package com.nailabs.abac.process;

import com.nailabs.abac.credential.RtmlCredential;

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

/**
 * A message contains a set of operations to be transmitted between two 
 * negotiators.
 */
public class Message implements Serializable, XMLizable {
    /** A history list of operations */
    private LinkedList ops;

    private transient Iterator opsIterator = null;

    /** Credentials used for proving edge operations. */ 
    private HashSet evidence;

    /** Default contructor for a message instance. */
    public Message() {
	ops = new LinkedList();
	evidence = new HashSet(10);
    }

    /** Public accessor method for iterating over operations in the message */
    public Iterator getOperations() { return ops.iterator(); }

    /** Accessor method for the graph delta queue. */
    public Operation getNextOperation() { 
	if(opsIterator == null)
	    opsIterator = ops.iterator();
	return (Operation)opsIterator.next(); 
    }

    /** Adds an operation that contains internal evidence. */
    public synchronized void addOperationWithoutEvidence(Operation op) {
        ops.add(op);
    }

    /** Add and operation to end of the operations queue */
    public synchronized void addOperation(Operation op) {
        ops.add(op);
        //add the evidence
        if(op instanceof EdgeOperation) {
            HashSet subEvidence = ((EdgeOperation)op).getEvidence();
            if(subEvidence == null) {
                //Debug.debug("message", "Message: No evidence available..."); 
                return;
            }
            Iterator i = subEvidence.iterator();
            while(i.hasNext()) {
                Object proof = i.next();
                evidence.add(proof);
            }
        }
    }

    /** Message count of operations in this message. */
    public int getOperationsCount() { 
        return (ops == null)? 0: ops.size();
    }

    /** Accessor method for the combined evidence. */
    public Iterator  getEvidence() { return evidence.iterator(); }

    /** Evidence (credentials) count. Convenience method for Iterator */
    public int getEvidenceCount() { 
	return (evidence == null)? 0: evidence.size();
    }
    
    /** Add a new credential to the list of evidence. */
 public synchronized void addEvidence(Credential cred) {
        if(cred instanceof RtmlCredential) {
            evidence.add(((RtmlCredential)cred).toXML());
        } else {
	    evidence.add((Object)cred);
	}
    }

    /** Converts this message instance into an XML formatted string */
    public String toXML() {
	StringBuffer buff = new 
	    StringBuffer("<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>\n");
        buff.append("<Message xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:noNamespaceSchemaLocation=\"http://isrl.cs.byu.edu/xsd/message.xsd\">\n");
	Iterator creds = evidence.iterator();
	if(creds.hasNext()) {
	    int count = 0;
	    buff.append("<Evidence>\n");
	    while(creds.hasNext()) {
		Object cred = creds.next();
		buff.append("<!-- credential count = ").append(++count);
		buff.append(" -->\n");
		if(cred instanceof RtmlCredential)
		    buff.append(((RtmlCredential)cred).toXML()).append("\n");
		else 
		    buff.append(cred.toString()).append("\n");
	    }
	    buff.append("</Evidence>\n");
	}
	ListIterator i = ops.listIterator();
	int n = 0;
	while(i.hasNext()) {
	    Operation op = (Operation)i.next();
	    buff.append("<!--Operation no. ").append(++n).append("-->\n");
	    buff.append(op.toXML());
	}
	return buff.append("</Message>\n").toString();
    }

    /** Prints out this message in human readable format */
    public String toString() {
	StringBuffer buff = new StringBuffer("[Message ");
	int n = 0;
	ListIterator i = ops.listIterator();

	while(i.hasNext()) {
	    buff.append("\n\t(").append(++n).append(") ");
	    buff.append(i.next());
	}
	buff.append("\n").append(ops.size()).append(" operations total");
    buff.append("\n evidence: ");
    buff.append(evidence.toString());
	return buff.append("]").toString();
    }
    
}