more appropriate data to clients that kept in the caches.
	internal.RoomMetadata
	caches.UserRoomData
	// plus any per-conn data.

	// LastInterestedEventTimestamps is a map from list name to the origin_server_ts of
	// the most recent event seen in the room since the user's join that the list is
	// interested in.
	//
	// Connections can specify that a list is only interested in certain event types by
	// providing "bump_event_types" in their sliding sync request. This happens on a
	// list-by-list basis. Because the same room can appear in different lists with
	// different bump criteria, we need to track a LastInterestedEventTimestamp for each
	// list.
	//
	// While this conceptually tracks the internal.RoomMetadata.LastMessageTimestamp
	// field, said field can decrease rapidly at any moment---so
	// LastInterestedEventTimestamp can also decrease at any moment. When sorting by
	// recency, this means rooms can suddenly fall down and jump back up the room
	// list. See also the description of this in the React SDK docs:
	//     https://github.com/matrix-org/matrix-react-sdk/blob/526645c79160ab1ad4b4c3845de27d51263a405e/docs/room-list-store.md#tag-sorting-algorithm-recent
	LastInterestedEventTimestamps map[string]uint64
}

// SameRoomAvatar checks if the fields relevant for room avatars have changed between the two metadatas.
// Returns true if there are no changes.
func (r *RoomConnMetadata) SameRoomAvatar(next *RoomConnMetadata) bool {
	sameRoomAvatar := r.AvatarEvent == next.AvatarEvent
	if next.IsDM {
		// the avatar is the same IF:
		// - the m.room.avatar event is the same AND
		// - the heroes haven't changed AND
		// - the number of heroes is 1
		return sameRoomAvatar && sameHeroAvatars(r.Heroes, next.Heroes) && len(next.Heroes) == 1
	}
	// the avatar is the same IF:
	// - the m.room.avatar event is the same
	return sameRoomAvatar
}

func sameHeroAvatars(a, b []internal.Hero) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i].ID != b[i].ID {
			return false
		}
		if a[i].Avatar != b[i].Avatar {
			return false
		}
	}
	return true
}

func (r *RoomConnMetadata) GetLastInterestedEventTimestamp(listKey string) uint64 {
	ts, ok := r.LastInterestedEventTimestamps[listKey]
	if ok {
		return ts
	}
	// SetRoom is responsible for maintaining LastInterestedEventTimestamps.
	// However, if a brand-new list appears we don't call SetRoom until we have
	// some RoomEventUpdates to process. We need to ensure we hand back a sensible
	// timestamp. So: use the (current) LastMessageTimestamp as a fallback.
	// TODO: if we had access to the request's bump event types, we could lookup the
	//       a timestamp by event type from the global metadata (c.f. ConnState.load).
	ts = r.LastMessageTimestamp
	// Write this value into the map. If we don't and only uninteresting events
	// arrive after, the fallback value will have jumped ahead despite nothing of
	// interest happening.
	r.LastInterestedEventTimestamps[listKey] = ts
	return ts
}