/*******************************************************************************
 * Copyright (c) 2009 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *     
 *******************************************************************************/
package org.eclipse.wst.xml.ui.internal.projection;

import org.eclipse.jface.text.Position;
import org.eclipse.wst.sse.core.internal.provisional.IndexedRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.ui.internal.projection.AbstractStructuredFoldingStrategy;
import org.eclipse.wst.xml.core.internal.document.CommentImpl;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMNode;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMText;


/**
 * A folding strategy for XML type structured documents.
 * See AbstractStructuredFoldingStrategy for more details.
 */
public class XMLFoldingStrategy extends AbstractStructuredFoldingStrategy {

	/**
	 * Create an instance of the folding strategy.
	 * Be sure to set the viewer and document after creation.
	 */
	public XMLFoldingStrategy() {
		super();
	}

	/**
	 * @see org.eclipse.wst.sse.ui.internal.projection.AbstractFoldingStrategy#calcNewFoldPosition(org.eclipse.wst.sse.core.internal.provisional.IndexedRegion)
	 */
	protected Position calcNewFoldPosition(IndexedRegion indexedRegion) {
		Position retPos = null;
		
		//only want to fold regions of the valid type and with a valid range
		if(indexedRegionValidType(indexedRegion) && indexedRegion.getStartOffset() >= 0 && indexedRegion.getLength() >= 0) {
			IDOMNode node = (IDOMNode)indexedRegion;
			IStructuredDocumentRegion startRegion = node.getStartStructuredDocumentRegion();
			IStructuredDocumentRegion endRegion = node.getEndStructuredDocumentRegion();
			
			//if the node has an endRegion (end tag) then folding region is
			//	between the start and end tag
			//else if the region is a comment
			//else if the region is only an open tag or an open/close tag then don't fold it
			if(startRegion != null && endRegion != null) {
				retPos = new XMLElementFoldingPosition(startRegion, endRegion);
			} else if(startRegion != null && indexedRegion instanceof CommentImpl) {
				retPos = new XMLCommentFoldingPosition(startRegion);
			}
		}
		
		return retPos;
	}

	/**
	 * @see org.eclipse.wst.sse.ui.internal.projection.AbstractFoldingStrategy#indexedRegionValidType(org.eclipse.wst.sse.core.internal.provisional.IndexedRegion)
	 */
	protected boolean indexedRegionValidType(IndexedRegion indexedRegion) {
		return (indexedRegion instanceof IDOMNode) && !(indexedRegion instanceof IDOMText);
	}
}