@Override
	public Set<Long> addUsersToMeetup(long userId, long meetupId, Set<Long> inviteeIds) throws Exception {
		Meetup meetup = meetupDao.findById(meetupId);
        if(meetup == null) {
        	throw new Exception("Meetup not found. Please check the id");
        }
        if(!meetup.getInviteeIds().contains(userId)) {
		 	throw new Exception("User does not belong to meetup");
		}
        
        Set<Long> addedUsers = new HashSet<Long>();
        for(Long inviteeId : inviteeIds) {
        	if(meetup.getInviteeIds().contains(inviteeId)) {
        		//throw new Exception("Invitee already belongs to meetup");
        		continue;
        	}
        	User invitee = userDao.findById(inviteeId);
        	if(invitee == null) {
        		//throw new Exception("Invitee not found. Please check the id");
        		continue;
        	}
        	meetup.getInviteeIds().add(inviteeId);
        	addedUsers.add(inviteeId);
        }
        for(Suggestion suggestion : meetup.getSuggestions()) {
    		suggestion.getUndecidedUserIds().addAll(addedUsers);
    	}
		checkAndFinalizeDetails(meetupId);
		return addedUsers;
	}