bundles/org.eclipse.ui.ide.application/src/org/eclipse/ui/internal/ide/application/dialogs/UriSchemeHandlerPreferencePage.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
 * Copyright (c) 2018, 2021 SAP SE 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
 *
 * Contributors:
 *     SAP SE - initial API and implementation
 *******************************************************************************/
 package org.eclipse.ui.internal.ide.application.dialogs;

 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Confirm_Handle;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp_Confirmation;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp_Confirmation_Description;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp_Description;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_ColumnName_Handler;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_ColumnName_SchemeDescription;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_ColumnName_SchemeName;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Column_Handler_Text_Current_Application;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Column_Handler_Text_Other_Application;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Error_Reading_Scheme;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Error_Writing_Scheme;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Handler_Label;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Handler_Text_No_Application;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_LauncherCannotBeDetermined;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_LoadingText;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Page_Description;
 import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_UnsupportedOperatingSystem;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;

 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.layout.GridDataFactory;
 import org.eclipse.jface.layout.GridLayoutFactory;
 import org.eclipse.jface.layout.PixelConverter;
 import org.eclipse.jface.layout.TableColumnLayout;
 import org.eclipse.jface.preference.PreferencePage;
 import org.eclipse.jface.viewers.ArrayContentProvider;
 import org.eclipse.jface.viewers.CheckStateChangedEvent;
 import org.eclipse.jface.viewers.CheckboxTableViewer;
 import org.eclipse.jface.viewers.ColumnWeightData;
 import org.eclipse.jface.viewers.ICheckStateListener;
 import org.eclipse.jface.viewers.ISelectionChangedListener;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.jface.viewers.ITableLabelProvider;
 import org.eclipse.jface.viewers.LabelProvider;
 import org.eclipse.jface.viewers.SelectionChangedEvent;
 import org.eclipse.jface.widgets.TableColumnFactory;
 import org.eclipse.jface.widgets.WidgetFactory;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swt.widgets.Table;
 import org.eclipse.swt.widgets.TableColumn;
 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.internal.IWorkbenchHelpContextIds;
 import org.eclipse.ui.internal.ide.IDEWorkbenchPlugin;
 import org.eclipse.ui.statushandlers.StatusManager;
 import org.eclipse.urischeme.IOperatingSystemRegistration;
 import org.eclipse.urischeme.IScheme;
 import org.eclipse.urischeme.ISchemeInformation;
 import org.eclipse.urischeme.IUriSchemeExtensionReader;

 /**
  * This page contributes to URL handler for URISchemes in preference page of
  * General section
  *
  */
 public class UriSchemeHandlerPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {

 	Text handlerLocation;
 	CheckboxTableViewer tableViewer;
 	private String currentLocation = null;
 	IStatusManagerWrapper statusManagerWrapper = new IStatusManagerWrapper() {
 	};
 	IMessageDialogWrapper messageDialogWrapper = new IMessageDialogWrapper() {
 	};

 	OsRegistrationReadingJob osRegistrationReadingJob = new OsRegistrationReadingJob();

 	IOperatingSystemRegistration operatingSystemRegistration = null;
 	IUriSchemeExtensionReader extensionReader = null;
 	private Composite handlerComposite;
 	private volatile boolean isLoading = false;

 	@SuppressWarnings("javadoc")
 	public UriSchemeHandlerPreferencePage() {
 		super.setDescription(UrlHandlerPreferencePage_Page_Description);
 	}

 	@Override
 	public void init(IWorkbench workbench) {
 		if (operatingSystemRegistration == null) {
 			operatingSystemRegistration = IOperatingSystemRegistration.getInstance();
 		}
 		if (extensionReader == null) {
 			extensionReader = IUriSchemeExtensionReader.newInstance();
 		}
 		if (operatingSystemRegistration != null) {
 			currentLocation = operatingSystemRegistration.getEclipseLauncher();
 		}
 	}

 	@Override
 	protected Control createContents(Composite parent) {
 		if (PlatformUI.isWorkbenchRunning()) {
 			// enabled plain JUnit tests
 			PlatformUI.getWorkbench().getHelpSystem().setHelp(parent,
 					IWorkbenchHelpContextIds.LINK_HANDLERS_PREFERENCE_PAGE);
 		}
 		noDefaultAndApplyButton();
 		addFiller(parent);
 		createTableViewerForSchemes(parent);
 		createHandlerLocationControls(parent);

 		if (operatingSystemRegistration == null) {
 			setErrorMessage(NLS.bind(UrlHandlerPreferencePage_UnsupportedOperatingSystem,
 					Platform.isRunning() ? Platform.getOS() : null)); // running check for plain JUnit tests
 			setDataOnTableViewer(Collections.emptyList());

 		} else if (currentLocation == null) {
 			setErrorMessage(UrlHandlerPreferencePage_LauncherCannotBeDetermined);
 			setDataOnTableViewer(Collections.emptyList());

 		} else {
 			setDataOnTableViewer(getLoadingSchemeInformationList());
 			startRegistrationReadingJob();
 		}
 		tableViewer.getControl().setEnabled(false);

 		return parent;
 	}

 	private void startRegistrationReadingJob() {
 		isLoading = true;
 		osRegistrationReadingJob.setSystem(true);
 		osRegistrationReadingJob.schedule();
 	}

 	private void addFiller(Composite composite) {
 		PixelConverter pixelConverter = new PixelConverter(composite);
 		GridData gd = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
 		gd.horizontalSpan = 2;
 		gd.heightHint = pixelConverter.convertHeightInCharsToPixels(1) / 2;

 		WidgetFactory.label(SWT.LEFT).layoutData(gd).create(composite);
 	}

 	private void createTableViewerForSchemes(Composite parent) {
 		GridDataFactory gridDataFactory = GridDataFactory.fillDefaults().grab(true, true);
 		gridDataFactory.span(2, 1).indent(0, SWT.DEFAULT);

 		TableColumnLayout tableColumnLayout = new TableColumnLayout();

 		Composite tableComposite = WidgetFactory.composite(SWT.NONE).layoutData(gridDataFactory.create())
 				.layout(tableColumnLayout).create(parent);

 		Table schemeTable = WidgetFactory
 				.table(SWT.H_SCROLL | SWT.V_SCROLL | SWT.SINGLE | SWT.BORDER | SWT.FULL_SELECTION | SWT.CHECK)
 				.headerVisible(true).linesVisible(true).font(parent.getFont()).create(tableComposite);

 		TableColumnFactory columnFactory = WidgetFactory.tableColumn(SWT.NONE);

 		TableColumn nameColumn = columnFactory.text(UrlHandlerPreferencePage_ColumnName_SchemeName).create(schemeTable);
 		TableColumn descriptionColumn = columnFactory.text(UrlHandlerPreferencePage_ColumnName_SchemeDescription)
 				.create(schemeTable);
 		TableColumn appColumn = columnFactory.text(UrlHandlerPreferencePage_ColumnName_Handler).create(schemeTable);

 		tableColumnLayout.setColumnData(nameColumn, new ColumnWeightData(20));
 		tableColumnLayout.setColumnData(descriptionColumn, new ColumnWeightData(60));
 		tableColumnLayout.setColumnData(appColumn, new ColumnWeightData(20));

 		tableViewer = new CheckboxTableViewer(schemeTable);
 		tableViewer.setContentProvider(ArrayContentProvider.getInstance());
 		tableViewer.setLabelProvider(new ItemLabelProvider());

 		TableSchemeSelectionListener listener = new TableSchemeSelectionListener();
 		tableViewer.addSelectionChangedListener(listener);
 		tableViewer.addCheckStateListener(listener);
 	}

 	private void setDataOnTableViewer(Collection<UiSchemeInformation> schemeInformationList) {
 		// Gets the schemes from extension points for URI schemes
 		tableViewer.setInput(schemeInformationList);

 		for (UiSchemeInformation schemeInformation : schemeInformationList) {
 			tableViewer.setChecked(schemeInformation, schemeInformation.checked);
 		}
 	}

 	private void createHandlerLocationControls(Composite parent) {
 		handlerComposite = new Composite(parent, SWT.NONE);
 		GridLayoutFactory.fillDefaults().numColumns(2).applyTo(handlerComposite);
 		GridDataFactory.fillDefaults().grab(true, false).applyTo(handlerComposite);

 		WidgetFactory.label(SWT.NONE).text(UrlHandlerPreferencePage_Handler_Label).create(handlerComposite);

 		handlerLocation = WidgetFactory.text(SWT.READ_ONLY | SWT.BORDER)
 				.layoutData(new GridData(SWT.FILL, SWT.CENTER, true, false)).create(handlerComposite);

 		handlerComposite.setVisible(false); // set visible on table selection
 	}

 	private Collection<UiSchemeInformation> getLoadingSchemeInformationList() {
 		Collection<UiSchemeInformation> returnList = new ArrayList<>();
 		Collection<IScheme> schemes = extensionReader.getSchemes();
 		for (IScheme scheme : schemes) {
 			returnList.add(new LoadingSchemeInformation(scheme));
 		}
 		return returnList;
 	}

 	@SuppressWarnings("unchecked")
 	@Override
 	public boolean performOk() {
 		if (operatingSystemRegistration == null || currentLocation == null || isLoading) {
 			return true;
 		}

 		List<IScheme> toAdd = new ArrayList<>();
 		List<IScheme> toRemove = new ArrayList<>();
 		for (UiSchemeInformation info : (Collection<UiSchemeInformation>) tableViewer.getInput()) {
 			if (info.checked && !info.information.isHandled()) {
 				toAdd.add(info.information);
 			}
 			if (!info.checked && info.information.isHandled()) {
 				toRemove.add(info.information);
 			}
 		}

 		try {
 			operatingSystemRegistration.handleSchemes(toAdd, toRemove);
 		} catch (Exception e) {
 			IStatus status = new Status(IStatus.ERROR, IDEWorkbenchPlugin.IDE_WORKBENCH, 1,
 					UrlHandlerPreferencePage_Error_Writing_Scheme, e);
 			statusManagerWrapper.handle(status, StatusManager.BLOCK | StatusManager.LOG);
 		}
 		return true;
 	}

 	private class TableSchemeSelectionListener implements ICheckStateListener, ISelectionChangedListener {
 		@Override
 		public void selectionChanged(SelectionChangedEvent event) {
 			handleSelection();

 		}

 		@Override
 		public void checkStateChanged(CheckStateChangedEvent event) {
 			handleCheckbox(event);

 		}

 		private void handleSelection() {
 			IStructuredSelection selection = tableViewer.getStructuredSelection();
 			Object firstElement = selection != null ? selection.getFirstElement() : null;
 			if (firstElement instanceof UiSchemeInformation) {
 				setSchemeDetails((UiSchemeInformation) firstElement);
 				handlerComposite.setVisible(true);
 			}
 		}

 		private void setSchemeDetails(UiSchemeInformation schemeInfo) {
 			if (schemeInfo.checked) {
 				handlerLocation.setText(currentLocation);

 			} else if (schemeInfo.information.schemeIsHandledByOther()) {
 				handlerLocation.setText(schemeInfo.information.getHandlerInstanceLocation());
 			} else {
 				// checkbox not checked and:
 				// - no other handler handles it
 				// - or this eclipse handled it before (checkbox was unchecked but not yet
 				// applied)
 				handlerLocation.setText(UrlHandlerPreferencePage_Handler_Text_No_Application);
 			}
 		}

 		private void handleCheckbox(CheckStateChangedEvent event) {
 			UiSchemeInformation schemeInformation = (UiSchemeInformation) event.getElement();
 			if (event.getChecked() && schemeInformation.information.schemeIsHandledByOther()) {
 				if (operatingSystemRegistration.canOverwriteOtherApplicationsRegistration()) {
 					boolean answer = messageDialogWrapper.openQuestion(getShell(),
 							UriHandlerPreferencePage_Warning_OtherApp_Confirmation,
 							NLS.bind(UriHandlerPreferencePage_Warning_OtherApp_Confirmation_Description,
 									schemeInformation.information.getHandlerInstanceLocation(),
 									schemeInformation.information.getName()));
 					if (!answer) {
 						schemeInformation.checked = false;
 						tableViewer.setChecked(schemeInformation, schemeInformation.checked);
 						return;
 					}
 				} else {
 					schemeInformation.checked = false;
 					tableViewer.setChecked(schemeInformation, schemeInformation.checked);

 					messageDialogWrapper.openWarning(getShell(), UriHandlerPreferencePage_Warning_OtherApp,
 							NLS.bind(UriHandlerPreferencePage_Warning_OtherApp_Description,
 									schemeInformation.information.getHandlerInstanceLocation(),
 									schemeInformation.information.getName()));

 					return;
 				}

 			}
 			schemeInformation.checked = event.getChecked();
 			setSchemeDetails(schemeInformation);
 			tableViewer.update(schemeInformation, null);
 		}
 	}

 	private final class ItemLabelProvider extends LabelProvider implements ITableLabelProvider {

 		@Override
 		public Image getColumnImage(Object element, int columnIndex) {
 			return null;
 		}

 		@Override
 		public String getColumnText(Object element, int columnIndex) {
 			if (element instanceof UiSchemeInformation) {
 				UiSchemeInformation schemeInfo = (UiSchemeInformation) element;
 				switch (columnIndex) {
 				case 0:
 					return schemeInfo.getName();

 				case 1:
 					return schemeInfo.getDescription();
 				case 2:
 					String text = ""; //$NON-NLS-1$
 					if (UrlHandlerPreferencePage_LoadingText.equals(schemeInfo.getHandlerInstanceLocation()))
 						text = schemeInfo.getHandlerInstanceLocation();
 					else if (schemeInfo.isChecked()) {
 						text = UrlHandlerPreferencePage_Column_Handler_Text_Current_Application;
 					} else if (schemeInfo.information.schemeIsHandledByOther()) {
 						text = UrlHandlerPreferencePage_Column_Handler_Text_Other_Application;
 					}
 					return text;
 				default:
 					throw new IllegalArgumentException("Unknown column"); //$NON-NLS-1$
 				}
 			}
 			return null; // cannot happen
 		}

 		@Override
 		public boolean isLabelProperty(Object element, String property) {
 			return false;
 		}
 	}

 	static class UiSchemeInformation {
 		private boolean checked;
 		private ISchemeInformation information;

 		public UiSchemeInformation(boolean checked, ISchemeInformation information) {
 			this.checked = checked;
 			this.information = information;
 		}

 		public String getHandlerInstanceLocation() {
 			return information.getHandlerInstanceLocation();
 		}

 		public String getName() {
 			return information.getName();
 		}

 		public String getDescription() {
 			return information.getDescription();
 		}

 		public boolean isChecked() {
 			return checked;
 		}
 	}

 	static final class LoadingSchemeInformation extends UiSchemeInformation {

 		private IScheme scheme;

 		public LoadingSchemeInformation(IScheme scheme) {
 			super(false, null);
 			this.scheme = scheme;
 		}

 		@Override
 		public String getName() {
 			return scheme.getName();
 		}

 		@Override
 		public String getDescription() {
 			return scheme.getDescription();
 		}

 		@Override
 		public String getHandlerInstanceLocation() {
 			return UrlHandlerPreferencePage_LoadingText;
 		}

 		@Override
 		public boolean isChecked() {
 			return false;
 		}

 	}

 	interface IStatusManagerWrapper {
 		default void handle(IStatus status, int style) {
 			StatusManager.getManager().handle(status, style);
 		}
 	}

 	interface IMessageDialogWrapper {
 		default void openWarning(Shell shell, String title, String message) {
 			MessageDialog.openWarning(shell, title, message);
 		}

 		default boolean openQuestion(Shell parent, String title, String message) {
 			MessageDialog dlg = new MessageDialog(parent, title, null, message, MessageDialog.CONFIRM, 0,
 					UriHandlerPreferencePage_Confirm_Handle, IDialogConstants.CANCEL_LABEL);
 			dlg.open();
 			return dlg.getReturnCode() == IDialogConstants.OK_ID;
 		}
 	}

 	class OsRegistrationReadingJob extends Job {
 		private OsRegistrationReadingJob() {
 			super("Retrieving Link Handlers registration status from Operating System"); //$NON-NLS-1$
 		}

 		@Override
 		protected IStatus run(IProgressMonitor monitor) {
 			try {
 				Collection<UiSchemeInformation> schemeInformationList = retrieveSchemeInformationList();
 				if (!schemeInformationList.isEmpty()) {
 					Display.getDefault().asyncExec(() -> {
 						if (!UriSchemeHandlerPreferencePage.this.tableViewer.getControl().isDisposed()) {
 							setDataOnTableViewer(schemeInformationList);
 							UriSchemeHandlerPreferencePage.this.tableViewer.getControl().setEnabled(true);
 						}
 					});
 				}
 			} finally {
 				UriSchemeHandlerPreferencePage.this.isLoading = false;
 			}
 			return Status.OK_STATUS;
 		}

 		/**
 		 * Schemes which are part of extension points for URI Schemes and are registered
 		 * to operating system are consolidated here
 		 *
 		 * @return the supported and registered URI schemes of this instance of eclipse
 		 * @throws Exception
 		 */
 		private Collection<UiSchemeInformation> retrieveSchemeInformationList() {
 			Collection<UiSchemeInformation> returnList = new ArrayList<>();
 			Collection<IScheme> schemes = extensionReader.getSchemes();
 			try {
 				for (ISchemeInformation info : operatingSystemRegistration.getSchemesInformation(schemes)) {
 					returnList.add(new UiSchemeInformation(info.isHandled(), info));
 				}
 			} catch (Exception e) {
 				IStatus status = new Status(IStatus.ERROR, IDEWorkbenchPlugin.IDE_WORKBENCH, 1,
 						UrlHandlerPreferencePage_Error_Reading_Scheme, e);
 				statusManagerWrapper.handle(status, StatusManager.BLOCK | StatusManager.LOG);
 			}
 			return returnList;
 		}
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2018, 2021 SAP SE 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
	*
	* Contributors:
	* SAP SE - initial API and implementation
	*******************************************************************************/
	package org.eclipse.ui.internal.ide.application.dialogs;

	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Confirm_Handle;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp_Confirmation;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp_Confirmation_Description;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UriHandlerPreferencePage_Warning_OtherApp_Description;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_ColumnName_Handler;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_ColumnName_SchemeDescription;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_ColumnName_SchemeName;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Column_Handler_Text_Current_Application;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Column_Handler_Text_Other_Application;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Error_Reading_Scheme;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Error_Writing_Scheme;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Handler_Label;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Handler_Text_No_Application;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_LauncherCannotBeDetermined;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_LoadingText;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_Page_Description;
	import static org.eclipse.ui.internal.ide.IDEWorkbenchMessages.UrlHandlerPreferencePage_UnsupportedOperatingSystem;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.List;

	import org.eclipse.core.runtime.IProgressMonitor;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Platform;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.core.runtime.jobs.Job;
	import org.eclipse.jface.dialogs.IDialogConstants;
	import org.eclipse.jface.dialogs.MessageDialog;
	import org.eclipse.jface.layout.GridDataFactory;
	import org.eclipse.jface.layout.GridLayoutFactory;
	import org.eclipse.jface.layout.PixelConverter;
	import org.eclipse.jface.layout.TableColumnLayout;
	import org.eclipse.jface.preference.PreferencePage;
	import org.eclipse.jface.viewers.ArrayContentProvider;
	import org.eclipse.jface.viewers.CheckStateChangedEvent;
	import org.eclipse.jface.viewers.CheckboxTableViewer;
	import org.eclipse.jface.viewers.ColumnWeightData;
	import org.eclipse.jface.viewers.ICheckStateListener;
	import org.eclipse.jface.viewers.ISelectionChangedListener;
	import org.eclipse.jface.viewers.IStructuredSelection;
	import org.eclipse.jface.viewers.ITableLabelProvider;
	import org.eclipse.jface.viewers.LabelProvider;
	import org.eclipse.jface.viewers.SelectionChangedEvent;
	import org.eclipse.jface.widgets.TableColumnFactory;
	import org.eclipse.jface.widgets.WidgetFactory;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.graphics.Image;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Shell;
	import org.eclipse.swt.widgets.Table;
	import org.eclipse.swt.widgets.TableColumn;
	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.internal.IWorkbenchHelpContextIds;
	import org.eclipse.ui.internal.ide.IDEWorkbenchPlugin;
	import org.eclipse.ui.statushandlers.StatusManager;
	import org.eclipse.urischeme.IOperatingSystemRegistration;
	import org.eclipse.urischeme.IScheme;
	import org.eclipse.urischeme.ISchemeInformation;
	import org.eclipse.urischeme.IUriSchemeExtensionReader;

	/**
	* This page contributes to URL handler for URISchemes in preference page of
	* General section
	*
	*/
	public class UriSchemeHandlerPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {

	Text handlerLocation;
	CheckboxTableViewer tableViewer;
	private String currentLocation = null;
	IStatusManagerWrapper statusManagerWrapper = new IStatusManagerWrapper() {
	};
	IMessageDialogWrapper messageDialogWrapper = new IMessageDialogWrapper() {
	};

	OsRegistrationReadingJob osRegistrationReadingJob = new OsRegistrationReadingJob();

	IOperatingSystemRegistration operatingSystemRegistration = null;
	IUriSchemeExtensionReader extensionReader = null;
	private Composite handlerComposite;
	private volatile boolean isLoading = false;

	@SuppressWarnings("javadoc")
	public UriSchemeHandlerPreferencePage() {
	super.setDescription(UrlHandlerPreferencePage_Page_Description);
	}

	@Override
	public void init(IWorkbench workbench) {
	if (operatingSystemRegistration == null) {
	operatingSystemRegistration = IOperatingSystemRegistration.getInstance();
	}
	if (extensionReader == null) {
	extensionReader = IUriSchemeExtensionReader.newInstance();
	}
	if (operatingSystemRegistration != null) {
	currentLocation = operatingSystemRegistration.getEclipseLauncher();
	}
	}

	@Override
	protected Control createContents(Composite parent) {
	if (PlatformUI.isWorkbenchRunning()) {
	// enabled plain JUnit tests
	PlatformUI.getWorkbench().getHelpSystem().setHelp(parent,
	IWorkbenchHelpContextIds.LINK_HANDLERS_PREFERENCE_PAGE);
	}
	noDefaultAndApplyButton();
	addFiller(parent);
	createTableViewerForSchemes(parent);
	createHandlerLocationControls(parent);

	if (operatingSystemRegistration == null) {
	setErrorMessage(NLS.bind(UrlHandlerPreferencePage_UnsupportedOperatingSystem,
	Platform.isRunning() ? Platform.getOS() : null)); // running check for plain JUnit tests
	setDataOnTableViewer(Collections.emptyList());

	} else if (currentLocation == null) {
	setErrorMessage(UrlHandlerPreferencePage_LauncherCannotBeDetermined);
	setDataOnTableViewer(Collections.emptyList());

	} else {
	setDataOnTableViewer(getLoadingSchemeInformationList());
	startRegistrationReadingJob();
	}
	tableViewer.getControl().setEnabled(false);

	return parent;
	}

	private void startRegistrationReadingJob() {
	isLoading = true;
	osRegistrationReadingJob.setSystem(true);
	osRegistrationReadingJob.schedule();
	}

	private void addFiller(Composite composite) {
	PixelConverter pixelConverter = new PixelConverter(composite);
	GridData gd = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
	gd.horizontalSpan = 2;
	gd.heightHint = pixelConverter.convertHeightInCharsToPixels(1) / 2;

	WidgetFactory.label(SWT.LEFT).layoutData(gd).create(composite);
	}

	private void createTableViewerForSchemes(Composite parent) {
	GridDataFactory gridDataFactory = GridDataFactory.fillDefaults().grab(true, true);
	gridDataFactory.span(2, 1).indent(0, SWT.DEFAULT);

	TableColumnLayout tableColumnLayout = new TableColumnLayout();

	Composite tableComposite = WidgetFactory.composite(SWT.NONE).layoutData(gridDataFactory.create())
	.layout(tableColumnLayout).create(parent);

	Table schemeTable = WidgetFactory
	.table(SWT.H_SCROLL \| SWT.V_SCROLL \| SWT.SINGLE \| SWT.BORDER \| SWT.FULL_SELECTION \| SWT.CHECK)
	.headerVisible(true).linesVisible(true).font(parent.getFont()).create(tableComposite);

	TableColumnFactory columnFactory = WidgetFactory.tableColumn(SWT.NONE);

	TableColumn nameColumn = columnFactory.text(UrlHandlerPreferencePage_ColumnName_SchemeName).create(schemeTable);
	TableColumn descriptionColumn = columnFactory.text(UrlHandlerPreferencePage_ColumnName_SchemeDescription)
	.create(schemeTable);
	TableColumn appColumn = columnFactory.text(UrlHandlerPreferencePage_ColumnName_Handler).create(schemeTable);

	tableColumnLayout.setColumnData(nameColumn, new ColumnWeightData(20));
	tableColumnLayout.setColumnData(descriptionColumn, new ColumnWeightData(60));
	tableColumnLayout.setColumnData(appColumn, new ColumnWeightData(20));

	tableViewer = new CheckboxTableViewer(schemeTable);
	tableViewer.setContentProvider(ArrayContentProvider.getInstance());
	tableViewer.setLabelProvider(new ItemLabelProvider());

	TableSchemeSelectionListener listener = new TableSchemeSelectionListener();
	tableViewer.addSelectionChangedListener(listener);
	tableViewer.addCheckStateListener(listener);
	}

	private void setDataOnTableViewer(Collection<UiSchemeInformation> schemeInformationList) {
	// Gets the schemes from extension points for URI schemes
	tableViewer.setInput(schemeInformationList);

	for (UiSchemeInformation schemeInformation : schemeInformationList) {
	tableViewer.setChecked(schemeInformation, schemeInformation.checked);
	}
	}

	private void createHandlerLocationControls(Composite parent) {
	handlerComposite = new Composite(parent, SWT.NONE);
	GridLayoutFactory.fillDefaults().numColumns(2).applyTo(handlerComposite);
	GridDataFactory.fillDefaults().grab(true, false).applyTo(handlerComposite);

	WidgetFactory.label(SWT.NONE).text(UrlHandlerPreferencePage_Handler_Label).create(handlerComposite);

	handlerLocation = WidgetFactory.text(SWT.READ_ONLY \| SWT.BORDER)
	.layoutData(new GridData(SWT.FILL, SWT.CENTER, true, false)).create(handlerComposite);

	handlerComposite.setVisible(false); // set visible on table selection
	}

	private Collection<UiSchemeInformation> getLoadingSchemeInformationList() {
	Collection<UiSchemeInformation> returnList = new ArrayList<>();
	Collection<IScheme> schemes = extensionReader.getSchemes();
	for (IScheme scheme : schemes) {
	returnList.add(new LoadingSchemeInformation(scheme));
	}
	return returnList;
	}

	@SuppressWarnings("unchecked")
	@Override
	public boolean performOk() {
	if (operatingSystemRegistration == null \|\| currentLocation == null \|\| isLoading) {
	return true;
	}

	List<IScheme> toAdd = new ArrayList<>();
	List<IScheme> toRemove = new ArrayList<>();
	for (UiSchemeInformation info : (Collection<UiSchemeInformation>) tableViewer.getInput()) {
	if (info.checked && !info.information.isHandled()) {
	toAdd.add(info.information);
	}
	if (!info.checked && info.information.isHandled()) {
	toRemove.add(info.information);
	}
	}

	try {
	operatingSystemRegistration.handleSchemes(toAdd, toRemove);
	} catch (Exception e) {
	IStatus status = new Status(IStatus.ERROR, IDEWorkbenchPlugin.IDE_WORKBENCH, 1,
	UrlHandlerPreferencePage_Error_Writing_Scheme, e);
	statusManagerWrapper.handle(status, StatusManager.BLOCK \| StatusManager.LOG);
	}
	return true;
	}

	private class TableSchemeSelectionListener implements ICheckStateListener, ISelectionChangedListener {
	@Override
	public void selectionChanged(SelectionChangedEvent event) {
	handleSelection();

	}

	@Override
	public void checkStateChanged(CheckStateChangedEvent event) {
	handleCheckbox(event);

	}

	private void handleSelection() {
	IStructuredSelection selection = tableViewer.getStructuredSelection();
	Object firstElement = selection != null ? selection.getFirstElement() : null;
	if (firstElement instanceof UiSchemeInformation) {
	setSchemeDetails((UiSchemeInformation) firstElement);
	handlerComposite.setVisible(true);
	}
	}

	private void setSchemeDetails(UiSchemeInformation schemeInfo) {
	if (schemeInfo.checked) {
	handlerLocation.setText(currentLocation);

	} else if (schemeInfo.information.schemeIsHandledByOther()) {
	handlerLocation.setText(schemeInfo.information.getHandlerInstanceLocation());
	} else {
	// checkbox not checked and:
	// - no other handler handles it
	// - or this eclipse handled it before (checkbox was unchecked but not yet
	// applied)
	handlerLocation.setText(UrlHandlerPreferencePage_Handler_Text_No_Application);
	}
	}

	private void handleCheckbox(CheckStateChangedEvent event) {
	UiSchemeInformation schemeInformation = (UiSchemeInformation) event.getElement();
	if (event.getChecked() && schemeInformation.information.schemeIsHandledByOther()) {
	if (operatingSystemRegistration.canOverwriteOtherApplicationsRegistration()) {
	boolean answer = messageDialogWrapper.openQuestion(getShell(),
	UriHandlerPreferencePage_Warning_OtherApp_Confirmation,
	NLS.bind(UriHandlerPreferencePage_Warning_OtherApp_Confirmation_Description,
	schemeInformation.information.getHandlerInstanceLocation(),
	schemeInformation.information.getName()));
	if (!answer) {
	schemeInformation.checked = false;
	tableViewer.setChecked(schemeInformation, schemeInformation.checked);
	return;
	}
	} else {
	schemeInformation.checked = false;
	tableViewer.setChecked(schemeInformation, schemeInformation.checked);

	messageDialogWrapper.openWarning(getShell(), UriHandlerPreferencePage_Warning_OtherApp,
	NLS.bind(UriHandlerPreferencePage_Warning_OtherApp_Description,
	schemeInformation.information.getHandlerInstanceLocation(),
	schemeInformation.information.getName()));

	return;
	}

	}
	schemeInformation.checked = event.getChecked();
	setSchemeDetails(schemeInformation);
	tableViewer.update(schemeInformation, null);
	}
	}

	private final class ItemLabelProvider extends LabelProvider implements ITableLabelProvider {

	@Override
	public Image getColumnImage(Object element, int columnIndex) {
	return null;
	}

	@Override
	public String getColumnText(Object element, int columnIndex) {
	if (element instanceof UiSchemeInformation) {
	UiSchemeInformation schemeInfo = (UiSchemeInformation) element;
	switch (columnIndex) {
	case 0:
	return schemeInfo.getName();

	case 1:
	return schemeInfo.getDescription();
	case 2:
	String text = ""; //$NON-NLS-1$
	if (UrlHandlerPreferencePage_LoadingText.equals(schemeInfo.getHandlerInstanceLocation()))
	text = schemeInfo.getHandlerInstanceLocation();
	else if (schemeInfo.isChecked()) {
	text = UrlHandlerPreferencePage_Column_Handler_Text_Current_Application;
	} else if (schemeInfo.information.schemeIsHandledByOther()) {
	text = UrlHandlerPreferencePage_Column_Handler_Text_Other_Application;
	}
	return text;
	default:
	throw new IllegalArgumentException("Unknown column"); //$NON-NLS-1$
	}
	}
	return null; // cannot happen
	}

	@Override
	public boolean isLabelProperty(Object element, String property) {
	return false;
	}
	}

	static class UiSchemeInformation {
	private boolean checked;
	private ISchemeInformation information;

	public UiSchemeInformation(boolean checked, ISchemeInformation information) {
	this.checked = checked;
	this.information = information;
	}

	public String getHandlerInstanceLocation() {
	return information.getHandlerInstanceLocation();
	}

	public String getName() {
	return information.getName();
	}

	public String getDescription() {
	return information.getDescription();
	}

	public boolean isChecked() {
	return checked;
	}
	}

	static final class LoadingSchemeInformation extends UiSchemeInformation {

	private IScheme scheme;

	public LoadingSchemeInformation(IScheme scheme) {
	super(false, null);
	this.scheme = scheme;
	}

	@Override
	public String getName() {
	return scheme.getName();
	}

	@Override
	public String getDescription() {
	return scheme.getDescription();
	}

	@Override
	public String getHandlerInstanceLocation() {
	return UrlHandlerPreferencePage_LoadingText;
	}

	@Override
	public boolean isChecked() {
	return false;
	}

	}

	interface IStatusManagerWrapper {
	default void handle(IStatus status, int style) {
	StatusManager.getManager().handle(status, style);
	}
	}

	interface IMessageDialogWrapper {
	default void openWarning(Shell shell, String title, String message) {
	MessageDialog.openWarning(shell, title, message);
	}

	default boolean openQuestion(Shell parent, String title, String message) {
	MessageDialog dlg = new MessageDialog(parent, title, null, message, MessageDialog.CONFIRM, 0,
	UriHandlerPreferencePage_Confirm_Handle, IDialogConstants.CANCEL_LABEL);
	dlg.open();
	return dlg.getReturnCode() == IDialogConstants.OK_ID;
	}
	}

	class OsRegistrationReadingJob extends Job {
	private OsRegistrationReadingJob() {
	super("Retrieving Link Handlers registration status from Operating System"); //$NON-NLS-1$
	}

	@Override
	protected IStatus run(IProgressMonitor monitor) {
	try {
	Collection<UiSchemeInformation> schemeInformationList = retrieveSchemeInformationList();
	if (!schemeInformationList.isEmpty()) {
	Display.getDefault().asyncExec(() -> {
	if (!UriSchemeHandlerPreferencePage.this.tableViewer.getControl().isDisposed()) {
	setDataOnTableViewer(schemeInformationList);
	UriSchemeHandlerPreferencePage.this.tableViewer.getControl().setEnabled(true);
	}
	});
	}
	} finally {
	UriSchemeHandlerPreferencePage.this.isLoading = false;
	}
	return Status.OK_STATUS;
	}

	/**
	* Schemes which are part of extension points for URI Schemes and are registered
	* to operating system are consolidated here
	*
	* @return the supported and registered URI schemes of this instance of eclipse
	* @throws Exception
	*/
	private Collection<UiSchemeInformation> retrieveSchemeInformationList() {
	Collection<UiSchemeInformation> returnList = new ArrayList<>();
	Collection<IScheme> schemes = extensionReader.getSchemes();
	try {
	for (ISchemeInformation info : operatingSystemRegistration.getSchemesInformation(schemes)) {
	returnList.add(new UiSchemeInformation(info.isHandled(), info));
	}
	} catch (Exception e) {
	IStatus status = new Status(IStatus.ERROR, IDEWorkbenchPlugin.IDE_WORKBENCH, 1,
	UrlHandlerPreferencePage_Error_Reading_Scheme, e);
	statusManagerWrapper.handle(status, StatusManager.BLOCK \| StatusManager.LOG);
	}
	return returnList;
	}
	}

	}