/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Roscoe Rush - Concept and prototype implementation
 *     IBM Corporation - current implementation
 *******************************************************************************/

package org.eclipse.ant.internal.ui.views;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;

import org.eclipse.ant.internal.core.IAntCoreConstants;
import org.eclipse.ant.internal.ui.IAntUIHelpContextIds;
import org.eclipse.ant.internal.ui.model.AntElementNode;
import org.eclipse.ant.internal.ui.model.AntModelContentProvider;
import org.eclipse.ant.internal.ui.model.AntModelLabelProvider;
import org.eclipse.ant.internal.ui.model.AntModelProblem;
import org.eclipse.ant.internal.ui.model.AntProjectNode;
import org.eclipse.ant.internal.ui.model.AntProjectNodeProxy;
import org.eclipse.ant.internal.ui.model.AntTargetNode;
import org.eclipse.ant.internal.ui.model.InternalTargetFilter;
import org.eclipse.ant.internal.ui.views.actions.AddBuildFilesAction;
import org.eclipse.ant.internal.ui.views.actions.AntOpenWithMenu;
import org.eclipse.ant.internal.ui.views.actions.FilterInternalTargetsAction;
import org.eclipse.ant.internal.ui.views.actions.RefreshBuildFilesAction;
import org.eclipse.ant.internal.ui.views.actions.RemoveAllAction;
import org.eclipse.ant.internal.ui.views.actions.RemoveProjectAction;
import org.eclipse.ant.internal.ui.views.actions.RunTargetAction;
import org.eclipse.ant.internal.ui.views.actions.SearchForBuildFilesAction;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.jface.action.IMenuManager;
import org.eclipse.jface.action.IToolBarManager;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.action.Separator;
import org.eclipse.jface.dialogs.IDialogSettings;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerComparator;
import org.eclipse.jface.viewers.ViewerFilter;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.FileTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.ui.IMemento;
import org.eclipse.ui.IViewSite;
import org.eclipse.ui.IWorkbenchActionConstants;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.WorkbenchException;
import org.eclipse.ui.XMLMemento;
import org.eclipse.ui.part.IShowInSource;
import org.eclipse.ui.part.ShowInContext;
import org.eclipse.ui.part.ViewPart;
import org.eclipse.ui.texteditor.IUpdate;
import org.osgi.framework.FrameworkUtil;

/**
 * A view which displays a hierarchical view of ant build files and allows the user to run selected targets from those files.
 */
public class AntView extends ViewPart implements IResourceChangeListener, IShowInSource {

	/**
	 * The view root elements
	 * 
	 * @since 3.5.00
	 */
	private List<AntProjectNode> fInput = new ArrayList<>();
	private boolean filterInternalTargets = false;
	private InternalTargetFilter fInternalTargetFilter = null;

	/**
	 * XML tag used to identify an ant project in storage
	 */
	private static final String TAG_PROJECT = "project"; //$NON-NLS-1$
	/**
	 * XML key used to store whether or not an Ant project is an error node. Persisting this data saved a huge amount of processing at startup.
	 */
	private static final String KEY_ERROR = "error"; //$NON-NLS-1$
	/**
	 * XML key used to store whether or not an Ant project is an error node. Persisting this data saved a huge amount of processing at startup.
	 */
	private static final String KEY_WARNING = "warning"; //$NON-NLS-1$
	/**
	 * XML key used to store an ant project's path
	 */
	private static final String KEY_PATH = "path"; //$NON-NLS-1$
	/**
	 * XML key used to store an ant node's name
	 */
	private static final String KEY_NAME = "name"; //$NON-NLS-1$
	/**
	 * XML key used to store an ant project's default target name
	 */
	private static final String KEY_DEFAULT = "default"; //$NON-NLS-1$
	/**
	 * XML tag used to identify the "filter internal targets" preference.
	 */
	private static final String TAG_FILTER_INTERNAL_TARGETS = "filterInternalTargets"; //$NON-NLS-1$
	/**
	 * XML key used to store the value of the "filter internal targets" preference.
	 */
	private static final String KEY_VALUE = "value"; //$NON-NLS-1$

	/**
	 * The tree viewer that displays the users ant projects
	 */
	private TreeViewer projectViewer;
	private AntModelContentProvider contentProvider;

	/**
	 * Collection of <code>IUpdate</code> actions that need to update on selection changed in the project viewer.
	 */
	private List<IUpdate> updateProjectActions;
	// Ant View Actions
	private AddBuildFilesAction addBuildFileAction;
	private SearchForBuildFilesAction searchForBuildFilesAction;
	private RefreshBuildFilesAction refreshBuildFilesAction;
	private RemoveProjectAction removeProjectAction;
	private RemoveAllAction removeAllAction;
	private FilterInternalTargetsAction filterInternalTargetsAction;
	private RunTargetAction runTargetAction;
	// Context-menu-only actions
	private AntOpenWithMenu openWithMenu;

	/**
	 * The given build file has changed. Refresh the view to pick up any structural changes.
	 */
	private void handleBuildFileChanged(AntProjectNode project) {
		((AntProjectNodeProxy) project).parseBuildFile(true);
		Display.getDefault().asyncExec(() -> {
			// must do a full refresh to re-sort
			projectViewer.refresh();
			// update the status line
			handleSelectionChanged((IStructuredSelection) projectViewer.getSelection());
		});
	}

	@Override
	public void createPartControl(Composite parent) {
		initializeActions();
		createProjectViewer(parent);
		initializeDragAndDrop();
		fillMainToolBar();
		if (getProjects().length > 0) {
			// If any projects have been added to the view during startup,
			// begin listening for resource changes
			ResourcesPlugin.getWorkspace().addResourceChangeListener(this);
		}
		PlatformUI.getWorkbench().getHelpSystem().setHelp(parent, IAntUIHelpContextIds.ANT_VIEW);
		updateProjectActions();
	}

	private void initializeDragAndDrop() {
		int ops = DND.DROP_COPY | DND.DROP_DEFAULT;
		Transfer[] transfers = new Transfer[] { FileTransfer.getInstance() };
		TreeViewer viewer = getViewer();
		AntViewDropAdapter adapter = new AntViewDropAdapter(this);
		viewer.addDropSupport(ops, transfers, adapter);
	}

	/**
	 * Creates a pop-up menu on the given control
	 * 
	 * @param menuControl
	 *            the control with which the pop-up menu will be associated
	 */
	private void createContextMenu(Viewer viewer) {
		Control menuControl = viewer.getControl();
		MenuManager menuMgr = new MenuManager("#PopUp"); //$NON-NLS-1$
		menuMgr.setRemoveAllWhenShown(true);
		menuMgr.addMenuListener(this::fillContextMenu);
		Menu menu = menuMgr.createContextMenu(menuControl);
		menuControl.setMenu(menu);

		// register the context menu such that other plugins may contribute to it
		getSite().registerContextMenu(menuMgr, viewer);
	}

	/**
	 * Adds actions to the context menu
	 * 
	 * @param menu
	 *            The menu to contribute to
	 */
	private void fillContextMenu(IMenuManager menu) {
		addOpenWithMenu(menu);
		menu.add(new Separator());
		menu.add(addBuildFileAction);
		menu.add(removeProjectAction);
		menu.add(removeAllAction);
		menu.add(refreshBuildFilesAction);

		menu.add(new Separator(IWorkbenchActionConstants.MB_ADDITIONS));
	}

	private void addOpenWithMenu(IMenuManager menu) {
		AntElementNode node = getSelectionNode();
		if (node != null) {
			IFile buildFile = node.getIFile();
			if (buildFile != null) {
				menu.add(new Separator("group.open")); //$NON-NLS-1$
				IMenuManager submenu = new MenuManager(AntViewMessages.AntView_1);
				openWithMenu.setNode(node);
				submenu.add(openWithMenu);
				menu.appendToGroup("group.open", submenu); //$NON-NLS-1$
			}
		}
	}

	/**
	 * Initialize the actions for this view
	 */
	private void initializeActions() {
		updateProjectActions = new ArrayList<>(5);

		addBuildFileAction = new AddBuildFilesAction(this);

		removeProjectAction = new RemoveProjectAction(this);
		updateProjectActions.add(removeProjectAction);

		removeAllAction = new RemoveAllAction(this);
		updateProjectActions.add(removeAllAction);

		runTargetAction = new RunTargetAction(this);
		updateProjectActions.add(runTargetAction);

		searchForBuildFilesAction = new SearchForBuildFilesAction(this);

		refreshBuildFilesAction = new RefreshBuildFilesAction(this);
		updateProjectActions.add(refreshBuildFilesAction);

		openWithMenu = new AntOpenWithMenu(this.getViewSite().getPage());

		filterInternalTargetsAction = new FilterInternalTargetsAction(this);
	}

	/**
	 * Updates the enabled state of all <code>IUpdate</code> actions associated with the project viewer.
	 */
	private void updateProjectActions() {
		for (IUpdate update : updateProjectActions) {
			update.update();
		}
	}

	/**
	 * Create the viewer which displays the Ant projects
	 */
	private void createProjectViewer(Composite parent) {
		projectViewer = new TreeViewer(parent, SWT.H_SCROLL | SWT.V_SCROLL | SWT.MULTI);
		contentProvider = new AntModelContentProvider();
		projectViewer.setContentProvider(contentProvider);

		filterInternalTargetsAction.setChecked(filterInternalTargets);
		setFilterInternalTargets(filterInternalTargets);

		projectViewer.setLabelProvider(new AntModelLabelProvider());
		projectViewer.setInput(fInput);
		projectViewer.setComparator(new ViewerComparator() {
			@Override
			public int compare(Viewer viewer, Object e1, Object e2) {
				if (e1 instanceof AntProjectNode && e2 instanceof AntProjectNode || e1 instanceof AntTargetNode && e2 instanceof AntTargetNode) {
					return e1.toString().compareToIgnoreCase(e2.toString());
				}
				return 0;
			}
		});

		projectViewer.addSelectionChangedListener(event -> handleSelectionChanged((IStructuredSelection) event.getSelection()));

		projectViewer.addDoubleClickListener(event -> {
			if (!event.getSelection().isEmpty()) {
				handleProjectViewerDoubleClick();
			}
		});

		projectViewer.getControl().addKeyListener(new KeyAdapter() {
			@Override
			public void keyPressed(KeyEvent event) {
				handleProjectViewerKeyPress(event);
			}
		});

		createContextMenu(projectViewer);
		getSite().setSelectionProvider(projectViewer);
	}

	private void handleProjectViewerKeyPress(KeyEvent event) {
		if (event.character == SWT.DEL && event.stateMask == 0) {
			if (removeProjectAction.isEnabled()) {
				removeProjectAction.run();
			}
		} else if (event.keyCode == SWT.F5 && event.stateMask == 0) {
			if (refreshBuildFilesAction.isEnabled()) {
				refreshBuildFilesAction.run();
			}
		}
	}

	private void handleProjectViewerDoubleClick() {
		AntElementNode node = getSelectionNode();
		if (node != null) {
			runTargetAction.run(node);
		}
	}

	/**
	 * Updates the actions and status line for selection change in one of the viewers.
	 */
	private void handleSelectionChanged(IStructuredSelection selection) {
		updateProjectActions();
		Iterator<AntElementNode> selectionIter = selection.iterator();
		AntElementNode selected = null;
		if (selectionIter.hasNext()) {
			selected = selectionIter.next();
		}
		String messageString = null;
		if (!selectionIter.hasNext()) {
			if (selected != null) {
				String errorString = selected.getProblemMessage();
				if (errorString != null) {
					getViewSite().getActionBars().getStatusLineManager().setErrorMessage(errorString);
					return;
				}
			}
			getViewSite().getActionBars().getStatusLineManager().setErrorMessage(null);
			messageString = getStatusLineText(selected);
		}
		getViewSite().getActionBars().getStatusLineManager().setMessage(messageString);
	}

	/**
	 * Returns text appropriate for display in the workbench status line for the given node.
	 */
	private String getStatusLineText(AntElementNode node) {
		if (node instanceof AntProjectNode) {
			AntProjectNode project = (AntProjectNode) node;
			StringBuilder message = new StringBuilder(project.getBuildFileName());
			String description = project.getDescription();
			if (description != null && description.length() > 0) {
				message.append(": "); //$NON-NLS-1$
				message.append(description);
			}
			return message.toString();
		} else if (node instanceof AntTargetNode) {
			AntTargetNode target = (AntTargetNode) node;
			StringBuilder message = new StringBuilder();
			Enumeration<String> depends = target.getTarget().getDependencies();
			if (depends.hasMoreElements()) {
				message.append(AntViewMessages.AntView_3);
				message.append(depends.nextElement()); // Unroll the loop to avoid trailing comma
				while (depends.hasMoreElements()) {
					String dependancy = depends.nextElement();
					message.append(',').append(dependancy);
				}
				message.append('\"');
			}
			String description = target.getTarget().getDescription();
			if (description != null && description.length() != 0) {
				message.append(AntViewMessages.AntView_4);
				message.append(description);
				message.append('\"');
			}
			return message.toString();
		}
		return null;
	}

	/**
	 * Returns the tree viewer that displays the projects in this view
	 * 
	 * @return TreeViewer this view's project viewer
	 */
	public TreeViewer getViewer() {
		return projectViewer;
	}

	/**
	 * Returns the <code>AntProjectNode</code>s currently displayed in this view.
	 * 
	 * @return AntProjectNode[] the <code>ProjectNode</code>s currently displayed in this view
	 */
	public AntProjectNode[] getProjects() {
		return fInput.toArray(new AntProjectNode[fInput.size()]);
	}

	/**
	 * Adds the given project to the view
	 * 
	 * @param project
	 *            the project to add
	 */
	public void addProject(AntProjectNode project) {
		fInput.add(project);
		projectViewer.refresh();
		ResourcesPlugin.getWorkspace().addResourceChangeListener(this);
		handleSelectionChanged(new StructuredSelection(project));
	}

	/**
	 * Removes the given project from the view
	 * 
	 * @param project
	 *            the project to remove
	 */
	private void removeProject(AntProjectNode project) {
		fInput.remove(project);
		projectViewer.refresh();
		setProjectViewerSelectionAfterDeletion();
	}

	private void setProjectViewerSelectionAfterDeletion() {
		Object[] children = getProjects();
		if (children.length > 0) {
			ViewerComparator comparator = projectViewer.getComparator();
			comparator.sort(projectViewer, children);
			IStructuredSelection selection = new StructuredSelection(children[0]);
			projectViewer.setSelection(selection);
			handleSelectionChanged(selection);
		}
	}

	/**
	 * Removes the given list of <code>AntProjectNode</code> objects from the view. This method should be called whenever multiple projects are to be
	 * removed because this method optimizes the viewer refresh associated with removing multiple items.
	 * 
	 * @param projectNodes
	 *            the list of <code>ProjectNode</code> objects to remove
	 */
	public void removeProjects(List<AntProjectNode> projectNodes) {
		for (AntProjectNode project : projectNodes) {
			fInput.remove(project);
		}
		projectViewer.refresh();
		setProjectViewerSelectionAfterDeletion();
	}

	/**
	 * Removes all projects from the view
	 */
	public void removeAllProjects() {
		for (AntProjectNode node : getProjects()) {
			node.dispose();
		}
		fInput.clear();
		ResourcesPlugin.getWorkspace().removeResourceChangeListener(this);
		updateProjectActions();
		projectViewer.refresh();
	}

	@Override
	public void init(IViewSite site, IMemento memento) throws PartInitException {
		super.init(site, memento);
		String persistedMemento = getDialogSettingsSection(getClass().getName()).get("memento"); //$NON-NLS-1$
		if (persistedMemento != null) {
			try {
				memento = XMLMemento.createReadRoot(new StringReader(persistedMemento));
			}
			catch (WorkbenchException e) {
				// don't do anything. Simply don't restore the settings
			}
		}
		if (memento != null) {
			restoreViewerInput(memento);
			IMemento child = memento.getChild(TAG_FILTER_INTERNAL_TARGETS);
			if (child != null) {
				filterInternalTargets = Boolean.valueOf(child.getString(KEY_VALUE)).booleanValue();
			}
		}
	}

	private IDialogSettings getDialogSettingsSection(String name) {
		IDialogSettings dialogSettings = PlatformUI.getDialogSettingsProvider(FrameworkUtil.getBundle(AntView.class)).getDialogSettings();
		IDialogSettings section = dialogSettings.getSection(name);
		if (section == null) {
			section = dialogSettings.addNewSection(name);
		}
		return section;
	}

	/**
	 * Restore the viewer content that was persisted
	 * 
	 * @param memento
	 *            the memento containing the persisted viewer content
	 */
	private void restoreViewerInput(IMemento memento) {
		IMemento[] projects = memento.getChildren(TAG_PROJECT);
		if (projects.length < 1) {
			return;
		}
		for (IMemento projectMemento : projects) {
			String pathString = projectMemento.getString(KEY_PATH);
			if (!ResourcesPlugin.getWorkspace().getRoot().getFile(new Path(pathString)).exists()) {
				// If the file no longer exists, don't add it.
				continue;
			}
			String nameString = projectMemento.getString(KEY_NAME);
			String defaultTarget = projectMemento.getString(KEY_DEFAULT);
			String errorString = projectMemento.getString(KEY_ERROR);
			String warningString = projectMemento.getString(KEY_WARNING);

			AntProjectNodeProxy project = null;
			if (nameString == null) {
				nameString = IAntCoreConstants.EMPTY_STRING;
			}
			project = new AntProjectNodeProxy(nameString, pathString);
			if (errorString != null && Boolean.valueOf(errorString).booleanValue()) {
				project.setProblemSeverity(AntModelProblem.SEVERITY_ERROR);
			} else if (warningString != null && Boolean.valueOf(warningString).booleanValue()) {
				project.setProblemSeverity(AntModelProblem.SEVERITY_WARNING);
			}
			if (defaultTarget != null) {
				project.setDefaultTargetName(defaultTarget);
			}
			fInput.add(project);
		}
	}

	/**
	 * Saves the state of the viewer into the dialog settings. Works around the issues of {@link #saveState(IMemento))} not being called when a view
	 * is closed while the workbench is still running
	 * 
	 * @since 3.5.500
	 */
	private void saveViewerState() {
		XMLMemento memento = XMLMemento.createWriteRoot("antView"); //$NON-NLS-1$
		StringWriter writer = new StringWriter();
		AntProjectNode[] projects = getProjects();
		if (projects.length > 0) {
			IMemento projectMemento;
			for (AntProjectNode project : projects) {
				projectMemento = memento.createChild(TAG_PROJECT);
				projectMemento.putString(KEY_PATH, project.getBuildFileName());
				projectMemento.putString(KEY_NAME, project.getLabel());
				String defaultTarget = project.getDefaultTargetName();
				if (project.isErrorNode()) {
					projectMemento.putString(KEY_ERROR, String.valueOf(true));
				} else {
					if (project.isWarningNode()) {
						projectMemento.putString(KEY_WARNING, String.valueOf(true));
					}
					if (defaultTarget != null) {
						projectMemento.putString(KEY_DEFAULT, defaultTarget);
					}
					projectMemento.putString(KEY_ERROR, String.valueOf(false));
				}
			}
			IMemento filterTargets = memento.createChild(TAG_FILTER_INTERNAL_TARGETS);
			filterTargets.putString(KEY_VALUE, isFilterInternalTargets() ? String.valueOf(true) : String.valueOf(false));
		}
		try {
			memento.save(writer);
			getDialogSettingsSection(getClass().getName()).put("memento", writer.getBuffer().toString()); //$NON-NLS-1$
		}
		catch (IOException e) {
			// don't do anything. Simply don't store the settings
		}
	}

	@Override
	public void saveState(IMemento memento) {
		saveViewerState();
	}

	@Override
	public void dispose() {
		saveViewerState();
		fInput.clear();
		super.dispose();
		if (openWithMenu != null) {
			openWithMenu.dispose();
		}
		ResourcesPlugin.getWorkspace().removeResourceChangeListener(this);
	}

	@Override
	public void resourceChanged(IResourceChangeEvent event) {
		IResourceDelta delta = event.getDelta();
		if (delta != null) {
			for (AntProjectNode project : getProjects()) {
				IPath buildFilePath = new Path(project.getBuildFileName());
				IResourceDelta change = delta.findMember(buildFilePath);
				if (change != null) {
					handleChangeDelta(change, project);
				}
			}
		}
	}

	/**
	 * Update the view for the given resource delta. The delta is a resource delta for the given build file in the view
	 * 
	 * @param delta
	 *            a delta for a build file in the view
	 * @param project
	 *            the project node that has changed
	 */
	private void handleChangeDelta(IResourceDelta delta, final AntProjectNode project) {
		IResource resource = delta.getResource();
		if (resource.getType() != IResource.FILE) {
			return;
		}
		if (delta.getKind() == IResourceDelta.REMOVED) {
			Display.getDefault().asyncExec(() -> removeProject(project));
		} else if (delta.getKind() == IResourceDelta.CHANGED && (delta.getFlags() & IResourceDelta.CONTENT) != 0) {
			handleBuildFileChanged(project);
		}
	}

	private void fillMainToolBar() {
		IToolBarManager toolBarMgr = getViewSite().getActionBars().getToolBarManager();
		toolBarMgr.removeAll();

		toolBarMgr.add(addBuildFileAction);
		toolBarMgr.add(searchForBuildFilesAction);
		toolBarMgr.add(filterInternalTargetsAction);

		toolBarMgr.add(runTargetAction);
		toolBarMgr.add(removeProjectAction);
		toolBarMgr.add(removeAllAction);

		toolBarMgr.update(false);
	}

	private AntElementNode getSelectionNode() {
		IStructuredSelection selection = (IStructuredSelection) getViewer().getSelection();
		if (selection.size() == 1) {
			Object element = selection.getFirstElement();
			if (element instanceof AntElementNode) {
				AntElementNode node = (AntElementNode) element;
				return node;
			}
		}
		return null;
	}

	@Override
	public ShowInContext getShowInContext() {
		AntElementNode node = getSelectionNode();
		if (node != null) {
			IFile buildFile = node.getIFile();
			if (buildFile != null) {
				ISelection selection = new StructuredSelection(buildFile);
				return new ShowInContext(null, selection);
			}
		}
		return null;
	}

	/**
	 * Returns whether internal targets are currently being filtered out of the view.
	 * 
	 * @return whether or not internal targets are being filtered out
	 */
	public boolean isFilterInternalTargets() {
		return filterInternalTargets;
	}

	/**
	 * Sets whether internal targets should be filtered out of the view.
	 * 
	 * @param filter
	 *            whether or not internal targets should be filtered out
	 */
	public void setFilterInternalTargets(boolean filter) {
		filterInternalTargets = filter;
		if (filter) {
			projectViewer.addFilter(getInternalTargetsFilter());
		} else {
			projectViewer.removeFilter(getInternalTargetsFilter());
		}
	}

	private ViewerFilter getInternalTargetsFilter() {
		if (fInternalTargetFilter == null) {
			fInternalTargetFilter = new InternalTargetFilter();
		}
		return fInternalTargetFilter;
	}

	@Override
	public void setFocus() {
		if (getViewer() != null) {
			getViewer().getControl().setFocus();
		}
	}
}