/*******************************************************************************
 * Copyright (c) 2005, 2017 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
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.ui.editor;

import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.eclipse.compare.rangedifferencer.IRangeComparator;
import org.eclipse.compare.rangedifferencer.RangeDifference;
import org.eclipse.compare.rangedifferencer.RangeDifferencer;
import org.eclipse.core.filebuffers.FileBuffers;
import org.eclipse.core.filebuffers.ITextFileBuffer;
import org.eclipse.core.filebuffers.ITextFileBufferManager;
import org.eclipse.core.filesystem.IFileStore;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IMarker;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IStorage;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.ISafeRunnable;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.SafeRunner;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.SubProgressMonitor;
import org.eclipse.dltk.core.DLTKCore;
import org.eclipse.dltk.core.IExternalSourceModule;
import org.eclipse.dltk.core.IMember;
import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.core.IScriptProject;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.ISourceRange;
import org.eclipse.dltk.core.ISourceReference;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.internal.corext.util.Messages;
import org.eclipse.dltk.internal.ui.DelegatedOpen;
import org.eclipse.dltk.internal.ui.IDLTKStatusConstants;
import org.eclipse.dltk.internal.ui.text.LineComparator;
import org.eclipse.dltk.ui.DLTKUILanguageManager;
import org.eclipse.dltk.ui.DLTKUIPlugin;
import org.eclipse.dltk.ui.IDLTKUILanguageToolkit;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.IAction;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextSelection;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.swt.SWT;
import org.eclipse.ui.IEditorDescriptor;
import org.eclipse.ui.IEditorInput;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IEditorSite;
import org.eclipse.ui.IFileEditorInput;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.actions.WorkspaceModifyOperation;
import org.eclipse.ui.ide.IDE;
import org.eclipse.ui.ide.IGotoMarker;
import org.eclipse.ui.part.FileEditorInput;
import org.eclipse.ui.texteditor.IDocumentProvider;
import org.eclipse.ui.texteditor.ITextEditor;
import org.eclipse.ui.texteditor.ITextEditorActionDefinitionIds;
import org.eclipse.ui.texteditor.TextEditorAction;

public class EditorUtility {
	/**
	 * Returns the DLTK project for a given editor input or <code>null</code> if
	 * no corresponding DLTK project exists.
	 *
	 * @param input
	 *            the editor input
	 * @return the corresponding DLTK project
	 */
	public static IScriptProject getScriptProject(IEditorInput input) {
		IScriptProject dProject = null;
		if (input instanceof IFileEditorInput) {
			IProject project = ((IFileEditorInput) input).getFile()
					.getProject();
			if (project != null) {
				dProject = DLTKCore.create(project);
				if (!dProject.exists())
					dProject = null;
			}
		} else if (input instanceof ExternalStorageEditorInput) {
			IModelElement element = input.getAdapter(IModelElement.class);
			if (element != null) {
				IScriptProject project = element.getScriptProject();
				if (project != null && project.exists()) {
					return project;
				}
			}
		}
		return dProject;
	}

	/**
	 * Returns the given editor's input as model element.
	 *
	 * @param editor
	 *            the editor
	 * @param primaryOnly
	 *            if <code>true</code> only primary working copies will be
	 *            returned
	 * @return the given editor's input as model element or <code>null</code> if
	 *         none
	 */
	public static ISourceModule getEditorInputModelElement(IEditorPart editor,
			boolean primaryOnly) {
		IEditorInput editorInput = editor.getEditorInput();
		if (editorInput == null)
			return null;
		ISourceModule je = DLTKUIPlugin.getEditorInputModelElement(editorInput);
		if (je != null || primaryOnly)
			return je;
		return DLTKUIPlugin.getDefault().getWorkingCopyManager()
				.getWorkingCopy(editorInput, primaryOnly);
	}

	/**
	 * Opens a Script editor for an element such as <code>IModelElement</code>,
	 * <code>IFile</code>, or <code>IStorage</code>. The editor is activated by
	 * default.
	 *
	 * @return the IEditorPart or null if wrong element type or opening failed
	 */
	public static IEditorPart openInEditor(Object inputElement)
			throws ModelException, PartInitException {
		return openInEditor(inputElement, true);
	}

	/**
	 * Opens a Script editor for an element (IModelElement, IFile, IStorage...)
	 *
	 * @return the IEditorPart or null if wrong element type or opening failed
	 */
	public static IEditorPart openInEditor(Object inputElement,
			boolean activate) throws ModelException, PartInitException {
		if (inputElement instanceof IFile) {
			return openInEditor((IFile) inputElement, activate);
		} else if (inputElement instanceof DelegatedOpen) {
			return ((DelegatedOpen) inputElement).openInEditor(activate);
		}

		IEditorInput input = getEditorInput(inputElement);
		if (input != null) {
			if (inputElement instanceof IModelElement) {
				// first try to get it from the system.
				String editorId = null;
				IDLTKUILanguageToolkit toolkit = DLTKUILanguageManager
						.getLanguageToolkit((IModelElement) inputElement);
				if (toolkit != null) {
					editorId = toolkit.getEditorId(inputElement);
				}
				if (editorId == null) { // Transitional code
					editorId = getEditorID(input, inputElement);
				}

				if (editorId != null) {
					return openInEditor(input, editorId, activate);
				}
			} else
				return openInEditor(input, getEditorID(input, inputElement),
						activate);
		}
		if (inputElement instanceof IModelElement) {
			IModelElement modelElement = (IModelElement) inputElement;
			ISourceModule cu = (ISourceModule) (modelElement)
					.getAncestor(IModelElement.SOURCE_MODULE);
			if (cu != null) {
				/*
				 * Support for non-primary or RSE working copy. Try to reveal it
				 * in the active editor.
				 */
				IWorkbenchPage page = DLTKUIPlugin.getActivePage();
				if (page != null) {
					IEditorPart editor = page.getActiveEditor();
					if (editor != null) {
						IModelElement editorCU = EditorUtility
								.getEditorInputModelElement(editor, false);
						if (editorCU == cu) {
							EditorUtility.revealInEditor(editor, modelElement);
							return editor;
						}
					}
				}
			}
		}
		return null;
	}

	public static String getEditorID(IEditorInput input, Object inputObject) {
		IEditorDescriptor editorDescriptor;
		try {
			if (input instanceof IFileEditorInput) {
				editorDescriptor = IDE.getEditorDescriptor(
						((IFileEditorInput) input).getFile(), true, false);
			} else if (input instanceof ExternalStorageEditorInput) {
				editorDescriptor = IDE.getEditorDescriptor(input.getName(),
						true, false);
			} else {
				editorDescriptor = IDE.getEditorDescriptor(input.getName(),
						true, false);
			}

		} catch (PartInitException e) {
			return null;
		}
		if (editorDescriptor != null)
			return editorDescriptor.getId();
		return null;
	}

	private static IEditorInput getEditorInput(IModelElement element) {
		while (element != null) {
			if (element instanceof IExternalSourceModule) {
				ISourceModule unit = ((ISourceModule) element).getPrimary();
				if (unit instanceof IStorage) {
					return new ExternalStorageEditorInput((IStorage) unit);
				}

			} else if (element instanceof ISourceModule) {
				ISourceModule unit = ((ISourceModule) element).getPrimary();
				IResource resource = unit.getResource();
				if (resource instanceof IFile && ((IFile) resource).exists())
					return new FileEditorInput((IFile) resource);
			}
			element = element.getParent();
		}
		return null;
	}

	public static IEditorInput getEditorInput(Object input) {
		if (input instanceof IModelElement)
			return getEditorInput((IModelElement) input);
		if (input instanceof IFile)
			return new FileEditorInput((IFile) input);
		if (DLTKCore.DEBUG) {
			System.err.println(
					"Add archive entry and external source folder editor input.."); //$NON-NLS-1$
		}
		if (input instanceof IStorage) {
			return new ExternalStorageEditorInput((IStorage) input);
		}
		return null;
	}

	/**
	 * Selects a Script Element in an editor
	 */
	public static void revealInEditor(IEditorPart part, IModelElement element) {
		if (element == null)
			return;
		if (part instanceof IScriptEditor) {
			((IScriptEditor) part).setSelection(element);
			return;
		}
		// Support for non-Script editor
		try {
			ISourceRange range = null;
			if (element instanceof IExternalSourceModule) {

			} else if (element instanceof ISourceModule) {
				range = null;
			}
			// else if (element instanceof IClassFile)
			// range= null;
			// else if (element instanceof ILocalVariable)
			// range= ((ILocalVariable)element).getNameRange();
			else if (element instanceof IMember)
				range = ((IMember) element).getNameRange();
			// else if (element instanceof ITypeParameter)
			// range= ((ITypeParameter)element).getNameRange();
			else if (element instanceof ISourceReference)
				range = ((ISourceReference) element).getSourceRange();
			if (range != null)
				revealInEditor(part, range.getOffset(), range.getLength());
		} catch (ModelException e) {
			// don't reveal
		}
	}

	/**
	 * Selects and reveals the given line in the given editor part.
	 *
	 * @param editorPart
	 * @param lineNumber
	 * @throws CoreException
	 */
	public static void revealInEditor(IEditorPart editorPart, int lineNumber)
			throws CoreException {
		if (editorPart instanceof ITextEditor && lineNumber >= 0) {
			final ITextEditor textEditor = (ITextEditor) editorPart;
			final IDocumentProvider provider = textEditor.getDocumentProvider();
			final IEditorInput input = editorPart.getEditorInput();
			provider.connect(input);
			final IDocument document = provider.getDocument(input);
			try {
				final IRegion line = document.getLineInformation(lineNumber);
				textEditor.selectAndReveal(line.getOffset(), line.getLength());
			} catch (BadLocationException e) {

			}
			provider.disconnect(input);
		}
	}

	/**
	 * Selects and reveals the given region in the given editor part.
	 */
	public static void revealInEditor(IEditorPart part, IRegion region) {
		if (part != null && region != null)
			revealInEditor(part, region.getOffset(), region.getLength());
	}

	/**
	 * Selects and reveals the given offset and length in the given editor part.
	 */
	public static void revealInEditor(IEditorPart editor, final int offset,
			final int length) {
		if (editor instanceof ITextEditor) {
			((ITextEditor) editor).selectAndReveal(offset, length);
			return;
		}
		// Support for non-text editor - try IGotoMarker interface
		if (editor instanceof IGotoMarker) {
			final IEditorInput input = editor.getEditorInput();
			if (input instanceof IFileEditorInput) {
				final IGotoMarker gotoMarkerTarget = (IGotoMarker) editor;
				WorkspaceModifyOperation op = new WorkspaceModifyOperation() {
					@Override
					protected void execute(IProgressMonitor monitor)
							throws CoreException {
						IMarker marker = null;
						try {
							marker = ((IFileEditorInput) input).getFile()
									.createMarker(IMarker.TEXT);
							marker.setAttribute(IMarker.CHAR_START, offset);
							marker.setAttribute(IMarker.CHAR_END,
									offset + length);
							gotoMarkerTarget.gotoMarker(marker);
						} finally {
							if (marker != null)
								marker.delete();
						}
					}
				};
				try {
					op.run(null);
				} catch (InvocationTargetException ex) {
					// reveal failed
				} catch (InterruptedException e) {
					// Assert.isTrue(false, "this operation can not be
					// canceled"); //$NON-NLS-1$
				}
			} else if (input instanceof ExternalStorageEditorInput) {
				System.err.println(
						"TODO: Add external storage editor input reveal..."); //$NON-NLS-1$
			}
			return;
		}
		/*
		 * Workaround: send out a text selection XXX: Needs to be improved, see
		 * https://bugs.eclipse.org/bugs/show_bug.cgi?id=32214
		 */
		if (editor != null
				&& editor.getEditorSite().getSelectionProvider() != null) {
			IEditorSite site = editor.getEditorSite();
			if (site == null)
				return;
			ISelectionProvider provider = editor.getEditorSite()
					.getSelectionProvider();
			if (provider == null)
				return;
			provider.setSelection(new TextSelection(offset, length));
		}
	}

	private static IEditorPart openInEditor(IFile file, boolean activate)
			throws PartInitException {
		if (file != null) {
			IWorkbenchPage p = DLTKUIPlugin.getActivePage();
			if (p != null) {
				IEditorPart editorPart = IDE.openEditor(p, file, activate);
				initializeHighlightRange(editorPart);
				return editorPart;
			}
		}
		return null;
	}

	private static IEditorPart openInEditor(IEditorInput input, String editorID,
			boolean activate) throws PartInitException {
		if (input != null) {
			IWorkbenchPage p = DLTKUIPlugin.getActivePage();
			if (p != null) {
				IEditorPart editorPart = p.openEditor(input, editorID,
						activate);
				initializeHighlightRange(editorPart);
				return editorPart;
			}
		}
		return null;
	}

	private static void initializeHighlightRange(IEditorPart editorPart) {
		if (editorPart instanceof ITextEditor) {
			IAction toggleAction = editorPart.getEditorSite().getActionBars()
					.getGlobalActionHandler(
							ITextEditorActionDefinitionIds.TOGGLE_SHOW_SELECTED_ELEMENT_ONLY);
			boolean enable = toggleAction != null;
			// if (enable && editorPart instanceof Editor)
			// enable=
			// DLTKUIPlugin.getDefault().getPreferenceStore().getBoolean(
			// PreferenceConstants.EDITOR_SHOW_SEGMENTS);
			// else
			if (DLTKCore.DEBUG) {
				System.err.println(
						"Add initializeHighlightRange support of preferences."); //$NON-NLS-1$
			}
			enable = enable && toggleAction.isEnabled()
					&& toggleAction.isChecked();
			if (enable) {
				if (toggleAction instanceof TextEditorAction) {
					// Reset the action
					((TextEditorAction) toggleAction).setEditor(null);
					// Restore the action
					((TextEditorAction) toggleAction)
							.setEditor((ITextEditor) editorPart);
				} else {
					// Un-check
					toggleAction.run();
					// Check
					toggleAction.run();
				}
			}
		}
	}

	/**
	 * Tests if a CU is currently shown in an editor
	 *
	 * @return the IEditorPart if shown, null if element is not open in an
	 *         editor
	 */
	public static IEditorPart isOpenInEditor(Object inputElement) {
		IEditorInput input = getEditorInput(inputElement);

		if (input != null) {
			IWorkbenchPage p = DLTKUIPlugin.getActivePage();
			if (p != null) {
				return p.findEditor(input);
			}
		}

		return null;
	}

	public static IEditorPart[] getDirtyEditors() {
		Set<IEditorInput> inputs = new HashSet<>();
		List<IEditorPart> result = new ArrayList<>(0);
		IWorkbench workbench = PlatformUI.getWorkbench();
		IWorkbenchWindow[] windows = workbench.getWorkbenchWindows();
		for (int i = 0; i < windows.length; i++) {
			IWorkbenchPage[] pages = windows[i].getPages();
			for (int x = 0; x < pages.length; x++) {
				IEditorPart[] editors = pages[x].getDirtyEditors();
				for (int z = 0; z < editors.length; z++) {
					IEditorPart ep = editors[z];
					IEditorInput input = ep.getEditorInput();
					if (!inputs.contains(input)) {
						inputs.add(input);
						result.add(ep);
					}
				}
			}
		}
		return result.toArray(new IEditorPart[result.size()]);
	}

	/**
	 * If the current active editor edits ascriptelement return it, else return
	 * null
	 */
	public static IModelElement getActiveEditorModelInput() {
		IWorkbenchPage page = DLTKUIPlugin.getActivePage();
		if (page != null) {
			IEditorPart part = page.getActiveEditor();
			if (part != null) {
				IEditorInput editorInput = part.getEditorInput();
				if (editorInput != null) {
					return DLTKUIPlugin.getEditorInputModelElement(editorInput);
				}
			}
		}
		return null;
	}

	/**
	 * Appends to modifier string of the given SWT modifier bit to the given
	 * modifierString.
	 *
	 * @param modifierString
	 *            the modifier string
	 * @param modifier
	 *            an int with SWT modifier bit
	 * @return the concatenated modifier string
	 *
	 */
	private static String appendModifierString(String modifierString,
			int modifier) {
		if (modifierString == null)
			modifierString = ""; //$NON-NLS-1$
		String newModifierString = Action.findModifierString(modifier);
		if (modifierString.length() == 0)
			return newModifierString;
		return Messages.format(
				DLTKEditorMessages.EditorUtility_concatModifierStrings,
				new String[] { modifierString, newModifierString });
	}

	/**
	 * Returns the modifier string for the given SWT modifier modifier bits.
	 *
	 * @param stateMask
	 *            the SWT modifier bits
	 * @return the modifier string
	 *
	 */
	public static String getModifierString(int stateMask) {
		String modifierString = ""; //$NON-NLS-1$
		if ((stateMask & SWT.CTRL) == SWT.CTRL)
			modifierString = appendModifierString(modifierString, SWT.CTRL);
		if ((stateMask & SWT.ALT) == SWT.ALT)
			modifierString = appendModifierString(modifierString, SWT.ALT);
		if ((stateMask & SWT.SHIFT) == SWT.SHIFT)
			modifierString = appendModifierString(modifierString, SWT.SHIFT);
		if ((stateMask & SWT.COMMAND) == SWT.COMMAND)
			modifierString = appendModifierString(modifierString, SWT.COMMAND);

		return modifierString;
	}

	/**
	 * Maps the localized modifier name to a code in the same manner as
	 * #findModifier.
	 *
	 * @param modifierName
	 *            the modifier name
	 * @return the SWT modifier bit, or <code>0</code> if no match was found
	 *
	 */
	public static int findLocalizedModifier(String modifierName) {
		if (modifierName == null)
			return 0;

		if (modifierName.equalsIgnoreCase(Action.findModifierString(SWT.CTRL)))
			return SWT.CTRL;
		if (modifierName.equalsIgnoreCase(Action.findModifierString(SWT.SHIFT)))
			return SWT.SHIFT;
		if (modifierName.equalsIgnoreCase(Action.findModifierString(SWT.ALT)))
			return SWT.ALT;
		if (modifierName
				.equalsIgnoreCase(Action.findModifierString(SWT.COMMAND)))
			return SWT.COMMAND;

		return 0;
	}

	/**
	 * Return the regions of all lines which have changed in the given buffer
	 * since the last save occurred. Each region in the result spans over the
	 * size of at least one line. If successive lines have changed a region
	 * spans over the size of all successive lines. The regions include line
	 * delimiters.
	 *
	 * @param buffer
	 *            the buffer to compare contents from
	 * @param monitor
	 *            to report progress to
	 * @return the regions of the changed lines
	 * @throws CoreException
	 *             if something goes wrong
	 * @since 3.0
	 */
	public static IRegion[] calculateChangedLineRegions(
			final ITextFileBuffer buffer, final IProgressMonitor monitor)
			throws CoreException {
		final IRegion[][] result = new IRegion[1][];
		final IStatus[] errorStatus = new IStatus[] { Status.OK_STATUS };

		try {
			SafeRunner.run(new ISafeRunnable() {

				@Override
				public void handleException(Throwable exception) {
					DLTKUIPlugin.log(new Status(IStatus.ERROR,
							DLTKUIPlugin.PLUGIN_ID,
							IDLTKStatusConstants.EDITOR_CHANGED_REGION_CALCULATION,
							exception.getLocalizedMessage(), exception));
					String msg = DLTKEditorMessages.CompilationUnitDocumentProvider_error_calculatingChangedRegions;
					errorStatus[0] = new Status(IStatus.ERROR,
							DLTKUIPlugin.PLUGIN_ID,
							IDLTKStatusConstants.EDITOR_CHANGED_REGION_CALCULATION,
							msg, exception);
					result[0] = null;
				}

				@Override
				public void run() throws Exception {
					monitor.beginTask(
							DLTKEditorMessages.CompilationUnitDocumentProvider_calculatingChangedRegions_message,
							20);
					IFileStore fileStore = buffer.getFileStore();

					ITextFileBufferManager fileBufferManager = FileBuffers
							.createTextFileBufferManager();
					fileBufferManager.connectFileStore(fileStore,
							getSubProgressMonitor(monitor, 15));
					try {
						IDocument currentDocument = buffer.getDocument();
						IDocument oldDocument = ((ITextFileBuffer) fileBufferManager
								.getFileStoreFileBuffer(fileStore))
										.getDocument();

						result[0] = getChangedLineRegions(oldDocument,
								currentDocument);
					} finally {
						fileBufferManager.disconnectFileStore(fileStore,
								getSubProgressMonitor(monitor, 5));
						monitor.done();
					}
				}

				/**
				 * Return regions of all lines which differ comparing
				 * <code>oldDocument</code>s content with
				 * <code>currentDocument</code>s content. Successive lines are
				 * merged into one region.
				 *
				 * @param oldDocument
				 *            a document containing the old content
				 * @param currentDocument
				 *            a document containing the current content
				 * @return the changed regions
				 * @throws BadLocationException
				 *             if fetching the line information fails
				 */
				private IRegion[] getChangedLineRegions(IDocument oldDocument,
						IDocument currentDocument) throws BadLocationException {
					/*
					 * Do not change the type of those local variables. We use
					 * Object here in order to prevent loading of the Compare
					 * plug-in at load time of this class.
					 */
					Object leftSide = new LineComparator(oldDocument);
					Object rightSide = new LineComparator(currentDocument);

					RangeDifference[] differences = RangeDifferencer
							.findDifferences((IRangeComparator) leftSide,
									(IRangeComparator) rightSide);

					// It holds that:
					// 1. Ranges are sorted:
					// forAll r1,r2 element differences: indexOf(r1)<indexOf(r2)
					// -> r1.rightStart()<r2.rightStart();
					// 2. Successive changed lines are merged into on
					// RangeDifference
					// forAll r1,r2 element differences:
					// r1.rightStart()<r2.rightStart() ->
					// r1.rightEnd()<r2.rightStart

					ArrayList<IRegion> regions = new ArrayList<>();
					for (int i = 0; i < differences.length; i++) {
						RangeDifference curr = differences[i];
						if (curr.kind() == RangeDifference.CHANGE
								&& curr.rightLength() > 0) {
							int startLine = curr.rightStart();
							int endLine = curr.rightEnd() - 1;

							IRegion startLineRegion = currentDocument
									.getLineInformation(startLine);
							if (startLine == endLine) {
								regions.add(startLineRegion);
							} else {
								IRegion endLineRegion = currentDocument
										.getLineInformation(endLine);
								int startOffset = startLineRegion.getOffset();
								int endOffset = endLineRegion.getOffset()
										+ endLineRegion.getLength();
								regions.add(new Region(startOffset,
										endOffset - startOffset));
							}
						}
					}

					return regions.toArray(new IRegion[regions.size()]);
				}
			});
		} finally {
			if (!errorStatus[0].isOK())
				throw new CoreException(errorStatus[0]);
		}

		return result[0];
	}

	/**
	 * Creates and returns a new sub-progress monitor for the given parent
	 * monitor.
	 *
	 * @param monitor
	 *            the parent progress monitor
	 * @param ticks
	 *            the number of work ticks allocated from the parent monitor
	 * @return the new sub-progress monitor
	 * @since 3.0
	 */
	private static IProgressMonitor getSubProgressMonitor(
			IProgressMonitor monitor, int ticks) {
		if (monitor != null)
			return new SubProgressMonitor(monitor, ticks,
					SubProgressMonitor.PREPEND_MAIN_LABEL_TO_SUBTASK);
		return new NullProgressMonitor();
	}
}