/*
 * Copyrighted (C) 2002, Networks Associates Technology, Inc. 
 * All rights reserved
 */
package com.nailabs.abac.trust;

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

/**
 * A generic node type for a trust target graph (TTG). The node encapsulates
 * a trust target and provides methods for processing a node. 
 */
public abstract class TTGNode extends Observable 
    implements Observer, Serializable, XMLizable {

    /** A trust target that this node represents on the graph */
    private Goal goal = null;

    /** A negotiation context which binds graph, strategy, and frontiers */
    protected NegotiationContext context;

    /** The processing state of this graph node */
    protected transient ProcessingState processor = new ProcessingState();

    /** Encapsulated set of parents for a TTG node */
    protected TTGNodeSet parents = new TTGNodeSet();

    /** Encapsulated set of children for a TTG node */
    protected TTGNodeSet children = new TTGNodeSet();
    
    /** Convenience debugging name to be overridden in subclasses */
    protected String subName = "TTGNode";

    /** Generic node factory method which creates a node based on a goal */
    public static TTGNode createNode(Goal seed) {
        if(seed instanceof TrustTarget) {
            EntityExpression target = ((TrustTarget)seed).getTargetRole();
            if(target instanceof Entity) {
                return new TrivialTTNode((TrustTarget)seed);
            }
            if(target instanceof Role) {
                return new SimpleTTNode((TrustTarget)seed);
            }
            if(target instanceof LinkedRole) {
                return new LinkTTNode((TrustTarget)seed);
            }
            if(target instanceof Intersection) {
                return new IntersectionTTNode((TrustTarget)seed);
            }
        }
        if(seed instanceof LinkingGoal) {
            return new LinkingGoalNode((LinkingGoal)seed);
        }
        return null;
    }

    /** Default constructor. Subclasses should access processing state field */
    public TTGNode(Goal target) { 
	goal = target; 
	processor.addObserver(this);
    }


    /** updates the processing state of this node */
    public void updateProcessingState(ProcessingState state) {
        processor.update(state);
    }

    /** 
     * This method should be polymorphic since children will have customized
     * fields.
     */
    public void update(Observable obs, Object obj) {
	if(obs == processor) {
	    setChanged();
	    notifyObservers(processor);
	}
    }

    /** Polymorphic method for initializing a node based on its context */
    public void init(NegotiationContext context) {
	System.out.println("TTGNode: initialize context for " + getGoal());
	if(context == null) {
	    System.out.println("WARNING NULL CONTEXT ENCOUNTERED!!!");
	}
	this.context = context;
    }

    /** 
     * A generic process method to determine whether to process this node
     * as a verifier or an opponent.
     * @param context The context of this trust negotiation
     */
    public void process(NegotiationContext context) {
	Entity verifier = getGoal().getVerifier();
	if(context.getSelf().equals(verifier)) {
	    // check verifier processed . . .
	    if(getProcessingState().isVerifierProcessed()) {
		System.out.println("TTGNode: already verifier processed node "
				   + getGoal());
		return;
	    }
	    verifierProcess(context);
	}
	// check opponent processed . . .
	else {
	    if(getProcessingState().isOpponentProcessed()) {
		System.out.println("TTGNode: already opponent processed node "
				   + getGoal());
		return;
	    }
	    opponentProcess(context);	    
	}
    }

    /** 
     * Each distinct node type should know how to process itself, so this 
     * method should be overridden in subclasses. 
     * @param context A context w/helper functions required for processing
     */
    public abstract void verifierProcess(NegotiationContext context);

    /** 
     * Each distinct node type should know how to process itself, so this 
     * method should be overridden in subclasses. 
     * @param context A context w/helper functions required for processing
     */
    public abstract void opponentProcess(NegotiationContext context);

    /** Public accessor method for the negotiation context */
    public NegotiationContext getContext() { return context; }

    /** Accessor/modifier method for  the verifier of the trust target. */
    public Entity getVerifier() { return goal.getVerifier(); }

    /** Accessor/modifier method for the subject (RHS) of the trust target. */
    public EntityExpression getSubject() { return goal.getSubject(); }

    /** Accessor method for the processing state of this node */
    public ProcessingState getProcessingState() { return processor; }

    /** Accessor method for the goal/trust target  of this graph node */
    public Goal getGoal() { return goal; }

    /** Accessor method for the type of this TTG node */
    public String getType() { return subName; }

    /** Accessor/modifier method for the target role of the trust target. */
    //public EntityExpression getTargetExpression() { return goal.getTargetRole();}

    /** Adds a parent node to this instance */
    public void addParent(TTGNode node) {
	parents.add(node);
    }

    /** Adds a child node to this instance. */
    public void addChild(TTGNode node) {
	children.add(node);
    }

    /** accessor for a set of all the child nodes of the current instance */
    public TTGNodeSet getChildren() { return children; }

    /** accessor for a set of all the parent nodes of the current instance */
    public TTGNodeSet getParents() { return parents; }

    /** Print out a node in human readable format */
    public String toString() {
	StringBuffer buff = new StringBuffer("[");
	buff.append(getClass().getName()).append(", ");
	buff.append(processor).append(", ");
	buff.append(getGoal().toString()).append("]");
	return buff.toString();
    }

    /** Polymorphic method for converting a node into an XML string */
    public abstract String toXML();

    /** Method for children to use for creating a XML compatible string */
    protected String toXML(String options, String elements) { 
	StringBuffer buff = new StringBuffer("<");
	buff.append(subName).append(options).append(">\n");
	buff.append(getGoal().toXML());
	buff.append(processor.toXML());
	buff.append(elements);
	buff.append("</").append(subName).append(">\n");
	return buff.toString();
    }

    /** Friendly debuggin method to be inherited by all children */
    protected void debug(String key, String message) {
	StringBuffer buff = new StringBuffer(subName);
	if(context != null)
	    buff.append("[").append(context.getSelf()).append("]");
	buff.append(": ").append(message);
	Debug.debug(key, buff.toString());
    }


}