func extraUserForEvent(event types.Event) *ct.UserId {
if event.GetEventType() == types.EventTypeMembership {
membership := event.GetContent().(*types.MembershipEventContent).Membership
isInvited := membership == types.MembershipInvited
isKnocking := membership == types.MembershipKnocking
isBanned := membership == types.MembershipBanned
if isInvited || isKnocking || isBanned {
state, ok := event.(*types.State)
if !ok {
log.Println("membership event was not a state event:", event)
return nil
}
user, err := ct.ParseUserId(state.StateKey)
if err != nil {
log.Println("failed to parse user id state key:", state.StateKey)
return nil
}
return &user
}
}
return nil
}
