import com.nailabs.abac.credential.*;
import com.nailabs.abac.process.*;
import com.nailabs.abac.trust.*;
import com.nailabs.abac.test.*;
import edu.stanford.peer.rbtm.credential.*;
import java.io.*;
import java.text.*;
import java.util.*;
import java.rmi.*;
import javax.servlet.*;
import javax.servlet.http.*;


public class AccessMediator implements Filter {
    private Entity eid = null;
    private EntityExpression target = null;
    NegotiatorFactory clientFactory = null;
    private FilterConfig conf = null;
    Calendar cal = Calendar.getInstance();
    DateFormat formatter = DateFormat.getDateInstance(DateFormat.FULL);

    /** maximum no. of rmi lookup retries if a remote exception occurs */
    private int MAX_RETRIES = 1;

    private void getClientFactory(String hostName) {
        StringBuffer url = new StringBuffer("//");
        url.append(hostName).append("/");
        url.append("ClientAuthenticationService");
        //url.append("ClientRTMLService");
        System.out.println("Attempting to contact" + url);
        try {
            clientFactory = 
                (NegotiatorFactory)Naming.lookup(url.toString());
        }
        catch(Exception ex) {
            ex.printStackTrace();
        }
    }

    private Negotiator getClient(String host, String client,
                                    RMINegotiator me)
    {
        for(int i = 0; i < MAX_RETRIES; i++) {
            try {
                return (Negotiator)clientFactory.getNegotiator(client, me);
            }
            catch(Exception ex) {
		ex.printStackTrace();
                getClientFactory(host);
            }
        }
        return null;
    } 

    /** shared configuration hash table */
    HashMap map = null;        

    public void init(FilterConfig config) throws ServletException {
        String hashCode = config.getInitParameter("EntityHash");
	String shortName = config.getInitParameter("EntityName");
        String cfile = config.getInitParameter("PolicyFile");
        String targetName = config.getInitParameter("PrimaryRole");
	map = FrontierManager.loadConfiguration(cfile);
	//map = RtmlTest.loadConfiguration(cfile); 
	config.getServletContext().log("map = " + map);	
        conf = config;
        conf.getServletContext().log("Loading new filter for " + shortName +
                                     " from " + cfile + " with role " + 
                                     targetName + "\n");
        //RtmlFrontier.addFrontier(map);	
        FrontierManager.addFrontier(map);	
	//ResourcePolicy resourcePolicy = 
	//    (ResourcePolicy)map.get("ResourcePolicy");

        try {
            //eid = new RtmlEntity(shortName, hashCode);
	    //target = resourcePolicy.requires(targetName);
            eid = new SimpleEntity(shortName);
            target = StaticCredential.getRole(targetName);
            System.out.println("Frontiers: " + 
            FrontierManager.getFrontiers().toString());
            //Iterator i = FrontierManager.getFrontiers().iterator();
        }
        catch(Exception ex) {
            ex.printStackTrace();
        }
    }

    public void destroy() { }

    public  RtmlEntity getEntityId(HttpServletRequest request) {
        final String KEY = "EntityID";
	final String HASH = "HashID";
        String shortName = null;
	String hashCode = null;
        HttpSession session = request.getSession();

        shortName = request.getParameter("id");
	hashCode = request.getParameter("hash");
        if(session.isNew()) {     // new id bootstrapped
            session.setAttribute(KEY, shortName);
        } else if(shortName != null) { // forcing a new id manually
            session.invalidate();
            session = request.getSession();
            session.setAttribute(KEY, shortName);
            session.setAttribute(HASH, hashCode);
        } else {                  // use the session's entity id value
            shortName = (String)session.getAttribute(KEY);
            hashCode = (String)session.getAttribute(HASH);
        }
	try {
	    System.out.println("Using RtmlEntity = " + shortName + "(" +
			       hashCode + ")");
	    return new RtmlEntity(shortName, hashCode);
	} catch(Exception ex) {
	    ex.printStackTrace();
	}
	return null;
    }

    public Entity getEntity(HttpServletRequest request) {
        final String KEY = "EntityID";
        String shortName = null;
        HttpSession session = request.getSession();

        shortName = request.getParameter("id");
        if(session.isNew()) {     // new id bootstrapped
            session.setAttribute(KEY, shortName);
        } else if(shortName != null) { // forcing a new id manually
            session.invalidate();
            session = request.getSession();
            session.setAttribute(KEY, shortName);
        } else {                  // use the session's entity id value
            shortName = (String)session.getAttribute(KEY);
        }
	try {
	    System.out.println("Using SimpleEntity = " + shortName);
	    SimpleEntity id = new SimpleEntity(shortName);
	    return (Entity)id;
	} catch(Exception ex) {
	    ex.printStackTrace();
	}
	return null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain)
        throws java.io.IOException, ServletException {
        Entity peer = getEntity((HttpServletRequest)request);
        //RtmlEntity peer = getEntityId((HttpServletRequest)request);
        System.out.print("Filtering request from id = " + peer );
        System.out.println(" for resource of " + eid.toString()); 
	HashMap localMap = (HashMap)map.clone();
	localMap.put("peer", peer);
        NegotiationContext context = new NegotiationContext(map);
        boolean success = false;
        
        if(peer == null) {
            printMessage(response.getWriter(), 
                         "<h1>Authentication required!</h1>");
            return;
        }
        try {
            String host = request.getRemoteHost();
            RMINegotiator agent = new RMINegotiator(context);
            //context.getGraph().addObserver(observer);
            Negotiator peerAgent = getClient(host, peer.toString(), agent);
            for(int i = 0; i < 4 && peerAgent == null; i++) {
                peerAgent = getClient(host, peer.toString(), agent);
            }
	    Entity realPeer = peerAgent.getSelf();
            TrustTarget primary = new TrustTarget(eid, target, realPeer); 
            agent.setPeer(peerAgent);
            agent.setRoot(primary);
            success = agent.negotiate();
        }
        catch(Exception ex) {
            ex.printStackTrace();
        }
        // allow or block this servlet
        if(!success) {
            printMessage(response.getWriter(),
                         "<h1>Sorry, page cannot be displayed!</h1>");
            return;
        }
        chain.doFilter(request, response);
    }


    protected void printExpiration(PrintWriter out) {
        out.print("<meta http-equiv=\"Expires\" content=\"");
        out.print(formatter.format(cal.getTime()));
        out.println("\">");
    }

    protected void printMessage(PrintWriter out, String body) {
        out.print("<html>\n\t<head>\n\t");
        printExpiration(out);
        out.println("\t</head>\n\t<body>");
            out.println(body);
            out.println("\t</body>\n</html>");
            out.flush();
            return;

    }
}