/*
 * $RCSfile: NonRuleBasedDamagerRepairer.java,v $
 *
 * Copyright 2002
 * CH-1700 Fribourg, Switzerland
 * All rights reserved.
 *
 *========================================================================
 * Modifications history
 *========================================================================
 * $Log: NonRuleBasedDamagerRepairer.java,v $
 * Revision 1.1  2003/05/28 15:17:11  agfitzp
 * net.sourceforge.jseditor 0.0.1 code base
 *
 *========================================================================
*/

package com.hundsun.ares.studio.ui.editor.text;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextAttribute;
import org.eclipse.jface.text.TextPresentation;
import org.eclipse.jface.text.presentation.IPresentationDamager;
import org.eclipse.jface.text.presentation.IPresentationRepairer;
import org.eclipse.jface.util.Assert;
import org.eclipse.swt.custom.StyleRange;


/**
 * 
 *
 * @author $Author: agfitzp $, $Date: 2003/05/28 15:17:11 $
 *
 * @version $Revision: 1.1 $
 */
public class NonRuleBasedDamagerRepairer implements IPresentationDamager, IPresentationRepairer
{
   /** The document this object works on */
   protected IDocument fDocument;

   /** The default text attribute if non is returned as data by the current token */
   protected TextAttribute fDefaultTextAttribute;

   /**
    * Constructor for NonRuleBasedDamagerRepairer.
    * @param defaultTextAttribute
    */
   public NonRuleBasedDamagerRepairer(TextAttribute defaultTextAttribute)
   {
      Assert.isNotNull(defaultTextAttribute);

      fDefaultTextAttribute = defaultTextAttribute;
   }

   /**
    * @see IPresentationRepairer#setDocument(IDocument)
    */
   public void setDocument(IDocument document)
   {
      fDocument = document;
   }

   /**
    * Returns the end offset of the line that contains the specified offset or if the offset is
    * inside a line delimiter, the end offset of the next line.
    * 
    * @param offset the offset whose line end offset must be computed
    * 
    * @return the line end offset for the given offset
    * 
    * @exception BadLocationException if offset is invalid in the current document
    */
   protected int endOfLineOf(int offset) throws BadLocationException
   {
      IRegion info = fDocument.getLineInformationOfOffset(offset);

      if(offset <= info.getOffset() + info.getLength())
      {
         return info.getOffset() + info.getLength();
      }

      int line = fDocument.getLineOfOffset(offset);

      try
      {
         info = fDocument.getLineInformation(line + 1);

         return info.getOffset() + info.getLength();
      }
      catch(BadLocationException x)
      {
         return fDocument.getLength();
      }
   }

   /**
    * @see IPresentationDamager#getDamageRegion(ITypedRegion, DocumentEvent, boolean)
    */
   public IRegion getDamageRegion(ITypedRegion partition, DocumentEvent event, 
                                  boolean documentPartitioningChanged)
   {
      if(!documentPartitioningChanged)
      {
         try
         {
            IRegion info = fDocument.getLineInformationOfOffset(event.getOffset());
            int start = Math.max(partition.getOffset(), info.getOffset());

            int end = event.getOffset() + 
                      (event.getText() == null ? event.getLength()
                                               : event.getText().length());

            if(info.getOffset() <= end && end <= info.getOffset() + info.getLength())
            {
               // optimize the case of the same line
               end = info.getOffset() + info.getLength();
            }
            else
            {
               end = endOfLineOf(end);
            }

            end = Math.min(partition.getOffset() + partition.getLength(), end);

            return new Region(start, end - start);
         }
         catch(BadLocationException x)
         {
         }
      }

      return partition;
   }

   /**
    * @see IPresentationRepairer#createPresentation(TextPresentation, ITypedRegion)
    */
   public void createPresentation(TextPresentation presentation, ITypedRegion region)
   {
      addRange(presentation, region.getOffset(), region.getLength(), fDefaultTextAttribute);
   }

   /**
    * Adds style information to the given text presentation.
    * 
    * @param presentation the text presentation to be extended
    * @param offset the offset of the range to be styled
    * @param length the length of the range to be styled
    * @param attr the attribute describing the style of the range to be styled
    */
   protected void addRange(TextPresentation presentation, int offset, int length, 
                           TextAttribute attr)
   {
      if(attr != null)
      {
         presentation.addStyleRange(
                new StyleRange(offset, length, attr.getForeground(), attr.getBackground(), 
                               attr.getStyle()));
      }
   }
}