/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.report.designer.internal.ui.dialogs.js;

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;

/**
 * 
 * Damager and repairer for javascript editor
 */
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( ) ) );
		}
	}
}