/* UnicastRef.java --
   Copyright (c) 1996, 1997, 1998, 1999, 2002, 2005, 2006
   Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 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 gnu.java.rmi.server;

import gnu.java.rmi.dgc.LeaseRenewingTask;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.rmi.ConnectException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.dgc.Lease;
import java.rmi.server.ObjID;
import java.rmi.server.Operation;
import java.rmi.server.RMIClientSocketFactory;
import java.rmi.server.RemoteCall;
import java.rmi.server.RemoteObject;
import java.rmi.server.RemoteRef;
import java.rmi.server.UID;

public class UnicastRef
    implements RemoteRef, ProtocolConstants
{

  /**
   * Use serial version UID for iteroperability
   */
  private static final long serialVersionUID = 1;

  public ObjID objid;

  UnicastConnectionManager manager;

  /**
   * Used by serialization, and let subclass capable of having default
   * constructor
   */
  // must be public otherwise java.rmi.RemoteObject cannot instantiate this
  // class
  // -- iP
  public UnicastRef()
  {
  }

  public UnicastRef(ObjID objid, String host, int port,
                    RMIClientSocketFactory csf)
  {
    this(objid);
    manager = UnicastConnectionManager.getInstance(host, port, csf);
  }

  public UnicastRef(ObjID objid)
  {
    this.objid = objid;
  }

  public Object invoke(Remote obj, Method method, Object[] params, long opnum)
      throws Exception
  {
    // Check if client and server are in the same VM, then local call can be
    // used to
    // replace remote call, but it's somewhat violating remote semantic.
    Object svrobj = manager.serverobj;

    // Make sure that the server object is compatible. It could be loaded from a
    // different
    // classloader --iP
    if (svrobj != null && method.getDeclaringClass().isInstance(svrobj))
      {
        // local call
        Object ret = null;
        try
          {
            ret = method.invoke(svrobj, params);
          }
        catch (InvocationTargetException e)
          {
            throw (Exception) e.getTargetException();
          }
        // System.out.println("\n\n ***** local call: " + method + "\nreturn: "
        // + ret + "\n\n");
        return ret;
      }
    // System.out.println("***************** remote call:" +
    // manager.serverPort);
    return (invokeCommon(obj, method, params, - 1, opnum));
  }

  /**
   * The ordinary number of the DGC messages.
   */
  static long dgcSequence;

  /**
   * The DGC object id, also serves as a synchronization target to increment the
   * dgcSequence safely.
   */
  static final ObjID dgcId = new ObjID(ObjID.DGC_ID);

  ObjID[] this_id;

  /**
   * The number of the method "dirty" in the DGC.
   */
  static int DIRTY = 1;

  /**
   * The DGC interface hash code.
   */
  static final long dgcInterfaceHash = - 669196253586618813L;

  /**
   * Notify the DGC of the remote side that we still hold this object.
   */
  public Lease notifyDGC(Lease lease) throws Exception
  {
    long seq;
    synchronized (dgcId)
      {
        seq = dgcSequence++;
      }

    if (this_id == null)
      this_id = new ObjID[] { objid };

    UnicastConnection conn;
    try
      {
        conn = manager.getConnection();
      }
    catch (IOException e1)
      {
        throw new RemoteException("connection failed to host: "
                                  + manager.serverName, e1);
      }

    ObjectOutputStream out;
    DataOutputStream dout;
    try
      {
        dout = conn.getDataOutputStream();
        dout.writeByte(MESSAGE_CALL);

        out = conn.startObjectOutputStream(); // (re)start ObjectOutputStream

        dgcId.write(out);
        // The number of the operation is 1 ("dirty")
        out.writeInt(DIRTY);
        out.writeLong(dgcInterfaceHash);

        RMIObjectOutputStream rout = (RMIObjectOutputStream) out;

        rout.writeValue(this_id, this_id.getClass());
        rout.writeLong(seq);
        rout.writeValue(lease, lease.getClass());

        out.flush();
      }
    catch (IOException e2)
      {
        throw new RemoteException("DGC call failed: ", e2);
      }

    int returncode;
    Object returnval;
    DataInputStream din;
    ObjectInputStream in;
    UID ack;
    try
      {
        din = conn.getDataInputStream();

        if ((returncode = din.readUnsignedByte()) != MESSAGE_CALL_ACK)
          {
            conn.disconnect();
            throw new RemoteException("DGC Call not acked:" + returncode);
          }

        in = conn.startObjectInputStream(); // (re)start ObjectInputStream
        returncode = in.readUnsignedByte();
        ack = UID.read(in);

        if (returncode == RETURN_NACK)
          {
            returnval = in.readObject(); // get Exception

          }
        else
          {
            returnval = ((RMIObjectInputStream) in).readValue(Lease.class);
          }
      }
    catch (IOException e3)
      {
        throw new RemoteException("DGC call return failed: ", e3);
      }

    manager.discardConnection(conn);

    if (returncode != RETURN_ACK && returnval != null)
      {
        if (returncode == RETURN_NACK)
          throw (Exception) returnval;
        else
          throw new RemoteException("DGC unexpected returncode: " + returncode);
      }

    return (Lease) returnval;
  }
  /**
   * Invoke the remote method on the given object. This part is overridden by
   * the activatable objects.
   */
  protected Object invokeCommon(Remote obj, Method method, Object[] params,
                                int opnum, long hash) throws Exception
  {
    UnicastConnection conn;
    try
      {
        conn = manager.getConnection();
        return invokeCommon(conn, obj, method, params, opnum, hash);
      }
    catch (IOException e1)
      {
        throw new RemoteException("connection failed to host: "
                                  + manager.serverName, e1);
      }
  }

  /**
   * Invoke the remote method on the given object when connection is already
   * established.
   */
  protected Object invokeCommon(UnicastConnection conn, Remote obj,
                                Method method, Object[] params, int opnum,
                                long hash) throws Exception
  {
    ObjectOutputStream out;
    DataOutputStream dout;
    try
      {
        dout = conn.getDataOutputStream();
        dout.writeByte(MESSAGE_CALL);

        out = conn.startObjectOutputStream(); // (re)start ObjectOutputStream

        objid.write(out);
        out.writeInt(opnum);
        out.writeLong(hash);

        // must handle primitive class and their wrapper classes
        Class clss[] = method.getParameterTypes();
        for (int i = 0; i < clss.length; i++)
          ((RMIObjectOutputStream) out).writeValue(params[i], clss[i]);

        out.flush();
      }
    catch (IOException e2)
      {
        throw new RemoteException("call failed: ", e2);
      }

    int returncode;
    Object returnval;
    DataInputStream din;
    ObjectInputStream in;
    UID ack;
    try
      {
        din = conn.getDataInputStream();

        if ((returncode = din.readUnsignedByte()) != MESSAGE_CALL_ACK)
          {
            conn.disconnect();
            throw new RemoteException("Call not acked:" + returncode);
          }

        in = conn.startObjectInputStream(); // (re)start ObjectInputStream
        returncode = in.readUnsignedByte();
        ack = UID.read(in);

        Class cls = method.getReturnType();

        if (returncode == RETURN_NACK)
          {
            returnval = in.readObject(); // get Exception

          }
        else if (cls == Void.TYPE)
          {
            returnval = null;
            // in.readObject() // not required! returntype 'void' means no field
            // is returned.
          }
        else
          {
            returnval = ((RMIObjectInputStream) in).readValue(cls); // get
            // returnvalue
          }
      }
    catch (IOException e3)
      {
        // for debug: e3.printStackTrace();
        throw new RemoteException("call return failed: ", e3);
      }

    /*
     * if DGCAck is necessary?? //According to RMI wire protocol, send a DGCAck //
     * to indicate receiving return value dout.writeByte(MESSAGE_DGCACK);
     * ack.write(dout); out.flush();
     */

    manager.discardConnection(conn);

    if (returncode != RETURN_ACK && returnval != null)
      {
        if (returncode == RETURN_NACK)
          throw (Exception) returnval;
        else
          throw new RemoteException("unexpected returncode: " + returncode);
      }

    return (returnval);
  }

  /**
   * @deprecated
   */
  public RemoteCall newCall(RemoteObject obj, Operation[] op, int opnum,
                            long hash) throws RemoteException
  {
    UnicastConnection conn;

    try
      {
        conn = manager.getConnection();
      }
    catch (IOException e1)
      {
        throw new ConnectException("connection failed to host: "
                                   + manager.serverName, e1);
      }

    // obj: useless?

    return (new UnicastRemoteCall(conn, objid, opnum, hash));
  }

  /**
   * @deprecated
   */
  public void invoke(RemoteCall call) throws Exception
  {
    UnicastRemoteCall c = (UnicastRemoteCall) call;
    call.executeCall();
  }

  /**
   * @deprecated
   */
  public void done(RemoteCall call) throws RemoteException
  {
    UnicastRemoteCall c = (UnicastRemoteCall) call;
    try
      {
        c.done();
      }
    catch (IOException e)
      {
      }
    UnicastConnection conn = c.getConnection();
    manager.discardConnection(conn);
  }

  public void writeExternal(ObjectOutput out) throws IOException
  {
    if (manager == null)
      {
        throw new IOException("no connection");
      }
    manager.write(out);
    objid.write(out);
    // This byte is somewhat confusing when interoperating with JDK
    out.writeByte(0); // RETURN_ACK);
  }

  public void readExternal(ObjectInput in) throws IOException,
      ClassNotFoundException
  {
    manager = UnicastConnectionManager.read(in);
    objid = ObjID.read(in);
    byte ack = in.readByte();
    // This byte is somewhat confusing when interoperating with JDK
    if (ack != RETURN_ACK && ack != 0/* jdk ack value */)
      {
        throw new IOException("no ack found");
      }

    // Notify the DGC of the remote side that we hold the reference to the
    // received object. Do not notify if the client and server are on the
    // same virtual machine.
    if (manager.serverobj == null)
      LeaseRenewingTask.scheduleLeases(this);
  }

  public boolean remoteEquals(RemoteRef ref)
  {
    throw new Error("Not implemented");
  }

  public int remoteHashCode()
  {
    throw new Error("Not implemented");
  }

  public String getRefClass(ObjectOutput out)
  {
    return ("UnicastRef");
  }
  
  /**
   * Return the string representing the remote reference information.
   */
  public String remoteToString()
  {
    if (manager!=null)
      return manager.toString();
    else
      return "null manager";
  }

  public void dump(UnicastConnection conn)
  {
    try
      {
        DataInputStream din = conn.getDataInputStream();
        for (;;)
          {
            int b = din.readUnsignedByte();
            System.out.print(Integer.toHexString(b));
            if (b >= 32 && b < 128)
              {
                System.out.print(": " + (char) b);
              }
            System.out.println();
          }
      }
    catch (IOException _)
      {
      }
  }

  /**
   * Check if this UnicastRef points to the object as the passed UnicastRef.
   * Both the object Id and manager must be the same.
   * 
   * @return true if the passed reference points to the same remote object as
   *         this reference, false otherwise.
   */
  public boolean equals(Object other)
  {
    if (other instanceof UnicastRef)
      {
        UnicastRef r = (UnicastRef) other;
        return r.manager.equals(manager) && r.objid.equals(objid);
      }
    else
      return false;
  }

  /**
   * Get the hash code of this UnicastRef, combining hash code of the manager
   * with hash code of the object id.
   */
  public int hashCode()
  {
    return manager.hashCode() ^ objid.hashCode();
  }

}