//-----------------------------------------------------------------------------
// $RCSfile: PythonPanel.java,v $
// $Revision: 1.6 $
// $Author: snoopdave $
// $Date: 2000/04/08 20:12:48 $
//-----------------------------------------------------------------------------

package org.relayirc.swingutil;

import org.python.util.PythonInterpreter; 
import org.python.core.*; 

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import java.util.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;

/** 
 * Interactive JPython panel that emulates the one in PythonWin IDE.
 * @author David M Johnson
 * @version $Revision: 1.6 $
 * <p>The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL</p>
 * Original Code: Relay IRC Chat Engine<br>
 * Initial Developer: David M. Johnson<br>
 * Contributor(s): No contributors to this file (yet)<br>
 * Copyright (C) 1997-2000 by David M. Johnson<br>
 * All Rights Reserved.
 */
public class PythonPanel extends JPanel {

   private PythonInterpreter _python = new PythonInterpreter();
   private JTextArea         _textArea = new JTextArea();

   public static int INDENT = 3;
   public static int PROMPT_LENGTH = 3;
   public static String START_PROMPT = ">>>";
   public static String CONTINUE_PROMPT = "...";

   //----------------------------------------------------------------------
   /** Construct PythonPanel and its embedded JPython interpreter. */

   public PythonPanel() {

      PythonInterpreter _python = new PythonInterpreter();
      _python.exec("zzz=1"); // warm-up the interpreter... 

      _textArea.setFont(new Font("Courier",Font.PLAIN,12));

      _textArea.getDocument().addDocumentListener(new DocumentListener() {
         public void insertUpdate(DocumentEvent de) {
            String text = "";
            int len = de.getLength();
            try {
               text = de.getDocument().getText(de.getOffset(),len);
            }
            catch (BadLocationException ble) {
               ble.printStackTrace();
            }
            if (text.equals("\n")) {
               SwingUtilities.invokeLater(new Runnable() {
                  public void run() {
                     handleNewLine();
                  }
               });
            }
         }
         public void changedUpdate(DocumentEvent de) {}
         public void removeUpdate(DocumentEvent de) {}
      });

      firstLine();

      setLayout(new BorderLayout());
      add(_textArea,BorderLayout.CENTER);
   }
   //----------------------------------------------------------------------
   /** This is where the emulate-PythonWin logic lives. */

   private void handleNewLine() {

      int pos = _textArea.getCaretPosition();
      Document doc = _textArea.getDocument();

      try {
      // Get line entered by user
         int prevline = searchBack("\n",pos - 2);
         String line = doc.getText( prevline + 1, (pos - prevline) );
         line = line.trim();

         boolean isCodeLine =    line.startsWith(START_PROMPT) 
                              || line.startsWith(CONTINUE_PROMPT);

         int prevPrompt = searchBack(START_PROMPT,doc.getLength());
         int nextPrompt = searchForth(START_PROMPT,pos);

         debug.println("["+line+"]");
         debug.println(
            "pos ="+pos+" prevline="+prevline+" iscode="+isCodeLine);
           
      // On empty start prompt before prev prompt -> send caret to new prompt
         if (line.equals( START_PROMPT ) && pos < prevPrompt) {
            debug.println("A");
            removeNewLine(pos);
            newLine();
         }
      // On empty start prompt line at end -> send caret to new prompt
         else if (line.equals( START_PROMPT ) && pos > prevPrompt) {
            debug.println("B");
            newPrompt();
         }
      // On empty continue prompt line -> execute script then new prompt
         else if (line.equals( CONTINUE_PROMPT ) && pos > prevPrompt) {
            debug.println("C");
            executeScript();
            newPrompt();
         }
      // On non-code line before last prompt -> send caret to new prompt
         else if (!isCodeLine && pos < prevPrompt) {
            debug.println("D");
            removeNewLine(pos);
            newLine();
         }
      // On code line before last start prompt -> grab script, put it at end 
         else if (isCodeLine && pos < prevPrompt) {
            debug.println("E");
            removeNewLine(pos);
            grabCode(pos);
         }
      // Within code after last start prompt -> execute code
         else if (isCodeLine && nextPrompt == -1 && pos < doc.getLength() - 1) {
            debug.println("F");
            removeNewLine(pos);
            executeScript();
            newPrompt();
         }
      // Within text in current script -> send caret to new prompt
         else if (isCodeLine && pos < doc.getLength()-1) {
            debug.println("G");
            newPrompt();
         }
      // At end of code line ending with a colon -> increate indent
         else if (isCodeLine && line.endsWith(":")) {
            debug.println("H");
            indentLine(_textArea.getCaretPosition(),figureIndent(line)+INDENT);
         }
      // At end of start prompt line with no colon -> execute line
         else if (line.startsWith( START_PROMPT )) {
            debug.println("I");
            executeScript();
            newPrompt();
         }
      // At end of ... prompt line with no colon -> indent
         else if (line.startsWith( CONTINUE_PROMPT )) {
            debug.println("J");
            indentLine(_textArea.getCaretPosition(),figureIndent(line));
         }
         else {
            debug.println("K");
            newPrompt();
         }
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Remove newline at specified position. */

   private void removeNewLine(int pos) {
      try {
         Document doc = _textArea.getDocument();
         doc.remove(pos-1,1);
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Grab the script at specified postion, copy it and paste it to the
     * end of the text area. 
     */
   private void grabCode(int pos) {

      int prevPrompt = 0;
      try {
         // Script begins at last start prompt before pos and ends
         // at last continue prompt after pos.
         Document doc = _textArea.getDocument();
         int bos = searchBack(START_PROMPT,pos) + PROMPT_LENGTH + 1; 

         int nextNewLine = searchForth("\n",pos);
         int eos = searchForth(START_PROMPT,pos) - 1;
         int lastCont = searchBack(CONTINUE_PROMPT,eos) - 1;
         if (lastCont < bos) {
            eos = nextNewLine; 
         }
         else {
            eos = lastCont;
         }

         // Put script at end
         String script = doc.getText(bos,eos-bos);
         debug.println("<GRABBED>\n"+script+"\n</GRABBED>\n");
         doc.insertString(doc.getLength()-1,script,null);
         _textArea.setCaretPosition(doc.getLength()-1);
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Execute the script at end of text area. */

   private void executeScript() {
      try {
         // Script begins a last start prompt and ends at end of text area 
         Document doc = _textArea.getDocument();
         int eos = doc.getLength() - 1;
         int bos = searchBack(START_PROMPT,eos);
         debug.println("bos="+bos+" eos="+eos);

         // Grab the script, strip off start and continue prompts
         String script = "";
         String rawScript = doc.getText(bos,eos-bos);
         StringTokenizer toker = new StringTokenizer(rawScript,"\n");
         while (toker.hasMoreTokens()) {
            try {
               String token = toker.nextToken();
               script += token.substring(PROMPT_LENGTH+1)+"\n";
            }
            catch (NoSuchElementException nsee) {
               // Ignored by design
            }
         }

         // Execute the script
         debug.println("<SCRIPT>\n"+script+"\n</SCRIPT>\n");
         StringWriter outw = new StringWriter();
         StringWriter errw = new StringWriter();
         _python.setOut(outw);
         _python.setErr(errw);
         try {
            _python.exec(script);
         }
         catch (Exception e) {
            e.printStackTrace(); 
         }         

         // Print out theo script results
         if (errw.toString().length() > 0) {
            doc.insertString(doc.getLength()-1,errw.toString(),null);
         }
         else {
            doc.insertString(doc.getLength()-1,outw.toString(),null);
         }
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Creates new line at end of text area and send caret there. */

   private void newLine() {
      Document doc = _textArea.getDocument();
      int pos = doc.getLength() > 0 ? doc.getLength() - 1 : 0;
      try {
         doc.insertString(pos,"\n",null);
         _textArea.setCaretPosition(doc.getLength()-1);
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Creates banner and initial start prompt. */ 

   private void firstLine() {
      Document doc = _textArea.getDocument();
      int pos = doc.getLength() > 0 ? doc.getLength() - 1 : 0;
      try {
         String banner = "JPython is Copyright (c) 1997-1999 CNRI\n";
         banner+="PythonPanel is Copyright (c) 1999-2000 by David M. Johnson\n";
         doc.insertString(pos,banner,null);
         doc.insertString(doc.getLength()-1,"\n",null);
         _textArea.setCaretPosition(doc.getLength()-1);
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Creates new prompt at end of text area and sends caret there. */

   private void newPrompt() {
      Document doc = _textArea.getDocument();
      int pos = doc.getLength() > 0 ? doc.getLength() - 1 : 0;
      String prefix = START_PROMPT+" ";
      try {
         doc.insertString(pos,prefix,null);
         _textArea.setCaretPosition(pos+prefix.length());
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Determine indent level of a string. */

   private int figureIndent(String inputstr) {
      String line = inputstr.substring(PROMPT_LENGTH+1);
      StringBuffer strbuf = new StringBuffer(line);
      int indent = 0;
      for (int i=0; i<line.length(); i++) {
         if (Character.isSpaceChar(strbuf.charAt(i)))
            indent++;
         else
            break;
      }
      return indent;
   }
   //----------------------------------------------------------------------
   /** Indents a new line of code at a specified caret position and sends 
     * caret to end of new line.
     * @param pos Position of line to be indented 
     * @param indentLevel Number of spaces to indent 
     */
   private void indentLine(int pos, int indentLevel) {
      Document doc = _textArea.getDocument();

      char indentChars[] = new char[indentLevel];
      for (int i=0; i<indentLevel; i++) indentChars[i] = ' ';
      String prefix = CONTINUE_PROMPT+" "+new String(indentChars);

      try {
         doc.insertString(pos,prefix,null);
         _textArea.setCaretPosition(pos+prefix.length());
      }
      catch (BadLocationException ble) {
         ble.printStackTrace();
      }
   }
   //----------------------------------------------------------------------
   /** Search text area backwards for str, starting at pos.
     * @param str Search string
     * @param pos Starting point of search
     * @return Index of str
     */
   private int searchBack(String str, int pos) {
      int result = -1;
      Document doc = _textArea.getDocument();

      while (pos >= 0) {
         try {
            String curstr = doc.getText(pos,str.length());
            if (curstr.equals(str)) {
               result = pos;
               break;
            }
         }
         catch (BadLocationException ble) {
            // Ignored by design
         }
         pos--;
      }
      return result;
   }
   //----------------------------------------------------------------------
   /** Seach text area forwards for str, starting at pos. 
     * @param str Search string
     * @param pos Starting point of search
     * @return Index of str, or -1 on error.
     */
   private int searchForth(String str, int pos) {
      int result = -1;
      Document doc = _textArea.getDocument();

      while (pos < doc.getLength()) {
         try {
            String curstr = doc.getText(pos,str.length());
            if (curstr.equals(str)) {
               result = pos;
               break;
            }
         }
         catch (BadLocationException ble) {
            // Ignored by design
         }
         pos++;
      }
      return result;
   }
   //----------------------------------------------------------------------
   static class debug {
      private static boolean _on = false;
      public static void setDebug(boolean flag) {
         _on = flag;
      }
      public static void println(String txt) {
         if (_on) System.out.println(txt);
      }
   }
   //----------------------------------------------------------------------
   /** For testing: turn on debugging and show a JFrame with PythonPanel. */
   public static void main(String args[]) {
       debug.setDebug(true);
       JFrame frame = new JFrame("PythonPanel Test Frame");
       frame.addWindowListener(new WindowAdapter() {
          public void windowClosing(WindowEvent we) {
             System.exit(-1);
          }
       });
       frame.getContentPane().setLayout(new BorderLayout());
       frame.getContentPane().add(new JScrollPane(new PythonPanel()));
       frame.setSize(500,300);
       frame.setLocation(250,400);
       frame.setVisible(true);
   }
}