DownloadButtonSection.java

/*******************************************************************************
 * Copyright (c) 2013, 2016 GoPivotal, Inc.
 * 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:
 *     GoPivotal, Inc. - initial API and implementation
 *******************************************************************************/
package org.springframework.ide.eclipse.boot.wizard.guides;

import java.lang.reflect.InvocationTargetException;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.jface.operation.IRunnableWithProgress;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.PlatformUI;
import org.springframework.ide.eclipse.boot.wizard.BootWizardActivator;
import org.springsource.ide.eclipse.commons.livexp.core.LiveExpression;
import org.springsource.ide.eclipse.commons.livexp.core.UIValueListener;
import org.springsource.ide.eclipse.commons.livexp.core.ValidationResult;
import org.springsource.ide.eclipse.commons.livexp.core.Validator;
import org.springsource.ide.eclipse.commons.livexp.ui.WizardPageSection;
import org.springsource.ide.eclipse.commons.livexp.ui.WizardPageWithSections;
import org.springsource.ide.eclipse.commons.livexp.util.ExceptionUtil;

/**
 * A 'Download' button. Can be clicked to perform a download operation.
 * It is enabled or disabled (i.e. greyed out) based on whether the
 * content is already downloaded.
 *
 * @author Kris De Volder
 */
public class DownloadButtonSection extends WizardPageSection {

	public static abstract class DownloadableModel {

		/**
		 * Reflects the state of the downloadable content. True when it is already downloaded
		 * false otherwise.
		 */
		public final LiveExpression<Boolean> isDownloaded;

		public DownloadableModel(LiveExpression<Boolean> isDownloaded) {
			this.isDownloaded = isDownloaded;
		}

		/**
		 * Subclass should implement to perform the download operation
		 * and update isDownloaded LiveExp as appropriate upon completion.
		 */
		public abstract void performDownload(IProgressMonitor monitor);

	}

	//
	private final DownloadableModel model;
	private Button button;

	public DownloadButtonSection(
			WizardPageWithSections owner,
			DownloadableModel model) {
		super(owner);
		this.model = model;
	}

	@Override
	public LiveExpression<ValidationResult> getValidator() {
		return Validator.OK;
	}

	@Override
	public void createContents(Composite page) {
		button = new Button(page, SWT.PUSH);
		button.setText("Download");
		enableDisable();
		GridDataFactory.fillDefaults().align(SWT.END, SWT.CENTER).grab(true, false).applyTo(button);
		model.isDownloaded.addListener(new UIValueListener<Boolean>() {
			@Override
			protected void uiGotValue(LiveExpression<Boolean> exp, Boolean value) {
				enableDisable();
			}
		});
		button.addSelectionListener(new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent evt) {
				try {
					PlatformUI.getWorkbench().getProgressService().busyCursorWhile(new IRunnableWithProgress() {
						//@Override
						public void run(IProgressMonitor monitor) throws InvocationTargetException,
								InterruptedException {
							try {
								model.performDownload(monitor);
							} catch (Exception e) {
								throw new InvocationTargetException(e);
							}
						}
					});
				} catch (InvocationTargetException e) {
					MessageDialog.openError(button.getShell(), "Error downloading", ExceptionUtil.getMessage(e));
					BootWizardActivator.log(e);
				} catch (InterruptedException e) {
				}

			}
		});
	}

	/**
	 * Update enablement state of the button. Button should be disabled if guide is
	 * already downloaded.
	 */
	private void enableDisable() {
		Boolean isDown = model.isDownloaded.getValue();
		if (isDown!=null) {
			button.setEnabled(isDown);
		}
	}

}