ViewerWizardSelectionPage.java

/*
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */

package eu.esdihumboldt.hale.ui.util.wizard;

import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.dialogs.IDialogPage;
import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.jface.viewers.DoubleClickEvent;
import org.eclipse.jface.viewers.IDoubleClickListener;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.SelectionChangedEvent;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.wizard.IWizardNode;
import org.eclipse.jface.wizard.WizardSelectionPage;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;

import eu.esdihumboldt.util.Pair;

/**
 * Wizard selection page based on a structured viewer.
 * 
 * @author Simon Templer
 */
public abstract class ViewerWizardSelectionPage extends WizardSelectionPage {

	private StructuredViewer viewer;

	/**
	 * @see WizardSelectionPage#WizardSelectionPage(String)
	 */
	protected ViewerWizardSelectionPage(String pageName) {
		super(pageName);
	}

	/**
	 * Get the size hint for the viewer height.
	 * 
	 * @return the size hint
	 */
	protected int getViewerHeightHint() {
		return SWT.DEFAULT;
	}

	/**
	 * @see IDialogPage#createControl(Composite)
	 */
	@Override
	public void createControl(Composite parent) {
		Font font = parent.getFont();

		// create composite for page.
		Composite outerContainer = new Composite(parent, SWT.NONE);
		outerContainer.setLayout(new GridLayout());
		outerContainer.setLayoutData(GridDataFactory.fillDefaults().grab(true, true).create());
		outerContainer.setFont(font);

		Pair<StructuredViewer, Control> viewerControl = createViewer(outerContainer);
		viewer = viewerControl.getFirst();
		viewerControl.getSecond().setLayoutData(
				GridDataFactory.fillDefaults().grab(true, true)
						.hint(SWT.DEFAULT, getViewerHeightHint()).create());

		// wire viewer
		viewer.addSelectionChangedListener(new ISelectionChangedListener() {

			@Override
			public void selectionChanged(SelectionChangedEvent event) {
				viewerSelectionChanged(event.getSelection());
			}
		});
		viewer.addDoubleClickListener(new IDoubleClickListener() {

			@Override
			public void doubleClick(DoubleClickEvent event) {
				doubleClicked(event);
			}
		});

		Dialog.applyDialogFont(outerContainer);

		// apply the initial selection
		viewerSelectionChanged(viewer.getSelection());

		setControl(outerContainer);
	}

	/**
	 * Called when the viewer selection has changed.
	 * 
	 * @param selection the current selection
	 */
	protected void viewerSelectionChanged(ISelection selection) {
		setErrorMessage(null);
		IStructuredSelection ss = (IStructuredSelection) selection;
		Object sel = ss.getFirstElement();
		if (sel instanceof IWizardNode) {
			IWizardNode currentWizardSelection = (IWizardNode) sel;
			updateSelectedNode(currentWizardSelection);
		}
		else {
			updateSelectedNode(null);
		}
	}

	/**
	 * Update the selected node
	 * 
	 * @param wizardNode the selected wizard node
	 */
	private void updateSelectedNode(IWizardNode wizardNode) {
		setErrorMessage(null);
		if (wizardNode == null) {
			updateMessage();
			setSelectedNode(null);
			return;
		}

		// set the message based on the wizard description
		if (wizardNode instanceof ExtendedWizardNode) {
			setMessage(((ExtendedWizardNode) wizardNode).getDescription(), INFORMATION);
		}
		else {
			setMessage(null);
		}

		// set the selected node
		setSelectedNode(wizardNode);
	}

	/**
	 * @see WizardSelectionPage#setSelectedNode(IWizardNode)
	 */
	@Override
	protected void setSelectedNode(IWizardNode node) {
		if (node != null) {
			String message = acceptWizard(node);

			if (message != null) {
				// display warning message
				setMessage(message, WARNING);
				// disable next
				super.setSelectedNode(null);
				return;
			}
		}

		super.setSelectedNode(node);
	}

	/**
	 * Accepts or doesn't accept a wizard node as a valid selection.
	 * 
	 * @param wizardNode the wizard node
	 * @return <code>null</code> if the node is accepted or a reason why it is
	 *         not accepted.
	 */
	protected String acceptWizard(IWizardNode wizardNode) {
		return null;
	}

	/**
	 * Update the selected node based on the viewer selection.
	 */
	protected void updateMessage() {
		if (viewer != null) {
			ISelection selection = viewer.getSelection();
			IStructuredSelection ss = (IStructuredSelection) selection;
			Object sel = ss.getFirstElement();
			if (sel instanceof IWizardNode) {
				updateSelectedNode((IWizardNode) sel);
			}
			else {
				setSelectedNode(null);
			}
		}
		else {
			setMessage(null);
		}
	}

	/**
	 * Called when a double click in the viewer occurs.
	 * 
	 * @param event the double click event
	 */
	protected void doubleClicked(DoubleClickEvent event) {
		ISelection selection = event.getViewer().getSelection();
		IStructuredSelection ss = (IStructuredSelection) selection;
		viewerSelectionChanged(ss);

		Object element = ss.getFirstElement();
		if (element instanceof IWizardNode) {
			if (canFlipToNextPage()) {
				getContainer().showPage(getNextPage());
				return;
			}
		}
		else if (event.getViewer() instanceof TreeViewer) {
			TreeViewer viewer = (TreeViewer) event.getViewer();
			viewer.setExpandedState(element, !viewer.getExpandedState(element));
		}
		getContainer().showPage(getNextPage());
	}

	/**
	 * Create the structured viewer and set it up with label and content
	 * providers as well as the input. The viewer must provide
	 * {@link IStructuredSelection}s with {@link IWizardNode}s.
	 * 
	 * @param parent the parent composite
	 * @return the viewer paired with the main control that should fill the
	 *         parent composite
	 */
	protected abstract Pair<StructuredViewer, Control> createViewer(Composite parent);

}