package com.nailabs.abac.trust;

import java.util.*;
import com.nailabs.abac.test.XMLizable;
/**
 * An instance used to represent the satisfaction state of a target node
 * and its descendants.
 */
public class SatisfactionState extends Observable implements XMLizable {
    /** The satisfaction state variable */
    private int state;

    /** 
     * The satisfaction state can be proved to be satisfied or unsatisfied.
     * For example, an access mediator may want to later reassess a subgraph.
     */
    public static final int UNKNOWN = 0;

    /**
     * Satisfaction mean that a trust target node has been proven correct,
     * possibly including a set of credential to verify the satisfaction.
     */
    public static final int SATISFIED = 1;

    /**
     * Unsatisified mean that the requirement of a trust target cannot be 
     * met. This generally means that an access mediator should not allow
     * resource access.
     */
    public static final int FAILED = 2;

    /** Default constructor where the state is UNKNOWN */
    public SatisfactionState() { state = UNKNOWN; }

    /** Explicitly defined statisfaction state. */    
    public SatisfactionState(int i) { state = i; }

    /** Accessor method for returninf the trust target satisfaction state. */
    public int getState() { return state; }

    /** Modifier method to change the satisfaction state */
    public void setState(int i) { 
	if(i > -1 && i < 3)state = i; 
	setChanged();
	notifyObservers();
    }

    /** convert this instance into an XML formatted string */
    public String toXML() {
	StringBuffer buff = new StringBuffer("<SatisfactionState>");
	switch(state) {
	case SATISFIED: 
	    buff.append("satisfied");
	    break;
	case FAILED:
	    buff.append("failed");
	    break;
	default:
	    buff.append("unknown");
	}
	buff.append("</SatisfactionState>");
	return buff.append("\n").toString();
    }


    /** Print a human readable version of this instance */
    public String toString() {
	StringBuffer buff = new StringBuffer("[");
	switch(state) {
	case SATISFIED: 
	    buff.append("satisfied");
	    break;
	case FAILED:
	    buff.append("failed");
	    break;
	default:
	    buff.append("unknown");
	}
	return buff.append("]").toString();
    }
    
}