/*******************************************************************************
 * Copyright (c) 2000, 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
 *     compeople AG    - created this example based on Snippet15
 *******************************************************************************/
package org.eclipse.riena.navigation.ui.swt.views;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;

/**
 * Create a tree with non-selectable items.
 */
public class SnippetNonSelectableTreeItems {

	public static void main(String[] args) {
		Display display = new Display();
		Shell shell = new Shell(display);
		shell.setLayout(new FillLayout());
		final Tree tree = new Tree(shell, SWT.BORDER | SWT.SINGLE);
		for (int i = 0; i < 4; i++) {
			TreeItem iItem = new TreeItem(tree, 0);
			iItem.setText("TreeItem (0) -" + i);
			if (i % 2 == 1) {
				markNonSelectable(iItem);
				iItem.setText("not selectable");
			}
			for (int j = 0; j < 4; j++) {
				TreeItem jItem = new TreeItem(iItem, 0);
				jItem.setText("TreeItem (1) -" + j);
				if (j % 2 == 0) {
					markNonSelectable(jItem);
					jItem.setText("not selectable");
				}
				for (int k = 0; k < 4; k++) {
					TreeItem kItem = new TreeItem(jItem, 0);
					kItem.setText("TreeItem (2) -" + k);
					for (int l = 0; l < 4; l++) {
						TreeItem lItem = new TreeItem(kItem, 0);
						lItem.setText("TreeItem (3) -" + l);
					}
				}
			}
		}

		new TreeListener(tree);

		shell.setSize(200, 200);
		shell.open();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch())
				display.sleep();
		}
		display.dispose();
	}

	/**
	 * Prevent selection of certain items. Find a matching alternative is
	 * possible.
	 */
	private static final class TreeListener extends KeyAdapter implements SelectionListener, MouseListener {

		private int lastKey;
		private int lastButton;
		private TreeItem lastItem;

		public TreeListener(Tree tree) {
			tree.addKeyListener(this);
			tree.addSelectionListener(this);
			tree.addMouseListener(this);
		}

		@Override
		public void keyPressed(KeyEvent e) {
			if (e.stateMask == 0) {
				lastKey = e.keyCode;
			}
		}

		@Override
		public void keyReleased(KeyEvent e) {
			lastKey = 0;
		}

		public void mouseDown(MouseEvent e) {
			lastButton = e.button;
		}

		public void mouseUp(MouseEvent e) {
			lastButton = 0;
		}

		public void widgetSelected(SelectionEvent e) {
			System.out.println(e);
			Tree tree = (Tree) e.widget;
			TreeItem[] sel = tree.getSelection();
			if (sel.length > 0) {
				TreeItem item = sel[0];
				if (!isSelectable(item)) {
					if (lastKey == SWT.ARROW_UP || lastKey == SWT.ARROW_LEFT) {
						item = findPrevious(item);
					} else if (lastKey == SWT.ARROW_DOWN || lastKey == SWT.ARROW_RIGHT || lastButton != 0) {
						item = findNext(item);
					}
					if (item != null) {
						item.getParent().select(item);
					} else {
						lastItem.getParent().setSelection(lastItem);
					}
				}
				if (item != null) {
					lastItem = item;
				}
			}
		}

		public void widgetDefaultSelected(SelectionEvent e) {
			// unused
		}

		public void mouseDoubleClick(MouseEvent e) {
			// unused
		}

	};

	private static boolean isSelectable(TreeItem item) {
		return item == null ? true : !Boolean.FALSE.equals(item.getData("s"));
	}

	/**
	 * Mark this item as 'non-selectable'.
	 */
	private static void markNonSelectable(TreeItem item) {
		item.setData("s", Boolean.FALSE);
	}

	private static TreeItem findPrevious(TreeItem item) {
		List<TreeItem> siblings = sequentialize(item.getParent().getItems());
		int index = siblings.indexOf(item);
		TreeItem result = index > 0 ? siblings.get(index - 1) : null;
		if (!isSelectable(result)) {
			result = findPrevious(result);
		}
		return result;
	}

	private static TreeItem findNext(TreeItem item) {
		List<TreeItem> siblings = sequentialize(item.getParent().getItems());
		int index = siblings.indexOf(item);
		TreeItem result = index != -1 && index < siblings.size() - 1 ? siblings.get(index + 1) : null;
		if (!isSelectable(result)) {
			result = findNext(result);
		}
		return result;
	}

	/**
	 * Do a DFS traversal and return all reachable nodes starting from root
	 * (excluded).
	 */
	private static List<TreeItem> sequentialize(TreeItem[] siblings) {
		List<TreeItem> stack = new ArrayList<TreeItem>(Arrays.asList(siblings));
		List<TreeItem> result = new ArrayList<TreeItem>();
		while (!stack.isEmpty()) {
			TreeItem item = stack.remove(0);
			result.add(item);
			if (item.getExpanded()) {
				stack.addAll(0, Arrays.asList(item.getItems()));
			}
		}
		return result;
	}
}