package edu.stanford.peer.rbtm.engine;

import edu.stanford.peer.rbtm.credential.*;
import edu.stanford.peer.rbtm.util.*;

import java.util.*;

/**
 * A predicate on role expressions used by a verifier to determine if a target
 * may be skipped over and not created.
 */
public class Oppo implements Predicate {
    /** issuer-traces-all roles */
    protected Vector issuerTraces;

    /** create a new oppo predicate w/o traceable role names */
    public Oppo() { issuerTraces = new Vector(); }

    /** create a new oppo predicate with a set of traceable role names */
    public Oppo(Vector roles) { issuerTraces = new Vector(roles); }

    /** add a role name to the subject-traces-all list */
    public void addSubject(String name) {
	addSubject(new SimpleRoleName(name));
    }

    /** add a role name to the subject-traces-all list */
    public void addSubject(RoleName role) {
	issuerTraces.add(role);
    }
    /** add a set of role names to the subject-traces-all list */
    public void addSubjects(Vector roles) { 
	issuerTraces.addAll(roles); 
    }

    /** remove a role name from the subject-traces-all list */
    public void removeSubject(String name) {
	removeSubject(new SimpleRoleName(name));
    }
    
    /** remove a role name from the subject-traces-all list */
    public void removeSubject(RoleName role) {
	issuerTraces.remove(role);
    }

    /** apply the predicate to determine if this role is subject-traces-all */
    public boolean test(EntityExpression obj) {
	if(obj instanceof Role) {
	    Role role = (Role)obj;
	    return (!issuerTraces.contains(role.getName()));
	}
	return true;
    }

}