/*******************************************************************************
 * Copyright (c) 2000, 2017 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:
 *     IBM Corporation - initial API and implementation
 *     Alex Blewitt <alex.blewitt@gmail.com> - replace new Boolean with Boolean.valueOf - https://bugs.eclipse.org/470344
 *     Conrad Groth - Bug 213780 - Compare With direction should be configurable
 *******************************************************************************/
package org.eclipse.compare.internal;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.eclipse.compare.CompareConfiguration;
import org.eclipse.compare.IEncodedStreamContentAccessor;
import org.eclipse.compare.ITypedElement;
import org.eclipse.compare.contentmergeviewer.TextMergeViewer;
import org.eclipse.compare.internal.core.ComparePlugin;
import org.eclipse.compare.structuremergeviewer.DiffNode;
import org.eclipse.compare.structuremergeviewer.Differencer;
import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.preference.FieldEditor;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.preference.PreferencePage;
import org.eclipse.jface.preference.RadioGroupFieldEditor;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.TabFolder;
import org.eclipse.swt.widgets.TabItem;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.IWorkbenchPreferencePage;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.dialogs.PreferenceLinkArea;
import org.eclipse.ui.preferences.IWorkbenchPreferenceContainer;


public class ComparePreferencePage extends PreferencePage implements IWorkbenchPreferencePage {

	private static class FakeInput implements ITypedElement, IEncodedStreamContentAccessor {
		static final String UTF_16= "UTF-16"; //$NON-NLS-1$
		String fContent;

		FakeInput(String name) {
			fContent= loadPreviewContentFromFile(name);
		}
		@Override
		public Image getImage() {
			return null;
		}
		@Override
		public String getName() {
			return "no name";	//$NON-NLS-1$
		}
		@Override
		public String getType() {
			return "no type";	//$NON-NLS-1$
		}
		@Override
		public InputStream getContents() {
			return new ByteArrayInputStream(Utilities.getBytes(fContent, UTF_16));
		}
		@Override
		public String getCharset() {
			return UTF_16;
		}

		private String loadPreviewContentFromFile(String key) {

			String preview= Utilities.getString(key);
			String separator= System.getProperty("line.separator"); //$NON-NLS-1$
			StringBuilder buffer= new StringBuilder();
			for (int i= 0; i < preview.length(); i++) {
				char c= preview.charAt(i);
				if (c == '\n')
					buffer.append(separator);
				else
					buffer.append(c);
			}
			return buffer.toString();
		}
	}

	private static final String PREFIX= CompareUIPlugin.PLUGIN_ID + "."; //$NON-NLS-1$
	public static final String OPEN_STRUCTURE_COMPARE= PREFIX + "OpenStructureCompare"; //$NON-NLS-1$
	public static final String USE_OUTLINE_VIEW= PREFIX + "UseOutlineView"; //$NON-NLS-1$
	public static final String SYNCHRONIZE_SCROLLING= PREFIX + "SynchronizeScrolling"; //$NON-NLS-1$
	public static final String SHOW_PSEUDO_CONFLICTS= PREFIX + "ShowPseudoConflicts"; //$NON-NLS-1$
	public static final String INITIALLY_SHOW_ANCESTOR_PANE= PREFIX + "InitiallyShowAncestorPane"; //$NON-NLS-1$
	public static final String PREF_SAVE_ALL_EDITORS= PREFIX + "SaveAllEditors"; //$NON-NLS-1$
	public static final String IGNORE_WHITESPACE= PREFIX + "IgnoreWhitespace"; //$NON-NLS-1$

	//public static final String USE_SPLINES= PREFIX + "UseSplines"; //$NON-NLS-1$
	public static final String USE_SINGLE_LINE= PREFIX + "UseSingleLine"; //$NON-NLS-1$
	public static final String HIGHLIGHT_TOKEN_CHANGES= PREFIX + "HighlightTokenChanges"; //$NON-NLS-1$
	//public static final String USE_RESOLVE_UI= PREFIX + "UseResolveUI"; //$NON-NLS-1$
	public static final String CAPPING_DISABLED= PREFIX + "CappingDisable"; //$NON-NLS-1$
	public static final String PATH_FILTER= PREFIX + "PathFilter"; //$NON-NLS-1$
	public static final String ADDED_LINES_REGEX= PREFIX + "AddedLinesRegex"; //$NON-NLS-1$
	public static final String REMOVED_LINES_REGEX= PREFIX + "RemovedLinesRegex"; //$NON-NLS-1$
	public static final String SWAPPED = PREFIX + "Swapped"; //$NON-NLS-1$


	private IPropertyChangeListener fPreferenceChangeListener;
	private List<CompareConfiguration> fCompareConfigurations = new ArrayList<>();
	private OverlayPreferenceStore fOverlayStore;
	private Map<Button, String> fCheckBoxes = new HashMap<>();
	private Text fFilters;
	private Text addedLinesRegex;
	private Text removedLinesRegex;
	private SelectionListener fCheckBoxListener;


	public final OverlayPreferenceStore.OverlayKey[] fKeys= new OverlayPreferenceStore.OverlayKey[] {
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, OPEN_STRUCTURE_COMPARE),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, USE_OUTLINE_VIEW),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, SYNCHRONIZE_SCROLLING),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, SHOW_PSEUDO_CONFLICTS),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, INITIALLY_SHOW_ANCESTOR_PANE),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, IGNORE_WHITESPACE),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, PREF_SAVE_ALL_EDITORS),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, ADDED_LINES_REGEX),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, REMOVED_LINES_REGEX),
		//new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, USE_SPLINES),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, USE_SINGLE_LINE),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, HIGHLIGHT_TOKEN_CHANGES),
		//new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, USE_RESOLVE_UI),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, CAPPING_DISABLED),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, PATH_FILTER),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, ICompareUIConstants.PREF_NAVIGATION_END_ACTION),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.STRING, ICompareUIConstants.PREF_NAVIGATION_END_ACTION_LOCAL),
		new OverlayPreferenceStore.OverlayKey(OverlayPreferenceStore.BOOLEAN, SWAPPED),
	};
	private List<FieldEditor> editors = new ArrayList<>();
	private TabItem fTextCompareTab;
	private Button fDisableCappingCheckBox;


	public static void initDefaults(IPreferenceStore store) {
		store.setDefault(OPEN_STRUCTURE_COMPARE, true);
		store.setDefault(USE_OUTLINE_VIEW, false);
		store.setDefault(SYNCHRONIZE_SCROLLING, true);
		store.setDefault(SHOW_PSEUDO_CONFLICTS, false);
		store.setDefault(INITIALLY_SHOW_ANCESTOR_PANE, false);
		store.setDefault(IGNORE_WHITESPACE, false);
		store.setDefault(PREF_SAVE_ALL_EDITORS, false);
		store.setDefault(ADDED_LINES_REGEX, ""); //$NON-NLS-1$
		store.setDefault(REMOVED_LINES_REGEX, ""); //$NON-NLS-1$
		store.setDefault(USE_SINGLE_LINE, true);
		store.setDefault(HIGHLIGHT_TOKEN_CHANGES, true);
		store.setDefault(CAPPING_DISABLED, false);
		store.setDefault(PATH_FILTER, ""); //$NON-NLS-1$
		store.setDefault(ICompareUIConstants.PREF_NAVIGATION_END_ACTION, ICompareUIConstants.PREF_VALUE_PROMPT);
		store.setDefault(ICompareUIConstants.PREF_NAVIGATION_END_ACTION_LOCAL, ICompareUIConstants.PREF_VALUE_LOOP);
		store.setDefault(SWAPPED, false);
	}

	public ComparePreferencePage() {

		setPreferenceStore(CompareUIPlugin.getDefault().getPreferenceStore());

		fOverlayStore= new OverlayPreferenceStore(getPreferenceStore(), fKeys);
		fPreferenceChangeListener= event -> {
			String key= event.getProperty();
			if (key.equals(INITIALLY_SHOW_ANCESTOR_PANE)) {
				boolean b= fOverlayStore.getBoolean(INITIALLY_SHOW_ANCESTOR_PANE);
				for (CompareConfiguration compareConfiguration : fCompareConfigurations) {
					compareConfiguration.setProperty(INITIALLY_SHOW_ANCESTOR_PANE, Boolean.valueOf(b));
				}
			}
		};
		fOverlayStore.addPropertyChangeListener(fPreferenceChangeListener);
	}

	@Override
	public void init(IWorkbench workbench) {
		// empty
	}

	@Override
	public boolean performOk() {
		fOverlayStore.setValue(ADDED_LINES_REGEX, addedLinesRegex.getText());
		fOverlayStore.setValue(REMOVED_LINES_REGEX, removedLinesRegex.getText());

		editors.forEach(FieldEditor::store);
		fOverlayStore.propagate();

		ComparePlugin.getDefault().setCappingDisabled(
				getPreferenceStore().getBoolean(
						ComparePreferencePage.CAPPING_DISABLED));
		return true;
	}

	@Override
	protected void performDefaults() {

		fOverlayStore.loadDefaults();
		initializeFields();

		super.performDefaults();
	}

	@Override
	public void dispose() {

		if (fOverlayStore != null) {
			if (fPreferenceChangeListener != null) {
				fOverlayStore.removePropertyChangeListener(fPreferenceChangeListener);
				fPreferenceChangeListener= null;
			}
			fOverlayStore.stop();
			fOverlayStore= null;
		}

		super.dispose();
	}

	public static boolean getSaveAllEditors() {
		IPreferenceStore store= CompareUIPlugin.getDefault().getPreferenceStore();
		return store.getBoolean(PREF_SAVE_ALL_EDITORS);
	}

	public static void setSaveAllEditors(boolean value) {
		IPreferenceStore store= CompareUIPlugin.getDefault().getPreferenceStore();
		store.setValue(PREF_SAVE_ALL_EDITORS, value);
	}

	@Override
	protected Control createContents(Composite parent) {
		if (PlatformUI.isWorkbenchRunning()) {
			PlatformUI.getWorkbench().getHelpSystem().setHelp(parent, ICompareContextIds.COMPARE_PREFERENCE_PAGE);
		}

		fOverlayStore.load();
		fOverlayStore.start();

		TabFolder folder= new TabFolder(parent, SWT.NONE);
		folder.setLayout(new TabFolderLayout());
		folder.setLayoutData(new GridData(GridData.FILL_BOTH));

		TabItem item= new TabItem(folder, SWT.NONE);
		item.setText(Utilities.getString("ComparePreferencePage.generalTab.label"));	//$NON-NLS-1$
		item.setControl(createGeneralPage(folder));

		item= new TabItem(folder, SWT.NONE);
		item.setText(Utilities.getString("ComparePreferencePage.textCompareTab.label"));	//$NON-NLS-1$
		item.setControl(createTextComparePage(folder));
		fTextCompareTab = item;

		initializeFields();
		Dialog.applyDialogFont(folder);
		return folder;
	}

	private Control createGeneralPage(Composite parent) {
		Composite composite= new Composite(parent, SWT.NULL);
		GridLayout layout= new GridLayout();
		layout.numColumns= 1;
		composite.setLayout(layout);

		addCheckBox(composite, "ComparePreferencePage.structureCompare.label", OPEN_STRUCTURE_COMPARE, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.structureOutline.label", USE_OUTLINE_VIEW, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.ignoreWhitespace.label", IGNORE_WHITESPACE, 0);	//$NON-NLS-1$

		// a spacer
		new Label(composite, SWT.NONE);

		addCheckBox(composite, "ComparePreferencePage.saveBeforePatching.label", PREF_SAVE_ALL_EDITORS, 0);	//$NON-NLS-1$

		// a spacer
		new Label(composite, SWT.NONE);

		Label l= new Label(composite, SWT.WRAP);
		l.setText(Utilities.getString("ComparePreferencePage.regex.description")); //$NON-NLS-1$

		Composite c2= new Composite(composite, SWT.NONE);
		c2.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
		layout= new GridLayout(2, false);
		layout.marginWidth= 0;
		c2.setLayout(layout);

		l= new Label(c2, SWT.NONE);
		l.setText(Utilities.getString("ComparePreferencePage.regexAdded.label")); //$NON-NLS-1$
		addedLinesRegex = new Text(c2, SWT.BORDER);
		addedLinesRegex.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
		addedLinesRegex.setText(fOverlayStore.getString(ADDED_LINES_REGEX));

		l= new Label(c2, SWT.NONE);
		l.setText(Utilities.getString("ComparePreferencePage.regexRemoved.label")); //$NON-NLS-1$
		removedLinesRegex = new Text(c2, SWT.BORDER);
		removedLinesRegex.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
		removedLinesRegex.setText(fOverlayStore.getString(REMOVED_LINES_REGEX));

		// a spacer
		new Label(composite, SWT.NONE);

		l= new Label(composite, SWT.WRAP);
		l.setText(Utilities.getString("ComparePreferencePage.filter.description")); //$NON-NLS-1$

		Composite c3= new Composite(composite, SWT.NONE);
		c3.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
		layout= new GridLayout(2, false);
		layout.marginWidth= 0;
		c3.setLayout(layout);

		l= new Label(c3, SWT.NONE);
		l.setText(Utilities.getString("ComparePreferencePage.filter.label")); //$NON-NLS-1$

		fFilters= new Text(c3, SWT.BORDER);
		fFilters.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
		fFilters.setText(fOverlayStore.getString(PATH_FILTER));
		fFilters.addModifyListener(
			e -> {
				String filters= fFilters.getText();
				String message= CompareResourceFilter.validateResourceFilters(filters);
				setValid(message == null);
				setMessage(null);
				setErrorMessage(message);
				fOverlayStore.setValue(PATH_FILTER, filters);
			}
		);

		return composite;
	}

	private Control createTextComparePage(Composite parent) {

		Composite composite= new Composite(parent, SWT.NULL);
		GridLayout layout= new GridLayout();
		layout.numColumns= 1;
		composite.setLayout(layout);

		addCheckBox(composite, "ComparePreferencePage.synchronizeScrolling.label", SYNCHRONIZE_SCROLLING, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.initiallyShowAncestorPane.label", INITIALLY_SHOW_ANCESTOR_PANE, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.showPseudoConflicts.label", SHOW_PSEUDO_CONFLICTS, 0);	//$NON-NLS-1$

		//addCheckBox(composite, "ComparePreferencePage.useSplines.label", USE_SPLINES, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.useSingleLine.label", USE_SINGLE_LINE, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.highlightTokenChanges.label", HIGHLIGHT_TOKEN_CHANGES, 0);	//$NON-NLS-1$
		//addCheckBox(composite, "ComparePreferencePage.useResolveUI.label", USE_RESOLVE_UI, 0);	//$NON-NLS-1$
		fDisableCappingCheckBox = addCheckBox(composite, "ComparePreferencePage.disableCapping.label", CAPPING_DISABLED, 0);	//$NON-NLS-1$
		addCheckBox(composite, "ComparePreferencePage.swapped.label", SWAPPED, 0);	//$NON-NLS-1$

		Composite radioGroup = new Composite(composite, SWT.NULL);
		radioGroup.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, false));
		RadioGroupFieldEditor editor = new RadioGroupFieldEditor(
				ICompareUIConstants.PREF_NAVIGATION_END_ACTION,
				CompareMessages.ComparePreferencePage_0, 1,
				new String[][] {
					new String[] { CompareMessages.ComparePreferencePage_1, ICompareUIConstants.PREF_VALUE_PROMPT },
					new String[] { CompareMessages.ComparePreferencePage_2, ICompareUIConstants.PREF_VALUE_LOOP },
					new String[] { CompareMessages.ComparePreferencePage_3, ICompareUIConstants.PREF_VALUE_NEXT },
					new String[] { CompareMessages.ComparePreferencePage_4, ICompareUIConstants.PREF_VALUE_DO_NOTHING}
				},
		radioGroup, true);
		editor.setPreferenceStore(fOverlayStore);
		editor.fillIntoGrid(radioGroup, 1);
		editors.add(editor);

		PreferenceLinkArea area = new PreferenceLinkArea(composite, SWT.NONE,
				"org.eclipse.ui.preferencePages.ColorsAndFonts", //$NON-NLS-1$
				Utilities.getString("ComparePreferencePage.colorAndFontLink"), //$NON-NLS-1$
				(IWorkbenchPreferenceContainer) getContainer(),
				"selectCategory:org.eclipse.compare.contentmergeviewer.TextMergeViewer"); //$NON-NLS-1$

		GridData data = new GridData(SWT.FILL, SWT.CENTER, false, false);
		area.getControl().setLayoutData(data);

		// a spacer
		Label separator= new Label(composite, SWT.SEPARATOR | SWT.HORIZONTAL);
		separator.setVisible(false);

		{
			Label previewLabel = new Label(composite, SWT.NULL);
			previewLabel.setText(Utilities.getString("ComparePreferencePage.preview-2way.label")); //$NON-NLS-1$

			Control previewer = create2WayPreviewer(composite);
			GridData gd = new GridData(GridData.FILL_BOTH);
			gd.widthHint = convertWidthInCharsToPixels(60);
			gd.heightHint = convertHeightInCharsToPixels(12);
			previewer.setLayoutData(gd);
		}

		{
			Label previewLabel = new Label(composite, SWT.NULL);
			previewLabel.setText(Utilities.getString("ComparePreferencePage.preview.label")); //$NON-NLS-1$

			Control previewer = create3WayPreviewer(composite);
			GridData gd = new GridData(GridData.FILL_BOTH);
			gd.widthHint = convertWidthInCharsToPixels(60);
			gd.heightHint = convertHeightInCharsToPixels(9);
			previewer.setLayoutData(gd);
		}

		return composite;
	}

	private Control create3WayPreviewer(Composite parent) {
		CompareConfiguration compareConfiguration = new CompareConfiguration(fOverlayStore);
		compareConfiguration.setAncestorLabel(Utilities.getString("ComparePreferencePage.ancestor.label")); //$NON-NLS-1$

		compareConfiguration.setLeftLabel(Utilities.getString("ComparePreferencePage.left.label")); //$NON-NLS-1$
		compareConfiguration.setLeftEditable(false);

		compareConfiguration.setRightLabel(Utilities.getString("ComparePreferencePage.right.label")); //$NON-NLS-1$
		compareConfiguration.setRightEditable(false);

		TextMergeViewer previewViewer = new TextMergeViewer(parent, SWT.BORDER, compareConfiguration);

		previewViewer.setInput(
			new DiffNode(Differencer.CONFLICTING,
				new FakeInput("ComparePreferencePage.previewAncestor"),	//$NON-NLS-1$
				new FakeInput("ComparePreferencePage.previewLeft"),	//$NON-NLS-1$
				new FakeInput("ComparePreferencePage.previewRight")	//$NON-NLS-1$
			)
		);

		Control c = previewViewer.getControl();
		c.addDisposeListener(e -> {
			if (compareConfiguration != null)
				compareConfiguration.dispose();
		});

		fCompareConfigurations.add(compareConfiguration);
		return  c;
	}

	private Control create2WayPreviewer(Composite parent) {
		CompareConfiguration compareConfiguration = new CompareConfiguration(fOverlayStore);
		compareConfiguration.setLeftLabel(Utilities.getString("ComparePreferencePage.workingCopy.label")); //$NON-NLS-1$
		compareConfiguration.setRightLabel(Utilities.getString("ComparePreferencePage.baseline.label")); //$NON-NLS-1$
		compareConfiguration.setRightEditable(false);

		TextMergeViewer previewViewer = new TextMergeViewer(parent, SWT.BORDER, compareConfiguration);

		previewViewer.setInput(new DiffNode(
				new FakeInput("ComparePreferencePage.workingCopy"), //$NON-NLS-1$
				new FakeInput("ComparePreferencePage.baseline") //$NON-NLS-1$
		));

		Control c = previewViewer.getControl();
		c.addDisposeListener(e -> {
			if (compareConfiguration != null)
				compareConfiguration.dispose();
		});

		fCompareConfigurations.add(compareConfiguration);
		return c;
	}

	private void initializeFields() {

		Iterator<Button> e = fCheckBoxes.keySet().iterator();
		while (e.hasNext()) {
			Button b = e.next();
			String key= fCheckBoxes.get(b);
			b.setSelection(fOverlayStore.getBoolean(key));
		}

		if (fFilters != null)
			fFilters.setText(fOverlayStore.getString(PATH_FILTER));
		if (addedLinesRegex != null)
			addedLinesRegex.setText(fOverlayStore.getString(ADDED_LINES_REGEX));
		if (removedLinesRegex != null)
			removedLinesRegex.setText(fOverlayStore.getString(REMOVED_LINES_REGEX));

		editors.forEach(FieldEditor::load);
	}

	// overlay stuff

	private Button addCheckBox(Composite parent, String labelKey, String key, int indentation) {

		String label= Utilities.getString(labelKey);

		Button checkBox= new Button(parent, SWT.CHECK);
		checkBox.setText(label);

		GridData gd= new GridData(GridData.FILL_HORIZONTAL);
		gd.horizontalIndent= indentation;
		checkBox.setLayoutData(gd);

		if (fCheckBoxListener == null) {
			fCheckBoxListener= new SelectionAdapter() {
				@Override
				public void widgetSelected(SelectionEvent e) {
					Button button= (Button) e.widget;
					fOverlayStore.setValue(fCheckBoxes.get(button), button.getSelection());
				}
			};
		}
		checkBox.addSelectionListener(fCheckBoxListener);

		fCheckBoxes.put(checkBox, key);

		return checkBox;
	}

	@Override
	public void applyData(Object data) {
		if (ComparePreferencePage.CAPPING_DISABLED.equals(data)) {
			fTextCompareTab.getParent().setSelection(fTextCompareTab);
			fDisableCappingCheckBox.setFocus();
		}
	}
}