// ******************************************************************************
   //
   // Title:       Force Field X.
   // Description: Force Field X - Software for Molecular Biophysics.
   // Copyright:   Copyright (c) Michael J. Schnieders 2001-2024.
   //
   // This file is part of Force Field X.
   //
   // Force Field X is free software; you can redistribute it and/or modify it
  // under the terms of the GNU General Public License version 3 as published by
  // the Free Software Foundation.
  //
  // Force Field X is distributed in the hope that it will be useful, but WITHOUT
  // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
  // details.
  //
  // You should have received a copy of the GNU General Public License along with
  // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
  // Place, Suite 330, Boston, MA 02111-1307 USA
  //
  // Linking this library statically or dynamically with other modules is making a
  // combined work based on this library. Thus, the terms and conditions of the
  // GNU General Public License cover the whole combination.
  //
  // As a special exception, the copyright holders of this library give you
  // permission to link this library with independent modules to produce an
  // executable, regardless of the license terms of these independent modules, and
  // to copy and distribute the resulting executable under terms of your choice,
  // provided that you also meet, for each linked independent module, the terms
  // and conditions of the license of that module. An independent module is a
  // module which is not derived from or based on this library. If you modify this
  // library, you may extend this exception to your version of the library, but
  // you are not obligated to do so. If you do not wish to do so, delete this
  // exception statement from your version.
  //
  // ******************************************************************************
  package ffx.ui.commands;
  
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.ServerSocket;
  import java.net.Socket;
  import java.util.ListIterator;
  import java.util.Vector;
  import java.util.logging.Logger;
  
  /**
   * The FFXServer is launched by an FFX instance to allow Force Field X Clients to connect.
   *
   * @author Michael J. Schnieders
   */
  public class FFXServer implements Runnable {
  
    private static final Logger logger = Logger.getLogger(FFXServer.class.getName());
    private static SimulationMessage closing = new SimulationMessage(SimulationMessage.CLOSING);
    private ServerSocket server;
    private int serverPort = 2000;
    private int serverTimeout = 100;
    private Thread thread;
    private int sleepTime = 1;
    private boolean init = true;
    private int cycle = 0;
    private boolean shutdown = false;
    private boolean request = false;
    private Vector<Socket> clients = new Vector<Socket>();
    private Vector<ObjectOutputStream> outputs = new Vector<ObjectOutputStream>();
    private Vector<ObjectInputStream> inputs = new Vector<ObjectInputStream>();
    private SimulationDefinition system = null;
    private SimulationUpdate update = null;
  
    /**
     * Constructor for FFXServer.
     *
     * @param s a {@link ffx.ui.commands.SimulationDefinition} object.
     */
    public FFXServer(SimulationDefinition s) {
      system = s;
    }
  
    /**
     * isAlive
     *
     * @return a boolean.
     */
    public boolean isAlive() {
      if (thread == null) {
        return false;
      } else if (thread.isAlive()) {
        return true;
      } else {
        return false;
      }
    }
  
    /**
     * loadUpdate
    *
    * @param u a {@link ffx.ui.commands.SimulationUpdate} object.
    */
   public void loadUpdate(SimulationUpdate u) {
     update = u;
   }
 
   /**
    * needUpdate
    *
    * @return a boolean.
    */
   public boolean needUpdate() {
     if (clients.isEmpty()) {
       sleepTime = 100;
       return false;
     }
     if (request != true) {
       return false;
     }
     sleepTime = 1;
     return true;
   }
 
   /** run */
   public void run() {
     startServer();
     while (!shutdown) {
       accept();
       send();
       try {
         Thread.sleep(sleepTime);
       } catch (Exception e) {
         // What to do here ??
         logger.severe("Server: thread sleep interrupted\n");
       }
       if (init) {
         cycle++;
         if (cycle >= 10) {
           init = false;
           serverTimeout = 1;
         }
       }
     }
     accept();
     send();
     closeServer();
   }
 
   /** setUpdated */
   public void setUpdated() {
     request = false;
   }
 
   /** start */
   public void start() {
     if (thread == null || !thread.isAlive()) {
       thread = new Thread(this);
       thread.setPriority(Thread.MAX_PRIORITY);
       thread.start();
     }
   }
 
   /** stop */
   public void stop() {
     shutdown = true;
   }
 
   private void accept() {
     Socket client = null;
     ObjectOutputStream oout = null;
     ObjectInputStream oin = null;
     if (server != null) {
       try {
         client = server.accept();
         if (client != null && client.isConnected()) {
           client.setTcpNoDelay(true);
           clients.add(client);
           oout = new ObjectOutputStream(client.getOutputStream());
           outputs.add(oout);
           oin = new ObjectInputStream(client.getInputStream());
           inputs.add(oin);
           Logger.getLogger("ffx").info("Client connected\n" + client);
         }
       } catch (Exception e) {
         if (client != null) {
           clients.remove(client);
         }
         if (oout != null) {
           outputs.remove(oout);
         }
         if (oin != null) {
           inputs.remove(oin);
         }
       }
     }
   }
 
   private void closeClient(int index) {
     Socket client = clients.get(index);
     ObjectOutputStream oout = outputs.get(index);
     ObjectInputStream oin = inputs.get(index);
     try {
       oout.reset();
       oout.writeObject(closing);
       oout.flush();
     } catch (Exception e) {
       try {
         outputs.remove(index);
         inputs.remove(index);
         clients.remove(index);
         if (oout != null) {
           oout.close();
         }
         if (oin != null) {
           oin.close();
         }
         if (client != null) {
           client.close();
         }
       } catch (Exception ignored) {
       }
     }
   }
 
   private void closeServer() {
     for (int i = 0; i < clients.size(); i++) {
       lastUpdate(i);
     }
     while (!clients.isEmpty()) {
       closeClient(0);
       try {
         synchronized (this) {
           wait(10);
         }
       } catch (Exception e) {
         Logger.getLogger("ffx").severe(e.toString());
       }
     }
     try {
       if (server != null) {
         server.close();
         server = null;
       }
     } catch (Exception ignored) {
     }
   }
 
   private void lastUpdate(int index) {
     try {
       ObjectOutputStream oout = outputs.get(index);
       Socket client = clients.get(index);
       if (client != null && client.isConnected() && oout != null) {
         SimulationMessage last = new SimulationMessage(SimulationMessage.SYSTEM);
         if (system != null) {
           oout.reset();
           oout.writeObject(last);
           oout.writeObject(system);
           oout.flush();
         }
         if (update != null) {
           oout.reset();
           last.setMessage(SimulationMessage.UPDATE);
           oout.writeObject(last);
           oout.writeObject(update);
           oout.flush();
         }
         last.setMessage(SimulationMessage.CLOSING);
         oout.reset();
         oout.writeObject(last);
         oout.flush();
       }
     } catch (Exception e) {
       logger.severe("" + e);
     }
   }
 
   private void send() {
     if (system == null) {
       return;
     }
     if (clients.isEmpty()) {
       return;
     }
     ObjectOutputStream oout;
     ObjectInputStream oin;
     Socket client;
     ListIterator<ObjectOutputStream> lout;
     ListIterator<ObjectInputStream> lin;
     ListIterator<Socket> lclient;
     Vector<Socket> closed = new Vector<Socket>();
     for (lout = outputs.listIterator(),
             lin = inputs.listIterator(),
             lclient = clients.listIterator();
         lout.hasNext(); ) {
       oout = lout.next();
       oin = lin.next();
       client = lclient.next();
       if (!client.isConnected() || client.isClosed()) {
         closed.add(client);
       } else {
         try {
           SimulationMessage message = null;
           while (oin != null && client.getInputStream().available() > 0) {
             Object o = oin.readObject();
             if (o instanceof SimulationMessage) {
               message = (SimulationMessage) o;
               if (message.getMessage() == SimulationMessage.CLOSING) {
                 closed.add(client);
                 message = null;
                 break;
               }
             }
           }
           if (message != null) {
             if (message.getMessage() == SimulationMessage.SYSTEM) {
               synchronized (system) {
                 oout.reset();
                 oout.writeObject(message);
                 oout.writeObject(system);
                 oout.flush();
               }
             } else if (message.getMessage() == SimulationMessage.UPDATE) {
               request = true;
               if (update != null && update.isNewer(message)) {
                 synchronized (update) {
                   // logger.info("Sending Update");
                   oout.reset();
                   oout.writeObject(message);
                   oout.writeObject(update);
                   oout.flush();
                 }
               }
             }
           }
         } catch (Exception e) {
           closed.add(client);
         }
       }
     }
     for (Socket s : closed) {
       int index = closed.indexOf(s);
       closeClient(index);
     }
   }
 
   private void startServer() {
     try {
       server = new ServerSocket();
       server.setSoTimeout(serverTimeout);
       server.setReuseAddress(true);
       server.bind(new InetSocketAddress(InetAddress.getLocalHost(), serverPort));
     } catch (Exception e) {
       try {
         server.bind(new InetSocketAddress(InetAddress.getByName(null), serverPort));
       } catch (Exception ex) {
         Logger.getLogger("ffx").severe("SERVER -- Could not start\n" + e);
         return;
       }
     }
     Logger.getLogger("ffx").info("FFX Server Address: " + server.getLocalSocketAddress());
     // JOptionPane.showMessageDialog(null, server.getLocalSocketAddress(),
     // "Server Address", JOptionPane.ERROR_MESSAGE);
   }
 }