package com.nailabs.abac.trust;

import com.nailabs.abac.process.*;
import edu.stanford.peer.rbtm.credential.*;
import java.util.*;

/**
 * An instance of this class repsent a trust target of the form: <BR>
 * <CENTER> &lt;V: e &lt;-- S &gt; </CENTER> <BR>
 * where V is on the negotiators; 
 * e is a role expression called the target role; and
 * S is a role expression called the subject role. S is frequently the 
 * opponent negotiator of V.
 */
public class TrustTarget extends Goal {

    /** The target expression of this trust target */
    protected EntityExpression targetRole;


    /** Itemized default constructor */
    public TrustTarget(Entity v, EntityExpression e, EntityExpression s) 
	throws TrustTargetParsingException, CredentialParsingException {
	verifier = v;
	targetRole = e;
	subject = s;
    }

    /** Construct a new trust target from a string */
    public TrustTarget(String s) 
	throws TrustTargetParsingException, CredentialParsingException {
	StringTokenizer st = new StringTokenizer(s, ":<?-");
	if(st.countTokens() < 3) 
	    throw new TrustTargetParsingException("Too few elements!", s);
	verifier = (Entity)	    
	    StaticCredential.getEntityExpression(st.nextToken().trim());
	targetRole = 
	    StaticCredential.getEntityExpression(st.nextToken().trim());
	subject = 
	    StaticCredential.getEntityExpression(st.nextToken().trim());
    }

    /** Unique hash function based on a verifier-target-subject triplet */
    public int hashCode() {
	return verifier.hashCode() * 4 + targetRole.hashCode() * 2 + 
	    subject.hashCode();
    }


    /** accessor method for the target role expressin of this target */
    public EntityExpression getTargetRole() { return targetRole; }


    public String getType() {
        if(targetRole instanceof Role) {
            return new String("RoleTarget");
        }
        else if(targetRole instanceof LinkedRole) {
            return new String("LinkedRoleTarget");
        }
        else if(targetRole instanceof Intersection) {
            return new String("IntersectionTarget");
        }
        else if(targetRole instanceof Entity) {
            return new String("TrivialTarget");
        }
        return new String("TrustTarget");
    }

    public ProcessingState getInitialProcessingState(NegotiationContext ctx) {
        if(targetRole instanceof Entity) { // trivial trust target
            return new ProcessingState(true, true);
        }
        else if(targetRole instanceof Role) { // simple trust target
            RoleName r = ((Role)targetRole).getName();
            if(ctx.subjectTracesAll(r))
                return new ProcessingState(true, false);
            else
                return new ProcessingState(false, true);
        }
        else if(targetRole instanceof LinkedRole) { // linked role trust target
            RoleName r1 = ((LinkedRole)targetRole).getFirstRole().getName();
            RoleName r2 = ((LinkedRole)targetRole).getSecondRoleName();
            if(ctx.subjectTracesAll(r1) && ctx.subjectTracesAll(r2)) {
                return new ProcessingState(true, false);
            }
            else {
                return new ProcessingState(false, true);
            }
        }
        else if(targetRole instanceof Intersection) { // intersection TT
            if(ctx.getSelf().equals(getVerifier())) {
                return new ProcessingState(false, true);
            } else {
                return new ProcessingState(true, false);
            }
        }
        return new ProcessingState();
    }

    public String toString() {
	StringBuffer buff = new StringBuffer();
	buff.append(getVerifier().toString()).append(": ");
	buff.append(getTargetRole().toString());
	buff.append(" <<-?- ").append(getSubject().toString());
	//buff.append("]");
	return buff.toString();
    }

    public String toXML() {
    /*    
	StringBuffer buff = new StringBuffer("<TrustTarget>\n");
	buff.append("\t<Verifier>");
	buff.append(getVerifier().toString());
	buff.append("</Verifier>\n");
	buff.append("\t<Target>");
	buff.append(getTargetRole().toString());
	buff.append("</Target>\n");
	buff.append("\t<Subject>");
	buff.append(getSubject().toString());
	buff.append("</Subject>\n");
	buff.append("</TrustTarget>\n");
	return buff.toString();	
    */
        return toString().replaceAll("<","&lt;");
    }
}