/*******************************************************************************
 * Copyright (c) 2006, 2017 Brad Reynolds, 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:
 *    Brad Reynolds - initial API and implementation
 *    IBM Corporation - Bug 493357
 *******************************************************************************/
package org.eclipse.jface.tests.viewers;

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

import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.ListViewer;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

import junit.framework.TestCase;

public class ListViewerRefreshTest extends TestCase {
	/**
	 * Used for viewing the UI. Set to 0 if not wanting to see the UI.
	 */
	private static final int DELAY = 0;

	private Shell shell = null;

	private Label label = null;

	private ListViewer viewer = null;

	private ArrayList input = null;

	protected boolean disableTestsBug493357 = false;


	@Override
	protected void setUp() throws Exception {
		disableTestsBug493357 = System.getProperty("org.eclipse.swt.internal.gtk.version", "").startsWith("3."); // $NON-NLS-1//$NON-NLS-2//$NON-NLS-3
		shell = new Shell();
		shell.setSize(400, 200);
		shell.setLayout(new FillLayout());
		label = new Label(shell, SWT.WRAP);
		viewer = new ListViewer(shell);
		input = new ArrayList();

		for (int i = 0; i < 50; i++) {
			input.add("item " + i); //$NON-NLS-1$
		}

		viewer.setContentProvider(new ContentProvider());
		viewer.setInput(input);
		shell.layout();
		shell.open();
	}

	@Override
	protected void tearDown() throws Exception {
		shell.dispose();
		shell = null;
	}

	/**
	 * Asserts the ability to refresh without a selection and preserve the
	 * scrolled to position.
	 *
	 * @throws Exception
	 */
	public void testNoSelectionRefresh() throws Exception {
		if (disableTestsBug493357) {
			System.out.println(getName() + " disabled due to Bug 493357");
			return;
		}

		shell.setText("Lost Scrolled Position Test"); //$NON-NLS-1$
		readAndDispatch();

		run("Scrolled to position 30.", () -> viewer.reveal(input.get(30)));

		run("Refreshed viewer without a selection.", () -> viewer.refresh());

		// BUG: The top index should not be the first item.
		assertTrue(viewer.getList().getTopIndex() != 0);
	}

	/**
	 * Asserts the ability to refresh with a selection and preserve the scrolled
	 * to position.
	 *
	 * @throws Exception
	 */
	public void testSelectionRefresh() throws Exception {
		if (disableTestsBug493357) {
			System.out.println(getName() + " disabled due to Bug 493357");
			return;
		}
		shell.setText("Preserved Scrolled Position Test"); //$NON-NLS-1$
		readAndDispatch();

		run("Setting selection to index 30.", () -> viewer.setSelection(new StructuredSelection(input.get(30))));

		// Ensure that to index is 0
		viewer.getList().setTopIndex(0);

		run("Refreshed viewer with selection.", () -> viewer.refresh());

		// Checking that the viewer is not scrolling
		assertTrue(viewer.getList().getTopIndex() == 0);

		viewer.getList().showSelection();

		assertTrue(viewer.getList().getTopIndex() != 0);
	}

	/**
	 * Runs the runnable and displays the description.
	 *
	 * @param description
	 * @param runnable
	 */
	private void run(String description, Runnable runnable) {
		runnable.run();
		label.setText(description);

		readAndDispatch();
	}

	/**
	 * Flush UI events and {@link #DELAY delays}.
	 */
	private void readAndDispatch() {
		Display display = Display.getCurrent();
		while(display.readAndDispatch()) {
			;
		}

		try {
			Thread.sleep(DELAY);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	private class ContentProvider implements IStructuredContentProvider {

		@Override
		public Object[] getElements(Object inputElement) {
			return ((List) inputElement).toArray();
		}

		@Override
		public void dispose() {
		}

		@Override
		public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
		}
	}
}