/*
 * KeyEventWorkaround.java - Works around bugs in Java event handling
 * :tabSize=8:indentSize=8:noTabs=false:
 * :folding=explicit:collapseFolds=1:
 *
 * Copyright (C) 2000, 2001, 2002 Slava Pestov
 *
 * This program 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 any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

package org.gjt.sp.jedit.gui;

//{{{ Imports
import java.awt.event.*;
import java.awt.*;
import org.gjt.sp.jedit.OperatingSystem;
//}}}

/**
 * This class contains various hacks to get keyboard event handling to behave in
 * a consistent manner across Java implementations, many of which are
 * hopelessly broken in this regard.
 *
 * @author Slava Pestov
 * @version $Id: KeyEventWorkaround.java,v 1.3 2002/10/25 17:29:57 gfx Exp $
 */
public class KeyEventWorkaround
{
  //{{{ processKeyEvent() method
  public static KeyEvent processKeyEvent(KeyEvent evt)
  {
    int keyCode = evt.getKeyCode();
    char ch = evt.getKeyChar();

    switch(evt.getID())
    {
    //{{{ KEY_PRESSED...
    case KeyEvent.KEY_PRESSED:
      // get rid of keys we never need to handle
      switch(keyCode)
      {
      case KeyEvent.VK_ALT:
      case KeyEvent.VK_ALT_GRAPH:
      case KeyEvent.VK_CONTROL:
      case KeyEvent.VK_SHIFT:
      case KeyEvent.VK_META:
      case KeyEvent.VK_DEAD_GRAVE:
      case KeyEvent.VK_DEAD_ACUTE:
      case KeyEvent.VK_DEAD_CIRCUMFLEX:
      case KeyEvent.VK_DEAD_TILDE:
      case KeyEvent.VK_DEAD_MACRON:
      case KeyEvent.VK_DEAD_BREVE:
      case KeyEvent.VK_DEAD_ABOVEDOT:
      case KeyEvent.VK_DEAD_DIAERESIS:
      case KeyEvent.VK_DEAD_ABOVERING:
      case KeyEvent.VK_DEAD_DOUBLEACUTE:
      case KeyEvent.VK_DEAD_CARON:
      case KeyEvent.VK_DEAD_CEDILLA:
      case KeyEvent.VK_DEAD_OGONEK:
      case KeyEvent.VK_DEAD_IOTA:
      case KeyEvent.VK_DEAD_VOICED_SOUND:
      case KeyEvent.VK_DEAD_SEMIVOICED_SOUND:
      case '\0':
        return null;
      default:

        if(!OperatingSystem.isMacOS())
          handleBrokenKeys(evt,keyCode);
        else
          last = LAST_NOTHING;
        break;
      }

      return evt;
    //}}}
    //{{{ KEY_TYPED...
    case KeyEvent.KEY_TYPED:
      // need to let \b through so that backspace will work
      // in HistoryTextFields
      if((ch < 0x20 || ch == 0x7f || ch == 0xff) && ch != '\b')
        return null;

      // "Alt" is the option key on MacOS, and it can generate
      // user input
      if(OperatingSystem.isMacOS())
      {
        if(evt.isControlDown() || evt.isMetaDown())
          return null;
      }
      else
      {
        if((evt.isControlDown() ^ evt.isAltDown())
          || evt.isMetaDown())
          return null;
      }

      // On JDK 1.4 with Windows, some Alt-key sequences send
      // bullshit in a KEY_TYPED afterwards. We filter it out
      // here
      if(last == LAST_MOD)
      {
        switch(ch)
        {
        case 'B':
        case 'M':
        case 'X':
        case 'c':
        case '!':
        case ',':
        case '?':
          last = LAST_NOTHING;
          return null;
        }
      }

      // if the last key was a broken key, filter
      // out all except 'a'-'z' that occur 750 ms after.
      else if(last == LAST_BROKEN && System.currentTimeMillis()
        - lastKeyTime < 750 && !Character.isLetter(ch))
      {
        last = LAST_NOTHING;
        return null;
      }
      // otherwise, if it was ALT, filter out everything.
      else if(last == LAST_ALT && System.currentTimeMillis()
        - lastKeyTime < 750)
      {
        last = LAST_NOTHING;
        return null;
      }

      return evt;
    //}}}
    //{{{ KEY_RELEASED...
    case KeyEvent.KEY_RELEASED:
      if(keyCode == KeyEvent.VK_ALT)
      {
        // bad workaround... on Windows JDK 1.4, some
        // Alt-sequences generate random crap afterwards
        if(OperatingSystem.isWindows()
          && OperatingSystem.hasJava14())
          last = LAST_MOD;
      }
      return evt;
    //}}}
    default:
      return evt;
    }
  } //}}}

  //{{{ numericKeypadKey() method
  /**
   * A workaround for non-working NumLock status in some Java versions.
   * @since jEdit 4.0pre8
   */
  public static void numericKeypadKey()
  {
    last = LAST_NOTHING;
  } //}}}

  //{{{ Private members

  //{{{ Static variables
  private static long lastKeyTime;

  private static int last;
  private static final int LAST_NOTHING = 0;
  private static final int LAST_ALT = 1;
  private static final int LAST_BROKEN = 2;
  private static final int LAST_NUMKEYPAD = 3;
  private static final int LAST_MOD = 4;
  //}}}

  //{{{ handleBrokenKeys() method
  private static void handleBrokenKeys(KeyEvent evt, int keyCode)
  {
    if(evt.isAltDown() && evt.isControlDown()
      && !evt.isMetaDown())
    {
      last = LAST_NOTHING;
      return;
    }
    else if(!(evt.isAltDown() || evt.isControlDown() || evt.isMetaDown()))
    {
      last = LAST_NOTHING;
      return;
    }

    if(evt.isAltDown())
      last = LAST_ALT;

    switch(keyCode)
    {
      case KeyEvent.VK_LEFT:      case KeyEvent.VK_RIGHT:
      case KeyEvent.VK_UP:        case KeyEvent.VK_DOWN:
      case KeyEvent.VK_DELETE:    case KeyEvent.VK_BACK_SPACE:
      case KeyEvent.VK_TAB:       case KeyEvent.VK_ENTER:
        last = LAST_NOTHING;
        break;
      default:
        if(keyCode < KeyEvent.VK_A || keyCode > KeyEvent.VK_Z)
          last = LAST_BROKEN;
        else
          last = LAST_NOTHING;
        break;
    }

    lastKeyTime = System.currentTimeMillis();
  } //}}}

  //}}}
}