TreeViewerNavigator.java

/*******************************************************************************
 * Copyright (c) 2010 itemis AG (http://www.itemis.eu) 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:
 *    itemis AG - implementation
 *    Cloudsmith - adaption to Geppetto/PP
 *******************************************************************************/
package org.cloudsmith.geppetto.pp.dsl.ui.editor.findrefs;

import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.OpenEvent;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;

/**
 * Mostly copied from {@link org.eclipse.search2.internal.ui.basic.views.TreeViewerNavigator}.
 * 
 * @author Jan Koehnlein - Initial contribution and API
 */
public class TreeViewerNavigator {

	private TreeViewer viewer;

	private PPReferenceSearchViewPage page;

	/**
	 * Same as the class with the same name in the corresponding Xtext pacakge except the Geppetto specific SearchViewPage
	 * required (as the implementation is not free from implementation concerns, and package private things).
	 * 
	 * @param page
	 */
	public TreeViewerNavigator(PPReferenceSearchViewPage page) {
		this.page = page;
		this.viewer = page.getViewer();
	}

	private TreeItem[] getChildren(TreeItem item) {
		viewer.setExpandedState(item.getData(), true);
		return item.getItems();
	}

	private TreeItem getCurrentItem(boolean forward) {
		Tree tree = viewer.getTree();
		TreeItem[] selection = tree.getSelection();
		if(selection.length == 0) {
			selection = tree.getItems();
		}

		TreeItem nextItem = null;
		if(selection.length > 0) {
			nextItem = forward
					? selection[0]
					: selection[selection.length - 1];
		}
		return nextItem;
	}

	private TreeItem getFirstChildWithMatches(TreeItem item) {
		TreeItem[] children = getChildren(item);
		if(children.length == 0)
			return null;
		TreeItem child = children[0];

		if(hasMatches(child))
			return child;
		return getFirstChildWithMatches(child);
	}

	private TreeItem getFirstItem() {
		TreeItem[] roots = viewer.getTree().getItems();
		if(roots.length == 0)
			return null;
		for(int i = 0; i < roots.length; i++) {
			if(hasMatches(roots[i]))
				return roots[i];
			TreeItem firstChild = getFirstChildWithMatches(roots[0]);
			if(firstChild != null)
				return firstChild;
		}
		return null;
	}

	private TreeItem getLastChildWithMatches(TreeItem currentItem) {
		TreeItem[] children = getChildren(currentItem);
		if(children.length == 0)
			return null;
		TreeItem recursiveChild = getLastChildWithMatches(children[children.length - 1]);
		if(recursiveChild == null)
			return children[children.length - 1];
		return recursiveChild;
	}

	private TreeItem getLastItem() {
		TreeItem[] roots = viewer.getTree().getItems();
		if(roots.length == 0)
			return null;
		return getLastChildWithMatches(roots[roots.length - 1]);
	}

	private TreeItem getNextItemBackward(TreeItem currentItem) {
		TreeItem previousSibling = getNextSibling(currentItem, false);
		if(previousSibling != null) {
			TreeItem lastChild = getLastChildWithMatches(previousSibling);
			if(lastChild != null)
				return lastChild;
			if(hasMatches(previousSibling))
				return previousSibling;
			return null;
		}
		TreeItem parent = currentItem.getParentItem();
		if(parent != null) {
			if(hasMatches(parent))
				return parent;
			return getNextItemBackward(parent);
		}
		return null;
	}

	private TreeItem getNextItemForward(TreeItem currentItem) {
		TreeItem child = getFirstChildWithMatches(currentItem);
		if(child != null)
			return child;
		TreeItem nextSibling = getNextSibling(currentItem, true);
		if(nextSibling != null) {
			if(hasMatches(nextSibling))
				return nextSibling;
			return getFirstChildWithMatches(nextSibling);
		}
		TreeItem parent = currentItem.getParentItem();
		while(parent != null) {
			nextSibling = getNextSibling(parent, true);
			if(nextSibling != null) {
				if(hasMatches(nextSibling))
					return nextSibling;
				return getFirstChildWithMatches(nextSibling);
			}
			parent = parent.getParentItem();
		}
		return null;
	}

	private TreeItem getNextSibling(TreeItem currentItem, boolean forward) {
		TreeItem[] siblings = getSiblings(currentItem);
		if(siblings.length < 2)
			return null;
		int index = -1;
		for(int i = 0; i < siblings.length; i++) {
			if(siblings[i] == currentItem) {
				index = i;
				break;
			}
		}
		if(forward && index == siblings.length - 1) {
			return null;
		}
		else if(!forward && index == 0) {
			return null;
		}
		return forward
				? siblings[index + 1]
				: siblings[index - 1];
	}

	private TreeItem[] getSiblings(TreeItem currentItem) {
		Tree tree = viewer.getTree();
		TreeItem parentItem = currentItem.getParentItem();
		if(parentItem != null)
			return parentItem.getItems();
		return tree.getItems();
	}

	private boolean hasMatches(TreeItem item) {
		Object element = item.getData();
		if(element == null)
			return false;
		return true;// page.getDisplayedMatchCount(element) > 0;
	}

	private void internalSetSelection(TreeItem ti) {
		if(ti != null) {
			Object data = ti.getData();
			if(data != null) {
				ISelection selection = new StructuredSelection(data);
				viewer.setSelection(selection, true);
				page.handleOpen(new OpenEvent(viewer, selection));
			}
		}
	}

	public void navigateNext(boolean forward) {
		TreeItem currentItem = getCurrentItem(forward);
		if(currentItem == null)
			return;
		TreeItem nextItem = null;
		if(forward) {
			nextItem = getNextItemForward(currentItem);
			if(nextItem == null)
				nextItem = getFirstItem();
		}
		else {
			nextItem = getNextItemBackward(currentItem);
			if(nextItem == null)
				nextItem = getLastItem();
		}
		if(nextItem != null) {
			internalSetSelection(nextItem);
		}
	}

}