/*******************************************************************************
 * Copyright (c) 2008, 2010 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.handlers;

import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextSelection;
import org.eclipse.wst.sse.core.internal.provisional.IndexedRegion;
import org.eclipse.wst.sse.ui.internal.handlers.AbstractStructuredSelectHandler;
import org.w3c.dom.Node;

public class StructuredSelectPreviousXMLHandler extends AbstractStructuredSelectHandler {

	protected IndexedRegion getCursorIndexedRegion(IDocument document, ITextSelection textSelection) {
		IndexedRegion indexedRegion = null;

		indexedRegion = getIndexedRegion(document, textSelection.getOffset());

		return indexedRegion;
	}

	protected Region getNewSelectionRegion(IndexedRegion indexedRegion, ITextSelection textSelection) {
		Region newRegion = null;
		if (indexedRegion instanceof Node) {
			Node cursorNode = (Node) indexedRegion;

			// use parent node for empty text node
			if ((cursorNode.getNodeType() == Node.TEXT_NODE) && (cursorNode.getNodeValue().trim().length() == 0)) {
				cursorNode = cursorNode.getParentNode();

				if (cursorNode instanceof IndexedRegion) {
					indexedRegion = (IndexedRegion) cursorNode;
				}
			}

			Region cursorNodeRegion = new Region(indexedRegion.getStartOffset(), indexedRegion.getEndOffset() - indexedRegion.getStartOffset());

			if ((cursorNodeRegion.getOffset() >= textSelection.getOffset()) && (cursorNodeRegion.getOffset() <= textSelection.getOffset() + textSelection.getLength()) && (cursorNodeRegion.getOffset() + cursorNodeRegion.getLength() >= textSelection.getOffset()) && (cursorNodeRegion.getOffset() + cursorNodeRegion.getLength() <= textSelection.getOffset() + textSelection.getLength())) {
				
				newRegion = getNewSelectionRegion2(indexedRegion, textSelection);
			
			}
			else {
				newRegion = cursorNodeRegion;
			}
		}
		return newRegion;
	}
	
	/**
	 * This method was separated out from getNewSelectionRegion2 because the
	 * code in here is allowed to be called recursively.
	 * 
	 * @param indexedRegion
	 * @param textSelection
	 * @return new region to select or null if none
	 */
	protected Region getNewSelectionRegion2(IndexedRegion indexedRegion, ITextSelection textSelection) {
		Region newRegion = null;
		if (indexedRegion instanceof Node) {
			Node node = (Node) indexedRegion;
		
			Node newNode = node.getPreviousSibling();
			if (newNode == null) {
				newNode = node.getParentNode();
	
				if (newNode instanceof IndexedRegion) {
					IndexedRegion newIndexedRegion = (IndexedRegion) newNode;
					newRegion = new Region(newIndexedRegion.getStartOffset(), newIndexedRegion.getEndOffset() - newIndexedRegion.getStartOffset());
				}
			}
			else {
				if (newNode instanceof IndexedRegion) {
					IndexedRegion newIndexedRegion = (IndexedRegion) newNode;
					newRegion = new Region(newIndexedRegion.getStartOffset(), textSelection.getOffset() + textSelection.getLength() - newIndexedRegion.getStartOffset());
	
					if (newNode.getNodeType() == Node.TEXT_NODE) {
						newRegion = getNewSelectionRegion2(newIndexedRegion, new TextSelection(newRegion.getOffset(), newRegion.getLength()));
					}
				}
			}
		}
		return newRegion;
	}
}