/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0 .
 */

import com.sun.star.accessibility.*;
import com.sun.star.uno.UnoRuntime;

import javax.swing.tree.*;
import javax.swing.event.*;

/** listen to tree model changes in order to update XAccessibleText objects
*/
class TextUpdateListener implements TreeModelListener
{
    public void treeNodesChanged(TreeModelEvent e)
    {
        try {
        // if the change is to the first child of a DefaultMutableTreeNode
        // with an XAccessibleText child, then we call updateText
        int[] aIndices = e.getChildIndices();
        if( (aIndices != null) &&
            (aIndices.length > 0) )
        {
            // we have a parent... lets check for XAccessibleText then
            DefaultMutableTreeNode aParent = (DefaultMutableTreeNode)
                (e.getTreePath().getLastPathComponent());
            DefaultMutableTreeNode aNode = (DefaultMutableTreeNode)
                (aParent.getChildAt(aIndices[0]));
            if( aParent.getUserObject() instanceof XAccessibleText)
            {
                // aha! we have an xText. So we can now check for
                // the various cases we support
                XAccessibleText xText =
                    (XAccessibleText)aParent.getUserObject();

                if( aIndices[0] == 0 )
                {
                    // first child! Then we call updateText
                    updateText( xText, aNode.toString() );
                }
            }
        }
        }
        catch (com.sun.star.lang.IndexOutOfBoundsException aException)
        {}
    }

    // don't care:
    public void treeNodesInserted(TreeModelEvent e) { }
    public void treeNodesRemoved(TreeModelEvent e) {  }
    public void treeStructureChanged(TreeModelEvent e) { }

    /** update the text */
    boolean updateText( XAccessibleText xText, String sNew )
        throws com.sun.star.lang.IndexOutOfBoundsException
    {
        // is this text editable? if not, fudge you and return
        XAccessibleEditableText xEdit =
            UnoRuntime.queryInterface (
            XAccessibleEditableText.class, xText);
        if (xEdit == null)
            return false;

        String sOld = xText.getText();

        // false alarm? Early out if no change was done!
        if( sOld.equals( sNew ) )
            return false;

        // get the minimum length of both strings
        int nMinLength = sOld.length();
        if( sNew.length() < nMinLength )
            nMinLength = sNew.length();

        // count equal characters from front and end
        int nFront = 0;
        while( (nFront < nMinLength) &&
            (sNew.charAt(nFront) == sOld.charAt(nFront)) )
            nFront++;
        int nBack = 0;
        while( (nBack < nMinLength) &&
            ( sNew.charAt(sNew.length()-nBack-1) ==
                sOld.charAt(sOld.length()-nBack-1)    ) )
            nBack++;
        if( nFront + nBack > nMinLength )
            nBack = nMinLength - nFront;

        // so... the first nFront and the last nBack characters
        // are the same. Change the others!
        String sDel = sOld.substring( nFront, sOld.length() - nBack );
        String sIns = sNew.substring( nFront, sNew.length() - nBack );

        System.out.println("edit text: " +
            sOld.substring(0, nFront) +
            " [ " + sDel + " -> " + sIns + " ] " +
            sOld.substring(sOld.length() - nBack) );

        boolean bRet = false;
        try
        {
            // edit the text, and use
            // (set|insert|delete|replace)Text as needed
            if( nFront+nBack == 0 )
                bRet = xEdit.setText( sIns );
            else if( sDel.length() == 0 )
                bRet = xEdit.insertText( sIns, nFront );
            else if( sIns.length() == 0 )
                bRet = xEdit.deleteText( nFront, sOld.length()-nBack );
            else
                bRet = xEdit.replaceText(nFront, sOld.length()-nBack,sIns);
        }
        catch( IndexOutOfBoundsException e )
        {
            bRet = false;
        }

        return bRet;
    }

    boolean setSelection( XAccessibleText xText, int p1, int p2 )
    {
        try
        {
            return xText.setSelection( p1, p2 );
        }
        catch( com.sun.star.lang.IndexOutOfBoundsException f )
        {
            return false;
        }
    }

}