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/*
    This file is part of JLog.

    Created by Glendon Holst for Alan Mackworth and the 
    "Computational Intelligence: A Logical Approach" text.
    
    Copyright 1998, 2000, 2002 by University of British Columbia and 
    Alan Mackworth.
    
    This notice must remain in all files which belong to, or are derived 
    from JLog.
    
    Check  or 
     for further information
    about JLog, or to contact the authors.
     
    JLog 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 of the License, or
    (at your option) any later version.

    JLog 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 JLog; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    URLs:  or 
*/
//#########################################################################
//	jUserQueryThread
//#########################################################################

package ubc.cs.JLog.Foundation;

import java.lang.*;
import java.util.*;
import java.io.PrintWriter;
import ubc.cs.JLog.Terms.*;
import ubc.cs.JLog.Parser.*;

/**
* This class is the thread that attempts to prove a user query. It can parse an
* input stream into the predicates of a user query, and it contains the 
* Prolog prover itself.  The prover runs as part of this thread.
*
* @author       Glendon Holst
* @version      %I%, %G%
*/
public class jUserQueryThread extends jRetryQueryThread
{
 protected iPrologServiceText 			qinput;
 protected PrintWriter					output;
 protected jPrologServiceBroadcaster 		beginq = null,retryq = null,endq = null;
 protected jPrologServiceBroadcaster 		debugm = null;
 

 protected jProver 				prover = null;
 protected jPredicateTerms		query = null;
 protected boolean 				result = false;
 protected int 					retry = 0;
 protected jVariableVector		var_vector = null;
 
 public 	jUserQueryThread(jPrologServices ps,iPrologServiceText qin,PrintWriter o)
 {
  super(ps);

  setName("UserQueryThread");
 // setPriority(NORM_PRIORITY + 1); //MRJ 2.1 doesn't permit UI interaction with this setting
  
  qinput = qin;
  output = o;  
 };

 public void 	setListeners(jPrologServiceBroadcaster b,jPrologServiceBroadcaster r,
                                jPrologServiceBroadcaster e,jPrologServiceBroadcaster s,
 				jPrologServiceBroadcaster d)
 {
  setStoppedListeners(s);
  beginq = b;
  retryq = r;
  endq = e;
  debugm = d;
 };

 public synchronized void 	retry()
 {
  retry++;
  notify();
 };

 protected synchronized boolean 	waitForRetry()
 {
  while (retry <= 0)
  {
   try
   {
    wait();   
   }
   catch (InterruptedException e)
   {
    return false;
   }
  }
  retry--;
  return true;
 };

 public void 	run()
 {
  if (beginq != null)
   beginq.broadcastEvent(new jPrologServiceEvent());
 
  try
  {
   query();
 
   if (retryq != null)
    retryq.broadcastEvent(new jUserQueryEvent(result));
  
   while (result)
   {
    if (waitForRetry())
    {
     internal_retry();
     internal_display();
    
     if (retryq != null)
      retryq.broadcastEvent(new jUserQueryEvent(result));
    }
   }
  }
  catch (ThreadDeath e)
  {
   throw e; // thread death is user controlled
  }
  catch (Error e)
  {
   output.println("JAVA ERROR:");
   output.println(e.toString()+"\n");
   output.flush();
   qinput.requestFocus();
   throw e; 
  }
  finally
  {
   if (allow_release)
    prolog.release();

   var_vector = null;

   if (endq != null)
    endq.broadcastEvent(new jPrologServiceEvent());
  }
 };
 
 protected void 	query()
 {pParseStream 	parser;
   
  parser = new pParseStream(qinput.getText(),prolog.getKnowledgeBase(),
                             prolog.getPredicateRegistry(),
                             prolog.getOperatorRegistry());
   
  try
  {
   result = false;
   query = parser.parseQuery(); 
    
   if (query != null)
   {
    var_vector = new jVariableVector();
    query.registerVariables(var_vector);
	
    output.println(query.toString(true));
    output.flush();
	
    internal_prove();
    internal_display();
   }
   else
   {
    output.println("empty query.");
	output.flush();
   }
  }
  catch (SyntaxErrorException e)
  {
   output.println("SYNTAX ERROR:");
   output.println(e.toString()+"\n");
   output.flush();
   qinput.setCaretPosition(e.getPosition());
   qinput.select(e.getPosition(),e.getPosition()+1);
   qinput.requestFocus(); 
  }
  catch (TokenizeStreamException e)
  {
   output.println("INTERNAL ERROR:");
   output.println(e.toString()+"\n");
   output.flush();
   qinput.setCaretPosition(e.getPosition());
   qinput.select(e.getPosition(),e.getPosition()+1);
   qinput.requestFocus(); 
  }
  catch (RuntimeException e)
  {
   output.println("ERROR:");
   output.println(e.toString()+"\n");
   output.flush();
   qinput.requestFocus(); 
  }
 };
 
 protected void 	internal_prove()
 {
  prover = (prolog.getDebugging() ? 
  				new jDebugProver(prolog.getKnowledgeBase(),debugm) :
  				new jProver(prolog.getKnowledgeBase()));
  				
  result = prover.prove(query);
 };
 
 protected void 	internal_retry()
 {
  if (result)
  {
   try
   {
    result = prover.retry();
   }
   catch (InvalidInputException e)
   {
    if (!e.isHandled())
    {
     output.println("ERROR:");
     output.println(e.toString()+"\n");
	 output.flush();
     qinput.requestFocus();
    }
    result = false; 
   }
   catch (RuntimeException e)
   {
    output.println("ERROR:");
    output.println(e.toString()+"\n");
    output.flush();
    qinput.requestFocus();
    result = false; 
   }
  }
 };
 
 protected void 	internal_display()
 {
  if (query == null)
   return;
   
  if (result)
  {jVariable[] 		vars;
   int				i,max;
      
   vars = var_vector.getVariables(); 
     
   for (i = 0, max = vars.length; i < max; i++)
    if (vars[i].isNamedForDisplay())
     output.println(vars[i].getName() + " = " + vars[i].toString(false));

   output.println("yes");
  }
  else
   output.println("no");
  
  output.flush();
 };
};