/*
 *
 * Copyright (c) 2000 Scott Oaks and Henry Wong. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and
 * without fee is hereby granted.
 *
 * This sample source code is provided for example only,
 * on an unsupported, as-is basis. 
 *
 * AUTHOR MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. AUTHOR SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE
 * CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE
 * PERFORMANCE, SUCH AS IN THE OPERATION OF NUCLEAR FACILITIES, AIRCRAFT
 * NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL, DIRECT LIFE
 * SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH THE FAILURE OF THE
 * SOFTWARE COULD LEAD DIRECTLY TO DEATH, PERSONAL INJURY, OR SEVERE
 * PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH RISK ACTIVITIES").  AUTHOR
 * SPECIFICALLY DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR
 * HIGH RISK ACTIVITIES.
 */


import java.rmi.*;
import java.rmi.server.*;
import java.util.*;
import net.jini.core.lease.*;
import net.jini.core.event.*;
import com.sun.jini.lease.landlord.*;

public class ServerDelivery {
    private Remote source;              // Owner of this delivery object
    private ServerLandlord lord;        // The landlord that manages leases
    private Vector leases;              // Event specific leases
    private long seqnum = 0;

    // The client-specific session data for the event leases
    // holds the listener and the callback data
    private class SessionData {
        public RemoteEventListener listener;
        public MarshalledObject key;
    }

    public ServerDelivery(Remote source, ServerLandlord ll) {
        this.source = source;
        lord = ll;
        leases = new Vector();
    }

    public synchronized EventRegistration addListener(RemoteEventListener l, long duration, MarshalledObject key) {
        SessionData sd = new SessionData();
        sd.listener = l;
        sd.key = key;

        Lease lease = lord.newLease(sd, duration);
        leases.addElement(lease);

        return new EventRegistration(ConvertEvent.ID, source, lease, seqnum);
    }

    // Deliver an event to all listeners
    public synchronized void deliver(int value) {
        long seq = seqnum++;                // Deliver request number
        if (leases.isEmpty())
            return;

        lord.expireLeases();                // Clean up the leases first
        Vector expiredLeases = new Vector();
        // Deliver to each client. Save all the expired leases
        // and remove those leases after the loop
        for (Enumeration e = leases.elements(); e.hasMoreElements();) {
            Lease l = (Lease) e.nextElement();
            SessionData obj = (SessionData) lord.getSessionData(l);
            if (obj == null) {
                expiredLeases.addElement(l);
            } else {
                try {
                    deliverEvent(obj, seq, value);
                } catch (RemoteException rex) {
                    // Can't really do anything here --
                    // cancelling the lease is not allowed;
                    // we'll have to try again next time
                } catch (UnknownEventException uee) {
                    // The client told us it didn't want these events
                    // anymore, cancel it's registration
                    expiredLeases.addElement(l);
	        }
            }
        }

        // Get rid of all the failed clients
        for (Enumeration e = expiredLeases.elements(); e.hasMoreElements();) {
            Lease l = (Lease) e.nextElement();
            leases.remove(l);
        }
    }

    // Actually send the event
    private void deliverEvent(SessionData data, long seq, int value) 
            throws RemoteException, UnknownEventException {
        ConvertEvent event = new ConvertEvent(source, value, seq, data.key);
        data.listener.notify(event);
    }
}